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Organic fertilizer source effects on protected Solanum lycopersicon L. (tomato) production in south coastal… Rekken, Gregory Kyle 2012

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  Organic Fertilizer Source Effects on Protected Solanum lycopersicon L. (Tomato) Production in South Coastal British Columbia By Gregory Rekken B.Sc., University of British Columbia, 2006 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in The Faculty of Graduate Studies (Plant Science) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) December 2012 © Gregory Rekken, 2012  ii  Abstract Low-cost hoop houses are common climate enhancing structures used by small to medium- scale farmers for intensive production of high-value crops.  On-farm fertilizer production and utilization of locally available soil amendments can reduce input costs, while increasing regional sustainability.  Production system specific organic fertilization programs, with respect to relative nutrient concentrations, mineralization rates, and pest and disease suppressing capabilities, are crucial for sustained high yields.  The objectives of this study were to assess organic fertilizer source effects on protected, organic Solanum lycopersicon L. (tomato) production in South Coastal British Columbia, and to assess whether genotype x fertilizer source interactions are present for various growth and yield traits.  Two cultivars of tomato, cv. Black Cherry and cv. Pollock were grown in a randomized complete block, split plot design, consisting of four fertilizer treatments replicated three times.  Fertilizer treatments included: 1) Vicia villosa Roth. (hairy vetch) green manure (HV), 2) composted poultry manure (CPM), 3) Ecofert® ‘EcoGrow’ 3-3-4 (OMRI certified) liquid fertilizer, and 4) a no treatment control.  All fertilizers were applied at a rate of 100 kg total nitrogen per hectare.  Treatments had no effect on vegetative growth, except increased biomass in cv. Pollock treated with EcoGrow.  Yield responses in cv. Black Cherry commenced from harvest week six onwards for CPM and HV treatments and from week eight for EcoGrow. By seasons end, all fertilizer treatments produced yield increases of 23% over the control in cv. Black Cherry plants while no yield response occurred in cv. Pollock.  Both EcoGrow and HV had positive effects on foliar potassium, which was the most limiting nutrient. Total soil nitrogen and available phosphorus were considered sufficient, except foliar phosphorus was near the critical level at mid-harvest in all treatments.  Foliar calcium and magnesium were high.  Several fungal diseases, including late blight, powdery mildew, grey mould and verticillium wilt, infected the crop from mid-July and may have affected plant nutrition and yield.  This study shows that a range of organic fertility sources can be effectively used in protected tomato production.  However, cultivar lifecycle and growth habit should be considered when devising fertilization programs.  iii  Table of Contents Abstract ......................................................................................................................................................... ii Table of Contents ......................................................................................................................................... iii List of Tables ................................................................................................................................................ vi List of Figures .............................................................................................................................................. vii List of Symbols, Acronyms, and Definitions ............................................................................................... viii Acknowledgements ....................................................................................................................................... x 1. INTRODUCTION ..................................................................................................................................... 1 1.1 Regional Context ........................................................................................................................... 1 1.2 Organic Hoop House Production Systems .................................................................................... 1 1.3 The Tomato ................................................................................................................................... 2 1.3.1 Tomato Types ........................................................................................................................ 5 1.3.2 Environmental Factors Affecting Crop Growth and Yield ..................................................... 5 1.3.3 Fruit Growth and Development ............................................................................................ 6 1.4 Organic Fertilization ...................................................................................................................... 7 1.5 Pests and Diseases of Tomato .................................................................................................... 12 1.5.1 Blossom End Rot ................................................................................................................. 12 1.5.2 Blotchy and Uneven Ripening ............................................................................................. 12 1.5.3 Fruit Cracking ...................................................................................................................... 13 1.5.4 Grey Mould ......................................................................................................................... 13 1.5.5 Late Blight ........................................................................................................................... 13 1.5.6 Physiological Leaf Roll ......................................................................................................... 13 1.5.7 Powdery Mildew ................................................................................................................. 14 1.5.8 Verticillium Wilt .................................................................................................................. 14 2. RESEARCH OBJECTIVES ....................................................................................................................... 15 3. MATERIALS AND METHODS ................................................................................................................ 16 3.1 Experimental Design ................................................................................................................... 16 3.2 Cultivar Selection ........................................................................................................................ 17 3.2.1 Cv. Black Cherry................................................................................................................... 17 3.2.2 Cv. Pollock ........................................................................................................................... 18 3.3 Fertilizer Treatments ................................................................................................................... 18 iv  3.3.1 Hairy Vetch Green Manure ................................................................................................. 19 3.3.2 Composted Poultry Manure ................................................................................................ 19 3.3.3 EcoGrow® 3-3-4 by EcoFert Inc. .......................................................................................... 20 3.4 The Growing Environment .......................................................................................................... 20 3.4.1 Regional Climate ................................................................................................................. 20 3.4.2 Soil Description ................................................................................................................... 21 3.4.3 The Hoop House .................................................................................................................. 21 3.4.4 Ventilation ........................................................................................................................... 21 3.5 Cultural Practices ........................................................................................................................ 22 3.5.1 Soil Preparation ................................................................................................................... 22 3.5.2 Mulching ............................................................................................................................. 22 3.5.3 Seedling Production ............................................................................................................ 22 3.5.4 Transplanting ...................................................................................................................... 22 3.5.5 Pruning and Training of Plants ............................................................................................ 23 3.5.6 Irrigation and Fertigation .................................................................................................... 24 3.5.7 Weed Control ...................................................................................................................... 25 3.6 Data Collection and Analysis ....................................................................................................... 