Science, Irving K. Barber Faculty of (Okanagan)
Biology, Department of (Okanagan)
DSpace
UBCO
Yasari, Esmaeil
Master of Science - MSc
University of British Columbia
Organic-based material, including vermicompost and seaweed extract, can promote sustainable viticulture by enhancing productivity and minimizing environmental impact. In Okanagan Valley vineyards, studies conducted between 2020 and 2021 evaluated the effects of vermicompost, vermicompost tea, and seaweed extract on grapevine growth and productivity. Vermicompost applied to 10-year-old Chardonnay on SO4 rootstock vines at Thomas Ranch Vineyards did not significantly affect most growth parameters or yield, except for pruning weight in 2020 and yield in 2021. Medium and high rates maintained comparable yields to grower practice controls. Vermicompost notably increased soil organic C and total N, with a recommended application rate of 4.44 Mg ha⁻¹ in 2020 and 3.98 Mg ha⁻¹ in 2021 for cost-effectiveness. Vermicompost tea was tested on 34-year-old self-rooted Chardonnay Musqué vines at Blasted Church Vineyards. Application had minimal impact on growth and yield. Higher concentration and more frequent application occasionally improved berry weight and total soluble solids (TSS), but overall effects were inconsistent, suggesting that vermicompost tea's benefits depend on precise dosage and timing. The effect size of seaweed extract on Chardonnay vines in British Columbia and Nova Scotia on growth, fruit quality, and soil nutrients were small. It enhanced cluster looseness, however, and at high rate, reduced clusters per vine and yield. Lower rates and less frequent applications were more beneficial, indicating that moderate use is optimal for grapevine growth and yield. Overall, the studies suggested that while organic-based products like vermicompost and seaweed extract can maintain or enhance soil productivity and grape yield, their efficacy depends on appropriate application rates and frequencies.
THE EFFECTS OF VERMICOMPOST, VERMICOMPOST TEA, AND SEAWEED EXTRACT ON GRAPEVINE AND SOIL PARAMETERS OF VINEYARDS IN BRITISH COLUMBIA AND NOVA SCOTIA, CANADA by Esmaeil Yasari Ph.D., University of Pune, India (2007) MSc., University of Jiroft, Iran (1999) A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE COLLEGE OF GRADUATE STUDIES (Biology) THE UNIVERSITY OF BRITISH COLUMBIA (Okanagan) December 2024 © Esmaeil Yasari, 2024 ii The following individuals certify that they have read, and recommend to the College of Graduate Studies for acceptance, a thesis entitled: The effects of vermicompost, vermicompost tea, and seaweed extract on grapevine and soil parameters of vineyards in British Columbia and Nova Scotia, Canada submitted by Esmaeil Yasari in partial fulfilment of the requirements of the degree of Master of Science. Dr. Melanie Jones, Irving K. Barber Faculty of Science Supervisor Dr. Mehdi Sharifi, Agriculture and Agri-Food Canada Co-Supervisor Dr. Louise Nelson, Irving K. Barber Faculty of Science Supervisory Committee Member Dr. Simone Castellarin, University of British Columbia (Vancouver) Supervisory Committee Member Dr. Sean Smukler, University of British Columbia (Vancouver) University Examiner iii Abstract Organic-based material, including vermicompost and seaweed extract, can promote sustainable viticulture by enhancing productivity and minimizing environmental impact. In Okanagan Valley vineyards, studies conducted between 2020 and 2021 evaluated the effects of vermicompost, vermicompost tea, and seaweed extract on grapevine growth and productivity. Vermicompost applied to 10-year-old Chardonnay on SO4 rootstock vines at Thomas Ranch Vineyards did not significantly affect most growth parameters or yield, except for pruning weight in 2020 and yield in 2021. Medium and high rates maintained comparable yields to grower practice controls. Vermicompost notably increased soil organic C and total N, with a recommended application rate of 4.44 Mg ha-1 in 2020 and 3.98 Mg ha-1 in 2021 for cost-effectiveness. Vermicompost tea was tested on 34-year-old self-rooted Chardonnay Musqué vines at Blasted Church Vineyards. Application had minimal impact on growth and yield. Higher concentration and more frequent application occasionally improved berry weight and total soluble solids (TSS), but overall effects were inconsistent, suggesting that vermicompost tea's benefits depend on precise dosage and timing. The effect size of seaweed extract on Chardonnay vines in British Columbia and Nova Scotia on growth, fruit quality, and soil nutrients were small. It enhanced cluster looseness, however, and at high rate, reduced clusters per vine and yield. Lower rates and less frequent applications were more beneficial, indicating that moderate use is optimal for grapevine growth and yield. Overall, the studies suggested that while organic-based products like vermicompost and seaweed extract can maintain or enhance soil productivity and grape yield, their efficacy depends on appropriate application rates and frequencies. iv Lay Summary The efficacy of organic-based material like vermicompost, vermicompost tea, and seaweed extract on vineyard and soil productivity in the Okanagan Valley, BC was investigated. In 2020, vermicompost positively impacted wine grape yield and in 2020 and 2021 vermicompost increased soil organic C and total N at medium and high rates. Application of vermicompost tea, however, produced minimal effects on grape traits and productivity. Seaweed extract experiments in both BC and Nova Scotia yielded small effect on wine grape growth and quality. These findings indicate that vermicompost can serve as a viable alternative to chemical fertilizers when applied at appropriate rates. v Preface This thesis is submitted in partial fulfillment of the requirements for the Master of Science degree in Biology at the University of British Columbia, Okanagan. The research presented here, entitled "The Effects of Vermicompost, Vermicompost Tea, and Seaweed Extract on Grapevine and Soil Parameters in Vineyards in British Columbia and Nova Scotia, Canada," was carried out under the supervision of Dr. Mehdi Sharifi and Dr. Melanie Jones, with the support of my committee members, Dr. Louise Nelson and Dr. Simone Castellarin. I played a central role in shaping this research, including refining the objectives, formulating hypotheses, and conducting an extensive literature review to establish the study’s context. The experimental design and encompassing treatment selection was developed by Dr. Mehdi Sharifi. Fieldwork, including treatment applications, soil and plant sampling, and associated measurements, was conducted by me, with assistance from technicians and students. In the laboratory, I performed analyses of soil and plant samples, including measurements of soil nitrogen, vine growth, fruit quality parameters, and yield. These tasks were carried out with support from lab technicians to ensure precision and adherence to standard protocols. I conducted statistical analyses using Mixed Effects Models, Factorial Analysis, and Repeated Measures ANOVAs, employing software tools such as Minitab and R. Additionally, I interpreted the data, created all figures and tables, and authored this thesis with guidance from my supervisors. While I received valuable feedback and guidance from my supervisors throughout the research process, I authored the Introduction, Materials and Methods, Results, and Discussion sections. No generative artificial intelligence was used for any aspects of this work. Further input from my supervisory committee members helped refine the thesis at key stages. This thesis is based on original research conducted during my graduate studies. While it contributes to ongoing investigations, none of the material presented here has been previously published. Completing this research has been a rewarding journey, and I am grateful for the support and encouragement of my family and mentors. vi Table of Contents Abstract………………………………………………………………………………………………………. iii Lay Summary………………………………………………………………………………………………… iv Preface………………………………………………………………………………………………………... v Table of Contents…………………………………………………………………………………………….. vi List of Tables………………………………………………………………………………………………… ix List of Figures………………………………………………………………………………………………... xii Acknowledgements…………………………………………………………………………………………... xiv Dedication……………………………………………………………………………………………………. xv Chapter 1. Introduction………………………………………………………………………………………. 1 1.1. Literature review………………………………………………………………………………………… 3 1.1.1. Vermicompost ……………………………………………………………………………………... 3 1.1.1.1. Effects of vermicompost on soil…………………………………………………………….. 3 1.1.1.2. Effects of vermicompost on plant growth, yield, and fruit quality …………………………. 5 1.1.2. Vermicompost Tea ………………………………………………………………………………… 6 1.1.2.1. Effects of vermicompost tea on plant growth and yield…………..…………………………. 6 1.1.2.2. Effects of vermicompost tea on fruit quality and yield………………………………………. 7 1.1.3. Seaweed extract…………………………………………………………………………………….. 8 1.1.3.1. Effects of seaweed extract on soil…………………………………………………………….. 9 1.1.3.2. Effects of seaweed extract on plant growth and yield………….…...………………………… 10 1.1.3.3. Effects of seaweed extract on fruit quality…………….……………………………………… 12 1.2. Research objectives and hypotheses…………………………………………………………………….. 12 Chapter 2. Vermicompost …………………………………………………………………………………… 14 2.1. Synopsis…………………………………………………………………………………………………. 14 2.2. Materials and Methods…………………………………………………………………………………... 15 2.2.1. Experimental site……………………….………………………………………………………….. 15 2.2.2. Experimental design and treatment application…………………………………………………..... 15 2.2.3. Sampling and analyses……………………………………………………………………………... 18 2.2.3.1. Soil sampling and analyses………………………………………………………………….. 18 2.2.3.2. Petiole sampling and analysis……………………………………………………………….. 19 2.2.3.3. Yield and grape cluster sampling and analysis……………………………………………… 19 2.2.3.4. Trunk cross-sectional area (TCSA)………………………………………………………….. 20 2.2.4. Statistical analysis………………………………………..………………………………………… 20 vii 2.3. Results…………………………………………………………………………………………………… 21 2.3.1. Effects of vermicompost on growth, nutrition, and yield…………………………………….…… 21 2.3.2. Effects of vermicompost on wine grapes fruit quality parameters……………………………….. 23 2.3.3. Effects of vermicompost on soil organic C and total N concentrations…………………………… 24 2.3.4. Effects of vermicompost on soil ammonium and nitrate concentrations………………………….. 26 2.4. Discussion……………………………………………………………………………………………….. 34 2.4.1. Effects of vermicompost on growth………………………………………………………………. 34 2.4.2. Effects of vermicompost on yield………………………………………………………………… 36 2.4.3. Effects of vermicompost on fruit quality……..…………………………………………………... 37 2.4.4. Effects of vermicompost on soil organic C concentration………………………………………... 38 2.4.5. Effects of vermicompost on soil ammonium, nitrate, and total N concentrations……………….. 39 Chapter 3. Vermicompost Tea……………………………………………………………………………….. 42 3.1. Synopsis…………………………………………………………………………………………………. 42 3.2. Materials and Methods………………………………………………………………………………….. 42 3.2.1. Experimental site ……………………...…………………………………….…………………….. 42 3.2.2. Experimental design and treatment application …………………………………………………... 42 3.2.3. Vermicompost tea aerobic preparation and application…………………………………………… 45 3.2.4. Samplings and Analyses…………………………………………………………………………... 46 3.2.5. Statistical analyses…………………………………………………………….…………………... 46 3.3. Results…………………………………………………………………………………………………… 47 3.3.1. Effects of vermicompost tea on wine grape growth, yield and fruit quality……………………… 47 3.4. Discussion……………………………………………………………………………………………….. 52 Chapter 4. Seaweed Extract………………………………………………………………………………….. 55 4.1. Synopsis…………………………………………………………………………………………………. 55 4.2. Materials and Methods…………………………………………………………………………………... 55 4.2.1. Experimental sites……………….………………………………………………………………... 55 4.2.2. Experimental design and treatment application…………….…………………………………….. 56 4.2.3. Sampling and Analyses………….……………………………………………………………….. 60 4.2.3.1. Soil sampling and analyses…..…………………………………………………………... 60 4.2.3.2. Petiole, yield and grape cluster sampling and analysis…………………………………... 60 4.2.3.3. Cluster looseness…………………………………………………………………………. 60 4.2.3.4. Pedicle and rachis length…………………………………………………………………. 60 4.2.3.5. Bud cold hardiness……………………………………………………………………….. 61 viii 4.2.4. Statistical analyses………………………………………………………………………………... 62 4.3. Results…………………………………………………………………………………………………… 63 4.3.1. Results of the British Columbia experiment………………………………………………………. 63 4.3.1.1. Effects of seaweed extract on growth and petiole nitrogen………………………………. 63 4.3.1.2. Effects of seaweed extract on wine grape fruit quality parameters………………………. 69 4.3.1.3. Effects of seaweed extract on bud cold hardiness of wine grapes………………………... 71 4.3.1.4. Effects of seaweed extract on soil ammonium and nitrate concentrations……………….. 75 4.3.1.5. Effects of seaweed extract on pedicle and rachis length…………………………………. 80 4.3.2. Results of Nova Scotia experiment………………………………………………………………... 83 4.3.2.1. Effects of seaweed extract on growth, petiole nitrogen and yield………………………… 83 4.3.2.2. Effects of seaweed extract on wine grapes fruit quality parameters……………………….. 86 4.4. Discussion……………………………………………………………………………………………….. 89 4.4.1. Effects of seaweed extract on wine grape growth and yield………...…………………………….. 89 4.4.2. Effects of seaweed extract on wine grape pedicle and rachis length and number………………… 91 4.4.3. Effect of seaweed extract on wine grape fruit quality parameters…………...……………………. 92 4.4.4. Effects of seaweed extract on wine grape bud cold hardiness…………………………………….. 93 4.4.5. Effects of seaweed extract on soil ammonium and nitrate concentrations………………………... 94 Chapter 5. Conclusion………………………………………………………………………………………... 96 5.1. Vermicompost…………………………………………………………………………………………… 96 5.2. Vermicompost tea……………………………………………………………………………………….. 98 5.3. Seaweed extract………………………………………………………………………………………….. 99 References……………………………………………………………………………………………………. 101 Error! Bookmark not defined. ix List of Tables Table 2.1. The nutrient concentrations of the vermicompost applied in 2021……………………………….. 18 Table 2.2. Residual effects of application of vermicompost in 2019 on growth, nutrition, and yield of Chardonnay wine grapes in 2020…………………………………………………………………………….. 21 Table 2.3. Effects of vermicompost on growth, nutrition, and yield of Chardonnay wine grapes in 2021….. 22 Table 2.4. Effects of application of vermicompost in 2019 on fruit quality parameters of Chardonnay wine grapes in 2020……………………………………………………………………………………………….. 23 Table 2.5. Effects of vermicompost on fruit quality parameters of Chardonnay wine grapes in 2021……… 24 Table 2.6. Effects of application of vermicompost on soil organic C (SOC) and N measured in summer 2020…………………………………………………………………………………………………………... 25 Table 2.7. Effects of application of vermicompost on soil organic C (SOC) and total N measured in summer 2021…………………………………………………………………………………………………. 26 Table 2.8. Effects of application of vermicompost on soil mineral N (mg kg-1) in July and October 2020…. 31 Table 2.9. Effects of vermicompost on soil mineral N (mg kg-1) in three sampling dates (May, July, and October 2021)………………………………...……………….……………………………………………… 33 Table 3.1. The characteristics of the vermicompost tea applied in the present study in 2021……………….. 46 Table 3.2. Effects of foliar application of vermicompost tea on growth and nutrition of Chardonnay wine grapes in 2021………………………...……………………………………..………………………………. 48 Table 3.3. Effects of foliar application of vermicompost tea on clusters, berry and yield of Chardonnay wine grapes in 2021……………………...……………………………………………………... 49 Table 3.4. Factorial analysis of the foliar application of vermicompost tea at two frequencies and two concentrations on growth and nutrition of Chardonnay wine grapes in 2021…….…….................................. 49 Table 3.5. Factorial analysis of the foliar application of vermicompost tea at two frequencies and two concentrations on clusters, berry and yield of Chardonnay wine grapes in 2021……………………………. 49 Table 3.6. Effects of foliar application of vermicompost tea on fruit quality parameters of Chardonnay wine grapes in 2021……………………………………...…………………………………………………... 50 Table 3.7. Factorial analysis of the application of vermicompost tea at two frequencies and two concentrations on fruit quality parameters of Chardonnay wine grapes in 2021…………………………….. 50 Table 4.1. The nutrient concentrations of the seaweed extract applied in the present study………………… 57 Table 4.2. Effects of seaweed extract on growth of Chardonnay wine grapes in the British Columbia experiment in 2020………….………………………………………………………………………………... 63 Table 4.3. Effects of seaweed extract on growth and nutrition of Chardonnay wine grapes in the British Columbia experiment in 2021………………………………………………………………………………... 64 x Table 4.4. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on Chardonnay wine grapes growth and nutrition in the British Columbia experiment in 2020………………………………………………………………………………........................................... 64 Table 4.5. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on Chardonnay wine grapes growth and nutrition in the British Columbia experiment in 2021……………………………………………………………………………….......................................... 65 Table 4.6. Effects of seaweed on clusters, berry and yield of Chardonnay wine grapes in the British Columbia experiment in 2020…………………..……………………………………………………………. 65 Table 4.7. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on Chardonnay wine grapes growth and yield in the British Columbia experiment in 2020……………….………………………………………………………………………………………….. 66 Table 4.8. Effects of seaweed extract on growth and yield of Chardonnay wine grapes in the British Columbia experiment in 2021………………………….………...………………………………………… 67 Table 4.9. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on Chardonnay wine grapes growth and yield in the British Columbia experiment in 2021…..………………………………………………………………………………………………………. 67 Table 4.10. Effects of seaweed extract on fruit quality parameters of Chardonnay wine grapes in the British Columbia experiment in 2020……………………………………………………………………… 69 Table 4.11. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on Chardonnay wine grapes fruit quality parameters in the British Columbia experiment in 2020……………………..……………………………………………………………………………………. 70 Table 4.12. Effects of seaweed extract on fruit quality parameters of Chardonnay wine grapes in the British Columbia experiment in 2021…………………………...…………………………………………. 70 Table 4.13. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on Chardonnay wine grapes fruit quality parameters in the British Columbia experiment in 2021………..…………………………………………………………………………………………………. 71 Table 4.14. Effects of seaweed extract on Chardonnay wine grapes bud cold hardiness at different samplings in the British Columbia experiment in 2020……………………...………………………………. 71 Table 4.15. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on Chardonnay wine grapes bud cold hardiness in the British Columbia experiment in 2020……………………..…............................................................................................................................. 72 Table 4.16. Effects of seaweed extract on Chardonnay wine grapes bud cold hardiness at different samplings in the British Columbia experiment in 2021……………………………………………………… 73 Table 4.17. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on Chardonnay wine grapes bud cold hardiness in the British Columbia experiment in 2021…………..……………............................................................................................................................. 74 Table 4.18. Effects of seaweed extract on soil ammonium and nitrate (mg kg-1) as affected by seaweed extract in the British Columbia experiment in 2020…………………………………………………………. 75 xi Table 4.19. Effects of seaweed extract on soil ammonium and nitrate (mg kg-1) in the British Columbia experiment in 2021…………………………………...………………………………………………………. 78 Table 4.20. Effects of seaweed extract on pedicle and rachis length of Chardonnay wine grapes in the British Columbia experiment in 2021………………………………………………………………………... 81 Table 4.21. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on pedicle and rachis length of Chardonnay wine grapes in the British Columbia experiment in 2021……………………………….………………………………………………………….. 81 Table 4.22. Effects of seaweed extract on growth and nutrition of Chardonnay wine grapes in the Nova Scotia experiment in 2020……………………………………………………………………………………. 83 Table 4.23. Effects of seaweed extract on growth and nutrition of Chardonnay wine grapes in the Nova Scotia experiment in 2021……………………………………………………………………………………. 84 Table 4.24. Effects of seaweed extract on yield parameters of Chardonnay wine grapes in the Nova Scotia experiment in 2020…………………………………...……………………………......................................... 84 Table 4.25. Effects of seaweed extract on Chardonnay wine grapes growth and yield in the Nova Scotia experiment in 2021…………………………………………………………………………………………… 85 Table 4.26. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on Chardonnay wine grapes growth and nutrition in the Nova Scotia experiment in 2020………………………………………………..……...………………………………………………….. 85 Table 4.27. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on Chardonnay wine grapes growth and nutrition in the Nova Scotia experiment in 2021………………………………………………………………………………....................................... 85 Table 4.28. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on Chardonnay wine grapes growth and nutrition in Nova Scotia experiment in 2020……... 86 Table 4.29. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on Chardonnay wine grapes growth and yield in the Nova Scotia experiment in 2021……... 86 Table 4.30. Effects of seaweed extract on fruit quality parameters of Chardonnay wine grapes in the Nova Scotia experiment in 2020…………………..……………………………………..…………………………. 87 Table 4.31. Effects of seaweed extract on fruit quality parameters of Chardonnay wine grapes in the Nova Scotia experiment in 2021………………………………….………………………………………………… 88 Table 4.32. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on Chardonnay wine grapes fruit quality parameters in the Nova Scotia experiment in 2020 88 Table 4.33. Factorial analysis of the foliar application of seaweed extract at two frequencies and two concentrations on Chardonnay wine grapes fruit quality parameter in the Nova Scotia experiment in 2021.. 88 xii List of Figures Figure 2.1. The layout of the plots in vermicompost experiment……………………………………………. 17 Figure 2.2. Soil ammonium concentration in two sampling dates (July and October) in 0-15 and 15-30 cm depth in 2020…………………………………………………………………………………………………. 27 Figure 2.3. Soil nitrate concentration in two sampling dates (July and October) in 0-15 and 15-30 cm depth in 2020……………….………………………………………………………………………………………. 28 Figure 2.4. Soil ammonium concentration in three sampling dates (May, July and October) in 0-15 and 15-30 cm depth in 2021………………………………..……………………………............................................ 29 Figure 2.5. Soil nitrate concentration of the soil in three sampling dates (May, July and October) in 0-15 and 15-30 cm depth in 2021…………………..……………………………………....................................... 30 Figure 3.1. The layout of the plots in vermicompost tea experiment………………...……………………… 44 Figure 3.2. Box plot showing the interacting effects of rate and frequency of vermicompost tea application on berry weight based on the factorial analysis with two frequencies and two rates………………………... 51 Figure 3.3. Box plot showing the interacting effects of rate and frequency of vermicompost tea application on Total Soluble Solid based on the factorial analysis with two frequencies and two rates…………………. 51 Figure 3.4. Box plot showing the interacting effects of rate and frequency of vermicompost tea application on Titratable Acidity based on the factorial analysis with two frequencies and two rates…………………... 52 Figure 4.1. The layout of the plots in Seaweed Extract experiment in BC…………………………………... 58 Figure 4.2. The layout of the plots in Seaweed Extract experiment in NS…………………………………... 59 Figure 4.3. Box plot showing the interacting effects of rate and frequency of seaweed extract application on the number of clusters per vine based on the factorial analysis of the application of seaweed extract in two levels of frequency and two levels of rate in 2021……………………………………………………… 68 Figure 4.4. Box plot showing the interacting effects of rate and frequency of seaweed extract application on yield based on the factorial analysis of the application of seaweed extract in two levels of frequency and two levels of rate in 2021……………………………………………………………………………….. 68 Figure 4.5. Wine grapes bud cold hardiness in four sampling dates (Nov 2020, Dec 2020, Feb 2021, and Mar 2021)……………………………………………………………………………………………………. 72 Figure 4.6. Wine grapes bud cold hardiness in seven sampling dates (Nov 4, 2021, Nov 25, 2021, Dec 13, 2021, Feb 10, 2022, Mar 3, 2022, Mar 17, 2022, and Apr 14, 2022)……………………………………….. 74 Figure 4.7. Soil ammonium concentration in two sampling dates (July and October) in 0-15 and 15-30 cm depth in 2020………………………………………………………………………………………………… 76 Figure 4.8. Soil nitrate concentration of the soi in two sampling dates (July and October) in 0-15 and 15-30 cm depth in 2020………………………………………………………………………………………….. 77 Figure 4.9. Soil ammonium concentration in three sampling dates (May, July and October) in 0-15 and 15-30 cm depth in 2021……………………………………………………………......................................... 