25 3.6.1 Environmental Parameters ................................................................................................. 25 3.6.1.1 Hoop House Ambient Temperature and Humidity ............................................................. 25 3.6.1.2 Soil Temperature ................................................................................................................. 26 3.6.1.3 Soil Moisture ....................................................................................................................... 26 3.6.1.4 Outside Temperature and Humidity ................................................................................... 26 3.6.2 Soil Fertility Monitoring ...................................................................................................... 26 3.6.3 Vegetative Growth .............................................................................................................. 27 3.6.4 Foliar Sampling .................................................................................................................... 27 3.6.5 Senescence Rates and Chlorophyll Measures ..................................................................... 27 3.6.6 Disease Assessment ............................................................................................................ 27 3.6.7 Yield ..................................................................................................................................... 28 3.6.8 Fruit Quality ........................................................................................................................ 28 3.6.8.1 Total Soluble Solids ............................................................................................................. 28 3.6.9 Statistical Analysis ............................................................................................................... 28 4. RESULTS............................................................................................................................................... 29 v  4.1 Growing Environment ................................................................................................................. 29 4.1.1 Soil Temperature ................................................................................................................. 30 4.1.2 Soil Fertility ......................................................................................................................... 31 4.1.2.1 Pre-treatment Conditions ................................................................................................... 31 4.1.2.2 Treatment Effects on Soil Fertility ...................................................................................... 31 4.2 Vegetative Growth ...................................................................................................................... 32 4.2.1 Height and Nodes ................................................................................................................ 32 4.2.2 Foliar Nutrient Status .......................................................................................................... 35 4.2.3 Chlorophyll Status and Senescence Rates .......................................................................... 40 4.2.4 Yield ..................................................................................................................................... 44 4.2.6 Cumulative Fruit Yields ....................................................................................................... 45 4.2.7 Cv. Black Cherry Harvest Distribution ................................................................................. 46 4.2.8 Cv. Pollock Harvest Distribution .......................................................................................... 49 4.2.8.1 Pruning Effects on cv. Pollock Yield Distribution ................................................................ 50 4.3 Fruit Quality ................................................................................................................................ 51 4.3.1 Total Soluble Solids ............................................................................................................. 51 4.4 Physiological, Pest and Disease Symptoms ................................................................................. 52 5. DISCUSSION ......................................................................................................................................... 58 5.1 Growing Conditions..................................................................................................................... 58 5.2 Fertilizer Characteristics .............................................................................................................. 60 5.3 Cultivar Effects on Fertility and Crop Performance .................................................................... 63 5.4 Tomato Crop Nutrition ................................................................................................................ 63 5.5 Growth: Biomass Accumulation .................................................................................................. 68 5.6 Yield ............................................................................................................................................. 69 5.7 Fruit Quality ................................................................................................................................ 70 5.8 Nutrition and Plant Defense ....................................................................................................... 71 6. CONCLUSION ....................................................................................................................................... 73 Bibliography ................................................................................................................................................ 76 Appendices .................................................................................................................................................. 88 Appendix A. ............................................................................................................................................. 88 Appendix B Irrigation and Sensor Details ............................................................................................... 88  vi  List of Tables Table 1. Organic Fertilizer Nutrient Profiles ......................................................................................... 19 Table 2. Vancouver Climate Normals 1971 – 2000* .......................................................................... 20 Table 3. Tomato Seedling Foliar Nutrient Status ................................................................................ 23 Table 4. Mean Monthly Temperatures (oC) .......................................................................................... 29 Table 5. Pre-Amendment Soil Fertility .................................................................................................. 31 Table 6. Soil Nutrient Status at Fruit Set .............................................................................................. 31 Table 7. Soil Nutrient Status at Mid-Harvest ........................................................................................ 32 Table 8. Growth Rate (cm day-1) by Cultivar ........................................................................................ 32 Table 9. Cumulative Plant Height and Nodes ...................................................................................... 34 Table 10. Foliar Nutrient Concentrations at Fruit Set ......................................................................... 36 Table 11. Foliar Nutrient Concentrations at Mid-Harvest ................................................................... 36 Table 12. Soil and Foliar Nutrient Correlations by Cultivar ................................................................ 37 Table 13. Cv. Black Cherry Nutrient Ratios by Treatment and Sampling Event ............................ 38 Table 14. Cv. Black Cherry M-DRIS Indices ........................................................................................ 38 Table 15. Cv. Black Cherry Nutrient Requirement Ranking .............................................................. 39 Table 16. Cv. Pollock Nutrient Ratios by Treatment and Sampling Event ...................................... 39 Table 17. Cv. Pollock M-DRIS Indices .................................................................................................. 40 Table 18. Cv. Pollock Nutrient Sufficiency Ranking ............................................................................ 40 Table 19. Cv. Black Cherry Total Yield Per Plant ............................................................................... 45 Table 20. Cv. Black Cherry Marketable Yield Per Plant..................................................................... 45 Table 21. Cv. Pollock Total Yield Per Plant ......................................................................................... 46 Table 22. Cv. Pollock Marketable Yield Per Plant .............................................................................. 46 Table 23. Pruning Effects on cv. Pollock Marketable Yield Per Plant (g) ........................................ 46 Table 24. Treatment Effects on cv. Black Cherry Weekly Per Plant Marketable Yield (g) ........... 47 Table 25. Treatment Effects on cv. Black Cherry Fruit Weight (g) ................................................... 48 Table 26. Cv. Black Cherry Fruit Diameter (cm) ................................................................................. 