79 Figure 4.10. Soil nitrate concentration of the soil in three sampling dates (May, July and October) in 0-15 and 15-30 cm depth in 2021…………………………..……………………………………………………… 80 xiii Figure 4.11. Box plot showing the interacting effects of rate and frequency of seaweed extract application on rachis total length based on the factorial analysis of the application of seaweed extract in two levels of frequency and two levels of rate, in 2021……………………………………………………………………. 82 xiv Acknowledgements This thesis forms a part of the Agriculture and Agri-Food Canada Project (Project P-60) and I would like to thank my supervisors Mehdi Sharifi and Melanie Jones for their irreplaceable guidance throughout all stages of my research. Additionally, I would like to thank Bill Rabie and all of the research scientists, technicians, assistants and students whose hard work was responsible for the data used herein. I also would like to thank Greensciences Technology Inc., Arterra Canada for providing the vermicompost used in the study. I am grateful to the Thomas Ranch Vineyards in Oliver, Blasted Church Vineyards in South of Penticton BC, and Ellslea Farms in NS for providing the experimental sites. Finally, special thanks to my wife, Niloufar, for her endless support and encouragement and my beloved sons, Bardia and Pouria for their support and patience. xv Dedication This thesis is dedicated to my wife, Niloufar, for her unwavering support, and to my sons, Bardia and Pouria, for making our life happier and more beautiful. 1 Chapter 1. Introduction Grapes are one of the largest fruit crops globally, with an annual worldwide production of 74.94 million tonnes, where 57 % of it is used in winemaking (Statistical Report on World Viticulture, 2022). In 2022 Canada imported 4.2 million hectoliters of wine. British Columbia is the second largest wine-producing province after Ontario, accounting for 33 percent of Canada's wine production (Lupescu, 2017). British Columbia is home to 1049 vineyards, covering 4486 ha (BC Government News, 2023), of which 3488 ha are located in the Okanagan Valley and the nearby Similkameen Valley (BC Wine Institute, 2023). The dominant soils in the Okanagan Valley are light-textured and stony with low soil organic matter content (< 1%) and cation exchange capacity (>10 meq 100 g), hence leading to low soil nutrient supply and water holding capacity (Wittenben, 1986). The area has semi-arid and arid conditions with very hot and dry summers; therefore, good water holding capacity is an important factor to provide moisture for plants during the growing season. To maintain high yield and productivity, growers need to apply considerable amounts of chemical fertilizers every year. Although the application of mineral nutrients can result in enhanced fruit yield and quality (Brunetto et al., 2015), long-term application of chemical fertilizers can lead to soil degradation, nutritional imbalance, and deterioration of the rhizosphere micro-ecological environment (Lin et al., 2019). Alternative management practices that enhance soil organic matter can greatly contribute to soil nutrient supply and holding capacity, soil biological activities, and water holding capacity. Organic fertilizers comprise various plant-derived materials that range from fresh or dried plant material to animal manures and litters to agricultural by-products (Das and Jana, 2003; Towett et al., 2020). Organic fertilization improves vegetative growth and nutritional status, and reduces the residuals of nitrate and nitrite in grape berries; therefore, continuous fertilization with organic fertilizer is promising in the long run for grapevine production (Kassem and Marzouk, 2002; Farag, 2006). Vermicompost is an organic fertilizer derived from the accelerated biological degradation of organic wastes by earthworms and microorganisms. As a soil organic amendment, it contains significantly higher nutrient concentrations than traditional compost; when mixed with the soil, vermicompost also has a larger microbial population size and activity (Tognetti et al., 2005). Application of vermicompost can improve soil water holding capacity and organic carbon (C) (Kumar et al., 2018), increase grape yield (Javed et al., 2017), and supply a balanced amount of 2 nutrients (Deepamala et al., 2017). It also enhances arbuscular mycorrhizal fungal colonization (Cavender et al., 2003) and improves the sorption and degradation rate of pesticides and herbicides (Fernández-Bayo et al., 2008). Vermicompost can suppress populations of parasitic nematodes and help to remediate high concentrations of heavy metals (Santana et al., 2015). Vermicompost tea is another organic fertilizer that can be considered an alternative to chemical fertilization to enhance plant growth. Application of an aqueous extract of vermicompost (i.e., vermicompost tea) to either the foliage or the soil has been shown to improve the yield and nutritional quality of many crops, including cereals (oats, barley, wheat, and corn), beets, carrots, potatoes, vegetables (cucumber, tomato), and perennial grasses (for hay or silage) (Gamaley et al., 2001; Pant et al., 2009). For example, the nutritional value of beets as animal feed increased by 20-40 % with the application of the vermicompost extract as compared to the control treatment. The soluble mineral nutrients, organic acids, and water-soluble plant-growth regulators extracted in the tea have positive effects on initial root development and plant growth with both foliar and soil application (Keeling et al., 2003; Edwards et al., 2006; Arancon et al., 2007). Living microorganisms present in vermicompost tea can also stimulate nutrient uptake and plant growth and induce disease resistance (Scheuerell and Mahaffee, 2004; Ingham, 2005). A third type of organic-based material is seaweed extract. Seaweed extract has been used in grapevine production to improve plant establishment, enhance rachis stretch, increase fruit set, and enhance yields (Wiens and Reynolds, 2008). Seaweed extracts can contribute to plant vigor and vitality due to several bioactive substances (Khan et al., 2007; Gupta and Abu-Ghannam, 2011). They can also improve nutrient uptake from soil (Turan and Köse, 2004). There are many advantages of using seaweed extracts to stimulate plant growth, including higher germination rates, root-system development, increased leaf area, and fruit quality (Rayorath et al., 2008a; Craigie, 2011). Furthermore, plants treated with seaweed extracts have a higher content of chlorophyll, carotenoids, protein, and amylases (Zhang and Schmidt, 2000) and acquire more resistance against pathogens (Jayaraj et al., 2008). Although there is an interest among grape growers in using each of these organic-based materials, there is a knowledge gap on the efficacy of these products on grapevine growth and productivity in the Okanagan Valley BC, Canada. To address these knowledge gaps, three studies were established in 2018 to examine the effects of vermicompost, vermicompost tea, and seaweed extract on plant and soil parameters in Okanagan Valley vineyards. My MSc project is 3 part of this larger 5-year study, and the data from the last two years of the project (2020 and 2021) are used in my thesis. My research aimed to evaluate the effects of soil application of vermicompost on soil nutrients and grapevine growth and productivity, foliar application of vermicompost tea on grapevine growth and productivity, and the combined foliar and soil application of seaweed extract on soil nutrients and grapevine growth and productivity. 1.1. Literature review 1.1.1. Vermicompost Vermicompost is the excreta of earth SOCs, which can improve soil organic C and nutrient status. Vermiculture is a process by which different types of biodegradable wastes such as farm, kitchen, market, and bio-wastes of agro-based industries, livestock wastes, etc., are converted while passing through the worm-gut to nutrient-rich vermicompost (Adhikary, 2012). Earthworms consume and fragment the organic wastes into finer particles by passing them through a grinding gizzard and derive their nourishment from microorganisms that grow upon them (Katheem et al., 2016). The process accelerates the rates of decomposition of the organic matter. It alters the physical and chemical properties of the material, leading to a humification effect in which unstable organic matter is fully oxidized and stabilized (Kiyasudeen et al., 2016). Unavailable forms of minerals like N, P, K, and Ca in organic materials are converted into plant-available forms by the earthworm gut, which secrets various enzymes like lipases, proteases, cellulases, amylases, and chitinases (Bhat et al., 2018). The effects of vermicompost depend greatly on the type and nature of feedstock used in the vermicomposting process. In the present study, we used a vermicompost formed from a wide range of urban and agricultural waste streams such as food, paper, garden debris, textiles, and equine or dairy residuals (greenscience.ca). 1.1.1.1. Effects of vermicompost on soil Vermicompost can enhance soil fertility physically, chemically, and biologically. Vermicompost enhances soil physical characteristics by improving air and water permeability. It enhances total soil porosity and aggregate stability through diminishing penetration resistance and bulk density (Aksakal et al., 2016). Vermicompost also improves soil chemical properties, 4 organic C and fertility conditions and increases the availability of nutrients for the plants (Piya et al., 2018). It can accelerate soil biological and enzymatic activity (Cavender et al., 2003; Romero et al., 2010; Hřebečková et al., 2019) and increase microbial population size and activity (Bürgmann et al., 2005; Manivannan et al., 2009). Vermicompost from different vegetative bases and agricultural sources has positive effects on soil organic C and fertility. For example, vermicompost from the wine and distillery industry containing spent grape marc changed soil properties and enhanced sorption capacity by two- to four-fold (Fernández-Bayo et al., 2009). Evidence from various studies suggests that the application of vermicompost is associated with an increase in soil C levels (Fernández-Bayo et al., 2009; Deepamala et al., 2017; Sarma et al., 2017; Zhao et al., 2017). Addition of grape marc vermicompost to a low C soil vineyard could maintain the initial levels of organic matter in the same vineyards from which it originates, making up for the loss of organic matter due to mineralization (Fernández-Bayo et al., 2008). Paradelo et al. (2011) suggested that the optimal rates of grape marc vermicompost to be added to vineyard soil is 1.7 t ha−1 year−1. Compost and vermicompost derived from rice straw increased levels of organic C, total N , available P, extractable K and C:N ratio of the soil, and decreased soil pH, which may further promote colonization of roots by arbuscular mycorrhiza fungi (Deepamala et al., 2017). Linee et al. (2017) reported that soil nutrient availability, physical stability, and microbial diversity were all improved following application of compost and vermicompost derived from vegetable waste, rice straw and husk, cow dung, and weeds. A study on the effects of food and paper waste vermicompost on soil chemical and biological properties in field plots planted with strawberries showed that it increased soil dehydrogenase activity and microbial biomass-N (Arancon et al., 2005). This increase was accompanied by the increased amounts of nitrate and ammonium, and orthophosphates in the vermicompost-treated plots. Additionally, vermicompost from food waste accelerates the bio-degradation of environmental contaminants. For example, adding vermicompost made from olive cake to soils contaminated by imidacloprid favored dissipation of the neonicotinoid insecticide and increased soil microbial activity and abundance of bacterial communities (Castillo Diaz et al., 2017; Morillo and Villaverde, 2017). 5 1.1.1.2. Effects of vermicompost on plant growth, yield, and fruit quality The application of vermicompost has been shown to significantly enhance the yield and growth of different crops (Arancon et al., 2006; 2007). A surface application of vermicompost derived from grape marc and animal manures covered with a straw and paper mulch increased bunch weights, and the number and total yield of Pinot Noir and Chardonnay grapes in South Australia (Buckerfield, 1998). Vermicompost applications tended to have greater effects on yields when applied under the paper and straw mulches than when applied directly to the soil surface, possibly through degradation of vermicompost following exposure to sun and air (Buckerfield, 1998). Similarly, Venkatesh et al. (1998) reported an increase in the yield of Thompson seedless grapes following application of farm yard manure-based vermicompost along with NPK. Javed et al. (2017) reported that the application of 1 Mg ha-1 cow dung and sugarcane filter cake-based vermicompost enhanced bunch weight and fruit quality of table grapes variety King's Ruby, and increased total yield by 23 % compared with untreated control plots in Pakistan. Martínez et al. (2018) studied the effects of the application of vermicompost derived from chicken manure and poplar sawdust on wine grape cv. Sauvignon Blanc in Mendoza, Argentina and observed increased pruning weight and trunk diameter compared to control; however, yield was not affected. In a sandy loam soil in Egypt, Abd Elrahman, and Bakr, (2022) found that a combined application of vermicompost and 50 % recommended rate of NPK via mineral sources was very effective in improving growth properties of Superior seedless grapevines, including length of shoot, leaf area, leaf mineral contents as well as yield. Vermicompost can enhance grapevine fruit quality. Cow dung and sugarcane filter cake-based vermicompost increased total soluble solids, titratable acidity, reducing sugars and total sugars of the table grape variety King's Ruby (Javed et al., 2017). Application of vermicompost along with 50 % of recommended NPK via mineral sources and 150 mL biofertilizers per vine resulted in the highest values of total soluble solids (TSS), total sugars and the lowest total acidity percentages in the berries of Superior grapevine cultivar in a sandy loam soil in Egypt (Abd Elrahman, and Bakr, 2022). 6 1.1.2. Vermicompost Tea Vermicompost tea is prepared by steeping vermicompost in water with or without aeration (Edwards et al., 2010). Vermicompost tea induces responses in smaller amounts than solid vermicomposts, but can contain some of the same beneficial microbiological and chemical characteristics. Vermicompost tea application supplies beneficial microorganisms, fine particulate organic matter, humic and fulvic acids, soluble mineral nutrients, and plant growth regulators to plant surfaces and soil (Edwards et al., 2010; Radovich and Arancon, 2011). These beneficial components can be the key factors that affect plant growth positively (Radovich and Arancon, 2011). Vermicompost tea has a tremendous potential to protect plants from diseases. Its application to plants can coat leaf surfaces and reduce available sites for pathogen infection or increase microbial diversity that can kill harmful pathogens. Vermicompost teas also have significant potential for pest control because of the presence of phenolic substances that makes the plant tissues unpalatable (Pathma and Sakthivel, 2012). 1.1.2.1. Effects of vermicompost tea on plant growth and yield Like vermicompost, the number of studies on the effect of vermicompost tea on grapevine growth is limited. In one of the few studies, Elmehrat et al. (2018) found that foliar application of organic waste vermicompost tea resulted in an 18 % increase in cluster weight of table grapes cv. ARRA15 in Egypt. Popescu and Popescu (2018) reported that foliar application of humic substances derived from vermicompost enhanced plant growth, chlorophyll a, b and carotenoid content, photosynthesis rate and crop yield of two commercial table grapevine cultivars when applied at the pre-bloom and fruit set phenological stages. Across a range of horticultural crops, including tomatoes, cucumbers, peppers, marigold (Calendula officinalis), and petunia (Petunia alpicola), vermicompost tea stimulated seed germination, crop growth, flowering, yield, and quality (Arancon et al., 2007; Siddiqui et al., 2008). Positive effects of vermicompost tea on wheat, oilseed rape, and strawberry growth and yield have also been reported (Keeling et al., 2003; Hargreaves et al., 2008; Reeve et al., 2010; Pant et al., 2011). Chicken manure-based vermicompost tea increased production of greenhouse-grown pak choi (Brassica rapa cv Bonsai, Chinensis group), as well as N, P, K, Ca and Mg content, and total carotenoids (Pant et al., 2009; 2011). Similarly, Fritz et al. (2012) evaluated the 7 effects of foliar spray of agricultural plant waste and cattle manure-based vermicompost tea on different plants, including cress (Lepidium sativum) and tomato grown in laboratory and radish (Raphanus sativus), rucola (Rucola selvatica), peas (Pisum sativum), wheat and barley (Hordeum vulgar) planted in the field. Vermicompost tea increased tomato and cress biomass by 162 % and 127 %, respectively, but yield of radish, rucola, peas, wheat, and barley did not change. Foliar application of vermicompost extracts did not affect growth, biomass or nutrient allocation, or yield and number of fruits of three tomato varieties in a field experiment in Germany; however, it significantly reduced the number of flowers for several dates (Zaller, 2006). Phytohormones play an important role in various physiological activities in plants. Trace amount of phytohormones such as auxins, gibberellic acids, and cytokinins have been found in vermicompost tea (Arancon et al., 2010), and may be responsible for some of its effects. Growth of tomato and lettuce after adding vermicompost tea to soil showed similar growth patterns as with the addition of exogenous auxins, gibberellic acids, and cytokinins (Rehman et al., 2023). The rate of rooting of stem cuttings from sugarcane (Saccharum officinarum var Honomalino) and mint (Mentha sp.), and leaf cuttings from begonia (Begonia hybrida), differed in their response to food and paper-waste vermicompost tea, possibly as a result of the combination of auxins, cytokinins, gibberellic acids and humic acids found in the vermicompost teas (Arancon et al., 2020). 1.1.2.2. Effects of vermicompost tea on fruit quality Studies of the effects of vermicompost tea on the fruit quality of grapes are rare. In one of the few studies Elmehrat et al. (2018) reported that foliar application of organic waste-based vermicompost tea resulted in an 11 % increase in TSS, a 13 % decrease in titratable acidity (TA) and a 16 % increase in fruit yield of table grapes cv. ARRA15 compared to a control treatment in Egypt. In another study Popescu and Popescu (2018) found that foliar application of humic substances derived from vermicompost enhanced TSS and TA of two commercial table grapevine cultivars when applied at the pre-bloom and fruit set phenological stages. There are also a few studies that evaluated the effects of vermicompost tea on tomato and radish quality in field and greenhouse conditions. For example, Zaller (2006) reported that foliar application of fruit, vegetable, and cotton waste-based vermicompost on three tomato varieties in a field experiment either increased or decreased peel firmness dependent on tomato 8 variety, increased fruit circumference and nitrogen content, and decreased L-ascorbic acid. Similarly, under controlled greenhouse conditions, vermicompost tea from horse and goat manure and alfalfa plus sand treatment increased fruit size, quality, yield, and nitrate reductase activity in tomato plants (Márquez-Quiroz, 2014). Radishes sprayed with vermicompost tea produced from mixed organic materials, mainly green plant parts, cattle manure, and agricultural plant waste on crop quality of radish in a field crop were described as having more typical radish flavor, specifically more aromatic, and more chewy texture, as opposed to control treatments, which were sweet, watery, fibrous, and crisp (Fritz et al., 2012). 1.1.3. Seaweed extract Seaweeds are green, brown, and red marine macroalgae. The current commercial seaweed extracts are manufactured mainly from the brown seaweeds Ascophyllum nodosum., Laminaria spp., Ecklonia maxima, Sargassum spp., and Durvillaea spp. A. nodosum is recognized as the dominant intertidal seaweed of the North Atlantic coastline where water temperatures do not exceed 27 °C (Keser et al., 2005). In general, seaweed extracts are made by processes using water, alkalis, or acids, or by physically disrupting the seaweed by low-temperature milling to give a micronized suspension of fine particles (Hervé and Rouillier, 1977). Seaweeds have been applied to soils as manure and as soil conditioning agents for millennia (Hong et al., 2007; Chatzissavvidis and Therios, 2014; Dinakarkumar and Kothandaraman, 2017; Raghunandan et al., 2019). The observed benefits to the growth, health, and yields of plant crops have been attributed to the supply of essential nutrients, as well as improved soil texture and water holding capacity. The use of seaweed extract has gained popularity due to its potential use in organic and sustainable agriculture (Kholssi et al., 2022) as a result of being biodegradable, non-toxic, non-polluting, and non-hazardous to humans, animals, and birds (Dhargalkar and Pereira, 2005). It has been applied as a foliar spray for many crops, including various grasses, cereals, flowers, and vegetable species (Crouch and van Staden, 1994). Seaweed extracts contain macro and micronutrients, amino acids, vitamins, and phytohormones like cytokinins, auxin, and abscisic acid (Mondal and Panda, 2019), and polysaccharides, minerals, oils, fats, acids, antioxidants, and pigments (Khan et al., 2009; 9 Craigie, 2011). Seaweed extracts stimulate the growth and yield of plants (Rama Rao, 1991; Fornes et al., 2002; Battacharyya, et al., 2015), encourage plant tolerance to environmental stresses (Zhang and Schmidt, 2000; Zhang et al., 2003; Battacharyya, et al., 2015), increase nutrient uptake from soil (Turan and Kose, 2004), and enhance antioxidant content (Corsetto et al., 2020). 1.1.3.1. Effects of seaweed extract on soil Most of the studies examining the effects of seaweed extract focus on plant physiological changes. Its impact on the soil is rarely investigated because seaweed extract is typically, although not always, applied through foliar spray (Boukhari et al., 2020). Application of seaweed extract to soil in alginate beads increased rhizosphere-available P of chrysanthemum plants by 49 % compared to the control; however, the soil microbial community was not affected (Ji et al., 2017). Chemical constituents of seaweed extracts can combine with soil metal ions to produce colloids and protect soil aggregates (Halpern et al., 2015). Richardson et al. (2009) noted that a seaweed extract originating from A. nodosum could replace EDTA to chelate trace elements. The ability of liquefied seaweed extracts to provide an enriched trace metal mixture (Cu, Co, Zn, Mn, Fe, Ni, and Mo and B) in a soluble form for application to the soil or use as foliar sprays has been reported (Milton, 1962). Applying seaweed extract derived from South American kelp (Lessonia nigrescens and Lessonia flavicans) to soil increased activities of soil enzymes including invertase, urease, proteinase, and phosphatase (Wang et al., 2016). Seaweed extract improves soil properties by enhancing aeration, moisture-holding capacity, nutrients, and pH (Bulluck et al., 2002; Khan et al., 2009; Halpern et al., 2015); however, this improved soil structure does not explain the enhanced plant nutrition seen in hydroponic systems (Vernieri et al., 2006) or with foliar application (Rathore et al., 2009). Seaweed fertilizer can support soil bacterial and fungal growth (Bulluck et al., 2002) and can also improve colonization of roots by various symbionts. For example, extracts of both red and green macro-algae applied to the soil stimulated hyphal growth and root colonization by arbuscular mycorrhizal fungi on trifoliate orange (Poncirus trifoliate L.), papaya (Carica papaya L.) and passion fruit (Passiflora edulis Sims.) seedlings (Ishii et al., 2000; Kuwada et al., 1999; 2000; 2006). Extracts of A. nodosum also promoted root colonization of alfalfa by its bacterial symbiont Sinorhizobium meliloti (Wajahatullah et al., 2012; 2013). 