48 Table 27. Cv. Pollock Weekly Yield Per Plant (g) ............................................................................... 49 Table 28. Cv. Pollock Weekly Harvested Fruit Count Per Plant ....................................................... 50 Table 29. Seasonal Changes in cv. Pollock Fruit Weight (g) ............................................................ 50 Table 30. Tomato Soluble Solids Content (oBrix) ................................................................................ 52   vii  List of Figures Figure 1. Treatment Layout .................................................................................................................... 17 Figure 2. Research Tomato Cultivars ................................................................................................... 18 Figure 3. EcoGrow Nutrient Solution Reservoir with Submersible Pump for Fertigation .............. 24 Figure 4. Hoop house vs. Outdoor Mean Daily Temperatures ......................................................... 29 Figure 5. Hoop House Soil Temperatures at 10 cm Depth ................................................................ 30 Figure 6. Cumulative Growth of cv. Black Cherry ............................................................................... 33 Figure 7. Cumulative Growth of cv. Pollock ......................................................................................... 33 Figure 8. Vegetative Biomass ................................................................................................................ 34 Figure 9. Pruning Effects on cv. Pollock Dry Matter Accumulation .................................................. 35 Figure 10. Cv. Black Cherry First Leaf Chlorophyll Readings ........................................................... 41 Figure 11. Cv. Pollock First Leaf Chlorophyll Readings ..................................................................... 42 Figure 12. Cv. Black Cherry Fourth Leaf Chlorophyll Readings ....................................................... 42 Figure 13. Cv. Pollock Fourth Leaf Chlorophyll Readings ................................................................. 43 Figure 14. Cv. Pollock Mid-Canopy Senescence ................................................................................ 44 Figure 15. Cv. Black Cherry Cumulative Marketable Yield ................................................................ 47 Figure 16. Seasonal Changes in cv. Black Cherry Fruit Weight by Treatment .............................. 48 Figure 17. Cv. Pollock Weekly Marketable Yield Distribution ........................................................... 49 Figure 18. Pruning Effects on cv. Pollock Harvest Distribution ......................................................... 51 Figure 19. Pruning Effects on cv. Pollock Marketable Yields ............................................................ 51 Figure 20. Irregular Interveinal Necrotic Spots in cv. Black Cherry (July 30) ................................. 53 Figure 21. Verticillium Wilt on cv. Pollock (August 24) ....................................................................... 54 Figure 22. Verticillium Wilt in cv. Pollock (August 24) ........................................................................ 54 Figure 23. Late Blight in cv. Black Cherry (August 10) ...................................................................... 55 Figure 24. Late Blight Infected cv. Pollock Fruit (August 24) ............................................................ 55 Figure 25. Powdery Mildew Disease Progression in cv. Black Cherry ............................................ 56 Figure 26. Gray Mold on cv. Black Cherry (September 20)............................................................... 56 Figure 27. Potential Potassium Deficiency in cv. Black Cherry (August 10) ................................... 57    viii  List of Symbols, Acronyms, and Definitions Term Units Definition ø  diameter Al  aluminum apoplast  The apparent free space in plant cell walls comprised of both water free space, through which ions, water and small organic molecules passively diffuse, and the Donnon free space, characterized by cation exchange and anion repulsion. B  boron BER  blossom end rot Ca  calcium cm  centimetre CPM  composted poultry manure cv.  cultivated variety oC  degree Celsius CCI unitless Chlorophyll content index – a unitless numerical scale used by the Opti-Science chlorophyll meter (model: CCM-200) to measure ratios of light (653 nm & 931 nm) transmitted through leaves CEC cmol+ kg -1  or meq+ 100g -1  cation exchange capacity Cu  copper cytokinin  A class of plant growth hormones primarily produced in root meristems.  Cytokinins promote cell enlargement and division, stimulate RNA and protein synthesis, suppress apical dominance and regulate leaf senescence. DON  Dissolved organic nitrogen DRIS  Diagnosis and Recommendation Integrated System Fe  iron GDD  growing degree days, where: GDD = Ʃ(Tmax +Tmin/2-Tbase); Tbase = 10 oC Ha  hectare HV  hairy vetch (Vicia villosa Roth.) K  potassium ix  Term Units Definition kg  kilogram kPa  kilopascal m  metre Mg  magnesium μL  microlitre Mn  manganese monopodial  Plant growth habit where apical shoot grows indefinitely. N  nitrogen NH4 +  ammonium NII  nutrient imbalance index NO3 -  nitrate OM  organic matter OMRI  Organic Materials Review Institute P  phosphorus ppm  parts per million RH % relative humidity RuBisCO  ribulose-1,5-bisphosphate carboxylase oxygenase RuBP  ribulose-1,5-bisphosphate sympodial  Plant growth habit where apical shoot is terminated and further growth arises from lateral shoots. TSS o Brix total soluble solids VPD kPa vapour pressure deficit Zn  zinc     x  Acknowledgements This thesis would not have been possible without the many people who selflessly provided me with assistance, mentorship, guidance, encouragement, and support throughout this degree.  I am grateful to the UBC Farm for providing a location and materials to carry out this field research, especially Timothy Carter and Andrew Rushmere for making it all run smoothly. EcoFert Inc. was very kind to donate fertilizers used in this study. I sincerely appreciate all the work and guidance from my supervisory committee.  I would like to thank my supervisor, Dr. Andrew Riseman for his support during this degree, for covering research expenses and especially for going that extra mile to ensure my timely graduation.  Dr. Art Bomke deserves special thanks for his many years of mentorship, well beyond the scope of this degree.  It is because of your wisdom, encouragement, and balanced perspectives that I have made it this far academically and personally.  It has also been a real pleasure to work with Dr. Mahesh Upadhyaya.  Your calm and thoughtful approach to all things academic and otherwise have been a real inspiration. In the lab I am grateful to Dr. Santokh Singh, Jarnail Mehroke, and to Judy Saunders who also helped immensely with data entry and experimental procedures.  Janice Lo proved invaluable with gifts of editing and pie. Many other faculty members in the Faculty of Land and Food Systems, especially the soils group, deserve a tip of the hat for their support and guidance; thank-you Dr. Sandra Brown, Dr. Maja Krzic, Dr. Les Lavkulich and Martin Hilmer for going beyond the call of duty.  Dr. Wayne Temple was an enthusiastic and knowledgeable resource in the design and set-up of this project, and is well deserving of acknowledgement. I am also indebted to my fabulous parents and Dale Boothby for their endless encouragement and support. 1  1. INTRODUCTION 1.1 Regional Context Industrialization and vertical integration of the food system over the preceding decades has negatively impacted small to medium-sized agricultural enterprises that have historically been the backbone of rural economies in North America.  Despite an unprecedented abundance of cheap food, numerous reports of food-borne illnesses and the social and environmental implications of this industrial paradigm have left producers and consumers searching for alternatives (Lang & Heasman, 2004). The most popular consumer alternative has been certified organic foods, making this “the most dynamic and rapidly growing sector of the global food industry” (“Organic Production,” 2012), with annual growth rates of approximately 15% (Lohr, 2000).  In 2009, there were 475 organic farms in British Columbia and another 87 in transition; a 6.7% increase over 2008 (Anonymous, 2011a).  Of these, mixed vegetable producers make up the largest market segment (Nimmo & Macey, 2007). In recent years, the growth of organic food consumption has outpaced production (“Organic Production,” 2012). These trends indicate a re-localization of the food system involving a broad spectrum of conscientious stakeholders, including a new generation of farmers, many of whom are pursuing organic production and direct marketing avenues. The southwest coast of British Columbia is a key example of a high density urban region, with scarce land resources and a healthy appetite for locally grown, organic food.  Between 2005 and 2009, Vancouver farmers’ markets experienced 30-35% annual growth, and almost 75% of consumers expressed willingness to pay farmer direct premiums for Canadian produced goods (Hild, 2009).  Nutrient dense, high-value crops demanded by urban consumers offer the greatest profit potential in an area where land prices have proven a formidable barrier to local agricultural enterprises.  Many of these crops, including Solanum lycopersicon L. (tomato), benefit from protective cover; being only marginally adapted to the region’s cool, maritime climate.  Hoop houses, low cost movable crop covers, are one such technology suited to these crops and small to medium scale organic farms with insecure land tenure. 1.2 Organic Hoop House Production Systems Hoop houses, or ‘high tunnels’ as they are also called, offer an affordable way for farmers to increase product range and extend the production season.  These simple, polyethylene skinned structures can be either stationary or moveable.  Year round production in all but the coldest 2  climates is possible with moveable hoop houses, facilitating up to 6 crops per year from a single, moveable structure (Coleman, 2009).  Main season production typically focuses on heat- loving crops, such as tomatoes, peppers and cucumbers, while shoulder season and winter production suit cold-hardy crops, such as salad greens and members of the Brassicaceae family.  Moveable systems are better suited for temporal and spatial crop rotations, including cover crops, without sacrificing valuable production area. When stationary, effective hoop house crop rotations (for managing pests, diseases and soil fertility) are usually limited to a narrow taxonomic range and the desire to maximize productivity. In addition to other cultural practices, soil fertilization programs should not only satisfy plant needs, but also enhance immunity and foster disease suppression.  Depending upon the production system and available resources, nutrient sources may be produced on-farm (i.e., plant residues and animal manures), from neighboring operations (i.e., manures), or by purchasing commercially available, OMRI certified products.  Effective nutrient management strategies that integrate additional agro-ecological components (i.e., pests, disease and resource utilization) will enhance on-farm sustainability and in turn, strengthen the surrounding rural community. Hoop house fertility management requires some additional considerations, especially when the structure is stationary.  Protection from rain may reduce nutrient leaching, but can lead to salt and disease build up.  While cover cropping is possible when the structure is not in year-round production, infrastructure costs and premium off-season prices often warrant season extension. Intercropping with living legume ground covers is one possibility for in situ fertility improvements; otherwise fertilizer inputs must be derived from elsewhere. 1.3 The Tomato The tomato is one of the most popular and highly consumed fruits in North America.  Annual fresh tomato consumption in Canada is on average 8.3 kg person-1, and continues to increase as the population shifts towards healthier diets (Anonymous, 2002).  The nutritional attributes of tomatoes include folate, potassium (K), vitamins C and E, flavonoids, chlorophyll, β-carotene, and lycopene (Jones, 2008).  Lycopene and β-carotene are powerful antioxidants, which have been associated with the prevention of cardiovascular disease, and cancers of the prostrate and gastrointestinal tract (Clinton, 1998; Perera & Yen, 2007; Rao & Agarwal, 2000).  In order to satisfy year-round consumer demand, breeding efforts have focused on improving durability and shelf-life.  While the results have been remarkable, these enhancements have been at the 3  expense of flavour and texture.  Indeed, the ‘cardboard’ tomato has become an icon for the inadequacies of an industrial food system (Allen, 2010).  Through a resurgence in local food production, the tomato has become almost obligatory in home and community gardens, as well as at farmers’ markets.  Containing approximately 93% water (Jones, 2008) and tasting best when harvested ripe, it is both healthier and environmentally prudent to produce these perishable, high-value fruits close to where they are consumed. Tomato fruit flavour is challenging to characterize since over 400 fleeting volatile aromatic compounds have been identified, while only 17 of those contribute to the characteristic tomato aroma (Allen, 2010; Heuvelink, 2005).  Total soluble solids (TSS) and titratable acidity are also important components of fruit flavour and are much easier to quantify.  Flavour is dependent not only on their individual effects, but the ratio of soluble solids to titratable acidity (Heuvelink, 2005). As a perennial, highland, tropical crop originating from Peru (Allen, 2010), tomatoes are grown as annuals in temperate climates.  Due to oceanic influence, South Coastal British Columbia, which is characterized by mild summers and cool, wet winters, is only marginally suited for outdoor tomato production.  Late season warm days, cool nights and  increasing humidity adversely affect crop growth and favour fungal diseases, most notably Phytophthora infestans (Mont.) de bary (late blight) (Barrett et al., 1991; Heuvelink, 2005).  Despite this, the Vancouver area is home to the second most intensive greenhouse tomato industry in Canada (Anonymous, 2003).  To be successful in this climate, tomatoes must be under a protective cover to improve growing conditions and protect against diseases. Tomatoes are considered a moderate to heavy feeding crop (Jones, 2008; Papadopoulos, 1991).  Nitrogen (N) and K are most important with absorption rates varying between developmental stages (OMAFRA, 2001).  High N supply is required during vegetative growth but during fruiting, K uptake increases to twice that of N (OMAFRA, 2001).  Photosynthetic rate is positively correlated with N content and decreases under N deficient conditions (Guidi et al., 1997; Osaki et al., 2001).  This relationship has been applied to the use of chlorophyll meters for non-destructive monitoring of leaf N status. Chlorophyll meters, such as the Opti-Sciences CCM-200, determine leaf greenness by measuring the transmission ratio of two radiation wavelengths (653 nm and 931 nm) through a leaf. Numerical readings are on a unitless, relative scale referred to as ‘chlorophyll content index’ (CCI) (Anonymous, n.d.).  This necessitates the use of cultivar specific reference crops 4  for correlating readings with N sufficiency levels (Fontes & de Araujo, 2006; Shapiro & Francis, 2006).  Chlorophyll meters have proven accurate indicators of leaf N for a number of crops, including tomato (Fontes & de Araujo, 2006; Güler & Büyük, 2007; Peng et al., 1996; Sandoval‐ Villa, Guertal, & Wood, 2000). Foliar sampling to quantify leaf nutrient status is a more traditional technique for evaluating plant nutrition.  Leaf nutrient levels are compared against established sufficiency ranges, where the lower, critical limit corresponds with a 10% reduction in growth.  The upper limit is defined as the threshold between maximum growth and luxury consumption (Anonymous, 2011b; Hochmuth, Maynard, Vavrina, Hanlon, & Simonne, 1991).  Since nutrient concentrations vary between plant parts and developmental phases, sufficiency ranges have been determined for several tomato growth stages. For tomatoes sampling is conducted on the most recently matured leaf (Hochmuth et al., 1991).  Cultivar, soil, climate, and production system effects on sufficiency ranges as well as the timing of sampling have been identified as the major limitations of this analytical method.  The Diagnostic and Recommendation Integrated System (DRIS) has been suggested as a more holistic method for overcoming these limitations and recognizing the important relationships between plant nutrients (Caron & Parent, 1989; Mourao Filho, 2004; Sumner, 1979).  Individual nutrient indices, based on the ratio of a particular nutrient against all others, are compared against established norms to rank nutrients from most limiting to most sufficient.  These indices are then summed to determine a nutrient imbalance index (NII).   A plant with optimal nutrition would have a NII value of zero; the greater the deviation from zero, the greater the nutritional imbalance (Beverly, 1991).  Norm values are claimed to be independent of bio-region, cultivar, developmental stage and production system.  However, significant variation between established norms under differing conditions and growth phases has been found (Caron & Parent, 1989; Hartz, Miyao, & Valencia, 1998).  While all these methods of evaluating plant nutrition have their limitations, when used together they can be a powerful set of diagnostic tools. Overall, crop yield is a function of total biomass production, biomass partitioning and fruit dry matter content (Heuvelink, 2005), and is significantly affected by the production system.  Field production yields range between 40 to 100 tonnes ha-1, whereas advanced greenhouses with nearly year-round production can produce in excess of 500 tonnes ha-1, with yields as high as 700 tonne ha-1 reported (Anonymous, 2003; Heuvelink, 2005).  Higher greenhouse yields can be attributed to longer growing seasons, climate optimization and intensive cultural practices (Heuvelink, 2005).  Hoop house tomato yields should fall between greenhouse and field 5  production values, due to passive enhancement of environmental parameters.  Cultural management of crop and soil will further affect yield. 1.3.1 Tomato Types Indeterminate tomatoes are the most common greenhouse cultivars for fresh market consumption due to their long life and high yield potential per unit area (Heuvelink, 2005; Papadopoulos, 1991).  Determinate tomato cultivars, with a bushy and erect growth habit and uniform ripening, are better suited to field production destined for processing.  In determinate types, the apex is transformed into a terminal inflorescence after the development of five to eleven leaves, with further growth arising from axillary buds (Picken, Stewart, & Klapwijk, 1986); senescence typically coincides with fruit ripening.  Semi-determinate tomato cultivars have intermediate morphology, producing 19-21 nodes before losing apical dominance (Scholberg et al., 2000).  Total nutrient uptake and seasonal uptake rates will vary among types depending on lifecycle characteristics. 