10 1.1.3.2. Effects of seaweed extract on plant growth and yield Application of A. nodosum extract has recently been proposed as a promising tool to increase grapevine growth and productivity (Frioni et al., 2018, 2019; Salvi et al., 2019; Taskos et al., 2019; Guti'errez-Gamboa et al., 2019, 2021). Wiens and Reynolds (2008) determined that applying seaweed extracts to 'Baco Noir' grapevines from bloom to 2 weeks post-veraison did not enhance berry size, number and weight of the cluster, nor total yield; however, when combined with control as 150 kg ha-1 ammonium nitrate (51 kg N ha-1) added one week before bloom, yield increased by 15 %, with higher cluster weight and berries per cluster compared to the plots that received only seaweed extracts and did not receive 150 kg ha-1 ammonium nitrate. Application of A. nodosum extracts increased chlorophyll concentration, nutrient uptake, and nutrient use efficiency of grapevine and other horticultural crops (Khan et al., 2009; Battacharyya et al., 2015; Basile et al., 2020). In their experiment on grapevines (cv. Narince) grown under alkaline soil conditions in Central Anatolia Turkey, Sabir et al. (2014) observed that application of A. nodosum seaweed extract alone did not increase grape yield in 2010 and 2011, but a combined application with nano-size calcite fertilizer [CaCO3 (40%), SiO2 (4%), MgO (1%), and Fe2O3 (1%)] enhanced leaf chlorophyll content and total yield compared to the control group that received none of the treatments. Application of A. nodosum did not affect leaf gas exchange, yield, or cluster and berry size, but hastened veraison of grapevines cv. Sangiovese grown under Mediterranean conditions in central Italy and cv. Pinot Noir and Cabernet Franc within a cool-climate viticulture region in Michigan, USA (Frioni et al., 2018). A. nodosum extract significantly increased grapevine yield and number of berries of cv. Merlot in Greece (Taskos et al., 2019) and cv. Flame seedless in Egypt (Stino et al., 2017). A positive effect of foliar application of seaweed extract on cluster length in cv. Merlot in northern Italy (Botelho et al., 2018), and length of rachis in Thompson Seedless table grape in California (Norrie and Keathley, 2006) has also been reported. Positive effects of A. nodosum seaweed extract on growth and production of other crops like Arabidopsis thaliana (Rayorath et al., 2008a; Rayirath, 2009), barley (Rayorath et al., 2008b), wheat (Beckett and van Staden, 1989), alfalfa (Wajahatullah et al., 2012), potato (Blunden and Wildgoose, 1977; Kowalski et al., 1999), and mung bean (Crouch and van Staden, 1991) are also available. Some researchers have suggested that the effects of seaweed extracts on 11 plant growth were related to hormones induced in the treated plants. For example, Rayorath et al. (2008b) suggested that the organic components of A. nodosum extract induced gibberellic acid (GA3), which led to increased amylase activity and enhanced germination and seedling vigor in barley. Similarly, Wally et al. (2013) reported that root application of a commercial seaweed extract produced from A. nodosum to in vitro-grown Arabidopsis thaliana plants increased the total concentration of cytokinins (CKs) of trans-zeatin and cis-zeatin types. Blunden and Wildgoose (1977) also related the foliar application of an aqueous seaweed extract with increased cytokinin and kinetin activity in the plants, which resulted in a significant increase in the tuber yield of King Edward and Pentland Dell potato varieties. The positive effect of foliar applications of commercially available seaweed concentrate (Kelpak 66), prepared from the brown alga Elckonia maxima (Osbeck) Papenfuss, on the growth of bean (Phaseolus vulgaris L.), wheat, and pine (Pinus pinea L.) has also been observed. Featonby-Smith and van Staden (1984) reported that Kelpak 66 significantly improved the growth and yield of bean plants. Beckett and van Staden (1989) observed that Kelpak 66 had no significant effect on the yield of wheat receiving an adequate K supply but increased the yield of K stressed plants by increasing grain number and weight. Kelpak 66 improved P. pinea grown in a greenhouse by increasing shoot and root growth and the seedling's ability to survive transplanting into plastic containers (Atzmon and van Staden, 1994). Seaweed extracts may also enhance plant tolerance of freezing stress. Rayirath et al. (2009) reported that A. nodosum untreated plants exhibited severe chlorosis and tissue damage, and failed to recover from freezing treatments while the extract-treated plants recovered from freezing temperature of -7.5 °C in in vitro and -5.5 °C in in vivo assays. Similarly, Nair et al. (2012) showed that lipophilic components of A. nodosum extracts induced specific biochemical changes leading to enhanced tolerance to freezing stress in A. thaliana, and application of lipophilic components resulted in a 50 % increase in free proline in response to freezing as compared to control plants. 12 1.1.3.3. Effects of seaweed extract on fruit quality The application of seaweed extract can enhance grapevine fruit quality. The positive effects of foliar application of A. nodosum extract on grape juice volume, TSS, TSS to acidity ratio, and anthocyanin content on cv. Flame seedless (Stino et al., 2017), anthocyanin accumulation and phenolic content of cv. Sangiovese (Frioni et al., 2018), and on berry skin anthocyanins of cv. Merlot (Taskos et al., 2019), have been reported. However, Frioni et al. (2019) found that multiple foliar applications of A. nodosum extract did not affect soluble solids or the acidity of grapes; instead, it improved their anthocyanin and phenolic concentrations, by 10.4 % and 14.5 %, at the time of harvest, when compared to the control. Similarly, Salvi et al. (2019) reported that foliar application of A. nodosum extract on cv. Sangiovese resulted in higher anthocyanin content in treated berry skins. The treatments also affected the content and the partitioning of secondary metabolites in berry skins, as anthocyanin and flavonol contents were higher in treated than control plants. By contrast, the ratio of methoxylated to non-methoxylated anthocyanins was lower in treated than in control vines. El-Sese et al. (2020) reported that TA decreased in response to application of seaweed extracts on table grape cultivars Bez-El-Anza, Thompson Seedless, and Red Roomy grown in Egypt. Ali and Moumen (2016) examined the effect of seaweed extract on early sweet wine grape grown in Minia region in Egypt and observed that increasing seaweed extract concentrations from 0.05 to 0.4 % caused a significant decrease in TA. 1.2. Research objectives and hypotheses There were three objectives in this study: 1- To assess the effects of vermicompost application rates on grapevine parameters and soil chemical properties. 2- To evaluate the effects of vermicompost tea concentration and frequency of foliar application on grapevine parameters. 3- To evaluate the effects of seaweed extract (Stella MarisTM) concentration and frequency of foliar application, and combined foliar and soil application on grapevine parameters, bud cold hardiness, cluster looseness, and soil mineral N in two regions of Canada with different climate. 13 I hypothesized that: 1- Soil application of vermicompost would enhance wine grape yield, growth, fruit quality, and soil C and N contents compared to standard vineyard management. 2- Foliar application of vermicompost tea would enhance wine grape yield, growth, fruit quality, and petiole N relative to a standard grower’s practice control. 3- Foliar application of vermicompost tea at 1:25 dry weight/water ratio would have similar effects on wine grape yield, growth, and fruit quality as vermicompost tea at 1:12.5 dry weight/water ratio when applied with the same frequency during the growing season without comparing with water spray control. 4- Foliar application of vermicompost tea four times during the season would have similar effects on wine grape yield, growth, and fruit quality as eight applications of vermicompost tea at the same concentration. 5- Foliar application alone, or soil plus foliar applications of seaweed extract Stella MarisTM would improve wine grape yield, growth, fruit quality, cluster looseness, and cold hardiness compared with the control plot (sprayed with water only). 6- The effect of foliar application of seaweed extract Stella MarisTM at a lower rate (2.5 L ha-1) would be similar to the effect of a higher rate (5 L ha-1) on wine grape growth yield, fruit quality, cluster looseness, and bud cold hardiness. 7- Three foliar applications of seaweed extract Stella MarisTM during the growing season would be similar to six foliar applications on wine grape growth, yield, fruit quality, cluster looseness, and bud cold hardiness. 8- Soil application of seaweed extract Stella MarisTM would increase soil ammonium and nitrate concentrations relative to the control treatment. 9- Foliar application alone, or soil plus foliar application of seaweed extract Stella MarisTM would increase wine grape cluster looseness (pedicle and rachis length and number) compared with the control treatment. 14 Chapter 2. Vermicompost 2.1. Synopsis Vermicompost is an organic fertilizer produced by the accelerated degradation of organic wastes by earthworms and microorganisms; it offers higher nutrient concentrations and microbial activity than traditional compost. Its application improves soil water holding capacity, organic C, and grape yield, while enhancing mycorrhizal fungal colonization, pesticide degradation, and suppression of parasitic nematodes and heavy metals. There is a growing interest in using vermicompost among grape growers in the Okanagan Valley, but there is a knowledge gap on the efficacy of these products on grapevine growth and productivity. To address this knowledge gap, a study was conducted on a block of 10-year-old Chardonnay Clone 76 grapevines on SO4 rootstock in the Okanagan Valley to evaluate the impact of vermicompost on grapevine growth, yield, and soil. The experimental site, characterized by shallow, coarse-textured loamy sand soil, utilized a micro-sprinkler irrigation system and permanent ground cover. The experiment followed a randomized complete block design with three levels of vermicompost applications (2.22, 4.44, and 8.88 Mg ha-1 in 2019 and 1.99, 3.98 and 7.96 Mg ha-1 in 2021) and two control treatments (current grower practice with and without N fertilizer) in five treatments and six replications. Vermicompost was applied in early May 2019 and 2021; measurements were conducted in 2020 and 2021. Soil samples were collected and analyzed for organic C, total N and ammonium and nitrate levels. Grape clusters were harvested and evaluated for yield, berry weight, TSS, TA, and yeast assimilable nitrogen (YAN). Additionally, trunk cross-sectional area (TCSA) measurements were taken annually as an indicator of plant growth. 15 2.2. Materials and Methods 2.2.1. Experimental site The experimental site for the vermicompost experiment was located at a block of 10-year-old Chardonnay Clone 76 wine grape on SO4 rootstock at Thomas Ranch Vineyards in Oliver; south of Okanagan Falls, BC (49° 32′ N, 119° 55′ W). The soil of the experimental site was shallow, coarse textured over gravelly and stony loamy sand with the dominant soil series of Rutland, which was derived from gravelly and stony terraces in the dark brown soil zone (Gough et al., 1994). The distance between two adjacent vines was 1.22 m and the space between the two adjacent rows was 2 m. The irrigation system was micro-sprinkler. The vineyard had a permanent ground cover consisting of a mixture of rye grass, fescue, blue grass, white clover, and alfalfa. To manage the ground cover in the alleyways and undervine weeds, pre-emergence and Round upTM herbicides were used during spring and summer as required. Pest and disease management was consistent with local recommendations (British Columbia Wine Grape Council, 2010). The Okanagan Valley is characterized by hot, dry summers and cold winters. Over 30 years (1991-2020), the average minimum daily temperature for the Penticton station of Environment Canada was -2.8 °C and -3.2 °C in December and January and an average maximum of 29.2 °C and 28.4 °C in July and August, respectively (Environment Canada, 2024). The daily average temperature throughout the year was 9.6 °C. The average yearly rainfall was 318 mm, with the minimum in February and March (19.3 and 22.7 mm per month) and the maximum in May and June (38.2 and 43.8 mm). During the growing season (from April until October), the daily average temperature was 15.3 °C and the monthly average rainfall was 30.5 mm. 2.2.2. Experimental design and treatment application Vermicompost was applied in a randomized complete block design with four treatments including: treatment 2 or control 2 as grower practice but without N fertilizer, treatments 3, 4 and 5 as different rates of vermicompost, and the current grower practice including N fertilizer as control 1, which was not fully randomized (Figure 2.1.). Expressed as per hectare of vineyard, treatments consisted of: 16 1- Control 1 (current grower practice including N fertilizer). The Granular Blend 4 (in 2019 and 2020) and Blend 6 (in 2021) by Okanagan Fertilizer comprising a combination of N-P-K-Mg-S and B applied in two split applications at mid-May and June, at total rates of approximately 341 kg ha-1 in 2019, 237 kg ha-1 in 2020 and 233 kg ha-1 in 2021; adjusted each year based on a soil test. 2- Control 2 (grower practice, but without N fertilizer). Monoammonium Phosphate for phosphorus, Potassium Sulfate for potassium, Epsom Salts for magnesium and Solubor for boron were used. 3- Application of 2.22 Mg ha-1 vermicompost in 2019 and 1.99 Mg ha-1 in 2021 as low rate. 4- Application of 4.44 Mg ha-1 vermicompost in 2019 and 3.98 Mg ha-1 in 2021 as medium rate. 5- Application of 8.88 Mg ha-1 vermicompost in 2019 and 7.96 Mg ha-1 in 2021 as high rate. Each treatment was replicated six times for a total of 30 plots, each plot consisted of five vines: three data vines and two guard vines. The distance between adjacent vines within each row was 1.22 m, and the space between adjacent rows was 2 m. The plot length was 6.1 m and plot area was 12.26 m2. The vineyard had a permanent ground cover consisting of a mixture of rye grass, fescue, blue grass, white clover, and alfalfa. To manage the ground cover in the alleyways and undervine weeds, pre-emergence and Round upTM herbicides were used during spring and summer as required. Pest and disease management was consistent with local recommendations (British Columbia Wine Grape Council, 2010). 17 Figure 2.1. The layout of the plots in vermicompost experiment. 18 Vermicompst was applied in early May 2019 and 2021 to the herbicide strip, and mixed with the top 5 cm of soil. Due to the restrictions imposed by the COVID-19 pandemic, access to the experimental plots was restricted in early 2020; therefore, vermicompost was not applied to the field that year. The vermicompost was derived from urban and agricultural waste streams such as food waste from hospital, paper, garden debris, and equine or dairy residuals (greenscience.ca). For the purpost of this study, we received 2 batches of vermicompost. One in 2019, which was applied in that year; the second batch was received in 2020, kept at 4 oC and applied in 2021. The moisture content of the vermicompost was 65 %. The nutrient contents of the vermicompost from the 2021 batch are presented in Table 2.1. Table 2.1. The nutrient concentrations of the vermicompost applied in 2021. C (%) N (%) P (%) K (%) Ca (%) Mg (%) S (%) Fe (%) 28.13 2.09 1.253 2.141 7.291 1.854 0.566 0.623 Al (%) B (ppm) Mn (ppm) Zn (ppm) Na (%) Cu (ppm) Mo (ppm) Ni (ppm) 0.452 46.607 472.4 331.25 0.245 85.633 6.051 51.117 2.2.3. Sampling and analyses 2.2.3.1. Soil sampling and analyses In fall 2019, soil samples were collected from two depths (0-15 and 15-30 cm) and analyzed for EC, pH, soil texture, macro- and micro-nutrients, and soil organic C and N. Soil samples were taken again every fall to examine the total N and organic C, and three times per year for NO3- and NH4+. The soil electric conductivity was determined using an EC meter. The soil pH was analyzed in a 1:2 ratio of dry soil to deionized water using a glass electrode. The cation exchange capacity analysis was conducted following the pH 7.0 NH4OAC CEC method by Chapman (1965). Available P was extracted by the Olsen method (Olsen, 1954) and analyzed using the Ascorbic Acid Method (Murphy and Riley, 1962). For available K, soil samples were extracted using 1 M ammonium acetate (NH4OAC) and K concentration in the extract was determined using an inductively coupled plasma (ICP) emission spectrometer (Ziadi et al., 2008). The 19 percent organic C and total soil N was measured using a CHN elemental analyzer (628 Series, LECO Corp., St. Joseph, MI). The nitrate and ammonium were extracted using a modified 2 M KCl extraction (Keeney and Nelson, 1982). A 5:1 ratio of KCl to soil was used for the extraction. Nitrate and ammonium were measured colorimetrically using a Segmented Flow Analyzer (Analyzer III, Technicon Instrument Corp, Tarrytown, NY). 2.2.3.2. Petiole sampling and analysis Petiole samples were collected at veraison. They were taken from the 6th or 7th leaf from the branch tip; if there was a cluster at the 6th or 7th leaf, the petiole was taken directly across from the cluster. Five petioles were collected from each of the three data vines from each plot. The samples were weighed, dried in an oven at 55 °C for 48 h, and finely ground. The petiole samples were analyzed for N using the CHN elemental analyzer. 2.2.3.3. Yield and grape cluster sampling and analysis At harvest, 12 grape clusters, four from each data vine, were collected. They were weighed first, and the weights were summed and reported as total yield. In the laboratory, 216 berries were separated from the 12 clusters; the weight of the berries was measured and recorded for average berry weight. The 216 berries per plot were juiced, and the juice was used to measure Brix (TSS), TA and YAN. Juicing was done by mashing and squeezing in a cheese cloth. The Brix, which is a scale to measure TSS was measured using a handheld refractometer. The TA was measured by titration with sodium hydroxide (NaOH) to a pH end-point of 8.2 (Liu et al., 1987). The YAN was determined following the Formol method using Formaldehyde reagent (graded 37% v/v) (Gump et al., 2000). For yield, all grape clusters from each of the three test vines including the harvested clusters for fruit juicing were counted separately, weighed and data were recorded. The clusters smaller than the size of a toonie (28 mm in diameter) were excluded from counts and harvest measurements. 20 2.2.3.4. Trunk cross-sectional area (TCSA) Tree trunk cross-sectional area is an important indicator of plant growth. Every year annual measurements of trunk diameter were made at the end of dormant season (March) at a marked height 0.3 m above the graft union using a digital caliper. The trunk cross sectional area was determined by geometry. 2.2.4. Statistical analysis For the purpose of this thesis, data from 2020 and 2021 have been used which was part of a larger 5-year study that started in 2018 and ended in 2022. The normality and heteroscedasity of the data were checked; there was no need for data transformation in our study. Analyses of Variance (ANOVAs) were performed on the data using Minitab 12 software. Repeated measures ANOVA were used to assess significant differences in soil ammonium and nitrate concentrations across sampling dates using R version 4.1.0 (R Core Team, 2021) with the aov function from the nlme package (Pinheiro et al., 2021). Where significant differences were detected by the Mixed Effects Model ANOVA, mean differences were evaluated by Tukey’s multiple comparison test (P-value < 0.05). Vermicompost treatments were considered as fixed effects, and year and replication (block) considered as random effects. For this experiment, where the grower’s control treatment with N fertilizer (control 1) was not fully randomized, mean differences between this control and the rest of the treatments including the grower’s control without N fertilizer (control 2) and different rates of vermicompost application were evaluated using orthogonal polynomial contrasts with Minitab 12 software. 21 2.3. Results 2.3.1. Effects of vermicompost on growth, nutrition, and yield The effect of the treatments reported in 2020 are the residual effects of the vermicompost treatments in 2019. In 2020, most wine grape growth parameters and yield were not significantly affected by vermicompost application (Table 2.2). Only pruning weight was significantly affected by the treatments; vermicompost application at high rate resulted in lower pruning weight than application at low and medium rates. Table 2.2. Residual effects of application of vermicompost in 2019 on growth, nutrition, and yield of Chardonnay wine grapes in 2020. Treatmenta TCSAb at Fall (mm2) Pruning Weight (metric tonnes ha-1) Petiole N (%) No. of Cluster per vine Cluster Size (g) Berry Weight (g) Yield (metric tonnes ha-1) Control 1 (Grower practice) 13.1 (1.61)c 0.997 ab (0.09) 0.47 (0.02) 34.1 (1.75) 134.6 (15.4) 1.5 (0.06) 18.827 (2.49) Control 2 (Grower practice without N) 12.4 (1.17) 0.926 ab (0.05) 0.47 (0.01) 31.2 (0.84) 117.9 (11.4) 1.4 (0.03) 15.048 (1.68) Vermicompost at 2.22 Mg ha-1 11.6 (0.80) 1.049 a (0.07) 0.47 (0.02) 34.3 (1.76) 137.7 (8.81) 1.5 (0.08) 19.197 (1.38) Vermicompost at 4.44 Mg ha-1 13.2 (1.21) 1.071 a (0.11) 0.49 (0.02) 32.9 (2.44) 140.5 (11.4) 1.5 (0.03) 18.809 (2.14) Vermicompost at 8.88 Mg ha-1 14.6 (0.91) 0.728 b (0.04) 0.45 (0.01) 35.4 (1.71) 118.5 (3.16) 1.4 (0.06) 17.091 (0.83) P-value d 0.431 0.008 0.374 0.318 0.273 0.655 0.278 F-value d 1.00 4.68 1.12 1.26 1.39 0.62 1.38 DF Num de 20 20 20 20 20 20 20 DF Dendf 4 4 4 4 4 4 4 aTreatments applied in 2019, N = 6. b Trunk Cross-Sectional Area. cThe numbers in brackets show the Standard Error. The values in each column with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. dP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 5 treatments and 6 replications. eNum = numerator, f Den = denominator. 22 In 2021, the effect of vermicompost on wine grape growth and yield (Table 2.3) variables, was not significant except for yield. The yield was significantly lower with application of low rate of vermicompost than all other treatments. Table 2.3. Effects of vermicompost on growth, nutrition, and yield of Chardonnay wine grapes in 2021. Treatment TCSAa at Spring (mm2) TCSAa at Fall (mm2) Growth Increment (mm) Pruning Weight (metric tonnes ha-1) Petiole N (%) No. of Cluster per vine Cluster Size (g) Berry Weight (g) Yield (metric tonnes ha-1) Control 1 (Grower practice) 14.6 (0.91)b 16.6 (1.00) 2.0 (0.39) 2.157 (0.11) 0.42 (0.01) 30.5 (0.35) 121.9 (2.89) 1.45 (0.04) 15.166 a (0.43) Control 2 (Grower practice without N) 13.1 (1.61) 14.5 (1.45) 1.4 (0.21) 2.407 (0.20) 0.40 (0.04) 31.3 (1.98) 112.9 (5.53) 1.50 (0.03) 14.408 a (1.07) Vermicompost at 1.99 Mg ha-1 12.4 (1.71) 14.0 (1.40) 1.6 (0.44) 2.297 (0.13) 0.38 (0.01) 27.2 (2.35) 106.9 (6.19) 1.45 (0.05) 11.832 b (1.12) Vermicompost at 3.98 Mg ha-1 11.6 (0.80) 12.5 (0.06) 0.9 (0.56) 2.155 (0.16) 0.43 (0.03) 32.2 (1.38) 120.9 (3.35) 1.45 (0.06) 15.945 a (1.01) Vermicompost at 7.96 Mg ha-1 13.2 (1.21) 14.7 (0.89) 1.6 (0.55) 2.183 (0.26) 0.41 (0.02) 31.6 (1.74) 119.9 (6.60) 1.48 (0.04) 15.311 a (0.86) P-valuec 0.431 0.171 0.261 0.812 0.640 0.183 0.113 0.944 0.001 F-valuec 1.00 1.75 1.43 0.39 0.64 1.73 2.14 0.18 7.75 DF Numcd 20 25 20 20 19.23 20 20 24 20 DF Dence 4 4 4 4 4 4 4 4 4 ªTrunk Cross-Sectional Area. bThe numbers in brackets show the Standard Error. N = 6. The values in each column with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. cP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 5 treatments and 6 replications. dNum = numerator, eDen = denominator. 23 2.3.2. Effects of vermicompost on wine grape fruit quality parameters In 2020, TSS, juice pH, and calculated and measured YAN were not significantly affected by application of vermicompost (Table 2.4). Only TA was significantly affected, whereby application of vermicompost at medium rate resulted in the highest value of TA, while application of high rate of vermicompost resulted in the lowest value of TA. In 2021, vermicompost application did not affect TSS, TA, calculated and measured YAN; however, juice pH was higher at all rates of application compared to control 1 (grower practice with N) (Table 2.5). Table 2.4. Effects of application of vermicompost in 2019 on fruit quality parameters of Chardonnay wine grapes harvested in 2020. Treatmenta TSSb (Brix°) Juice pH TAc (g L-1) Calculated YANd (mg L-1) Measured YANd (mg L-1) Control 1 (Grower practice) 23.4 (0.30)e 3.5 (0.02) 9.2 ab (0.02) 208.8 (22.6) 329.2 (35.6) Control 2 (Grower practice without N) 23.4 (0.29) 3.6 (0.04) 8.9 ab (0.03) 209.8 (9.81) 330.8 (15.5) Vermicompost at 2.22 Mg ha-1 23.3 (0.25) 3.5 (0.03) 9.3 ab (0.03) 196.9 (10.9) 310.4 (17.2) Vermicompost at 4.44 Mg ha-1 23.3 (0.32) 3.5 (0.02) 9.6 a (0.03) 220.0 (14.4) 346.9 (22.8) Vermicompost at 8.88 Mg ha-1 24.2 (0.23) 3.5 (0.03) 8.7 b (0.03) 240.1 (7.44) 378.6 (11.7) P-valuef 0.138 0.576 0.034 0.136 0.136 F-valuef 1.97 0.74 3.23 1.98 1.98 DF Numfg 20 20 20 20 20 DF Denfh 4 4 4 4 4 aTreatments applied in 2019. bTotal Soluble Solid, cTitratable Acidity, dYeast Assimilable N. N = 6. eThe numbers in brackets show the Standard Error. The values in each column with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. fP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 5 treatments and 6 replications. gNum = numerator, hDen = denominator. 24 Table 2.5. Effects of vermicompost on fruit quality parameters of Chardonnay wine grapes in 2021. Treatment TSSa (Brix°) Juice pH TAb (g L-1) Calculated YANc (mg L-1) Measured YANc (mg L-1) Control 1 (Grower practice) 22.9 (0.15) 3.09 b (0.09) 9.9 (0.02) 185.4 (3.82) 277.4 (5.71) Control 2 (Grower practice without N) 22.8 (0.25) 3.33 ab (0.09) 10.4 (0.04) 191.5 (5.53) 286.6 (8.27) Vermicompost at 1.99 Mg ha-1 22.8 (0.13) 3.41 a (0.05) 10.2 (0.06) 188.6 (4.58) 282.2 (6.85) Vermicompost at 3.98 Mg ha-1 22.6 (0.24) 3.43 a (0.04) 10.2 (0.06) 193.1 (7.21) 288.9 (10.80) Vermicompost at 7.96 Mg ha-1 22.8 (0.23) 3.37 a (0.06) 10.6 (0.06) 203.5 (7.00) 304.5 (10.50) P-valued 0.817 0.009 0.801 0.161 0.161 F-valued 0.39 4.58 0.41 1.85 1.85 DF Numde 20 19.24 20 19.27 19.27 DF Dendf 4 4 4 4 4 ªTotal Soluble Solid, bTitratable Acidity, cYeast Assimilable N. dThe numbers in brackets show the Standard Error. N = 6. The values in each column with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. eP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 5 treatments and 6 replications. fNum = numerator, dDen = denominator. 