1.3.2 Environmental Factors Affecting Crop Growth and Yield Cumulative tomato biomass production follows a sigmoidal pattern over the growing season (Heuvelink, 2005).  Slow early season growth accelerates exponentially with increasing leaf area of young plants, resulting in a constant relative growth rate evolving into a long phase of linear growth (Hunt, 1982).  As plants mature, further increases in leaf area have a diminishing impact on growth as plant-to-plant and internal leaf shading reduce light interception (Goudriaan & Monteith, 1990).  For greenhouse grown indeterminate cultivars, linear growth rates continue until the end of the season, as long as light intensity and other abiotic factors are maintained. For determinate cultivars, the growth rate decreases with fruit ripening, as leaves senesce and photosynthetic energy is diverted from leaves to fruit (Heuvelink, 2005). Aside from nutrient supply, temperature and light interception are the abiotic factors having the greatest effect on tomato plant growth and development (Heuvelink, 2005), with temperatures between 20oC to 25oC being optimal (De Koning, 1990).  Relative growth rate decreases rapidly below 20oC, while 19oC is ideal for anthesis (Heuvelink, 2005; Venema, Posthumus, de Vries, & van Hasselt, 1999; Venema, Posthumus, & van Hasselt, 1999).  Photosynthetic rates are stable between 15oC to 25oC, (De Koning, 1994).  However, at temperatures below 15oC photosynthetic rate, RuBisCO activation state and RuBP concentrations are diminished by interference of thioredoxin/ferredoxin reduction (Byrd, Ort, & Ogren, 1995).  Furthermore, 6  metabolic enzymes controlled by circadian rhythms, such as sucrose phosphate synthase and nitrate reductase, are disrupted by chilling (Jones, Tucker, & Ort, 1998).  However, total crop growth and yield is determined primarily by long-term average temperatures, indicating tolerance to substantial diurnal variation as long as optimal average temperatures are maintained and extremes are not exceeded (De Koning, 1988, 1990). In British Columbia, daytime temperatures between 21oC and 24oC and nighttime temperatures between 17oC and 18oC have been deemed suitable for greenhouse tomato production (Maas & Adamson, 1980).  For every 1oC drop in nighttime temperature, harvesting is delayed by approximately 3 days (Tite, 1983).  Consistently low day and night temperatures can result in rough fruit, and when extreme, may result in a complete lack of fruit set (Maas & Adamson, 1980).  Temperatures below 13oC are known to adversely affect crop growth and disease incidence (Heuvelink, 2005; Morgan, 1984). 1.3.3 Fruit Growth and Development Depending on temperature, fruit developmental period is approximately two months (Heuvelink, 2005).  While 20oC to 25oC is optimal for crop growth, fruit growth rate and size potential increase with decreasing temperature down to 17oC.  This is due to: 1) transpiration induced moisture stress at high temperatures (> 30oC), and 2) slower development coupled with faster growth rates at low temperatures, resulting in increased assimilate supply over a longer time period (De Koning, 1994; Pearce, Grange, & Hardwick, 1993).  Conversely, under high temperature regimes, fruit are smaller due to faster developmental rates. Approximately 14 days after pollination, cell division ceases in the developing fruit and all subsequent growth is attributed to cell enlargement (Heuvelink, 2005).  Aside from temperature, assimilate supply, governed by photosynthesis and nutrient uptake, determines fruit size. Typically, assimilate demand is two to three times the potential assimilate supply (Bertin, 1995; De Koning, 1994).  As such, truss and shoot pruning are common sink management practices employed to maximize fruit size (Jones, 2008; Papadopoulos, 1991).  Assimilate supply affects fruit quality by influencing the acid-to-sugar ratio and soluble solids content (Smillie, Hetherington, & Davies, 1999).  Potassium nutrition is known to affect fruit quality and flavour and ripening disorders are known to increase under deficient conditions (Heuvelink, 2005; Rooda van Eysinga & Smilde, 1981).  Assimilate loading into fruit ceases with the development of an abscission layer at the mature green stage (Heuvelink, 2005). 7  During the ripening process, tomato fruit undergo significant physiological changes.  For example, chloroplasts are differentiated into chromoplasts, starches are converted into sugars, and cell walls are degraded, resulting in a softening of the fruit (Jones, 2008; Kok et al., 2008; Piechulla, Glick, Bahl, Melis, & Gruissem, 1987; Tucker & Grierson, 1982).  The conversion of chloroplasts to carotenoid-containing chromoplasts involves degradation of thylakoid membranes along with their associated photosystem proteins, while at the same time proteins controlling pigment production are up-regulated (Kok et al., 2008; Piechulla et al., 1987). 1.4 Organic Fertilization Tomatoes can be grown in many different soil types, but a deep, loamy, well-drained soil supplied with organic matter and nutrients is most suitable.  As with most garden vegetables, tomatoes grow best in a slightly acidic soil with a pH of 6.0 to 6.8 (Jones, 2008).  Most research on tomato fertilization has been for hydroponic greenhouse production (Zhai et al., 2009; Heeb et al., 2005; Heuvelink, 2005; Jones, 2008).  Work has also been conducted to evaluate composts, manures, and other organic byproducts as amendments to peat or sand substrates, but little research has been done in native soils under low-input hoop house conditions (Gale et al., 2006; Heeb, Lundegardh, Savage, & Ericsson, 2006; Heuvelink, 2005; Jones, 2008; Zhai et al., 2009). Organic fertility management requires a more holistic and long-term focus compared to prescriptive use of soluble, inorganic fertilizers.  A myriad of factors affect nutrient mineralization rates, including temperature, moisture, organic matter content, and biological activity (Grubinger, 2012).  Additionally, organic fertilizers contain different concentrations of plant nutrients depending on the source.  This is especially true for composts derived from a range of feed-stocks with often unknown nutrient values and variable processing practices (Gale et al., 2006; Grubinger, 2012; Zhai et al., 2009).  Due to uncertainties regarding nutrient availability, reliance on composts, manures and cover crops often results in ‘blind’ management (Grubinger, 2012).  Commercially available products advertise available macronutrients, but cost and sustainability considerations prohibit extensive use (Zhai et al., 2009). Canadian organic regulations state that “The objective of the soil fertility and crop nutrient management program shall be to establish and maintain a fertile soil using practices that maintain or increase soil humus levels, that promote an optimum balance and supply of nutrients, and that stimulate biological activity within the soil” (CAN/CGSB-32.310-2006 Organic Production Systems General Principles and Management Standards, 2006).  They further 8  assert that this should be achieved through diverse crop rotations and additions of composted and uncomposted animal and plant materials, obtained from compliant organic production systems whenever possible. The soil feeding mandate implied in the organic standards is supported by science.  Long-term studies have shown that when managed well, organic yields are comparable to conventional systems (Campiglia, Mancinelli, Radicetti, & Caporali, 2010; Delate, Cambardella, & Mckern, 2008; Herencia et al., 2007; Kumar, Abdul-baki, Anderson, & Mattoo, 2005).  However, many others have found insufficient nutrient supply from organic amendments, used either as soil amendments or in soilless culture (Heeb, Lundegardh, Ericsson, & Savage, 2005; Lawson, Fortuna, Cogger, Bary, & Stubbs, 2012; Zhai et al., 2009).  With slow mineralization rates, it is understandable that composts and other organic amendments would be insufficient for soilless crop production without supplemental fertilization.  In field-based systems, environmental and biological factors previously described affect nutrient cycling.  However, cropping history and amendment type have been found to affect nutrient mineralization and soil biology (Jack, Rangarajan, Culman, Sooksa-Nguan, & Thies, 2011; Janzen & Radder, 1989).  To further complicate nutrient management, species-specific root exudates have been found to preferentially stimulate rhizosphere specific microorganisms that stimulate nutrient mineralization (Cesco, Neumann, Tomasi, Pinton, & Weisskopf, 2010; Haichar, Marol, Berge, & Rangel-castro, 2008; Herman, Johnson, Schwartz, & Firestone, 2006; Landi et al., 2006). A long posited theory has been that plants are limited to the uptake of inorganic N forms (Black, 1993), and that they depend on decomposers to supply their inorganic N requirements (Nasholm, Huss-Danell, & Hogberg, 2000; Schimel & Bennett, 2004).  Another prior assumption was that microbes are better adapted for N acquisition, with plants being passive recipients relegated to scavenging leftover, excess N.  It has now been shown that plants are not only capable of absorbing soluble organic N compounds (Chapin, Moilanen, & Kielland, 1993; Finley, Frostegard, & Sonnerfeldt, 1992; Lipson & Monson, 1998; Melin & Nilsson, 1953; Raab, Lipson, & Monson, 1996; Schimel & Chapin III, 1996; Schmidt & Stewart, 1997; Stribley & Read, 1980), notably amino acids such as glycine, alanine, glutamic acid, and aspartic acid (Chapin et al., 1993; Kielland, 1994, 1995), but that they also compete effectively with soil microorganisms for available N supplies (Schimel & Bennett, 2004).  Conversely, Jones et al. (2005) argue that research methods used for determining plant uptake of dissolved organic nitrogen (DON) are inadequate and that the majority of organic N absorbed by plants is simply recapture of DON lost through root exudation.  This is a relevant research area for organic producers using 9  fertilizer sources containing DON.  A greater understanding of organic N uptake and factors affecting N mineralization will help to improve fertilizer recommendations specific to organic production systems and develop strategies to reduce leaching losses. Organic matter (OM), including composts, can be divided into three components: the active, passive and slow fractions.  The active component of OM, comprised of carbohydrates such as simple sugars, starches and cellulose (Brady & Weil, 2000),  is readily consumed by soil organisms, with plant available nutrients being the eventual end product of decomposition.  The passive fraction of OM consists of resistant compounds from the original organic residues and re-polymerized products of metabolic activity in soil organisms (Weil & Brady, 2002).  Passive organic matter compounds are mostly complex macromolecules containing phenol or other ring- like structures.  The passive fraction of OM is decomposed very slowly by specialist organisms, often over hundreds of years (Weil & Brady, 2002).  Stabilized humus is only able to support relatively low densities of specialist decomposers and does not permit microbial population growth without additions of a readily accessible energy source (Clarholm, 1985; Griffiths, 1994; Jones, Healey, Willett, & Farrar, 2005; Landi et al., 2006).  The slow organic matter fraction has intermediate properties between the active and passive organic matter fractions.  Thus, the composition and quality of compost, manure, and plant-derived fertility sources are important regulators of nutrient release.  While the active fraction of organic matter is most important for immediate crop uptake, passive and slow fractions are valuable for building soil organic matter, sequestering carbon and long-term nutrient cycling. Animal manure and composts are an important component for fertility management on BC organic farms.  Relative to stabilized, mature composts, fresh manures generally have higher nutrient availability, but may also contain weed seeds or pathogens and pose an environmental risk due to high levels of ammonium, nitrate and phosphorus (P) (Gale et al., 2006; Preusch, Adler, Sikora, & Tworkoski, 2002; Sheppard & Bittman, 2010; Wilson, 2010).  To manage pathogen risk, organic regulations require that food harvest from fields amended with fresh manures cannot be harvested for a minimum of 90 days for crops where the edible parts do not touch the ground and 120 days for foods in contact with the soil.  Certified organic producers must also use organic manure sources, but when these are unavailable they may resort to conventionally produced manures, as long as the animals were not caged or confined (CAN/CGSB-32.310-2006 Organic Production Systems General Principles and Management Standards, 2006). 10  Aerobic composting reduces pathogens and weed seeds through the heat produced by microbial metabolism, which also converts volatile nutrients, such as ammonium and nitrate, into stable, slow-release organic forms (Tyson & Cabrera, 1993).  However, processing and feed-stock inconsistencies can confound amendment rate calculations, unless they are derived from commercial composting operations able to provide nutrient reports.  Most small farms producing their own composts use a range of feed-stocks, depending on availability, and are unlikely to analyze compost batches; thus fertility value will remain unknown.  Gale et al. (2006) found poultry manure processing inconsistencies between advertised products.  Fresh manure handling ranged from being collected fresh to having been dry stacked for several months. Similarly, some ‘composted’ products were found to be proactively managed, including stringent monitoring of carbon-to-nitrogen ratios, moisture content and regular aeration, while others were merely stacked for a period of time, and were still producing heat and volatizing ammonia at the time of sale.  These marketing and processing inconsistencies suggest that purchasing composts may not simplify determination of application rates.  Indeed, within the academic literature, rates of N mineralization from composted poultry manure have been found to vary widely, likely due to these uncertainties as well as regional feed sources (Ajwa & Tabatabai, 1994; Gale et al., 2006; Preusch et al., 2002).  Composting has been found to decrease variation in N mineralization compared to fresh poultry manure (Preusch et al., 2002), permitting more predictable and reliable amendment rate determinations.  In contrast to N, P availability from composted and fresh poultry manures are similar (Gale et al., 2006; Preusch et al., 2002). Poultry manure contains almost equal amounts of P and N (Bellows, 2002; Preusch et al., 2002), which results in excessive P applications when amendment rates are based on N content, posing an eutrophication risk to neighbouring water sources. Integration of cover crops in the production system can help reduce erosion and nitrate leaching during the rainy season, while also building organic matter and improving soil structure. Legume cover crops improve soil N status through biological fixation of atmospheric N2.  In regards to other plant nutrients, cover crops do not affect soil levels, but do facilitate nutrient cycling, and deep rooting species may redistribute to the surface nutrients below the depth of crop roots.  Thus, under most conditions, cover crops are not able to correct some of the soil deficiencies that are amendable through the import of manures and composts.  Vica villosa Roth. (hairy vetch) is an annual, vining legume often used as an overwintering cover crop.  The mild climate in South Coastal BC is ideal for cover cropping.  Fall planted hairy vetch produces most of its biomass when conditions warm in the spring (Odhiambo & Bomke, 2001).  Biomass 11  production ranges from 3300 kg ha-1 to 5600 kg ha-1, depending on climate and planting date (Teasdale & Abdul-baki, 2007).  With a N content of 3.25%, a hairy vetch cover crop contributes between 107 and 180 kg N ha-1, of which 60% to 80% may become crop available in the first year when incorporated as a green manure (Lawson et al., 2012).  Several studies have found that tomatoes grown with hairy vetch mulches experience delayed leaf senescence, improved fruit quality, and increased disease suppression and yields (Abdul-baki, Stommel, Watada, Teasdale, & Morse, 1996; Campiglia et al., 2010; Kumar, Mills, Anderson, & Mattoo, 2004; Mills, Coffman, Teasdale, Everts, & Anderson, 2002; Neelam et al., 2008).  Observed benefits are thought to be more than just N contribution from hairy vetch, and are likely due to a range of beneficial interactions, including moderated soil temperatures and phytohormones released from mulch residues (Mattoo & Abdul-baki, 2006; Mills et al., 2002).  It is of interest to determine whether these purported benefits can be realized when hairy vetch is incorporated as a green manure, or whether both microclimate modification and mulch source interactions are required. A broad range of commercial organic fertilizers derived from numerous nutrient sources are available on the market.  These are often produced from industry waste products close to the processing plant.  Locally produced commercial products range from simple yard waste composts to highly processed liquid and pelletized products derived from a range of sources, including kelp, seed meals, and animal waste products.  The coastal waters of British Columbia are an excellent renewable source of fast growing giant sea kelps (Eklonia maxima and Macrocystis integrifolia), which have been shown to contain plant growth regulators, most notably cytokinins (Khan et al., 2009; Temple, Bomke, Radley, & Holl, 1989).  These products are often used as foliar sprays to stimulate plant growth, but also make good fertilizers, increasing K uptake in wheat (Beckett & Staden, 1989), improving tomato yields (Crouch & Staden, 1992) and suppressing nematode feeding on tomatoes (Featonby-Smith & Van Staden, 1983).  Several liquid, kelp-based organic fertilizers are produced locally.  Commercially processed OMRI certified organic fertilizers are desirable for organic producers since they have verified nutrient concentrations and facilitate easy record keeping.  In contrast, locally produced commercial composts may contain a variety of feed-stocks not permitted in organic production, requiring more rigorous tracking by compliant organic farmers.  Compared with bulky compost and fresh manure products, commercially available specialty fertilizer concentrates are less transport intensive.  However, long distance transport of liquid fertilizers may add substantially to the cost, making local use of these products more relevant.  The option of applying liquid fertilizers via drip irrigation systems is another cost-saving benefit.  On the downside, 12  commercial products may be prohibitively expensive and tend to do little to increase soil organic matter. In this study, three locally available fertilizer sources representative of the types described above were tested for their efficacy in organic hoop house tomato production.  These included: 1) hairy vetch as a green manure; 2) composted poultry manure and; 3) a liquid fertilizer derived from kelp and seed meals (EcoGrow 3-3-4; EcoFert, Surrey BC). 1.5 Pests and Diseases of Tomato From personal experience, pests have not been a concern for tomato crops at the UBC Farm, unless the plants are under great duress.  