2.3.3. Effects of vermicompost on soil organic C and total N concentrations In 2020, vermicompost application affected soil organic C (SOC) and total N at the 0-15 cm soil depth (Table 2.6). The lowest SOC was at the grower practice control with N, while application of vermicompost at medium rate resulted in a 72 % increase over that control. The lowest total N at 0-15 cm soil depth was at the grower practice control with N, while application of vermicompost at medium rate resulted in an 83.3 % increase over that control. Soil organic C and total N at 15-30 cm were not significantly affected by vermicompost application. 25 Table 2.6. Effects of application of vermicompost on soil organic C (SOC) and total N measured in summer 2020. Treatmenta SOC 0-15 cm (%) SOC 15-30 cm (%) Total Soil N 0-15 cm (%) Total Soil N 15-30 cm (%) Control 1 (Grower practice) 0.86 b (0.03)b 0.75 (0.02) 0.06 b (0.01) 0.06 (0.01) Control 2 (Grower practice without N) 1.11 ab (0.14) 0.86 (0.08) 0.08 ab (0.01) 0.06 (0.01) Vermicompost at 2.22 Mg ha-1 1.23 ab (0.17) 0.79 (0.03) 0.08 ab (0.01) 0.06 (0.00) Vermicompost at 4.44 Mg ha-1 1.48 a (0.21) 0.97 (0.13) 0.11 a (0.02) 0.07 (0.01) Vermicompost at 8.88 Mg ha-1 0.94 ab (0.07) 0.74 (0.05) 0.08 ab (0.01) 0.05 (0.01) P-valuec 0.031 0.157 0.029 0.172 F-valuec 3.17 1.86 3.22 1.78 DF Numcd 25 20 25 20 DF Dence 4 4 4 4 aTreatments applied in 2019. N = 6. bThe numbers in brackets show the Standard Error. The values in each column with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. cP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 5 treatments and 6 replications. dNum = numerator, eDen = denominator. In 2021, vermicompost application affected SOC and total N at both soil depths (Table 2.7). At 0-15 cm, the lowest SOC was at both grower practice controls, while application of vermicompost at high rate resulted in a 120 % increase over those controls. Similarly, the lowest total N at 0-15 cm soil depth was at both grower practice controls, while application of high rate of vermicompost resulted in a 133 % increase. At 15-30 cm soil depth, the lowest SOC was at the grower practice control with N, while application of vermicompost at high rate resulted in a 61 % increase over that control. The lowest total N at 15-30 cm soil depth was at both grower practice controls while application of 7.96 Mg ha-1 vermicompost resulted in a 75 % increase. 26 Table 2.7. Effects of application of vermicompost on soil organic C (SOC) and total N measured in summer 2021. Treatment SOC 0-15 cm (%) SOC 15-30 cm (%) Total Soil N 0-15 cm (%) Total Soil N 15-30 cm (%) Control 1 (Grower practice) 0.84 c (0.04) 0.73 c (0.05) 0.06 b (0.00) 0.04 c (0.00) Control 2 (Grower practice without N) 0.91 c (0.04) 0.76 bc (0.04) 0.06 b (0.01) 0.04 c (0.00) Vermicompost at 1.99 Mg ha-1 1.25 bc (0.11) 0.87 bc (0.05) 0.12 ab (0.04) 0.05 bc (0.00) Vermicompost at 3.98 Mg ha-1 1.57 ab (0.12) 1.04 ab (0.08) 0.11 ab (0.01) 0.06 ab (0.08) Vermicompost at 7.96 Mg ha-1 1.85 a (0.15) 1.18 a (0.10) 0.14 a (0.01) 0.07 a (0.01) P-valuea <0.001 <0.001 0.011 0.001 F-valueb 18.95 8.64 4.12 7.85 DF Numbc 20 20 25 20 DF Denbd 4 4 4 4 aThe numbers in brackets show the Standard Error. N = 6. The values in each column with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. bP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 5 treatments and 6 replications. cNum = numerator, dDen = denominator. 2.3.4. Effects of vermicompost on soil ammonium and nitrate concentrations In 2020, the soil ammonium and nitrate were sampled and measured from the vine rows twice during the growing season, once in summer (July) and then the second time in fall (October) from two depths 0-15 and 15-30 cm. Analyzing ammonium and nitrate concentration of the soil with a repeated measure approach showed that, at both depths, soil ammonium was higher in October than July (Figure 2.2) while soil nitrate was higher in July than October (Figure 2.3). The mean values of soil ammonium and nitrate in July and October for both depths 0-15 and 15-30 cm did not change much and remained constant. 27 Figure 2.2. Soil ammonium concentration (mg kg-1) on two sampling dates (July and October) at 0-15 and 15-30 cm depths in 2020. Season (DF numerator = 1.01, DF denominator = 29.43, F-value = 15.155, P-value < 0.0001). Depth (DF numerator = 1.00, DF denominator = 29, F-value = 0.212, P-value = 0.648). Interaction of season and depth (DF numerator = 1.18, DF denominator = 34.19, F-value = 1.128, P-value = 0.303) based on repeated measures test. The values in box with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test; there were six replicate blocks. 28 Figure 2.3. Soil nitrate concentration (mg kg-1) on two sampling dates (July and October) in 0-15 and 15-30 cm depth in 2020. Season (DF numerator = 1.43, DF denominator = 41.34, F-value = 59.994, P-value < 0.0001). Depth (DF numerator = 1.00, DF denominator = 29, F-value = 27.465, P-value < 0.0001). Interaction of season and depth (DF numerator = 1.33, DF denominator = 38.64, F-value = 22.525, P-value < 0.0001) based on repeated measure test. The values in box with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test; there were six replicate blocks. In 2021, the soil nitrate and ammonium were measured three times during the growing season: in spring (May), in summer (July), and in fall (October), from two depths 0-15 and 15-30 cm. Analyzing ammonium concentration of the soil with a repeated measure approach indicated that soil ammonium values at 0-15 cm were high in May, low in July and intermediate in October (Figure 2.4). The soil ammonium values at depth 15-30 cm remain constant and did not change across sampling times. Soil nitrate was high in May at both depths 0-15 and 15-30 cm and decreased in July and October and reached a minimum level in October at depth 15-30 cm (Figure 2.5). 29 Figure 2.4. Soil ammonium concentration (mg kg-1) at three sampling dates (May, July and October) and at 0-15 and 15-30 cm depth in 2021. Season (DF numerator = 1, DF denominator = 55, F-value = 23.82, P-value < 0.0001). Depth (DF numerator = 1, DF denominator = 55, F-value = 19.284, P-value < 0.0001). Interaction of season and depth (DF numerator = 1, DF denominator = 55, F-value = 9.020, P-value < 0.001) based on repeated measure test. The values in box with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test; there were six replicate blocks. 30 Figure 2.5. Soil nitrate concentration (mg kg-1) at three sampling dates (May, July and October) in 0-15 and 15-30 cm depth in 2021. Season (DF numerator = 1, DF denominator = 55, F-value = 41.218, P-value < 0.0001). Depth (DF numerator = 1, DF denominator = 55, F-value = 0.274, P-value = 0.0603). Interaction of season and depth (DF numerator = 1, DF denominator = 55, F-value = 9.020, P-value = 0.042) based on repeated measure test. The values in box with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test; there were six replicate blocks. In 2020, in the summer soil samples, ammonium concentrations at depths 0-15 and 15-30 cm and nitrate concentrations at 0-15 cm were not significantly different amongst treatments; however, application of 8.88 Mg ha-1 of vermicompost resulted in higher nitrate concentration at 15-30 cm compared to rest of the treatments (Table 2.8). In fall soil samples, nitrate concentrations at both depths were not significantly affected by vermicompost treatments, but the ammonium concentration of the soil was significantly affected. While treatment effects at 0-15 cm were barely detectable statistically, at the 15-30 cm depth the highest ammonium value was observed after application of 4.44 Mg ha-1 vermicompost, and the lowest was obtained in grower practice control with N and with application of 8.88 Mg ha-1 vermicompost. 31 Table 2.8. Effects of application of vermicompost in 2019 on soil mineral N (mg kg-1) in July and October 2020. Treatmenta July 2020 October 2020 NH4- 0-15 cm NO3- 0-15 cm NH4- 15-30 cm NO3- 15-30 cm NH4- 0-15 cm NO3- 0-15 cm NH4- 15-30 cm NO3- 15-30 cm Control 1 (Grower practice) 0.42 (0.03)b 22.2 (9.12) 1.03 (0.31) 21.1 b (7.2) 1.12 (0.22) 2.51 (0.60) 1.17 b (0.14 ) 1.98 (0.29) Control 2 (Grower practice without N) 0.45 (0.04) 23.8 (5.96) 0.68 (0.10) 24.3 b (9.34) 1.69 (0.22) 2.76 (0.62) 1.70 ab (0.25) 2.25 (0.31) Vermicompost at 2.22 Mg ha-1 0.46 (0.03) 26.6 (6.45) 0.81 (0.22) 30.3 b (9.79) 1.73 (0.21) 3.06 (0.65) 1.72 ab (0.12) 2.45 (0.24) Vermicompost at 4.44 Mg ha-1 0.43 (0.03) 19.0 (3.35) 1.19 (0.55) 19.2 b (6.31) 1.54 (0.23) 3.75 (0.89) 2.03 a (0.19) 2.62 (0.29) Vermicompost at 8.88 Mg ha-1 0.50 (0.04) 19.1 (2.31) 0.68 (0.08) 69.2 a (7.96) 1.10 (0.09) 2.56 (0.38 ) 1.06 b (0.22) 1.48 (0.25) P-valuec 0.412 0.857 0.623 0.001 0.046 0.298 0.007 0.069 F-valuec 1.03 0.33 0.67 7.85 2.96 1.32 4.84 2.61 DF Numcd 23 20 16.27 20 19.33 18.90 18.95 18.42 DF Dence 4 4 4 4 4 4 4 4 a Treatments applied in 2019. N = 6. b The numbers in brackets show the Standard Error. The values in each column with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test, c P value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 5 treatments and 6 replications. dNum = numerator, eDen = denominator. 32 In 2021, ammonium and nitrate concentrations in the soil in May were significantly affected by vermicompost at both depths (Table 2.9). The highest ammonium was measured with the high rate of vermicompost application and the lowest were in the two controls, with the other rates of vermicompost resulting in intermediate concentrations of ammonium. At 0-15 cm, the highest nitrate concentration was obtained with application of vermicompost at 3.98 and 7.96 Mg ha-1, and the lowest was at control 2 grower practice without N. At 15-30 cm the nitrate concentration was significantly higher with application of vermicompost at 7.96 Mg ha-1 than for the two controls, but not significantly different from other rates of vermicompost application. Nitrate concentration of the soil in July for depth 15-30 cm and ammonium concentrations for both depths were not significantly affected by vermicompost application in either July or October. By contrast, nitrate concentration at 0-15 cm depth was significantly higher in the treatment of application of vermicompost at 7.96 Mg ha-1 than grower practice control. In October, the nitrate concentration at 0-15 cm was significantly higher for the two higher rates of vermicompost application than grower practice control with N. 33 Table 2.9. Effects of vermicompost on soil mineral N (mg kg-1) at three sampling dates (May, July, and October 2021). Treatment May 2021 July 2021 October 2021 NH4- 0-15 cm NO3- 0-15 cm NH4- 15-30 cm NO3- 15-30 cm NH4- 0-15 cm NO3- 0-15 cm NH4- 15-30 cm NO3- 15-30 cm NH4- 0-15 cm NO3- 0-15 cm NH4- 15-30 cm NO3- 15-30 cm Control 1 (Grower practice) 1.16 c (0.09) 5.45 bc (1.26) 1.37 c (0.13) 3.68 bc (1.01) 0.90 (0.15) 2.38 b (0.23) 1.07 (0.17) 2.56 (0.16) 1.93 (0.27) 2.27c (0.13) 1.74 (0.17) 1.6 6 (0.16) Control 2 (Grower practice without N) 1.07 c (0.16) 3.61 c (0.41) 1.85 c (0.54) 3.39 c (0.35) 094 (0.11) 2.62 ab (0.27) 1.67 (0.37) 3.06 (0.36) 1.71 (0.21) 2.73 bc (0.24) 1.65 (0.14) 1.97 (0.28) Vermicompost at 1.99 Mg ha-1 3.44 bc (1.36) 8.62 ab (1.65) 4.03 bc (0.49) 4.99 abc (0.29) 1.08 (0.08) 3.16 ab (0.17) 1.63 (0.46) 3.18 (0.39) 1.72 (0.18) 2.68 bc (0.17) 1.65 (0.16) 1.97 (0.14) Vermicompost at 3.98 Mg ha-1 8.35 ab (2.64) 11.12 a (1.30) 8.29 b (1.32) 6.37 ab (0.83) 1.14 (0.10) 3.12 ab (0.40) 1.90 (0.40) 3.11 (0.41) 1.96 (0.28) 3.55 ab (0.30) 1.69 (0.19) 2.02 (0.22) Vermicompost at 7.96 Mg ha-1 13.79 a (2.41) 11.75 a (1.25) 13.91 a (2.02) 7.33 a (0.56) 1.25 (0.14) 3.71 a (0.65) 1.76 (0.33) 4.43 (0.90) 1.88 (0.21) 3.83 a (0.35) 1.69 (0.21) 2.38 (0.29) P-valueb < 0.001 < 0.001 < 0.001 0.002 0.152 0.043 0.422 0.695 0.814 < 0.001 0.993 0.242 F-valueb 12.48 8.94 21.65 6.57 1.90 3.01 1.02 0.56 0.39 9.90 0.06 1.50 DF Numbc 19.26 20 25 20 18.75 20 20 17.97 20 20 19.23 19.32 DF Denbd 4 4 4 4 4 4 4 4 4 4 4 4 ªThe numbers in brackets show the Standard Error. N = 6. The values in each column with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test, bP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 5 treatments and 6 replications. cNum = numerator, dDen = denominator. 34 2.4. Discussion It was hypothesized that soil application of vermicompost would enhance wine grape yield and growth, fruit quality, and soil C and N content compared to standard vineyard management. To test this hypothesis, we treated the herbicide strip under the vines with three rates of vermicompost in spring of 2019 and 2021 and monitored the wine grape and soil responses to treatments in 2020 and 2021. 2.4.1. Effects of vermicompost on growth In 2020, the application of vermicompost at low and medium rates resulted in an increase in pruning weight compared to the results from using the highest rate of vermicompost. The complexity of interpreting this result arises from the fact that superfluous primary and lateral shoots were trimmed from the top and sides of the vine canopy with a hedging machine from fruit set to veraison stage, a process known as hedging. The biomass removed during hedging was not accounted for in the pruning weight measurement. The excessive N supplied by the high vermicompost rate might have spurred vigorous primary branch growth, which was subsequently removed during hedging. In contrast, the low and medium vermicompost rates may have promoted more measured and balanced growth of both primary and secondary branches, which were less subject to removal by hedging. Consequently, the canopy appeared denser at these low and medium rates of vermicompost application, leading to greater pruning weights in comparison to the high rate treatment. Furthermore, there was no evidence to suggest that high rates of application caused soil toxicity; nitrate and ammonium levels in the soil remained below toxic thresholds, and the concentrations of heavy metals in the vermicompost were within the acceptable range set by the CMGC (Canadian Municipalities Guidelines for Compost Quality) guidelines (CCME, 2005). In 2021, however, the use of vermicompost did not significantly influence pruning weight. This could be due to the fact that vermicompost was not applied in 2020, and the applied vermicompost in 2021 required time to decompose and release nutrients to soil, as well as absorption by the wine grapes. Wine grapes do not have high nutrient demands and often exhibit a delayed response to nutrients (Schreiner et al., 2006). Therefore, while application of vermicompost in 2019 increased pruning weight in 2020, application of 35 vermicompost in 2021 did not produce a significant increase in pruning weight in 2021, possibly because no vermicompost was applied in 2020. An increase in wine grape pruning weight due to application of vermicompost has also been reported by other researchers. Travis et al. (2003) reported that compost made from animal manure, mushroom substrate and yard trimmings increased pruning weights of Chardonnay from 8 % with low application to 18 % with higher application rates, and Chambourcin from 97 to 131 % compared to non-treated vines in southeastern Pennsylvania. In their experiment the vines grew too vigorously at the higher rate of compost application (20 metric tonnes ha-1 dry weight) due to high supply of N, and this rapid growth created problems in management of canopy and disease, reduced fruiting and increased cold injury to the vines or buds. They suggested a lower rate of compost (7 to 10 metric tonnes ha-1 dry weight) as the optimal rate, which is almost similar to the high rate used here. Similarly, Martínez et al. (2018) studied the effects of the application of 8 metric tonnes ha-1 vermicompost derived from chicken manure and poplar sawdust on wine grape cv. Sauvignon Blanc in Mendoza, Argentina. They observed that application of vermicompost increased pruning weight by 65 % compared to control. They associated this increase in pruning weight to increasing total P and K content of the vine. Nguyen et al. (2013) found that application of 21 metric tonnes ha-1 dry weight compost from garden and food waste, incorporated in soil or surface applied under vines, increased the pruning weight of wine grape cv. Merlot in Adelaide, Australia by 31 and 53 %, respectively. They associated this increase in pruning weight to improved soil structure and nutrient accessibility, which was indicated in the greater leaf N and P concentrations. In our study the pruning weights in 2020 were in the range of 997 (grower control with N) to 1071 (medium rate of vermicompost application) metric tonnes ha-1 fresh weight, which was lower than observations of Nguyen et al. (2013) on Merlot in Adelaide Australia and Reynolds et al. (2007) on Chardonnay in Ontario. The lower pruning weights could be due to the humid climate of Ontario and the Mediterranean climate in Argentina, in which vines were more vigorous and resulted in greater pruning weight. Differences in soil could also be responsible: the soil of our study was light to medium texture with a large percentage of coarse fragments while the soils in the Ontario and Argentina studies were finer in texture with fewer coarse fragments, resulting in more vigorous vines. Since the result of the present study showed that the application of vermicompost did not affect growth traits other than the pruning weight, and considering the lack of confidence in 36 pruning weight as a measure of shoot growth, the hypothesis that soil application of vermicompost would enhance wine grape growth was rejected. 2.4.2. Effects of vermicompost on yield Most studies, though not all, indicate beneficial impacts of vermicompost on wine grape yield, with some reporting yield increases of 21-36 % (Atiyeh et al., 2002; Azarmi et al., 2009; Lim et al., 2015). These studies used vermicompost providing 7-25 kg ha-1 of available N, 2-14 kg ha-1 of available P, and 39-145 kg ha-1 of available K. Some of these applications were in conjunction with chemical fertilizers. This suggests a correlation between nutrients supplied by vermicompost and improved wine grape yields, although results vary (Javed et al., 2017; Abd El- Rahman and Bakr, 2022). However, Nguyen et al. (2013) reported no yield response with a combination of vermicompost and compost that supplied 30 kg ha-1 of available N, 24 kg ha-1 of available P and 39 kg ha-1 of available K. The nutrient concentration of vermicompost in the present study was 2.09 % of N, 1.25 % of P, and 2.14 % of K (Table 2.1.). Assuming a 10 % coefficient of availability for N and P, and 90 % for K, it can be concluded that the low, medium, and high rates of application supplied 4.18, 8.36 or 16.72 kg ha-1 of available N, 2.5, 5 or 10 kg ha-1 of available P, and 38.5, 77 or 154 kg ha-1 of available K, respectively, to the soil. Given that equivalent or greater quantities of N, P, and K in medium and high rates were added compared to the earlier studies, it was hypothesized that soil application of vermicompost in the current study, would enhance wine grape yield compared to the grower controls. Contrary to expectations, there was no increase in yield observed in 2020, nor was there any at the higher vermicompost application rates of 3.98 and 7.96 Mg ha-1 in 2021. Furthermore, applying vermicompost at the lowest rate actually led to a decrease in wine grape yields when compared to the standard practices of growers, regardless of whether N was applied or not. Understanding why a lower vermicompost application rate resulted in decreased yield is complex because nutrient levels from all rates of vermicompost and additional minerals were seemingly adequate. In 2020, the lingering effects of the prior year's vermicompost provided enough nutrients for the less vigorous vines in this semi-arid region. Typically, wine grapes have modest nutrient demands, and as woody perennials, they often exhibit a delayed response to nutrients. A portion of the wine grape's nutrient needs for the current year can be met through reserves stored in its woody parts 37 from the previous year. Consequently, the results observed in 2020 may actually reflect the nutrient application from 2019, while the results in 2021 may indicate the absence of application in 2020. The range of wine grape yields obtained in the present study was 11.8-15.9 metric tonnes ha-1, which was lower than 17.6-22.1 metric tonnes ha-1 yield range reported for Superior wine grape (Abd El- Rahman and Bakr, 2022), and within the wide yield range of 9.6-27.4 metric tonnes ha-1 reported for Chardonnay (Reynolds et al., 2007). Considering our 2020 and 2021 results, the hypothesis that soil application of vermicompost would enhance the wine grape yield over grower controls was rejected. 2.4.3. Effects of vermicompost on fruit quality The TA, TSS and pH of wine grape berry juice play an important role in winemaking, through affecting juice color, oxidation rate, biological and protein stability, tartrate stability, metal complexation, and sensory attributes of wine (Zoecklein et al., 2013). Across temperate and tropical regions, the most commonly observed effect of compost or vermicompost application on fruit quality has been a decrease in juice pH (Venkatesh, 1998; Sánchez-Monedero et al., 2019; Yeole, 2021). Effects on other juice characteristics have been measured more rarely and have been variable (Travis et al., 2003; Sánchez-Monedero et al., 2019). Nevertheless, based on these earlier reports it was hypothesized that soil application of vermicompost would enhance wine fruit quality. In the present study, TA and pH levels were slightly affected, depending on the application rate of vermicompost. In 2020, although there was some variation in TA across different rates of vermicompost application (ranging from 8.7 to 9.6 g L-1), none of them differed significantly from the grower controls (with mean values of 9.2 and 9.3 g L-1). Considering that the optimal TA value for white grape falls within the range of 8 to 11 g L-1 (Harbertson, 2010), these slight changes in TA were not considered a significant alteration in fruit quality. In 2021, application of vermicompost significantly increased berry pH value from 3.09 in the “grower control with N” to an average of 3.37-3.43 among vermicompost treatments. The optimum pH for white wine grape is between 3.1 to 3.5 (Zoecklein et al., 1999); therefore, the effect of vermicompost on juice pH could not be considered as an enhancement in juice pH, hence wine grape fruit quality. The TSS was not affected by vermicompost application and its value in the present study was within the optimum range of 20-25 Brix° (Gashu et al., 2020), regardless of 38 treatment. Therefore, the hypothesis that soil application of vermicompost would enhance the wine grape fruit quality when compared to the grower controls was rejected. 2.4.4. Effects of vermicompost on soil organic C concentration Soil organic C plays a fundamental role in enhancing soil biological, chemical and physical properties, which leads to improved water retention and nutrient efficiency, thereby directly contributing to increased crop productivity and resilience (Gerke, 2022). The present study showed that the residual effects of the application of vermicompost in 2019 increased SOC in 2020 relative to the control with added N, but only at the depth of 0-15 cm, and only at the medium application rate. The significant effect at 0-15 cm, can be explained by the fact that vermicompost was applied only on the soil surface and incorporated with the top 5 cm of the soil. In 2021, the medium and high rates of vermicompost increased SOC compared to the grower practice controls with and without N application at both soil depths. Increasing SOC by the application of vermicompost has been reported by other researchers (Syarifinnur et al., 2020; Shen et al., 2022; Wu et al., 2023). The study conducted by Shen et al. (2022) documented a notable augmentation in SOC through the application of sewage sludge-based vermicompost. In their study, various vermicompost application rates (25, 50, 125, and 250 t ha−1) were incorporated into the 0-20 cm surface soil, resulting in increases of 49.8 %, 63.9 %, 89.0 %, and 145.7 % of SOC content over the control, respectively. The findings of our study aligned with these trends, because application of the medium rate of vermicompost in 2019 resulted in a 72 % increase in SOC in 2020, compared to the grower control with added N, and application of the medium and high rates of vermicompost in 2021 resulted in 86.9 %, and 120 % increases in SOC, respectively. Contrary to the results of Shen et al. (2022), the low vermicompost application rate in our study did not result in a statistically significant increase in SOC compared to the grower practice controls. This observation suggests that the low vermicompost application rate did not surpass the rate of decomposition: therefore, there was no increase in SOC. In summary, it was observed that vermicompost enhanced SOC compared to the grower control by the third year of the study; therefore, the hypothesis was accepted. 39 2.4.5. Effects of vermicompost on soil ammonium, nitrate, and total N concentrations Vermicompost is a N-rich material (Elissen et al., 2023), so its application to soil can increase ammonium, nitrate, and total N content of soil (Arancon et al., 2006; Fernández-Bayo et al., 2009; Roy et al., 2010; Zhao et al., 2017). In our study, the lasting impact of using vermicompost in 2019 was mostly negligible on the soil's ammonium and nitrate levels in the samples taken in 2020. However, there were a couple of exceptions, notably, an increase in nitrate concentration during the summer in samples where vermicompost was applied at the highest rate, and an increase in ammonium levels in the fall where it was applied at a medium rate. These changes were observed at a soil depth of 15-30 cm when compared to a standard grower control using N. The increase of nitrate in summer at the highest rate of vermicompost application could be due to the fact that adding vermicompost provided an energy source for soil microorganisms and substrate for mineralization and nitrification processes. The higher temperatures in the summer with presence of moisture from irrigation would have sped up those processes. Nitrification tends to occur more prominently in summer compared to ammonification in soil (Cookson et al., 2002). This is primarily because nitrification is an aerobic process that is favored by higher temperatures and adequate oxygen supply, both of which are typically more prevalent during the warmer summer months when there is enough moisture in soil (Trygar, 2009). On the other hand, while ammonification also occurs throughout the year, its rates are generally less influenced by temperature variations compared to nitrification (Hoyle et al., 2006). Decomposer microorganisms responsible for ammonification are active over a wider temperature range, including temperatures below and above the optimal range for nitrification (Young, 2017). Therefore, while ammonification still occurs in summer, its rate may be relatively low compared to nitrification (Hu et al., 2023). The lack of a residual effect of vermicompost application on soil ammonium and nitrate concentration in most of the sampled soils in 2020 suggests that the nutrients from the vermicompost were utilized by wine grape in 2019, or leached, the downward movement of nitrate with water, during the fall/winter and early spring and did not carry over to the following years. Application of vermicompost increased the ammonium and nitrate concentrations of the soil at both depths in spring 2021; the highest value was observed at the higher application rates of vermicompost. The increase in ammonium and nitrate concentrations of the soil in spring 40 2021 following vermicompost application can be explained by the initial rapid mineralization rate of vermicompost, which was applied four weeks before the spring soil sampling. Application of vermicompost continued to increase nitrate concentration of the soil in 0-15 cm in summer and fall of 2021, but the magnitude of the effect was reduced. This reduction could be attributed to nutrient uptake and consumption by wine grape and soil microbes during the summer growth period (Zhu et al., 2023). Leaching might have also contributed to the decrease in nitrate concentration in fall 2021 (Craswell, 2021), except at 15-30 cm where it may have accumulated. These factors could collectively explain the temporary nature of the response and the observed variations in ammonium and nitrate levels at different sampling dates and soil depths. The nitrate content at 15-30 cm in summer 2020 due to application of vermicompost in 2019, ranged between 21 mg kg-1 in grower control with N to 69 mg kg-1 in high rate of vermicompost application and the ammonium content of soil in 15-30 cm in fall 2020 ranged between 1 mg kg-1 in high rate of vermicompost application to 2 mg kg-1 in medium rate of application. These figures were lower than those observed by Przemieniecki et al. (2021) in which application of 10 and 20 % of fruit waste vermicompost increased soil nitrate content from 78 mg kg-1 in control to 90 and 134 mg kg-1, and soil ammonium content from 14 mg kg-1 in control to 139 and 195 mg kg-1, respectively. On the other hand, the nitrate and ammonium contents of soil in the present study were higher than those observed by Xu and Mou (2016), in which addition of 10 % of commercial granular vermicompost increased nitrate and ammonium contents of sandy loam soil from 2 and 4.7 mg kg-1 to 3.2 and 6.6 mg kg-1, respectively in a greenhouse study in Salinas, California. The present study showed that the residual effects of the application of vermicompost in 2019 increased soil total N in 2020 relative to the control with added N, but only at the depth of 0-15 cm, and only at the medium application rate. Similar to SOC, the higher magnitude of the effect in 0-15 cm can be explained by the fact that vermicompost was applied only on the soil surface and incorporated with the top 5 cm of the soil. There was no significant difference in soil total N among the amended treatments. There was also no difference in soil total N between the grower practice controls with and without N, possibly because the amount of N fertilizer added to the grower control with N was very low when compared to the initial N content of the soil. Additionally, the amount of N fertilizer added to the grower control was easily accessible for 41 plant uptake, leaching, or denitrification. Total N concentrations increased at both soil depths in 2021, probably as cumulative result of fresh vermicompost application and residual effect of vermicompost application from 2019. In 2020, the total soil N in 0-15 cm ranged between 0.06 % at grower control with added N and 0.11 % at the medium rate of vermicompost application. Similarly in 2021 the soil total N in 15-30 cm ranged between 0.04 % in grower control with N to 0.14 % in medium rate of vermicompost application. The soil N concentration in the present study was relatively similar to the observation of Sabijon and Sudaria (2018) in which application of 15 metric tonnes ha-1 of corn cobs, sunflower and cow manure-based vermicompost in a pot culture increased soil total N from 0.12 % to 0.20 %. In summary, the results of present study showed that application of vermicompost in 2019 increased soil nitrate in summer and ammonium in fall at a depth of 15-30 cm in the following year, and application of vermicompost in 2021 increased ammonium and nitrate concentrations of the soil at both depths in spring. Additionally, application of vermicompost enhanced soil total N compared to the grower control in both years; therefore, the hypothesis that soil application of vermicompost would enhance soil extractable inorganic N and soil total N when compared to the grower control was accepted. 42 Chapter 3. Vermicompost Tea 3.1. Synopsis Vermicompost tea, prepared by steeping vermicompost in water, provides beneficial microorganisms, organic matter, humic and fulvic acids, soluble nutrients, and plant growth regulators to plants and soil. It can induce positive plant growth responses similar to solid vermicompost and has significant potential for disease and pest control. To examine the effects of vermicompost on grapevine growth, yield and fruit quality, an experiment was conducted at Blasted Church Vineyards, located south of Penticton, BC, focusing on 34-year-old self-rooted Chardonnay Musqué vines under drip irrigation. The experiment was a randomized complete block design with five treatments and five replications, totaling 25 plots. Treatments included the grower’s standard practice, distilled water sprays as a control, and various frequencies and concentrations of vermicompost tea applications. 3.2. Materials and Methods 3.2.1. Experimental site The experimental site for the vermicompost tea experiment was located at Blasted Church Vineyards; south of Penticton, BC (49° 38′ N, 119° 55′ W). The experimental block consists of 34-year-old self-rooted Chardonnay Musqué under drip irrigation. The soil was a silty loam in the Olhausen soil series (Gough et al., 1994). The vineyard had a permanent ground cover consisting of a mixture of rye grass, fescue, blue grass, white clover, and alfalfa. To manage the ground cover in the alleyways and undervine weeds, pre-emergence and Round upTM herbicides were used during spring and summer as required. The vineyard management including fertilizer application, pest and disease control were consistent with local recommendations (British Columbia Wine Grape Council, 2010). 3.2.2. Experimental design and treatment application The experiment was a randomized complete block design of five treatments and five replications, for total of 25 plots (Figure 3.1). In addition to the five treatments, five plots were randomly selected from five adjacent rows for measurements and samplings as the grower’s practice plots. However, the data from these plots were not fully randomized with the other 43 treatments. The plot size for the vermicompost tea experiment was the same as described for the vermicompost experiment. Treatments were: 1. Grower’s practice 2. Eight distilled water sprays (control) per year 3. Four sprays per year at the recommended rate 4. Eight sprays per year at the recommended rate 5. Four diluted sprays per year 6. Eight diluted sprays per year The vermicompst tea in the present study was applied only in 2021. The application of vermicompost tea began at E-L stage 13, following the Eichhorn-Lorenz system, a standardized method for describing the phenological growth stages of wine grapes (Giese et al., 2020). Subsequent applications were made at E-L stages 17, 19, 21, 23, 25, 28, and 31. In total, eight-spray treatments, which included distilled water, the recommended rate, and diluted sprays, were applied from E-L stage 13 to E-L stage 31. Four-spray treatments, which included the recommended rate and diluted sprays, were applied at E-L stages 13, 19, 23, and 28. 44 Figure 3.1. The layout of the plots in vermicompost tea experiment. 45 3.2.3. Vermicompost tea aerobic preparation and application The vermicompost tea applied in this study was made from the same vermicompost used for the vermicompost experiment, with the same nutrient concentrations (Table 2.2). A 37.9 L compost brewer (Growing Solution Incorporated, Compost Tea System10TM, Eugene, Oregon) was filled with distilled water and 1.1 kg of dry vermicompost, along with 8.5 g of catalyst, added to the brewer tank and brewed for 24 h. During brewing air was pumped into the brewer, the water was stirred and then passed through a mesh containing the vermicompost. The catalyst supplied by the Growing Solutions was a microbial food source that contained complex carbohydrates, soluble kelp, rock powder and a blend of botanical ingredients for optimal microbial growth and diversity (https://store.growingsolutions.com/compost-tea-catalyst-15-oz/). The compost basket had a net body, but the mesh was not fine enough for this purpose. Therefore, after brewing, a second filtering was done to ensure that the fine particles of the compost could not flow into the system and plug the spray equipment and nozzles. Vermicompost tea to water ratios of 1:12.5 (v:v), the manufacturer’s recommended rate was considered as the standard rate. By diluting 10 L of the first rate (1:12.5) into 10 L of distilled water, 20 L of the second rate (1:25) was prepared as the diluted rate. Vermicompost tea was applied to foliage using a backpack CO2 sprayer at the rate of 800 L ha-1. The spray rate was calibrated by spraying into two graduated cylinders for 30 sec and measuring the volume. To accommodate the spray rate, each plot was sprayed for 51 sec (25.5 sec each side) at 40 psi using an aluminium boom with two nozzles (TEE JET 8002VS). The average spray rate was 375 mL per 30 sec. This information was used to calculate the volume of tea that was sprayed on each plot at each application date. Prior to the application, the electrical conductivity (EC) of the compost tea was assessed to ensure that the phytotoxicity risk due to excess salt was minimised. The EC of compost tea was tested to be lower than 1.5 mmhos cm-1. The brewing process was set to run early in the morning and the tea was applied to the plots the following morning. The charactristics of the vermicompost tea used in the present study is shown in Table 3.1. 46 Table 3.1. The characteristics of the vermicompost tea applied in the present study in 2021. aBelow detectable level 3.2.4. Samplings and Analyses The sampling and analysis for petiole N, plant growth, crop yield and fruit quality parameters were performed using the same procedures as described for the vermicompost experiment. The leaf chlorophyll content was measured by using a SPAD meter (Minolta SPAD-502) during veraision. 3.2.5. Statistical analyses For the purpose of this thesis, only data from 2021 have been used, which was part of a larger 5-year study that started in 2018 and ended in 2022. The normality and heteroscedasity of the data were checked; there was no need for data transformation in this study. Analyses of Variance (ANOVAs) were performed on the data using Minitab 12 software. Two types of analyses were performed in this study. In one type six treatments including four diluted sprays, four sprays at the recommended rate, eight diluted sprays, eight sprays at the recommended rate, eight distilled water sprays as control and a grower practice control were analyzed following Mixed Effects Model ANOVA. Whenever significant differences were detected, mean differences were evaluated by Tukey’s multiple comparison test (P-value < 0.05). Vermicompost tea was considered as fixed effects, and year and replication (block) considered as random effects. In the second type of analysis, the two frequencies and the two concentrations of vermicompost tea application were compared and analyzed based on factorial analysis without comparing with the distilled water spray and the grower practice controls. pH EC Total Alkalinity Bicarbonate SO4 SO2 Ca Mg (mmohs cm-1) (µg mL-1) 4.6 1.8 12.2 12.2 283 94.2 75.6 19.4 Na Nitrate-N K Cl Mn Fe B P (µg mL-1) 10.87 1.2 19.6 13.8 0.39 0.26 0.06 BDLa 47 3.3. Results 3.3.1. Effects of vermicompost tea on wine grape growth, yield and fruit quality In 2021, foliar application of vermicompost tea had no effect on the measured wine grape traits and crop production relative to the Grower’s practice or water controls (Tables 3.2; 3.3). Furthermore, when only the four vermicompost tea treatments were considered, most variables were not significantly affected by different frequencies and rates of vermicompost tea application (Tables 3.4; 3.5). Frequency and rate interacted to affect berry weight, however. When applied four times, high concentrations of vermicompost tea (standard rate) resulted in higher berry weight compared to the lower concentration of vermicompost tea (diluted) (Figure 3.2). On the other hand, when applied eight times, diluted vermicompost tea resulted in a higher berry weight than the standard concentration of vermicompost tea. Similarly, foliar application of vermicompost tea did not affect fruit quality parameters, relative to the Grower’s practice control, with the exception of TA (Tables 3.6; 3.7). The eight standard sprays had lower TA compared to the Grower’s practice control. When the vermicompost tea treatments were analyzed separately, while there were no differences between the vermicompost tea treatments and water controls, the frequency and rate of application interacted to affect TSS and TA. At four applications per year, TSS values remained similar for the high (standard rate) and low (diluted) concentrations (Figure 3.3). At eight applications per year, TSS value was higher in high concentration (standard rate) in comparison with low concentration (diluted). While there was no difference in TA between the application of high or low concentrations of vermicompost tea with four applications, when applied eight times per season, low concentration vermicompost tea (diluted) resulted in higher TA compared to high concentration of vermicompost tea (standard) (Figure 3.4). 48 Table 3.2. Effects of foliar application of vermicompost tea on growth and nutrition of Chardonnay wine grapes in 2021. ªTrunk Cross-Sectional Area. bSoil Plant Analysis Development showing leaf chlorophyll content. cThe numbers in brackets show the Standard Error. N = 5. The values in each column with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. dP value, F value and Degree of Freedom are for a Mixed Effects Model ANOVA with six treatments and five replications. deNum = numerator, dfDen = denominator. Treatment TCSAa at Spring (mm2) TCSAa at Fall (mm2) Growth Increment (mm) Pruning Weight (g vine-1) Petiole N (%) SPADb Grower’s practice - - - 706 (43.7) - - Eight water sprays (control) 38.7 (2.40)c 41.2 (3.61) 2.71 (0.35) 752 (28.2) 0.55 (0.03) 46.0 (0.64) Four standard sprays 47.6 (3.1) 51.5 (1.51) 3.92 (0.36) 783 (76.9) 0.52 (0.02) 46.2 (1.20) Eight standard sprays 39.5 (5.04) 44.2 (6.81) 4.62 (0.25) 653 (35.6) 0.64 (0.05) 46.9 (1.27) Four diluted sprays 39.5 (4.34) 44.3 (4.36) 4.17 (0.36) 820 (77.6) 0.58 (0.03) 47.4 (1.83) Eight diluted sprays 46.7 (3.3) 50.4 (3.58) 3.72 (0.12) 764 (92.8) 0.56 (0.02) 46.0 (1.12) P-valued 0.450 0.309 0.793 0.502 0.075 0.629 F-valued 0.96 0.41 0.42 0.90 2.61 0.66 DF Numde 20 16 20 20 16 16 DF Dendf 4 4 4 5 4 4 49 Table 3.3. Effects of foliar application of vermicompost tea on clusters, berry and yield of Chardonnay wine grapes in 2021. Treatment No. of Clusters per vine Cluster Size (g) Berry Weight (g) Yield (metric tonnes ha-1) Grower’s practice 21.40 (0.90)a 82.55 (6.06) 0.93 (0.05) 7.136 (0.34) Eight water sprays (control) 24.40 (1.40) 77.13 (10.20) 0.87 (0.04) 7.804 (1.45) Four standard sprays 20.93 (2.54) 85.51 (6.74) 0.89 (0.02) 7.390 (1.13) Eight standard sprays 24.06 (1.17) 81.15 (7.80) 0.79 (0.05) 7.901 (0.66) Four diluted sprays 23.00 (1.22) 70.66 (5.73) 0.81 (0.03) 6.537 (0.34) Eight diluted sprays 22.86 (2.33) 80.63 (4.06) 0.87 (0.04) 7.519 (0.87) P-valueb 0.657 0.744 0.172 0.901 F-valueb 0.66 0.54 1.70 0.31 DF Numbc 24 24 24 24 DF Denbd 5 5 5 5 ªThe numbers in brackets show the Standard Error. N = 5. bP value, F value and Degree of Freedom are for a Mixed Effects Model ANOVA with six treatments and five replications. cNum = numerator, dDen = denominator. Table 3.4. Factorial analysis of the foliar application of vermicompost tea at two frequencies1 and two concentrations2 on growth and nutrition of Chardonnay wine grapes in 2021. Source of Variation P-Value TCSAa at Spring TCSAa at Fall Pruning Weight Petiole N SPADb Frequency 0.905 0.870 0.226 0.149 0.771 Rate 0.900 0.859 0.333 0.817 0.912 Frequency*Rate 0.051 0.707 0.623 0.070 0.452 1Applying 4 and 8 times in growing season, 2 Standard (vermicompost tea: water at 1:12.5 dry VC/water ratio) and diluted (vermicompost tea: water at 1:25 dry VC/water ratio). ªTrunk Cross-Sectional Area, bSoil Plant Analysis Development showing leaf chlorophyll content. Table 3.5. Factorial analysis of the foliar application of vermicompost tea at two frequencies1and two concentrations2 on clusters, berry and yield of Chardonnay wine grapes in 2021. Source of Variation P-Value No. of Cluster per vine Cluster Size Berry Weight Yield Frequency 0.446 0.659 0.668 0.365 Rate 0.824 0.236 0.974 0.452 Frequency*Rate 0.408 0.267 0.041 0.773 1Applying 4 and 8 times in growing season, 2 Standard (vermicompost tea: water at 1:12.5 dry VC/water ratio) and diluted (vermicompost tea: water at 1:25 dry VC/water ratio). 50 Table 3.6. Effects of foliar application of vermicompost tea on fruit quality parameters of Chardonnay wine grapes in 2021. Treatment TSSa (Brix°) Juice pH TAb (g L-1) Calculated YANc (mg L-1) Measured YANc (mg L-1) Grower’s practice 21.9 (0.25)d 3.46 (0.03) 9.10 a (0.04) 211.2 (3.92) 316.1 (5.87) Eight water sprays (control) 22.1 (0.19) 3.45 (0.11) 8.20 ab (0.04) 220.4 (16.10) 329.8 (24.10) Four standard sprays 21.4 (0.24) 3.51 (0.05) 8.10 ab (0.01) 229.2 (14.80) 342.9 (22.10) Eight standard sprays 22.3 (0.24) 3.48 (0.15) 6.90 b (0.03) 235.9 (20.20) 352.9 (30.20) Four diluted sprays 21.7 (0.26) 3.51 (0.05) 7.90 ab (0.03) 209.3 (11.00) 313.2 (16.40) Eight diluted sprays 21.7 (0.11) 3.55 (0.03) 8.12 ab (0.04) 244.9 (18.80) 366.3 (28.10) P-valuee 0.089 0.956 0.006 0.295 0.295 F-valuee 2.19 0.21 4.35 1.32 1.32 DF Numef 24 24 24 20 20 DF Deneg 5 5 5 5 5 ªTotal Soluble Solid, bTitratable Acidity, cYeast Assimilable N. dThe numbers in brackets show the Standard Error. N = 5. The values in each column with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. eP value, F value and Degree of freedom are for a Mixed Effects Model ANOVA with 6 treatments and 5 replications. fNum = numerator, gDen = denominator. Table 3.7. Factorial analysis of the application of vermicompost tea at two frequencies1 and two concentrations2 on fruit quality parameters of Chardonnay wine grapes in 2021. Source of Variation P-Value TSSa Juice pH TAb Calculated and Measured YANc Frequency 0.068 0.928 0.116 0.221 Rate 0.563 0.653 0.089 0.747 Frequency*Rate 0.034 0.688 0.020 0.397 1Applying 4 and 8 times in growing season, 2Standard (vermicompost tea: water at 1:12.5 dry VC/water ratio) and diluted (vermicompost tea: water at 1:25 dry VC/water ratio). ªTotal Soluble Solid, bTitratable Acidity, cYeast Assimilable N. 51 Figure 3.2. Box plot showing the interacting effects of rate and frequency of vermicompost tea application on berry weight based on the factorial analysis with two levels of frequency (four and eight times per season) and two levels of rate (standard and diluted). Horizontal lines inside the boxes show medians and red dots show the mean values. The values in boxes with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test; P-value = 0.041, and N = 5. Figure 3.3. Box plot showing the interacting effects of rate and frequency of vermicompost tea application on Total Soluble Solid (TSS; Brix°) based on the factorial analysis with two frequencies (4 and 8 times per season) and two rates (standard and diluted). Horizontal lines inside the boxes show medians and red dots show the mean value. The values in box with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test; P-value = 0.034, and N = 5. 52 Figure 3.4. Box plot showing the interacting effects of rate and frequency of vermicompost tea application on Titratable Acidity based on the factorial analysis with two frequencies (4 and 8 per season) and two rates (standard and diluted). Horizontal lines inside the boxes show medians and red dots show the mean value. The values in box with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test; P-value = 0.020, and N = 5. 3.4. Discussion We hypothesized that the foliar application of vermicompost tea would enhance wine grape yield, growth, fruit quality, and petiole N relative to a standard grower’s practice control. The results did not show significant effects on foliar application of vermicompost tea on wine grape yield, growth, fruit quality and petiole N relative to standard grower’s practice control except for TA. The eight applications of vermicompost at the standard rate reduced TA compared to the Grower’s practice control but showed no significant difference from the eight water spray control. This effect may partly be attributed to the additional water applied to the foliage in both the eight water spray control and the eight vermicompost spray treatment, which was not provided to the Grower’s practice control. Therefore, the hypotheses that the foliar application of vermicompost tea would enhance wine grape yield, growth, and petiole N relative to a standard grower’s practice control were rejected. The hypothesis that the foliar application of vermicompost tea would enhance wine grape fruit quality relative to a standard grower’s practice control was also rejected. 