Flea beetles, aphids, white flies, thrips, and the occasional hornworm have caused minor damage in the past.  Fungal diseases are the most common parasites encountered in South Coastal British Columbia due to a cool, moist maritime climate.  Prophylactic use of copper (Cu) sprays is the preferred fungal control for organic potato and tomato crops in the region.  Tomato diseases and physiological conditions historically encountered at the UBC Farm are discussed in the following sections. 1.5.1 Blossom End Rot Blossom end rot (BER) is related to calcium (Ca) uptake, but is usually caused by uneven watering rather than limiting nutrient supply (Barrett et al., 1991).  Initial symptoms appear as a water-soaked patch near the blossom end, later becoming dark and shrivelled (Maas & Adamson, 1980).  When Ca is deficient, symptoms usually develop in young fruit less than 2.5 cm in diameter, and most often in the fourth or fifth cluster.  Moisture stress induced BER is most often observed in large fruit just prior to ripening.  Minor moisture stress that is not severe enough to cause BER may induce earlier ripening of the blossom end, resulting in over ripening and excessive softening of that fruit portion (Maas & Adamson, 1980). 1.5.2 Blotchy and Uneven Ripening Intermittent periods of dull and bright weather can induce a higher incidence of uneven ripening (Maas & Adamson, 1980).  Grey wall and internal browning disorders are expressed as blotchy, uneven ripening combined with internal greying or browning revealed in a cross-section (Maas & Adamson, 1980).  Potassium deficiency has also been implicated with increasing rates of uneven ripening (Lune & van Goor, 1977; Rooda van Eysinga & Smilde, 1981). 13  1.5.3 Fruit Cracking Cracks or splits near the blossom end of developing fruit are often due to uneven growth rates, but are also influenced by excessive humidity and cool night temperatures (Maas & Adamson, 1980).  Cracks on mature fruit, either radial from the stem or concentric, usually occur on large fruit during bright, hot weather.  Their occurrence can be exacerbated by high salt content in the growing medium.  Cracking can be induced by terminal shoot pruning as source-sink relationships are diverted to maturing fruit.  Control measures to temporarily reduce vigour, such as limiting moisture, shading and reducing apical pruning can help alleviate this type of induced cracking.  Increasing K and reducing N levels over the season can also help prevent cracking (Maas & Adamson, 1980). 1.5.4 Grey Mould Botrytis cinerea Pers.:Fr. (grey mould) is a common disease in greenhouse tomato crops (Barrett et al., 1991).  Conditions favouring development of this fungal pathogen are high humidity (> 90%), cool nighttime temperatures, and overcast days, which are all typical of late season conditions in South Coastal British Columbia (Ingram & Meister, 2006). 1.5.5 Late Blight Without protective cover, the incidence of late blight is almost a certainty in South Coastal BC from mid-August onward.  This fungal pathogen requires cool moist weather, particularly cool nights and warm days for development (Barrett et al., 1991).  Sporangia form under conditions of high humidity (91% to 100%) and across a temperature range of 3oC to 26oC, with 18oC to 22oC being optimal (Heuvelink, 2005). 1.5.6 Physiological Leaf Roll This is a non-pathogenic condition wherein the leaf margins curl upwards and inwards.  Lower leaves are the first to be affected.  Several causal factors have been suggested, including cool spring conditions followed by hot weather, excessive N fertilization, P deficiency, and prolonged dry soil conditions.  Susceptibility to leaf roll is cultivar dependent, with indeterminate cultivars tending to be more susceptible (Anonymous, 2011c). 14  1.5.7 Powdery Mildew Leveillula taurica (Lev.) G. Arnaud (powdery mildew) is a common fungal pathogen affecting Acer macrophyllum (Big-leaf Maple), cucurbits, and tomato plants beginning in late July in South Coastal BC.  Conidia can germinate between 10oC and 35oC and once established the disease progresses rapidly with temperatures above 30oC.  Leaves die, but fail to drop when heavily infected (Barrett et al., 1991). 1.5.8 Verticillium Wilt Verticillium wilt is caused by both Verticillium albo-atrum Reinke & Berthold and V. dahlia Kleb., and is present wherever tomatoes are grown (Barrett et al., 1991).  Cool temperatures, between 10oC and 20oC, are most favourable for microsclerotia formation.  Often, the first symptom is daytime crop wilting.  With further development, V-shaped necrotic lesions surrounded by chlorotic tissue form from the leaf apex, tapering proximally (Barrett et al., 1991).  15  2. RESEARCH OBJECTIVES The objectives of this study were: 1) To assess the fertilizer effects of hairy vetch, composted poultry manure, and a commercial kelp product on organic tomatoes grown under protective cover in South Coastal British Columbia and; 2) To determine whether genotype x fertilizer source interactions are present for plant growth and yield traits.     16  3. MATERIALS AND METHODS 3.1 Experimental Design The organic fertilizer field trial was conducted in a poly-covered hoop house, oriented lengthwise along a southeast – northwest trajectory, at The Centre for Sustainable Food Systems at UBC Farm (UBC Farm).  The farm is located near the Pacific Ocean on the University of British Columbia’s Point Grey campus in Vancouver, Canada.  The trial commenced with field preparation on May 28, 2010 and was terminated with final harvest and crop removal on October 11, 2010. Two cultivars of tomato, cv. Black Cherry and cv. Pollock, were grown in a randomized complete block, split plot design consisting of four fertilizer treatments split by cultivar and replicated three times.  Representing a range of locally available fertilizers, treatments included: 1) hairy vetch green manure (HV), 2) composted poultry manure (CPM), 3) EcoGrow 3-3-4 liquid fertilizer (OMRI certified liquid fertilizer, EcoCert Inc., Surrey, BC Canada), and 4) a no treatment control.  The hoop house covered six, 0.75 m x 15 m raised beds oriented lengthwise. Pathways were 0.5 m wide.  Each block occupied two adjacent rows divided in half to accommodate the four fertilizer treatments (Figure 1).  Four tomato plants of each cultivar constituted a treatment replicate.   Two additional cv. Pollock plants were planted at row ends and mid-row (straddling treatments) to control for edge effect.  Due to space limitations, perimeter border rows were not included. Experimental units were tracked using a four-part hyphenated coding system: <Block number> <Treatment> - <Cultivar> <Plant number>.  Treatments were abbreviated as CT, HV, LQ and PM for ‘control’, ‘hairy vetch’, ‘EcoGrow’, and ‘composted poultry manure’, respectively.  Cv. Black Cherry and cv. Pollock were abbreviated as ‘BC’ and ‘PO’, respectively.  Blocks were labelled 1 through 3, and plants within a treatment replicate numbered 1 through 4.  17  Figure 1. Treatment Layout Buffer Block 1: Poultry Manure Buffer Block 1: EcoGrow Buffer Pollock Black Cherry Pollock Black Cherry  Buffer Block 1: Hairy vetch Buffer Block 1: Control Buffer Black Cherry Pollock Pollock Black Cherry  Buffer Block 2: EcoGrow Buffer Block 2: Hairy vetch Buffer Black Cherry Pollock Black Cherry Pollock  Buffer Block 2: Poultry manure Buffer Block 2: Control Buffer Black Cherry Pollock Pollock Black Cherry  Buffer Block 3: Poultry manure Buffer Block 3: Control Buffer Black Cherry Pollock Pollock Black Cherry  Buffer Block 3: Hairy vetch Buffer Block 3: EcoGrow Buffer Pollock Black Cherry Black Cherry Pollock  3.2 Cultivar Selection Cultivar selection was based on availability, market popularity, and regional suitability.  Cultivars used included a cherry type (cv. Black Cherry) and a medium-sized slicing cultivar (cv. Pollock). 3.2.1 Cv. Black Cherry Cv. Black Cherry was recommended by Timothy Carter, the UBC Farm Production Coordinator. A popular cultivar with consumers, cv. Black Cherry produces abundant, attractive fruit with dark shoulders and a sweet, smoky flavour (Figure 2).  Plants have a reported 65 day maturation time (West Coast Seeds, 2012), producing 10 to 25 gram fruit with an average shoulder diameter of 3.4 cm.  Seeds for this cultivar were sourced through West Coast Seeds, Delta, British Columbia. North 18  3.2.2 Cv. Pollock Cv. Pollock is a medium-sized canning tomato bred from cv. Bonny Best, which was first commercialized by Stoke’s Seeds (Moorstown, NJ) in 1908.  Andy Pollock, of northern BC, selected cv. Pollock for earliness, productivity and good cores (Salt Spring Seeds, 2012). Seeds for this cultivar were sourced through Salt Spring Seeds, Salt Spring Island, BC.  The company’s website claims good blight resistance and high early yields for this cultivar.  No maturation time is stated, but cv. Bonny Best is reported to mature in 72 to 75 days.  Cv. Pollock produces 110 to 280 gram fruit with a mean shoulder diameter of 7.2 cm (Figure 2).  3.3 Fertilizer Treatments The three fertilizers trialed include: 1) hairy vetch green manure (HV); 2) composted poultry manure (CPM); 3) EcoGrow 3-3-4 liquid fertilizer (certified OMRI liquid fertilizer, by EcoCert Inc., Surrey, BC Canada).  All fertilizers were applied at a rate of 100 kg Ntotal ha -1.  Details on each fertilizer are found in Sections 3.3.1 to 3.3.3; nutrient profiles are in Table 1.  3.4 cm cv. Black Cherry 7.2 cm Mean Dia. cv. Pollock Figure 2. Research Tomato Cultivars 19  Table 1. Organic Fertilizer Nutrient Profiles Fertilizer Total (%)  Total (ppm) N P K Ca Mg   Cu Zn Fe Mn B EcoGrow1 2.85 1.02 3.12 0.62 0.30  1 0.5 2 0.4 3 CPM2 2.54 1.80 2.15 2.75 0.65  111 376 4502 567 38 HV2 3.25 0.33 2.40 0.59 0.13  8 47 57 22 19 1 Analyses conducted at Agri-Food Labs, Guelph ON, June 8, 2012. 