53 We also hypothesized that foliar application of vermicompost tea at 1:25 dry weight/water ratio would have similar effects on wine grape yield, growth and fruit quality as vermicompost tea at 1:12.5 dry weight/water ratio when applied with the same frequency during the growing season without comparing with water spray control. This hypothesis, as it related to grapevine growth and yield, was accepted because effects of application of vermicompost tea in both lower and higher concentrations with less and more number of applications on growth parameters and yield were the same. In one of the few studies on the effects of vermicompost tea on grapevines, Popescu and Popescu (2018) found that foliar application of humic substances derived from vermicompost enhanced total leaf area, leaf fresh and dry weight, plant growth, physiological activity, yield, and berry quality of two commercial table grapevine cultivars (Feteasca Regala and Riesling Italian) in Romania. In their study the maximum values of leaf area, fresh and dry weight were observed at the highest humic acid concentration (50 ml L-1). However, in agreement with our observations, Cangi et al. (2006) in their study of effects of soil and foliar application of humic acid on grapevine (Vitis vinifera L.) cv Ercis did not observe any significant effect on yield and bunch weight. We also hypothesized that foliar application of vermicompost tea four times during the season would have similar effects on wine grape yield, growth, and fruit quality as eight applications of vermicompost tea at the same concentration. The result of the present study showed that application frequency and concentration of vermicompost tea interacted to affect average berry weight. When applied four times, the high concentration of vermicompost tea resulted in higher berry weight compared to the lower concentration of vermicompost tea. On the other hand, when applied eight times, low concentration of vermicompost tea resulted in a higher berry weight than high concentration of vermicompost tea. Ferrara and Brunetti (2010) reported that lower levels of humic acid increased berry weight and size of table grape (Vitis vinifera L.) cv Italia. Furthermore, the higher frequency of application of vermicompost tea at the standard concentration resulted in the lowest value of TA. We also observed that high concentration and more frequent applications resulted in the highest level of TSS. This result was consistent with the results of a study on the effects of soil and foliar application of humic acid on wine grapevines (Vitis vinifera L.) cv Ercis (Cangi et al., 2006) in which they observed a significant decrease in TA and a significant increase in TSS. Ferrara and Brunetti (2010), in their study of spray application of soil-based humic acid on table grape (Vitis vinifera L.) cv Italia, observed 54 that application of humic acid induced a significant decrease of TA and a significant increase of the °Brix/TA ratio compared to the control treatment. Mohamadineia et al. (2015) in their study of the effects of soil and foliar application of humic acid on table grape (Vitis vinifera L.) cv Askari found the opposite. They found that foliar application of humic acid increased TA and decreased TSS while soil application of humic acid increased both TA and TSS compared to control. Therefore, the results of our experiment were consistent with those of Cangi et al. (2006) and Ferrara and Brunetti (2010) but different from those of Mohamadineia et al. (2015). Nevertheless, based on the experimental results the hypothesis were rejected for berry weight, TA and TSS. 55 Chapter 4. Seaweed Extract 4.1. Synopsis Seaweed extract can benefit grapevine production, by improving plant establishment, enhancing rachis stretch, increasing fruit set, and boosting yields. It contributes to plant vigor and vitality through various bioactive substances, improves nutrient uptake, and stimulates plant growth, leading to higher germination rates, better root development, increased leaf area, and enhanced fruit quality. To evaluate the effects of seaweed extract on grapevine growth, yield and fruit quality under different soil and climate conditions, two set of experiments were conducted: one in British Columbia (BC) and another one in Nova Scotia (NS), in 2020 and 2021. In both locations the randomized complete block designs were carried out with six treatments and five replications, totaling 30 plots. Treatments included three or six foliar or soil applications of low or high concentrations of seaweed extract, compared to a control group receiving foliar distilled water. 4.2. Materials and Methods 4.2.1. Experimental sites The experimental site for the experiment in BC was located at Thomas Ranch Vineyards in Oliver, south of Okanagan Falls, BC (49° 32′ N, 119° 55′ W). The experimental block consisted of 10-year-old Chardonnay Clone 76 wine grapes on SO4 rootstock under micro-sprinkler irrigation. The vine spacing for the experiment in BC was the same as the experiment of vermicompost. The soil at the BC site, and average annual precipitation and daily temperature, are described in Chapter 2 (section 2.2.1). The ground cover, weed, pest and disease management were the same as the vermicompost and vermicompost tea experiments. The NS site was at Ellslea Farms, NS (45° 09' N, 64° 29' W). The experimental block consisted of 10-year-old Chardonnay Clone 548 wine grapes on 3309 rootstock and the vineyard was rainfed. The distance between two adjacent vines was 0.9 m and space between two adjacent rows was 2.75 m. The vineyard had a permanent cover crop of rye grass, fescue, blue grass, red and white clover. Weeds were managed mechanically, and pest and disease management were consistent with local recommendations. The soil was a silty clay in PN Pelton soil series (Cann et al., 1965). The average annual precipitation over 30 years (1991-2020) in Greenwood Nova 56 Scotia (20 km west of the experimental site in Canning), was 1064 mm (Environment Canada, 2024). During the growing season (from April until October) the daily average temperature over 1991-2020 was 13.8 °C and the monthly average precipitation was 87.3 mm. The average minimum daily temperature was -9.8 °C and -9.6 °C in January and February, respectively, and the average maximum was 20.1 °C and 19.4 °C in July and August, respectively. The daily average temperature throughout the year was 7.4 °C. 4.2.2. Experimental design and treatment application The experiments in both BC and NS were randomized complete block designs with six treatments and 5 replications, for total of 30 plots (Figures 4.1 and 4.2). Treatments consisted of: 1. Six foliar applications of distilled water (control) per year. 2. Three foliar applications of seaweed extract at 2.5 L ha-1. 3. Six foliar applications of seaweed extract at 2.5 L ha-1. 4. Three foliar applications of seaweed extract at 5 L ha-1. 5. Six foliar applications of seaweed extract at 5 L ha-1. 6. Three foliar and two soil applications of seaweed extract at 5 L ha-1. Seaweed extract was in liquid form, and the values of 2.5 L ha-1 and 5 L ha-1 were the rates of application of the actual product. At each spraying date all the plots were sprayed by seaweed extract or distilled water. In treatments 2, 4 and 6, which received seaweed extract spray only three times per year, they were sprayed with distilled water at the other three times. The three times spray were only after flowering, but six times spray included sprays before and after flowering. Application of seaweed extract started in 2018 and continued until end of the 5-year- project in 2022. The plot size in BC was the same as the experiment of vermicompost. In NS, the experiment comprised five rows with six plots in each row. The treatments were randomly applied to the plots in each row. Each plot consisted of six vines; the first and last vines were guard vines, and three out of the four middle vines were data vines. The experimental design and treatment application was like the experiment in BC. In both experiments, similar to the vermicompost tea experiment, foliar applications of seaweed extract were made using a backpack CO2 sprayer at the rate of 800 L ha-1. The sprayers were calibrated using the same procedure as used for vermicompost tea (section 3.2.3). The nutrient concentrations of the 57 seaweed extract (Stella MerisTM) produced by Acadian Plant Health manufacturer in Dartmouth, Nova Scotia, a water-soluble, alkaline extract powder derived from the brown seaweed Ascophyllum nodosum (L.) applied in the present study are depicted in the Table 4.1 (Alam et al., 2013). Table 4.1. The nutrient concentrations of the seaweed extract applied in the present study. N (%) P (%) K (%) Ca (%) Mg (%) 1 0.5 15 0.4 0.4 Fe (ppm) B (ppm) Zn (ppm) Mn (ppm) Cu (ppm) 155 124 91 121 5 58 Figure 4.1. The layout of the plots in Seaweed Extract experiment in BC. 59 Figure 4.2. The layout of the plots in Seaweed Extract experiment in NS. 60 4.2.3. Sampling and Analyses 4.2.3.1. Soil sampling and analyses In the BC experiment, the soil samples were collected from two depths (0-15 and 15-30 cm) of the plots of treatment 1 (control) and treatment 6, which received two soil applications of seaweed extract. They were collected in July and October 2020 and in May, July and October 2021 to examine for nitrate and ammonium following the same procedure as vermicompost experiment. 4.2.3.2. Petiole, yield and grape cluster sampling and analysis The sampling and analysis for petiole, yield and cluster in both BC and NS experiments were performed using the same procedure as described in sections 2.2.3.2 and 2.2.3.3. The leaf chlorophyll content was measured by using a SPAD meter (Minolta SPAD-502) during veraision. 4.2.3.3. Cluster looseness Cluster looseness was measured only in the BC experiment. At harvest, cluster looseness was determined on the 12 clusters collected for the fruit quality measurement before they were processed for fruit quality using a rating scale adapted from Gohil and Ward (2020). The cluster looseness rating was as follows: 1 = almost all berries touching each other 2 = more than half of berries touching each other 3 = a few berries touching each other 4 = most not touching with a few gaps into the center of the cluster 5 = most berries are separate from each other with much of rachis clearly visible. 4.2.3.4. Pedicle and rachis length Pedicle and rachis length were measured only in the BC experiment. After harvest, pedicle and rachis length were measured on the 12 clusters collected for the fruit quality measurement after they were processed for fruit quality using a scanner. The rachis was scanned 61 by a scanner and the scanned pictures were saved in a file in a computer. Pedicle and rachis length was measured by Image J software. 4.2.3.5. Bud cold hardiness Bud cold hardiness measurement was conducted only in the BC experiment. It was measured by collecting buds from the data vines in each plot and placing them on thermocouples in a controlled temperature freezer (Martinson et al., 2011). Buds were collected four times in 2020, and seven times in 2021 from November till March, at the beginning of the cold season (during acclimation), during the period when hardiness was fully developed and at the end of the cold season (during deacclimation). The samplings were done to detect and record the response of buds to change of ambient temperature. At each sampling, one cane from each plot was collected randomly. After cutting the canes and labeling them, they were kept in a cooler and transported to the laboratory. In the laboratory, five buds from each cane were picked and placed in each cell of the trays. The buds were placed on thermocouples in a controlled-temperature freezer (Tenney Thermal Product Solutions, New Columbia, Pennsylvania) to determine lethal temperatures. The freezer was programmed to hold at 3 °C for 1 h, drop to -40 °C in 11 h (a cooling rate of 4 °C h-1). As the temperature in the freezer gradually decreased to -28 °C, each bud released a small amount of heat at the point when the bud froze, which is called a low temperature exotherm. In plant tissues, exotherms occur at different temperature ranges and indicate different freezing processes. High Temperature Exotherms (HTEs) generally occur at temperatures around -5 °C to -15 °C and are associated with the freezing of extracellular water, which does not usually cause lethal damage to the plant tissue. In contrast, Low Temperature Exotherms (LTEs) occur at lower temperatures, typically between -20 °C and -40 °C, and are associated with the freezing of intracellular water. LTEs are critical for determining cold hardiness because they indicate lethal freezing that damages the cells and can kill the buds. In the context of my study, the focus was on LTEs to measure the lethal temperature for buds, providing insight into their cold hardiness and freeze tolerance. The heat was detected by the thermocouples, allowing a precise estimate of the lethal temperature for that bud (Martinson et al., 2011). 62 4.2.4. Statistical analyses For the purpose of this thesis, data from 2020 and 2021 have been used which was part of a larger 5-year study that started in 2018 and ended in 2022. The normality and heteroscedasity of the data were checked; there was no need for data transformation in this study. Analyses of Variance (ANOVAs) were performed using the same procedures as in the vermicompost experiment by using Minitab 12 software. Three types of analyses were performed in this study. In one type six treatments including three foliar applications of seaweed extract at low rate, six foliar applications of seaweed extract at low rate, three foliar applications of seaweed extract at high rate, six foliar applications of seaweed extract at high rate, three foliar applications of seaweed extract at low rate and two soil applications of seaweed extract at high rate, and six distilled water sprays as control were analyzed following Mixed Effects Model ANOVA. Whenever significant differences were detected, mean differences were evaluated by Tukey’s multiple comparison test (P-value < 0.05). Seaweed extract was considered as a fixed effect, and year and replication (block) considered as random effects. In the second type of analysis, the two frequencies and the two concentrations of seaweed extract application were compared and analyzed based on factorial analysis without comparing with the distilled water spray and the soil application seaweed extract. In the third type of analysis Repeated Measures ANOVA were used to assess significant differences in soil ammonium and nitrate concentrations and bud cold hardiness across sampling dates using R version 4.1.0 (R Core Team, 2021) with the aov function from the nlme package (Pinheiro et al., 2021). Where significant differences were detected, mean differences were evaluated by Tukey’s multiple comparison test (P-value < 0.05). 63 4.3. Results 4.3.1. Results of the British Columbia experiment 4.3.1.1. Effects of seaweed extract on growth and petiole nitrogen In both 2020 and 2021, there were no effects of seaweed extract on the growth and nutrition of wine grapes (Tables 4.2, 4.3). Furthermore, these parameters were not significantly affected by different frequencies and rates of seaweed extract application when analyzed independently of the controls (Tables 4.4, 4.5). Table 4.2. Effects of seaweed extract on growth of Chardonnay wine grapes in the British Columbia experiment in 2020. ªTrunk Cross-Sectional Area. bThe numbers in brackets show the Standard Error. N = 5. cP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. dNum = numerator, eDen = denominator. Seaweed extract treatment TCSAa at Spring (mm2) TCSAa at Fall (mm2) Growth Increment (mm) Petiole N (%) Application rate (L ha-1) Number of applications 0 6 foliar 12.8 (0.48)b 14.4 (0.67) 1.55 (0.48) 0.45 (0.01) 2.5 3 foliar 13.1 (0.59) 13.5 (0.90) 0.23 (1.55) 0.43 (0.01) 2.5 6 foliar 13.8 (0.74) 14.9 (1.12) 1.03 (0.67) 0.43 (0.01) 5 3 foliar 12.4 (0.80) 12.8 (1.06) 0.38 (029) 0.44 (0.01) 5 6 foliar 12.9 (0.88) 14.5 (1.51) 1.53 (0.70) 0.43 (0.01) 5 3 foliar + 2 soil applications 12.5 (0.57) 14.3 (1.05) 1.71 (0.50) 0.45 (0.01) P-valuec 0.719 0.766 0.603 0.316 F-valuec 0.57 0.51 0.74 1.27 DF Numcd 19.45 24 23 20 DF Dence 5 5 5 5 64 Table 4.3. Effects of seaweed extract on growth and nutrition of Chardonnay wine grapes in the British Columbia experiment in 2021. Seaweed extract treatment TCSAa at Spring (mm2) (res)1 TCSAa at Fall (mm2) Growth Increment (mm) Petiole N (%) SPADb Application rate (L ha-1) Number of applications 0 6 foliar 14.4 (0.67)c 16.5 (0.90) 2.09 (0.37) 0.40 (0.01) 41.3 (1.16) 2.5 3 foliar 13.5 (0.90) 15.9 (0.27) 1.67 (0.23) 0.39 (0.02) 39.5 (1.30) 2.5 6 foliar 14.9 (1.12) 16.6 (0.38) 2.47 (0.63) 0.39 (0.02) 40.3 (1.27) 5 3 foliar 12.8 (1.06) 14.4 (0.99) 1.59 (0.14) 0.41 (0.02) 41.0 (1.46) 5 6 foliar 14.5 (1.51) 16.1 (1.51) 1.63 (0.08) 0.38 (0.01) 39.4 (0.80) 5 3 foliar + 2 soil applications 14.25 (1.05) 16.1 (0.92) 1.87 (0.25) 0.42 (0.01) 41.8 (0.82) P-valued 0.766 0.581 0.379 0.523 0.622 F-valued 0.51 0.77 1.12 0.86 0.71 DF Numde 24 24 22 20 24 DF Dendf 5 5 5 5 5 1As a result of applied treatment in 2020. ªTrunk Cross-Sectional Area. bSoil Plant Analysis Development showing leaf chlorophyll content. cThe numbers in brackets show the Standard Error. N = 5. The values in each column with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. dP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. eNum = numerator, fDen = denominator. Table 4.4. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on Chardonnay wine grapes growth and nutrition in the British Columbia experiment in 2020. Source of Variation P-value TCSAa at Spring TCSAa at Fall Growth Increment Petiole N Frequency 0.362 0.286 0.399 0.424 Rate 0.286 0.854 0.384 0.504 Frequency*Rate 0.834 0.861 0.838 0.179 1 3 and 6 frequencies, 2 Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. ªTrunk Cross-Sectional Area. 65 Table 4.5. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on Chardonnay wine grapes growth and nutrition in the British Columbia experiment in 2021. Source of Variation P-Value TCSAa at Spring TCSAa at Fall Growth Increment SPADb Petiole N Rate 0.286 0.520 0.399 0.650 0.632 Frequency 0.854 0.392 0.384 0.603 0.355 Frequency*Rate 0.861 0.908 0.838 0.196 0.234 1 3 and 6 frequencies, 2 Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. ªTrunk Cross-Sectional Area. bSoil Plant Analysis Development showing leaf chlorophyll content. In 2020, clusters, berry weight and yield were generally not affected by seaweed extract application, either in comparison with controls (Table 4.6) or when only the frequencies and rates of seaweed extract application were considered (Table 4.7). Table 4.6. Effects of seaweed on clusters, berry and yield of Chardonnay wine grapes in the British Columbia experiment in 2020. Seaweed extract treatment No. of Cluster per vine Cluster Size (g) Cluster looseness Berry Weight (g) Yield (metric tonnes ha-1) Application rate (L ha-1) Number of applications 0 6 foliar 28.9 (3.68)a 130.6 (13.0) 2.23 (0.71) 1.43 (0.06) 14.748 (1.02) 2.5 3 foliar 28.5 (1.62) 133.0 (11.3) 2.00 (0.32) 1.47 (0.04) 15.241 (0.87) 2.5 6 foliar 30.8 (2.63) 137.0 (14.7) 1.90 (0.26) 1.42 (0.07) 16.976 (1.37) 5 3 foliar 30.2 (2.33) 115.2 (6.7) 2.90 (0.53) 1.33 (0.08) 14.083 (1.10) 5 6 foliar 26.3 (2.21) 124.9 (17.1) 1.95 (0.12) 1.31 (0.09) 13.221 (2.18) 5 3 foliar + 2 soil applications 31.1 (1.71) 108.8 (7.2) 2.63 (0.28) 1.27 (0.06) 13.717 (0.95) P-valueb 0.436 0.378 0.374 0.052 0.477 F-valueb 1.01 1.13 1.14 2.67 0.93 DF Numbc 20 20 18.88 20 24 DF Denbd 5 5 5 5 5 ªThe numbers in brackets show the Standard Error. N = 5. bP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. cNum = numerator, dDen = denominator. 66 Table 4.7. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on Chardonnay wine grapes growth and yield in the British Columbia experiment in 2020. Source of Variation P-value No. of Cluster per vine Cluster Size Cluster looseness Berry Weight Yield Frequency 0.596 0.455 0.122 0.716 0.731 Rate 0.540 0.152 0.287 0.054 0.064 Frequency*Rate 0.104 0.692 0.208 0.646 0.385 1 3 and 6 frequencies, 2 Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. In 2021, the number of clusters per vine, cluster size, berry weight and yield were not affected by seaweed extract when compared to controls (Table 4.8). However, when the seaweed extract treatments were analyzed separately, frequency and rate interacted to affect number of clusters per vine and yield (Table 4.9). When applied three times, the number of clusters per vine and yield remained constant with increasing concentration of seaweed extract. On the other hand, when applied six times, the higher concentration of seaweed extract (5 L ha-1) resulted in fewer clusters per vine and yield than the lower concentration of seaweed extract (2.5 L ha-1) (Figures 4.3; 4.4). 67 Table 4.8. Effects of seaweed extract on growth and yield of Chardonnay wine grapes in the British Columbia experiment in 2021. ªThe numbers in brackets show the Standard Error. N = 5. The values in boxes with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. bP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. cNum = numerator, dDen = denominator. Table 4.9. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on Chardonnay wine grapes growth and yield in the British Columbia experiment in 2021. Source of Variation P-Value No. of Cluster per vine Cluster Size Berry Weight Yield Rate 0.468 0.848 0.520 0.537 Frequency 0.280 0.783 0.094 0.381 Frequency*Rate 0.008 0.838 0.057 0.031 1 3 and 6 frequencies, 2 Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. Seaweed extract treatment No. of Cluster per vine Cluster Size (g) Berry Weight (g) Yield (metric tonnes ha-1) Application rate (L ha-1) Number of applications 0 6 foliar 33.7 ab (1.16) 112.3 (6.31) 1.44 (0.02) 15.399 (0.90) 2.5 3 foliar 27.4 b (1.96) 123.9 (6.89) 1.57 (0.06) 13.977 (1.53) 2.5 6 foliar 35.4 a (1.59) 121.9 (7.55) 1.39 (0.06) 17.703 (1.69) 5 3 foliar 32.7 ab (3.01) 119.7 (3.97) 1.42 (0.02) 15.781 (1.07) 5 6 foliar 28.1 ab (0.78) 124.4 (2.90) 1.46 (0.04) 14.287 (0.61) 5 3 foliar + 2 soil applications 30.8 ab (2.66) 129.0 (4.73) 1.47 (0.06) 16.091 (1.16) P-valueb 0.064 0.445 0.181 0.265 F-valueb 2.44 0.99 1.67 1.40 DF Numbc 24 24 24 20 DF Denbd 5 5 5 5 68 Figure 4.3. Box plot showing the interacting effects of rate and frequency of seaweed extract application on the number of clusters per vine based on the factorial analysis of the application of seaweed extract in two frequencies (4 and 8 per season) and two rates (low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1), in the British Columbia experiment in 2021. Horizontal lines inside the boxes show medians and red dots show the mean value. The values in boxes with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test; P-value = 0.008, and N = 5. Figure 4.4. Box plot showing the interacting effects of rate and frequency of seaweed extract application on yield based on the factorial analysis of the application of seaweed extract in two frequencies (4 and 8 per season) and two rates (low concentration = 2.5 L ha-1 and high concentration= 5 L ha-1), in the British Columbia experiment in 2021. Horizontal lines inside the boxes show medians and red dots show the mean value. The values in box with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test; P-value = 0.031, N = 5. 69 4.3.1.2. Effects of seaweed extract on wine grape fruit quality parameters In 2020, the effect of seaweed extract on TSS, and Juice pH was not significant (Tables 4.10; 4.11), whereas TA was significantly affected by application of seaweed extract. TA was significantly higher with six foliar applications of seaweed extract at 2.5 L ha-1 than with three foliar applications of seaweed extract at 2.5 L ha-1; the remaining treatments were intermediate. In 2021, fruit quality parameters were not affected by seaweed extract either when compared with controls (Table 4.12) nor when the frequency and rate of seaweed extract foliar application were analyzed (Table 4.13). Table 4.10. Effects of seaweed extract on fruit quality parameters of Chardonnay wine grapes in the British Columbia experiment in 2020. Seaweed extract treatment TSSa (Brix°) Juice pH TAb (g L-1) Application rate (L ha-1) Number of applications 0 6 foliar 23.3 (0.08)c 3.53 (0.04) 8.8 ab (0.02) 2.5 3 foliar 22.9 (0.30) 3.51 (0.03) 8.0 b (0.03) 2.5 6 foliar 23.4 (0.06) 3.57 (0.05) 8.9 a (0.02) 5 3 foliar 23.2 (0.28) 3.50 (0.06) 8.3 ab (0.02) 5 6 foliar 23.3 (0.22) 3.58 (0.03) 8.2 ab (0.02) 5 3 foliar + 2 soil applications 23.4 (0.37) 3.59 (0.06) 8.7 ab (0.01) P-valued 0.687 0.657 0.026 F-valued 0.62 0.66 3.15 DF Numde 20 20 23 DF Dendf 5 5 5 ªTotal Soluble Solid, bTitratable Acidity, cThe numbers in brackets show the Standard Error. N = 5. The values in each column with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. dP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. eNum = numerator, fDen = denominator. 70 Table 4.11. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on Chardonnay wine grapes fruit quality parameters in the British Columbia experiment in 2020. Source of Variation P-Value TSSa Juice pH TAb Frequency 0.273 0.300 0.169 Rate 0.559 0.605 0.543 Frequency*Rate 0.290 0.836 0.010 1 3 and 6 frequencies, 2 Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. ªTotal Soluble Solid, bTitratable Acidity. Table 4.12. Effects of seaweed extract on fruit quality parameters of Chardonnay wine grapes in the British Columbia experiment in 2021. Seaweed extract treatment TSSa (Brix°) Juice pH TAb (g L-1) Calculated YANc (mg L-1) Measured YANc (mg L-1) Application rate (L ha-1) Number of applications 0 6 foliar 23.1 (0.14) 3.33 (0.13) 1.07 (0.10)d 190.7 (8.82) 285.3 (13.2) 2.5 3 foliar 23.2 (0.13) 3.06 (0.11) 1.08 (0.11) 181.9 (12.8) 272.3 (14.2) 2.5 6 foliar 23.1 (0.17) 3.33 (0.13) 1.04 (0.05) 163.8 (14.87) 245.1 (17.27) 5 3 foliar 23.2 (0.28) 3.26 (0.10) 0.99 (0.02) 154.6 (16.3) 231.3 (15.4) 5 6 foliar 23.2 (0.13) 3.43 (0.02) 1.10 (0.06) 190.0 (16) 284.3 (18.9) 5 3 foliar + 2 soil applications 23.1 (0.15) 3.32 (0.14) 1.02 (0.06) 162.6 (14.6) 243.3 (21.9) P-valued 0.989 0.295 0.740 0.578 0.578 F-valued 0.11 1.30 0.55 0.78 0.78 DF Numde 20 24 20 20 20 DF Dende 5 5 5 5 5 ªTotal Soluble Solid, bTitratable Acidity, cYeast Assimilable Nitrogen. dThe numbers in brackets show the Standard Error. N = 5. eP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. fNum = numerator, gDen = denominator. 71 Table 4.13. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on Chardonnay wine grapes fruit quality parameters in the British Columbia experiment in 2021. Source of Variation P-Value TSSa Juice pH TAb Calculated and Measured YANc Rate 0.869 0.106 0.376 0.937 Frequency 0.936 0.408 0.120 0.717 Frequency*Rate 0.840 0.502 0.678 0.183 1 3 and 6 frequencies, 2 Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. ªTotal Soluble Solid, bTitratable Acidity, cYeast Assimilable Nitrogen. 4.3.1.3. Effects of seaweed extract on bud cold hardiness of wine grapes Over the winter of 2020/21, application of seaweed extract had no effect on bud cold hardiness regardless of whether application treatments were compared with controls (Table 4.14) or analyzed separately (Table 4.15). A repeated measure approach indicated that, regardless of the treatment application, the greatest bud cold hardiness on the dates sampled was observed on Feb 02, 2021. Cold hardiness ranged between -24 to -25 °C on this date (Figure 4.5). Table 4.14. Effects of seaweed extract on Chardonnay wine grapes bud cold hardiness at different samplings in the British Columbia experiment in 2020. Seaweed extract treatment Nov 06, 2020 Dec 01, 2020 Feb 02, 2021 Mar 04, 2021 Application rate (L ha-1) Number of applications 0 6 foliar -19.0 (0.39) -23.2 (0.15) -23.8 (0.21) -22.5 (0.40) 2.5 3 foliar -19.2 (0.35) -23.5 (0.78) -24.2 (0.36) -22.3 (0.27) 2.5 6 foliar -18.5 (0.50) -22.7 (0.15) -24.2 (0.50) -22.3 (0.38) 5 3 foliar -18.8 (0.24) -22.9 (0.68) -24.2 (0.35) -22.1 (0.32) 5 6 foliar -19.1 (0.80) -23.4(0.36) -24.6 (0.47) -23.0 (0.44) 5 3 foliar + 2 soil applications -19.1 (0.39) -23.8 (0.50) -24.5 (0.38) -22.8 (0.23) P-valueb 0.876 0.546 0.486 0.240 F-valueb 0.35 0.83 0.93 1.48 DF Numbc 22 20 19.08 20 DF Denbd 5 5 5 5 ªThe numbers in brackets show the Standard Error. N = 5. bP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. cNum = numerator, dDen = denominator. 72 Table 4.15. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on Chardonnay wine grapes bud cold hardiness in the British Columbia experiment in 2020. Source of Variation P-Value Nov 06, 2020 Dec 01, 2020 Feb 02, 2021 Mar 04, 2021 Rate 0.744 0.589 0.482 0.192 Frequency 0.525 0.502 0.747 0.361 Frequency*Rate 0.304 0.456 0.783 0.397 1 3 and 6 frequencies, 2 Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. Figure 4.5. Wine grapes bud cold hardiness at four sampling dates (Nov 2020, Dec 2020, Feb 2021, and Mar 2021). Date of sampling (DF numerator = 3, DF denominator = 6, F-value = 44.873, P-value < 0.001). Treatment (DF numerator = 5, DF denominator = 10, F-value = 1.021, P-value = 0.455). Interacting of sampling date and treatment (DF numerator = 15, DF denominator = 30, F-value = 0.977, P-value = 0.501) based on repeated measure test, N = 5. 73 Over the winter of 2021/22, seaweed extract had an effect on measured bud cold hardiness only on March 3rd, regardless of whether the statistical tests included control treatments (Table 4.16) or when the effects of different frequencies and rates of seaweed extract application were evaluated separately (Table 4.17). On this date, three foliar and two soil applications of seaweed extract resulted in the greatest bud cold hardiness, while three and six foliar applications of seaweed extract at low rate had the least tolerance. Nevertheless, none of the seaweed extract applications resulted in bud cold hardiness that differed from the water spray control (Table 4.16). Table 4.16. Effects of seaweed extract on Chardonnay wine grapes bud cold hardiness at different sampling in British Columbia experiment in 2021. ªThe numbers in brackets show the Standard Error. N = 5. The values in each column with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. bP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 5 treatments and 6 replications. cNum = numerator, dDen = denominator. Seaweed extract treatment Sampling date Application rate (L ha-1) Number of applications Nov 4, 2021 Nov 25, 2021 Dec 13, 2021 Feb 10, 2022 Mar 3, 2022 Mar 17, 2022 April 14, 2022 0 6 foliar -19.5 (0.47)a -23.2 (0.17) -21.1 (1.98) -22.6 (0.59) -21.6 abc (0.35) -18.5 (0.47) -9.2 (1.83) 2.5 3 foliar -19.7 (0.45) -23.2 (0.33) -22.1 (0.33) -23.1 (0.73) -21.4 ab (0.34) -18.7 (0.41) -11.1 (0.84) 2.5 6 foliar -19.2 (0.56) -22.9 (0.34) -20.5 (1.82) -22.6 (0.25) -21.4 a (0.13) -18.6 (0.57) -9.3 (1.40) 5 3 foliar -19.8 (0.96) -23.4 (0.39) -22.3 (0.49) -22.5 (0.35) -21.7 abc (0.23) -19.2 (0.43) -10.2 (1.11) 5 6 foliar -20.4 (0.30) -23.6 (0.59) -20.6 (1.81) -23.1 (0.43) -22.5 bc (0.25) -18.6 (0.64) -11.5 (1.10) 5 3 foliar + 2 soil applications -20.1 (0.62) -23.8 (0.43) -23.3 (0.20) -22.7 (0.14) -22.6 c (0.41) -19.1 (0.56) -12.4 (1.04) P-valueb 0.731 0.701 0.636 0.846 0.003 0.791 0.410 F-valueb 0.56 0.60 0.69 0.40 5.54 0.47 1.06 DF Numbc 20 24 24 18.73 18.33 18.14 22 DF Denbd 5 5 5 5 5 5 5 74 Table 4.17. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on Chardonnay wine grapes bud cold hardiness in the British Columbia experiment in 2021. 13 and 6 frequencies, 2Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. Analyzing with a repeated measure approach showed that bud cold hardiness differed among sampling dates over the winter of 2021/22 (Figure 4.6). The lethal temperature for bud was lowest on November 25, 2021, and remained almost steady until March 3, 2021, and showed a rapid increase on March 17, 2022, and reached its maximum on April 14, 2022. There was no interaction between treatment applications. Figure 4.6. Bud cold hardiness of wine grapes at seven sampling dates. Date of sampling (DF numerator = 6, DF denominator = 18, F-value = 173.275, P-value < 0.0001). Treatment (DF numerator = 5, DF denominator = 15, F -value = 1.935, P-value = 0.148). Interaction of sampling date and treatment (DF numerator = 30, DF denominator = 90, F-value = 0.789, P-value = 0.765) based on repeated measure test, N = 5. Source of Variation P-Value Nov 4, 2021 Nov 25, 2021 Dec 13, 2021 Feb 10, 2022 Mar 3, 2022 Mar 17, 2022 April 14, 2022 Rate 0.209 0.201 0.730 0.923 0.055 0.717 0.286 Frequency 0.951 0.763 0.088 0.931 0.599 0.458 0.465 Frequency*Rate 0.393 0.676 0.781 0.198 0.557 0.814 0.371 75 4.3.1.4. Effects of seaweed extract on soil ammonium and nitrate concentrations In 2020, soil ammonium and nitrate concentrations at both 0-15 and 15-30 cm depths were not affected by the application of seaweed extract on the soil compared to the control neither in summer nor fall (Table 4.18). Analyzing ammonium and nitrate concentrations of the soil with a repeated measure approach showed that in October 2020, the ammonium concentrations of soil at 15-30 cm were three times more than July (Figure 4.7), while nitrate concentrations of soil in October for both depths (0-15 and 15-30 cm) were lower than July (Figure 4.8). In 2021, soil ammonium and nitrate concentrations at both depths were not affected by the application of seaweed extract on the soil compared to control regardless of season (Table 4.19). Analyzing ammonium and nitrate concentrations of the soil with a repeated measure approach showed that the ammonium concentrations of soil were almost two times higher in October 2021 than in May and July (Figure 4.9), while nitrate concentrations in October were lower than in May and July (Figure 4.10). Table 4.18. Effects of seaweed extract on soil ammonium and nitrate (mg kg-1) as affected by seaweed extract in the British Columbia experiment in 2020. ªThe numbers in brackets show the Standard Error. N = 5. bP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 2 treatments and 6 replications. cNum = numerator, dDen = denominator. Seaweed extract treatment July 2020 October 2020 Application rate (L ha-1) Number of applications NH4- 0-15 cm NO3- 0-15 cm NH4- 15-30 cm NO3- 15-30 cm NH4- 0-15 cm NO3- 0-15 cm NH4- 15-30 cm NO3- 15-30 cm 0 6 foliar 1.28 (0.16) 13.8 (1.52) 0.64 (0.06) 29.3 (2.10) 1.25 (0.09) 2.66 (0.57) 1.77 (0.13) 1.72 (0.28) 5 3 foliar + 2 soil applications 1.11 (0.17) 13.4 (1.48) 0.65 (0.06) 32.1 (8.69) 1.51 (0.16) 4.65 (0.57) 2.14 (0.28) 2.55 (0.37) P-valueb 0.503 0.743 0.789 0.758 0.137 0.065 0.258 0.109 F-valueb 0.49 0.12 0.09 0.10 3.45 6.40 1.48 3.26 DF Numbc 8 4 3 6 4 4 8 8 DF Denbd 1 1 1 1 1 1 1 1 76 Figure 4.7. Soil ammonium concentration (mg kg-1) in two sampling dates (July and October) in 0-15 and 15-30 cm depth in 2020. Season (DF numerator = 1, DF denominator = 7, F-value = 26.225, P-value < 0.001). Depth (DF numerator = 1, DF denominator = 7, F-value = 0.273, P-value = 0.617). Interacting of season and depth (DF numerator = 1, DF denominator = 7, F-value = 127.768, P-value < 0.001) based on repeated measure test. The values in box with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. N = 10. 77 Figure 4.8. Soil nitrate concentration of the soil (mg kg-1) in two sampling dates (July and October) in 0-15 and 15-30 cm depth in 2020. Season (DF numerator = 1, DF denominator = 7, F-value = 156.210, P-value < 0.001). Depth (DF numerator = 1, DF denominator = 7, F-value = 11.160, P-value < 0.001). Interacting of season and depth (DF numerator = 1, DF denominator = 7, F-value = 14.056, P value < 0.001) based on repeated measure test. The values in box with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. N = 10. 78 Table 4.19. Effects of seaweed extract on soil ammonium and nitrate (mg kg-1) in the British Columbia experiment in 2021. ªThe numbers in brackets show the Standard Error. N = 5. P value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. cNum = numerator, dDen = denominator. Seaweed extract treatment May 2021 July 2021 October 2021 Application rate (L ha-1) Number of applications NH4- 0-15 cm NO3- 0-15 cm NH4- 15-30 cm NO3- 15- 30 cm NH4- 0-15 cm NO3- 0-15 cm NH4- 15-30 cm NO3- 15-30 cm NH4- 0- 15 cm NO3- 0-15 cm NH4- 15-30 cm NO3- 15-30 cm 0 6 foliar 1.09 (0.13)a 3.10 (0.26) 1.19 (0.13) 3.09 (0.32) 0.82 (0.05) 3.05 (0.24) 0.78 (0.05) 3.33 (0.38) 1.93 (0.17) 2.01 (0.15) 1.75 (0.07) 1.59 (0.10) 5 3 foliar + 2 soil applications 1.04 (0.09) 3.57 (0.52) 1.27 (0.15) 2.78 (0.14) 0.95 (0.17) 3.13 (0.19) 0.80 (0.01) 4.19 (1.17) 1.78 (0.09) 2.18 (0.24) 2.05 (0.18) 1.79 (0.11) P-valueb 0.650 0.358 0.672 0.399 0.331 0.840 0.816 0.465 0.493 0.546 0.140 0.200 F-valueb 0.24 1.08 0.21 0.79 1.25 0.04 0.06 0.60 0.52 0.40 2.77 2.00 DF Numbc 4 4 4 8 3.68 7 3.72 7 7 7 7 7 DF Denbd 1 1 1 1 1 1 1 1 1 1 1 1 79 Figure 4.9. Soil ammonium concentration (mg kg-1) in three sampling dates (May, July and October) in 0-15 and 15-30 cm depth in 2021. Season (DF numerator = 2, DF denominator = 8, F-value = 21.471, P-value < 0.001). Depth (DF numerator = 1, DF denominator = 4, F-value = 0.831, P-value = 0.414). Interacting of season and depth (DF numerator = 2, DF denominator = 8, F-value = 1.238, P-value = 0.340) based on repeated measure test. The values in box with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. N = 20. 80 Figure 4.10. Soil nitrate concentration of the soil (mg kg-1) in three sampling dates (May, July and October) in 0-15 and 15-30 cm depth in 2021. Season (DF numerator = 2, DF denominator = 8, F-value = 25.376, P-value < 0.001). Depth (DF numerator = 1, DF denominator = 4, F-value = 0.130, P -value = 0.737). Interacting of season and depth (DF numerator = 2, DF denominator = 8, F-value = 2.450, P value = 0.148) based on repeated measure test. The values in box with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test. N = 20. 4.3.1.5. Effects of seaweed extract on pedicle and rachis length Application of seaweed extract had no effect on most of the measured cluster characters, either when compared to control treatments (Table 4.20) or when the effects of different frequencies and rates of seaweed extract application were evaluated separately (Table 4.21). An exception was that rachis total length was greater at 5 L ha-1 compared to 2.5 L ha-1 at both frequencies (Figure 4.11). 81 Table 4.20. Effects of seaweed extract on pedicle and rachis length of Chardonnay wine grapes in the British Columbia experiment in 2021. Seaweed extract treatment Pedicle average length per cluster (cm) Pedicle total length per cluster (cm) Rachis total length (cm) No. of berries per rachis length No. of berries /(rachis total length + pedicle total length) Application rate (L ha-1) Number of applications 0 6 foliar 0.72 (0.03)a 71.1 (5.20) 19.9 (1.51) 4.99 (0.16) 1.09 (0.03) 2.5 3 foliar 0.73 (0.03) 71.5 (3.61) 19.9 (1.24) 4.97 (0.29) 1.07 (0.03) 2.5 6 foliar 0.63 (0.05) 66.6 (3.25) 22.6 (2.16) 4.85 (0.34) 1.19 (0.06) 5 3 foliar 0.73 (0.03) 72.2 (2.32) 20.1 (1.04) 5.00 (0.27) 1.08 (0.03) 5 6 foliar 0.72 (0.03) 76.3 (3.89) 22.1 (1.01) 4.85 (0.17) 1.08 (0.03) 5 3 foliar + 2 soil applications 0.74 (0.03) 64.3 (3.29) 17.5 (1.21) 5.02 (0.18) 1.06 (0.02) P-valueb 0.195 0.277 0.164 0.989 0.151 F-valueb 1.61 1.35 1.77 0.11 1.80 DF Numbc 24 24 20 20 24 DF Denbd 5 5 5 5 5 ªThe numbers in brackets show the Standard Error. N = 5. bP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. cNum = numerator, dDen = denominator. Table 4.21. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on pedicle and rachis length of Chardonnay wine grapes in the British Columbia experiment in 2021. Source of Variation P-Value Pedicle average length per cluster Pedicle total length per cluster Rachis total length No. of berries per rachis length No. of berries /(rachis total length + pedicle total length) Rate 0.182 0.865 0.008 0.182 0.405 Frequency 0.975 0.531 0.711 0.975 0.767 Frequency*Rate 0.105 0.359 0.383 0.105 0.132 1 3 and 6 frequencies, 2 Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. 82 Figure 4.11. Box plot showing the interacting effects of rate and frequency of seaweed extract application on rachis total length based on the factorial analysis of the application of seaweed extract in two levels of frequency (4 and 8 per season) and two levels of rate (low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1), in 2021. Horizontal lines inside the boxes show medians and red dots show the mean value. The values in box with different letters are statistically different at 5 % probability level according to Tukey's multiple comparison test; P-value = 0.008, N = 25. 83 4.3.2. Results of Nova Scotia experiment 4.3.2.1. Effects of seaweed extract on growth, petiole nitrogen and yield In both 2020 and 2021, application of seaweed extract had no effect on wine grape growth, petiole N, and yield, either when compared to control treatments (Tables 4.22; 4.23; 4.24; 4.25) or when the effects of different frequencies and rates of seaweed extract application were evaluated separately (Tables 4.26; 4.27; 4.28; 4.29). Table 4.22. Effects of seaweed extract on growth and nutrition of Chardonnay wine grapes in Nova Scotia in 2020. Seaweed extract treatment TCSAa at Fall (mm2) Pruning Weight (g) Petiole N (%) Application rate (L ha-1) Number of applications 0 6 foliar 8.7 (0.30)b 1.75 (0.08) 0.50 (0.01) 2.5 3 foliar 8.1 (0.32) 1.78 (0.05) 0.49 (0.00) 2.5 6 foliar 8.3 (0.27) 1.71 (0.11) 0.50 (0.01) 5 3 foliar 8.6 (0.35) 1.68 (0.10) 0.51 (0.02) 5 6 foliar 8.2 (0.31) 1.72 (0.09) 0.50 (0.02) 5 3 foliar + 2 soil applications 8.0 (0.20) 1.53 (0.08) 0.51 (0.02) P-valuec 0.321 0.405 0.973 F-valuec 1.26 1.07 0.16 DF Numcd 20 20 20 DF Dence 5 5 5 ªTrunk Cross-Sectional Area. bThe numbers in brackets show the Standard Error. N = 5. cP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. dNum = numerator, eDen = denominator. 84 Table 4.23. Effects of seaweed extract on growth and nutrition of Chardonnay wine grapes in Nova Scotia in 2021. ªTrunk Cross-Sectional Area. bThe numbers in brackets show the Standard Error. N = 5. cP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. dNum = numerator, eDen = denominator. Table 4.24. Effects of seaweed extract on yield parameters of Chardonnay wine grapes in Nova Scotia in 2020. . aThe numbers in brackets show the Standard Error. N = 5. bP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. cNum = numerator, dDen = denominator. Seaweed extract treatment TCSAa at Spring (mm2) TCSAa at Fall (mm2) Growth Increment (mm) Pruning Weight (g) Petiole N (%) Application rate (L ha-1) Number of applications 0 6 foliar 8.70 (0.30)b 9.53 (0.84) 0.83 (0.69) 1.86 (0.13) 0.47 (0.01) 2.5 3 foliar 8.11 (0.32) 10.14 (0.81) 2.023 (0.52) 2.00 (0.16) 0.47 (0.02) 2.5 6 foliar 8.27 (0.27) 9.71 (1.08) 1.44 (1.11) 1.86 (0.14) 0.49 (0.01) 5 3 foliar 8.56 (0.35) 8.70 (0.75) 0.14 (0.53) 2.09 (0.15) 0.47 (0.02) 5 6 foliar 8.22 (0.31) 10.83 (1.10) 2.61 (1.07) 2.02 (0.11) 0.47 (0.02) 5 3 foliar + 2 soil applications 8.02 (0.20) 8.47 (0.98) 0.45 (1.07) 1.83 (0.12) 0.49 (0.02) P-valuec 0.321 0.460 0.258 0.579 0.609 F-valuec 1.26 0.97 1.43 0.78 0.73 DF Numcd 20 20 20 20 20 DF Dence 5 5 5 5 5 Seaweed extract treatment No. of Cluster per vine Cluster Size (g) Berry Weight (g) Yield (metric tonnes ha-1) Application rate (L ha-1) Number of applications 0 6 foliar 11.7 (0.80)a 72.7 (7.38) 1.27 (0.03) 3.396 (0.38) 2.5 3 foliar 8.2 (1.02) 77.2 (5.28) 1.31 (0.03) 2.574 (0.38) 2.5 6 foliar 9.3 (0.94) 81.1 (5.98) 1.32 (0.03) 2.986 (0.27) 5 3 foliar 8.7 (1.35) 70.2 (8.10) 1.11 (0.04) 2.447 (0.45) 5 6 foliar 8.2 (1.25) 73.9 (3.13) 1.18 (0.09) 2.442 (0.36) 5 3 foliar + 2 soil applications 9.8 (1.46) 75.5 (8.19) 1.21 (0.06) 2.877 (0.36) P-valueb 0.302 0.875 0.319 0.386 F-valueb 1.29 0.35 1.25 1.11 DF Numbc 24 20 24 20 DF Denbd 5 5 5 5 85 Table 4.25. Effects of seaweed extract on Chardonnay wine grapes growth and yield in the Nova Scotia experiment in 2021. ªThe numbers in brackets show the Standard Error. N = 5. bP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. cNum = numerator, dDen = denominator. Table 4.26. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on Chardonnay wine grapes growth and nutrition in the Nova Scotia experiment in 2020. Source of Variation P-Value TCSAa at Fall Pruning Weight Petiole Nitrogen Rate 0.828 0.343 0.725 Frequency 0.874 0.798 0.958 Frequency*Rate 0.686 0.284 0.584 1 3 and 6 frequencies, 2 Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. ªTrunk Cross-Sectional Area. Table 4.27. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on Chardonnay wine grapes growth and nutrition in Nova Scotia experiment in 2021. Source of Variation P-Value TCSAa at Spring TCSAa at Fall Pruning Weight Petiole Nitrogen Rate 0.828 0.804 0.693 0.842 Frequency 0.874 0.307 0.753 0.796 Frequency*Rate 0.686 0.141 0.438 0.303 1 3 and 6 frequencies, 2 Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. ªTrunk Cross-Sectional Area. Seaweed extract treatment No. of Cluster per vine Cluster Size (g) Berry Weight (g) Yield (metric tonnes ha-1) Application rate (L ha-1) Number of applications 0 6 foliar 15.8 (1.00)a 67.5 (4.80) 1.61 (0.04) 4.337 (0.49) 2.5 3 foliar 16.3 (0.60) 75.2 (3.52) 1.65 (0.03) 4.955 (0.25) 2.5 6 foliar 16.6 (0.76) 73.2 (4.46) 1.60 (0.04) 4.880 (0.26) 5 3 foliar 17.8 (0.76) 75.2 (4.12) 1.61 (0.03) 5.424 (0.41) 5 6 foliar 16.9 (0.65) 72.4 (7.24) 1.55 (0.04) 4.901 (0.49) 5 3 foliar + 2 soil applications 16.7 (0.79) 75.6 (7.22) 1.59 (0.03) 5.144 (0.64) P-valueb 0.322 0.824 0.553 0.395 F-valueb 1.25 0.43 0.82 1.09 DF Numbc 20 20 20 20 DF Denbd 5 5 5 5 86 Table 4.28. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on Chardonnay wine grapes growth and yield in the Nova Scotia experiment in 2020. Source of Variation P-Value No. of Cluster per vine Cluster Size Berry Weight Yield Rate 0.988 0.344 0.061 0.510 Frequency 0.988 0.681 0.876 0.780 Frequency*Rate 0.362 0.817 0.954 0.363 1 3 and 6 frequencies, 2 Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. Table 4.29. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on Chardonnay wine grapes growth and yield in the Nova Scotia experiment in 2021. Source of Variation P-Value No. of Cluster per vine Cluster Size Berry Weight Yield Rate 0.396 0.948 0.153 0.662 Frequency 0.942 0.620 0.135 0.578 Frequency*Rate 0.643 0.917 0.930 0.706 1 3 and 6 frequencies, 2 Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. 4.3.2.2. Effects of seaweed extract on wine grapes fruit quality parameters In both 2020 and 2021, wine grape fruit quality parameters were not affected by seaweed extract either when compared to control treatments (Tables 4.30; 4.31) or when the effects of different frequencies and rates of seaweed extract application were evaluated separately (Tables 4.32; 4.33). 87 Table 4.30. Effects of seaweed extract on fruit quality parameters of Chardonnay wine grapes in Nova Scotia in 2020. ªTotal Soluble Solid, bTitratable Acidity, cThe numbers in brackets show the Standard Error. N = 5. dP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. eNum = numerator, fDen = denominator. Seaweed extract treatment TSSa (Brix°) Juice pH TAb (g L-1) Application rate (L ha-1) Number of applications 0 6 foliar 18.4 (0.22)c 3.35 (0.12) 8.7 (0.02) 2.5 3 foliar 19.3 (0.37) 2.98 (0.33) 7.9 (0.02) 2.5 6 foliar 18.7 (0.22) 3.12 (0.13) 8.0 (0.04) 5 3 foliar 19.1 (0.56) 2.87 (0.30) 8.4 (0.04) 5 6 foliar 19.0 (0.29) 3.20 (0.12) 8.5 (0.04) 5 3 foliar + 2 soil applications 18.8 (0.29) 3.12 (0.08) 8.9 (0.03) P-valued 0.452 0.558 0.215 F-valued 0.98 0.81 1.54 DF Numde 20 20 24 DF Dendf 5 5 5 88 Table 4.31. Effects of seaweed extract on fruit quality parameters of Chardonnay wine grapes in Nova Scotia in 2021. ªTotal Soluble Solid, bTitratable Acidity, cYeast Assimilable Nitrogen. dThe numbers in brackets show the Standard Error. N = 5. eP value, F value and Degree of Freedom are from a Mixed Effects Model ANOVA with 6 treatments and 5 replications. fNum = numerator, gDen = denominator. Table 4.32. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on Chardonnay wine grapes fruit quality parameters in Nova Scotia in 2020. Source of Variation P-Value TSSa Juice pH TAb Rate 0.871 0.828 0.065 Frequency 0.471 0.419 0.929 Frequency*Rate 0.300 0.871 0.659 1 3 and 6 frequencies, 2 Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. ªTotal Soluble Solid, bTitratable Acidity. Table 4.33. Factorial analysis of the foliar application of seaweed extract at two frequencies1 and two concentrations2 on Chardonnay wine grapes fruit quality parameters in Nova Scotia in 2021. Source of Variation P-Value TSSa Juice pH TAb Calculated and Measured YANc Rate 0.793 0.500 0.504 0.959 Frequency 0.299 0.117 0.356 0.382 Frequency*Rate 0.125 0.798 0.634 0.194 13 and 6 frequencies, 2Low concentration = 2.5 L ha-1 and high concentration = 5 L ha-1. ªTotal Soluble Solid, bTitratable Acidity, cYeast Assimilable Nitrogen. Seaweed extract treatment TSSa (Brix°) Juice pH TAb (g L-1) Calculated YANc (mg L-1) Measured YANc (mg L-1) Application rate (L ha-1) Number of applications 0 6 foliar 18.9 (0.34)d 2.99 (0.28) 8.59 (0.05) 94.3 (11.90) 141.1 (17.80) 2.5 3 foliar 18.8 (0.26) 2.98 (0.16) 8.77 (0.03) 89.7 (12.30) 134.2 (18.50) 2.5 6 foliar 19.6 (0.30) 2.60 (0.18) 8.94 (0.05) 85.1 (7.40) 127.2 (11.10) 5 3 foliar 19.5 (0.35) 2.79 (0.26) 8.76 (0.04) 83.2 (8.13) 124.5 (12.20) 5 6 foliar 19.2 (0.33) 2.79 (0.24) 9.36 (0.03) 99.4 (16.10) 148.7 (24.00) 5 3 foliar + 2 soil applications 19.2 (0.37) 3.36 (0.18) 8.92 (0.05) 69.6 (9.13) 104.1 (13.70) P-valuee 0.479 0.241 0.837 0.266 0.266 F-valuee 0.93 1.48 0.41 1.40 1.40 DF Numef 24 20 20 20 20 DF Deneg 5 5 5 5 5 89 4.4. Discussion 4.4.1. Effects of seaweed extract on wine grape growth and yield Seaweed extracts contain macro and micronutrients, amino acids, vitamins, and phytohormones like cytokinin, auxin, and abscisic acid (Mooney and van Staden, 1986) and have been reported to stimulate the growth and yield of Pinot Noir in California (Holden et al., 2008) and Merlot under Mediterranean weather conditions in northern Greece (Taskos et al., 2019). By contrast, there are other studies that have reported no effect of application of seaweed extract on yield and yield components of Baco Noir and Syrah wine grape grown in Ontario and California (Wiens and Reynolds, 2008; Martin, 2012), Sangiovese grown under Mediterranean conditions in central Italy, and Pinot Noir and Cabernet Franc under cool-climate conditions in Michigan, USA (Frioni et al., 2018). Nevertheless, based on these earlier reports it was hypothesized that foliar application alone or soil plus foliar applications of seaweed extract would improve wine grape growth and yield compared with a control (sprayed with water only). It was also hypothesized that foliar application of seaweed extract at a lower rate (2.5 L ha-1) would be similar to a higher rate (5 L ha-1) on wine grape growth and yield, and that three foliar applications of seaweed extract during the growing season would be similar to six foliar applications on wine grape growth and yield. There was no effect of seaweed extract on wine grape growth compared to the control, but when analyzed independently of the control in 2021 in the British Columbia experiment, the number of clusters per vine and yield changed depended on the frequency and rate of application. When applied at the low rate, six foliar applications of seaweed extract resulted in a greater number of clusters per vine compared to three foliar applications. This can be attributed to the cumulative effect of the extract on the wine grapes (Gutiérrez-Gamboa et al., 2021). In other words, repeated applications allowed the beneficial effects of the extract to build up over time, enhancing the number of clusters per vine (Gastón and Yerko, 2021). When applied six times in our experiment, the wine grapes experienced a more consistent exposure to the beneficial bioactive compounds present in the seaweed extract throughout their growth cycle. It is worth mentioning that the three times spray were only after flowering, but six times spray included sprays before flowering, which is a key physiological stage in grapes. Formation of bud premordia is determined in the previous year (Samuels et al., 2022) and seaweed extract 90 therefore would not affect the number of clusters per vine in the year of application; however, some of the effects could have been from the sprays in 2018 and 2019. Additionally, prolonged exposure to seaweed extract through six applications might enhance flower development, and yield due to its effects on physiological processes and resource allocation in the current year (Gutiérrez-Gamboa et al., 2019). By contrast, when applied six times, the high rate of seaweed extract resulted in fewer clusters per vine and lower fruit yield than the low rate of seaweed extract; no information was found about the effect of seaweed extract on cluster number; therefore, the reason for this effect is unknown. Importantly, the results of the present study were consistent with those obtained by Frioni et al. (2018), Wiens and Reynolds (2008), and Martin (2012), who also did not find effects of application of seaweed extract on most of the wine grape growth characters, relative to a control. Therefore, the hypothesis that foliar application of seaweed extract would enhance wine grape growth and yield compared to control was rejected. Similarly, the hypothesis that three foliar applications of seaweed extract during the growing season would improve wine grape growth similar to six applications of the same concentration of seaweed extract when analyzed independently of the control was accepted. Furthermore, the hypothesis that foliar application of seaweed extract at a lower rate (2.5 L ha-1) would enhance wine grape fruit yield similar to application at high rate (5 L ha-1) when analyzed independently of the control was also accepted. The average number of clusters per vine in the BC experiment across 2020 and 2021 was 30, compared to 13 clusters per vine in the NS experiment, indicating a 2.3-fold increase in BC. Similarly, the average yield in the BC experiment over the same period was 15 metric tonnes per hectare, while the NS experiment yielded 3.86 metric tonnes per hectare, representing a 3.75-fold higher yield in BC. The Okanagan Valley in BC typically has a dry, warm climate with long growing seasons, which are favorable for grapevine development and fruit production, while Nova Scotia experiences cooler, wetter conditions with shorter growing seasons, which can limit vine growth, cluster formation, and fruit ripening. The heavy soil texture and heavy rainfall in NS create a less favorable environment for grapevine growth and productivity compared to the well-drained loamy sand soil and precise micro-jets irrigation used in BC. This likely contributed to the significant differences in cluster numbers and yield observed between the two regions. 91 4.4.2. Effects of seaweed extract on wine grape pedicle and rachis length and number One of the claimed benefits of seaweed extract in grapevine is the enhancement in cluster looseness, which improves air circulation among the berries and reduces moisture within the cluster. These characteristics are expected to reduce susceptibility of grapes to fungal diseases. A positive effect of foliar application of seaweed extract on cluster length in cv. Merlot in northern Italy (Botelho et al., 2018), and length of rachis in Thompson Seedless table grape in California (Norrie and Keathley, 2006), have been reported. By contrast, no effect of seaweed extract on the rachis length of Syrah wine grape was observed in an experiment in California (Martin, 2012). Based on these earlier findings it was hypothesized that foliar application of seaweed extract would increase wine grape cluster looseness (pedicle and rachis length and number) compared with the control treatment. It was also hypothesized that response to foliar application of seaweed extract at a lower rate would be similar to the higher rate, and that response to three foliar applications of seaweed extract during the growing season would be similar to six applications of the same concentration of seaweed extract. Foliar application of seaweed extract increased rachis total length at the high rate of application compared to the low rate, but not compared to the control treatment, across both frequencies. Similarly, eight foliar applications of 2 L ha-1 A. nodosum seaweed extract applied between bloom and berry development resulted in increased Thompson Seedless table grape rachis length as compared to untreated control in California (Norrie and Keathley, 2006). In another study two foliar applications of Ecklonia maxima seaweed extract at 3.75 L ha-1 on wine grape cv. Merlot, with the first application between 6-8 leaves and pre-flowering stages, and the second application at the beginning of anthesis, decreased the length of clusters, compared to a treatment of 2.5 L ha-1, but without differences in relation to the control with water, in the north of Italy (Botelho et al., 2018). They reported no difference in the length of cluster between the two application rates and a water control in Sangiovese and Cabernet Sauvignon; foliar application of 2.5 L ha-1 of E. maxima seaweed extract increased the cluster compactness in Cabernet Sauvignon, compared to the control. Given our results, the hypothesis that foliar application of seaweed extract would increase wine grape cluster looseness (pedicle and rachis length and number) compared with the control treatment was rejected. The hypothesis that three foliar applications of seaweed extract during the growing season would have similar effects to six 92 applications of the same concentration of seaweed extract was accepted for wine grape cluster lossness; however, the hypothesis that foliar application of seaweed extract at a lower rate would produce similar effects to the higher rate, was rejected for rachis total length. 4.4.3. Effect of seaweed extract on wine grape fruit quality parameters Positive effects of foliar application of seaweed extract on wine grape fruit quality variables including TSS, TSS/TA ratio, and anthocyanin content on Flame seedless (Stino et al., 2017), Sangiovese (Frioni et al., 2018; Salvi et al., 2019), and Merlot (Taskos et al., 2019) have been reported, although effects are not always observed (Frioni et al., 2019). Considering these earlier findings, it was hypothesized that foliar application alone, or soil plus foliar applications of seaweed extract would improve wine grape fruit quality variables compared with the control treatment, and that when analyzed independently of the control, foliar application of seaweed extract at the low rate would provide similar results to the high rate on wine grape fruit quality parameters, and three foliar applications of seaweed extract during the growing season would produce similar results to applications of the same concentration of seaweed extract. The result of the present study showed that both foliar and soil, or foliar alone, application of seaweed extract did not have significant effects on wine grape fruit quality parameters compared to the control. In the British Columbia experiment in 2020, six foliar applications of seaweed extract at the low rate resulted in higher TA compared to three foliar applications when analyzed independently of the controls. However, the TA values in all the treatments in 2020 were within the optimum range of TA for white grapes, 8 to 11 g L-1 (Harbertson, 2010); therefore, this increase was not considered as an improvement in wine grape fruit quality. Similar to these observations, Martin (2012) did not observe any effect on fruit quality parameters of wine grape cv. Syrah grown in heavy clay soil in cool-climate conditions in California and San Luis from 2009 to 2011. Multiple foliar applications of 1.5 L ha-1 A. nodosum extract at intervals of 7-15 days to Sangiovese wine grapes grown in a loamy soil in central Italy did not affect TSS and TA compared with untreated vines (Frioni et al., 2019). Instead, anthocyanin and phenolic concentrations improved. Unlike the observations of the present study, wine grape TA decreased in response to application of seaweed extracts on three wine grape cultivars of Bez-El-Anza, Thompson Seedless and Red Roomy grown in Egypt (El-Sese et al., 93 2020). Ali and Moumen (2016) examined the effect of seaweed extract on early sweet wine grape grown in Minia region in Egypt and observed that increasing seaweed extract concentrations from 0.5 to 4 L ha-1 caused a significant decrease in TA. Nevertheless, considering the results of our experiment, the hypothesis that foliar application alone, or soil plus foliar applications of seaweed extract would improve wine grape fruit quality relative to a control was rejected. The hypotheses about rate and frequency of foliar application on wine grape fruit quality were accepted. 4.4.4. Effects of seaweed extract on wine grape bud cold hardiness Seaweed extract may enhance cold hardiness of wine grape buds. For example, application of seaweed extract reduced the freezing point of cells in the shoots of wine grape (Wilson, 2001). Rayirath et al. (2009) and Nair et al. (2012) reported that A. nodosum seaweed extract induced specific biochemical changes leading to enhanced tolerance to freezing stress in barley and Arabidopsis thaliana. Considering these early reports, it was hypothesized that foliar application alone, or soil plus foliar applications of seaweed extract would improve wine grape bud cold hardiness compared with a control. It was also hypothesized that effects on wine grape bud cold hardiness of foliar application of seaweed extract at a lower rate would be similar to the high rate, and that three foliar applications of seaweed extract during the growing season would have effects on wine grape bud cold hardiness similar to six foliar applications of the same concentration of seaweed extract. In the present study the effect of seaweed extract on wine grape bud cold hardiness was only assessed in the British Columbia experiment, where seaweed extract did not affect bud cold hardiness compared to the control. However, when evaluated independent of the control, the effects of seaweed extract application differed among frequencies and rates on March 3rd, 2022. On this date only, cold hardiness was greater with six foliar applications of seaweed extract at 5 L ha-1 or three foliar and two soil applications at 5 L ha-1 than with six foliar applications at 2.5 L ha-1. Rayirath et al. (2009) observed that untreated A. thaliana plants exhibited severe chlorosis and tissue damage, and failed to recover from freezing treatments while the A. nodosum extract-treated plants recovered from exposure to - 7.5 °C in vitro and - 5.5 °C in vivo. They concluded that chemical components in the A. nodosum extracts protected membrane integrity and affected 94 the expression of stress response genes leading to freezing stress tolerance in A. thaliana. Similar mechanisms could have been responsible for the effects observed on March 3rd, 2022, in the present study. A difference in cold hardiness in the spring is important because it indicates different sensitivity to late spring frosts for the regions that are prone to spring frost. However, this requires further investigation. Nevertheless, since application of seaweed extract was effective only in one sampling date, the hypothesis that foliar application alone, or soil plus foliar applications of seaweed extract would improve wine grape bud cold hardiness compared with a control was rejected. The hypotheses related to rate and frequency of foliar application on wine grape cold hardiness were accepted. 4.4.5. Effects of seaweed extract on soil ammonium and nitrate concentrations Seaweed extract contains various polysaccharides, phenols, and organic materials that improve soil fertility and moisture retention (Craigie, 2011; Ma et al., 2022). Chen et al. (2020) reported that the soils treated with A. nodosum resulted in gradual decrease in total N content of soil, while ammonium and nitrate contents were much higher than those of the control soils. Based on these earlier reports, it was hypothesized that soil application of seaweed extract would increase soil ammonium and nitrate concentrations relative to the control treatment. Soil ammonium and nitrate concentrations were not affected by the application of seaweed extract on soil compared to the control, except for increased soil nitrate concentrations in fall 2020 at 0-15 cm depth with two soil applications of seaweed extract. Nitrate concentrations at both soil depths were higher at the summer than fall sampling date, while ammonium concentrations at 15-30 cm were three times more in the fall than summer. This is because during the summer, conditions favour nitrification. Therefore, while ammonification still occurs in summer, its rate may be relatively low compared to nitrification (Hu et al., 2023). Chen et al. (2020) reported an increase in nitrate and ammonium concentrations by the application of A. nodosum seaweed extract to corn rhizosphere soil in a pot experiment. They attributed the increased nitrate and ammonium concentrations to an increase in soil enzymatic activities, including urease and nitrite reductase. By contrast, Yao et al. (2020) did not find obvious differences in nitrate and ammonium contents of the soil due to application of seaweed extract originating from Sargassum horneri in a greenhouse experiment in Shandong, China. Considering the results of the present study it was concluded that seaweed extract could be 95 effective in increasing soil nitrate contents; however, in the present study soil nitrate concentrations were enhanced only in one year (2020), one depth (0-15 cm) and in one season (fall). Soil ammonium concentrations were not affected by seaweed extract; therefore, the hypothesis that soil application of seaweed extract would increase soil ammonium concentrations relative to control treatment was rejected. 96 Chapter 5. Conclusion Organic-based materials such as vermicompost, vermicompost tea, and seaweed extract have demonstrated varying degrees of effectiveness in improving vineyard productivity and sustainability. The findings from this study showed that vermicompost effectively maintained grape yield and quality in the absence of chemical fertilizers while improving soil SOC and total N. These results support its potential as an alternative for chemical fertilizers. The results of foliar application of vermicompost tea on yield and growth parameters were not significant, and the effect sizes were small on fruit quality and N status of the vine. Seaweed extract had small effects on growth, yield, fruit quality, cold hardiness, and soil N, except for enhancing cluster looseness under the high rate of seaweed extract compared to the lower rate, but not relative to control. This indicated that although seaweed extract had a concentration-derived effect on rachis length and the high rate showed some increase in the rachis length, the higher rate is not recommended over the low rate because it had no effect on other parameters of wine grape growth and yield. In summary, vermicompost showed strong potential as a sustainable vineyard amendment, while vermicompost tea and seaweed extract offered small specific effects. These short-term results suggest the need for further research on the long-term impacts, optimal application methods, and economic viability of these organic-based materials in vineyard management. The conclusions from each study are detailed in the following sections. 5.1. Vermicompost The findings of the current study indicated that the impact of vermicompost on grapevine growth and yield varied annually and across different treatments. Nevertheless, it was concluded that vermicompost was effective in maintaining wine grape yield at the grower’s production levels while omitting the application of mineral nutrients through chemical fertilizers. However, when vermicompost is applied at a low rate, supplemental N application is needed. It was evident that vermicompost serves as a viable alternative to chemical fertilizers, maintaining productivity without any detrimental effects and, notably, enhancing soil C and N contents. Vineyards can use this opportunity to not only compost their byproduct, but also to replace their 97 chemical fertilizers' application by vermicompost. It is crucial to consider that increasing yield is not always a goal in viticulture, and that grape quality and vineyard sustainability are the primary goals. The range of yield and fruit quality parameters were within the range for Chardonnay reported by other researchers. The fruit quality parameters were already within the optimum range and were not significantly affected by vermicompost application. In terms of soil N and C, the residual effect of vermicompost application in 2019 did not increase SOC in 2020. This is likely due to the rapid decomposition and utilization of organic matter by soil microorganisms and plants. However, the application of vermicompost in 2021 was effective in increasing SOC in the top 0-15 cm of soil. Repeated applications are necessary to achieve long-term improvements in SOC. Additionally, the application of vermicompost at medium and high rates in 2021 increased soil total N and provided a greater supply of ammonium and nitrate, effectively meeting the N requirements of wine grapes. Overall, vermicompost application enhanced SOC, mineral and organic N, and maintained wine grape yield, growth, and fruit quality within acceptable ranges. For optimal results, annual applications are recommended until soil organic C and N levels are sufficient, after which the frequency can be reduced based on soil test recommendations. Vermicompost gradually enriches the soil with nutrients and beneficial microorganisms, fostering improved soil structure and fertility over time. The cumulative effect of sustained application allows for nutrient buildup, enhanced microbial activity, and a gradual release of nutrients, resulting in significant impacts on plant growth and soil C and N contents. Considering the high price of vermicompost, the medium rate of application is recommended. In-house composting of winery byproducts allows wineries to recycle nutrients, reduce waste, minimize chemical fertilizer use, and promote sustainable viticulture. The study's design ensured reliable results, with various vermicompost application rates providing insights into its effects on grapevine growth, yield, and soil C and N contents. However, the study was location-specific, and applying the results to different climates, soil types, or cropping systems should be done cautiously. Longer-term research is needed to assess cumulative effects, refine optimal rates, and conduct economic analyses to evaluate cost-effectiveness. 98 Future research should focus on long-term experiments to evaluate the sustained impact of vermicompost on soil C and N contents, grape yield, and quality over multiple growing seasons. Investigating its effects on various wine grape cultivars will help understand its broad applicability. Determining optimal application rates and timings will maximize benefits and minimize costs. Exploring how vermicompost influences soil properties and plant physiology using molecular and biochemical techniques will provide deeper insights. Economic assessments are necessary to evaluate its cost-effectiveness compared to conventional fertilizers. Additionally, studying the environmental benefits, such as reducing greenhouse gas emissions and improving soil C sequestration, will help understand its full potential. 5.2. Vermicompost tea The study aimed to evaluate the impact of vermicompost tea concentration and application frequency on various aspects of wine grape production. The results did not support the initial hypothesis that lower concentrations or less frequent applications of vermicompost tea would have similar effects to its higher concentration and more frequent applications in enhancing wine grape growth, yield and fruit quality. However, there are a few important points which need to be considered as the benefits of vermicompost application on wine grape. Our standard compost tea solution was very dilute compared to the concentrations usually used. The brewing process also was only for 24 h. It seems that the concentrations higher than our standard rate and longer time of brewing would be more effective. It also can be said that continuous weekly or biweekly application of vermicompost tea at standard or higher concentrations can provide nutritional and yield quality benefits. The mechanism for this change involves the absorption of N compounds through leaves and the effects of hormones and microorganisms in the solution. The study's randomized complete block design with multiple treatments and replications provided reliable and statistically robust results. Including both high (standard) and low (diluted) concentrations of vermicompost tea applied at different frequencies offered detailed insights into their effects on grapevine growth and yield. The inclusion of grower’s practice control and distilled water spray controls provided clear baselines for comparison. 99 However, the study's location-specific results may vary in different regions with varying climates, and the two-year data collection leaves long-term effects and consistency over multiple growing seasons unaddressed. Additionally, the study lacks an economic analysis of vermicompost tea application, which is crucial for growers to understand its cost-effectiveness and potential financial benefits. These findings align with previous research on humic substances and grapevine responses, highlighting the potential of vermicompost-derived products in sustainable agriculture. However, further research is needed to understand the mechanisms driving these effects and to explore the impact of vermicompost tea on plant diseases. Future studies should examine different types of vermicompost tea based on feedstock, and their concentrations on various grapevine varieties in different regions. Investigating the combined effects of vermicompost tea application with cover cropping systems, such as legumes, which can enhance soil structure, improve nutrient cycling, and increase organic matter, could enhance overall strategies. Assessing the long-term impacts on grapevine productivity will provide a comprehensive understanding of its potential. Additionally, studying its potential to enhance disease resistance, particularly for prevalent diseases, will be valuable. Finally, conducting economic analyses to determine the financial viability and potential cost savings of using vermicompost tea is necessary for broader adoption by growers. 5.3. Seaweed extract Overall, the results of the British Columbia and Nova Scotia experiments did not fully support the hypotheses put forward, indicating small or negligible effects of seaweed extract on various aspects of wine grape growth, fruit quality, cold hardiness, soil N, and cluster characteristics. However, there was a notable interaction between frequency and rate, whereby high-rate, repeated applications led to a reduction in clusters per vine and yield among applied treatments. Conducting the experiment in both British Columbia and Nova Scotia provided valuable insights into the effects of seaweed extract under different soil and climate conditions, enhancing the generalizability of the findings. The randomized complete block design with six treatments and five replications ensured robust and reliable results. The study explored different frequencies and concentrations of seaweed extract, including foliar, and combined foliar and soil 100 applications, providing a comprehensive understanding of its potential benefits. The use of distilled water as a control allowed for clear comparisons to the treated plots, highlighting the specific effects of the seaweed extract. Additionally, the study measured a wide range of parameters, including wine grape growth, fruit quality, cold hardiness, soil N, and cluster characteristics, offering a thorough evaluation of the seaweed extract's impact. Although the study was conducted in two regions, the results might still vary in other wine-growing areas with different environmental conditions. The study's findings were based on a limited timeframe, potentially missing long-term effects and variability across multiple growing seasons. The results showed small or negligible effects on most growth and quality parameters, suggesting that the seaweed extract might not provide significant benefits under the tested conditions. Furthermore, the study did not include an economic analysis, which is crucial for understanding the cost-effectiveness and financial viability of using seaweed extract in vineyard management. These strengths and limitations provided a balanced view of the seaweed extract experiment's design and outcomes, helping to guide future research and practical applications in vineyard management. Future research should implement long-term studies to understand the sustained effects of seaweed extract on grapevine growth, yield, and quality across multiple seasons. Evaluating the performance of seaweed extract in diverse climatic conditions and soil types will broaden its applicability. Investigating the responses of different grapevine varieties to seaweed extract applications will help determine variety-specific benefits. It is essential to determine the most effective timings for applying seaweed extract to maximize its benefits on grapevine growth and fruit quality. Exploring the biochemical and physiological mechanisms through which seaweed extract influences grapevine health and development will provide deeper insights. Studying the interaction between seaweed extract and other vineyard inputs, such as fertilizers and pesticides, can help develop integrated management strategies. Lastly, conducting comprehensive economic assessment will evaluate the overall benefits of using seaweed extract in vineyards. 101 References Abd Elrahman, M., & Bakr, A. (2022). Effect of using vermicompost and biofertilizers as partial alternatives for chemical fertilizers on growth and fruiting of Superior grapevines. Scientific Journal of Agricultural Sciences, 4(1), 23-32. 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Thesis/Dissertation
eng
Biology
Vancouver : University of British Columbia Library
Attribution-NonCommercial-NoDerivatives 4.0 International
Graduate
Jones, Melanie D.
Sharifi, Mehdi
The effects of vermicompost, vermicompost tea, and seaweed extract on grapevine and soil parameters of vineyards in British Columbia and Nova Scotia, Canada
Text