2 Analysis by Pacific Soil Analysis Inc., Richmond BC, May 20, 2010. 3.3.1 Hairy Vetch Green Manure Above ground hairy vetch (HV) biomass was analyzed for nutritional content by Pacific Soil Analysis Inc., Richmond BC (Table 1).  Moisture content, averaging 84.3%, was determined by drying 3 replicate samples in a laboratory oven at 45oC for 96 hours (Appendix A).  Amendment rate was calculated by converting tissue N content (3.25%) to a fresh weight equivalent. Treatment beds were amended with fresh HV harvested from a cover cropped field at the UBC Farm on May 28, 2010. Plant matter was harvested into 117 litre Rubbermaid® plastic totes, with the lid secured to conserve moisture.  Weighed plant matter was distributed evenly along treatment beds and incorporated at a depth of 20 cm during cultivation, as described in Section 3.5.1. 3.3.2 Composted Poultry Manure Composted poultry (broiler) manure (CPM) was supplied by the UBC Farm.  The compost pile, stored uncovered, had formed a dry surface crust, but remained moist below.  Despite previous composting, the CPM retained a strong odour of ammonia and was actively producing heat.  A composite sample comprised of 7 discrete subsamples from at least 15 cm below the surface and 1 m from the piles edge was sent for analysis at Pacific Soil Analysis Inc., Richmond BC (Table 1).  Mean moisture content was 32.8% (Appendix A). Composted poultry manure was spread evenly over the surface of treatment beds at 100 kg Ntotal ha -1 and incorporated to a depth of 20 cm on May 28, 2010.  Cultivation procedure is described in Section 3.5.1. 20  3.3.3 EcoGrow® 3-3-4 by EcoFert Inc. EcoGrow® is certified by EcoCert® for organic production.  This proprietary fertilizer is formulated with kelp, legume seed meals, and a fulvic-humic combination.  Feed-stocks were fermented using a proprietary microbial culture (Waliwitiya, personal communication, August 27, 2012). EcoGrow was applied in 16 equal, weekly split applications (400 mL per fertigation event). Fertigation procedures are detailed in Section 3.5.6.  Product volume requirements were calculated based on label advertised N content (3%).  Actual nutrient concentrations were determined by Agrifood Laboratories, Guelph, ON (Table 1). 3.3.3.1 No Fertilizer Control Tomato plants grown in ‘no-fertilizer’ control treatment beds were dependent solely upon existing soil fertility.  Pre-amendment soil nutrient levels for each quadrant are detailed (Table 5).  Bed preparation, irrigation and all other cultural practices were as per other treatments. 3.4 The Growing Environment 3.4.1 Regional Climate This research was conducted at the UBC Farm, situated on a headland extending into the Strait of Georgia at a latitude of +49.28 (49°16'48"N) and a longitude of -123.13 (123°07'48"W).  The climate can be characterized as “humid cool temperate”.  Average summer temperature and precipitation values are displayed in Table 2. Table 2. Vancouver Climate Normals 1971 – 2000* Metric May June July August September October Mean Daily Temperature (oC) 12.5 15.2 17.5 17.6 14.6 10.1 Mean Daily Maximum (oC) 16.5 19.2 21.7 21.9 18.7 13.5 Mean Daily Minimum (oC) 8.4 11.2 13.2 13.4 10.5 6.6 Precipitation (mm) 67.9 54.8 39.6 39.1 53.5 112.6 *“Canadian Climate Normals 1971-2000 at YVR” Environment Canada. 05/29/12. Accessed: 08/29/12. Using 10oC as a base for heat-loving crops, the 18 year average number of growing degree days (GDD) over the research period (June 1 to October 11) is 845, as recorded at the 21  Vancouver Airport (http://www.farmwest.com/climate/gd).  In 2010 there were 839 GDD during the same period; less than one percent deviation from the norm. 3.4.2 Soil Description The hoop house soil is an agriculturally modified Humo-Ferric Podzol with sandy loam texture containing 33% coarse fragments (>2 mm).  This regionally characteristic soil, originating from a deforested area off-site, was placed inside the hoop house at a depth of 30 cm in 2005.  Since that time, it has received numerous amendments including compost, Sul-Po-Mag® (Langbeinite), and boron (B) to alleviate nutrient deficiencies.  Pre-treatment soil fertility is detailed in Table 5. 3.4.3 The Hoop House The hoop house, measuring 7 m wide x 15.25 m long, is roughly oriented lengthwise along a southeast-northwest trajectory.  The clear, polyethylene cover has been in use since 2006. Most recommendations suggest poly replacement every 2 to 4 years (Heuvelink, 2005). Oxidation, dust and algal growth likely reduced light intensity, which was not measured in this study and considered consistent across treatments.   Light transparency through the yellowed, fibreglass panels comprising the hoop house end walls would have been less compared to the poly cover. 3.4.4 Ventilation The hoop house sides could be manually opened approximately 1.2 metres high.  The sides were left open during the main summer season (June – August).  During the shoulder season (September – October), the sides were opened on hot days and closed at night.  This strategy was not strictly adhered to, resulting in episodic cooler nights and excessive heat during the day.  Two 1 m x 1 m shuttered vents on the southeast end wall remained open during the main season and closed during the shoulder season.  A door at the opposing end was opened during hot periods to further improve ventilation. Ventilation requirements were considered when determining planting density.  Plants were spaced 60 cm apart to maximize density without compromising air circulation.  In order to monitor leaf senescence, lower leaves were not pruned to improve air circulation. 22  3.5 Cultural Practices 3.5.1 Soil Preparation The soil in the research plot was cultivated and amended on May 28, 2010, ten days before transplanting.  All beds were double-dug by hand, two shovels deep (approximately 40 cm), using the method described by Jeavons (1995).  In the HV treatments fresh plant matter was laid 1 shovel blade deep (20 cm) and lightly incorporated into the underlying soil by chopping vertically with the shovel blade.  Composted poultry manure was surface applied after double digging and incorporated to 20 cm using a four-tined cultivation fork.  EcoGrow and Control treatment beds were prepared in a similar fashion but without amendments.  Beds were raked smooth into a convex shape in preparation for black plastic mulch.  The research plot was hand watered post cultivation, and again for two hours with an oscillating sprinkler on May 31, 2010 to re-wet the dry soil and stimulate HV decomposition. 3.5.2 Mulching Treatment beds were covered with black biodegradable plastic mulch derived from corn cellulose on June 3, 2010 in order to suppress weeds, conserve moisture, and increase soil temperatures.  The mulch was secured by rolling the edges around small diameter (approx. 8 to 13 mm dia.) lengths of bamboo fastened to the ground using metal garden staples.  This technique permitted easy access to the underlying soil for sampling and monitoring purposes. 3.5.3 Seedling Production Cv. Black Cherry tomatoes were seeded on March 27 and again on April 19, 2010.  Cv. Pollock tomatoes were sown on April 22, 2010.  All tomatoes were seeded into open flats containing farm produced organic potting mix and placed on heating pads in a passively heated glass greenhouse.  Seedlings were transplanted into 7.5 cm pots upon emergence of the first true leaf.  Tomato seedlings were tended by farm staff until transplanting on June 9. 3.5.4 Transplanting On June 9, 2010 tomato seedlings at similar growth stage were transplanted 60 cm apart in single rows spaced 1.0 m apart.  Cv. Black Cherry seedlings sown April 19th were transplanted into blocks 1 and 2, while those seeded March 27th were transplanted into block 3.  Seedlings 23  from both planting dates were at a comparable physiological stage.  Due to availability of planting stock, cv. Pollock was used for guard plants at row ends and to separate treatments. A 7 cm x 7 cm ‘X’ was cut through the plastic mulch at each planting location.  When necessary, lower leaves were removed during transplanting to facilitate a 15 cm planting depth.  The lower end of the vertical trellising twine was secured by tucking under the root ball during transplanting.  Mulch was closed around the tomato stem after transplanting to minimize exposed soil. To characterize seedling health, foliar samples from each cultivar were taken on June 11, 2010. Sampling procedure is described in Section 3.6.4, while foliar nutrient levels for the two cultivars are shown in Table 3.  At the time of transplanting, both cultivars were deficient in N, Zn, and B. Cv. Black Cherry was also deficient in K, while cv. Pollock was near the critical level.  High Fe levels were likely due to dust contamination. Table 3. Tomato Seedling Foliar Nutrient Status  *Five-leaf stage (Hochmuth et al., 1991) 3.5.5 Pruning and Training of Plants Axial shoots were pruned weekly to maintain a single leader.  No flowers or floral buds were removed.  Individual leaves were removed from plants only for the purpose of controlling disease.  All pruned vegetation was dried and stored in labelled paper bags for biomass determination.  At each weekly pruning, plants were also trained along a vertical trellis line by either twisting stems around the trellis or fastening with tomato trellis clips. 3.5.5.1 Pruning of Diseased Plant Matter At the onset of disease, affected leaves were pruned to control the spread of inoculum.  The first two plants (1HV-BC2 and 2CT-PO3) to exhibit extensive disease symptoms were removed on August 16th, 2010.  As disease symptoms progressed, control through leaf pruning was abandoned in favour of monitoring for potential treatment effects. Cultivar Nutrient % ppm N P K Ca Mg Cu Zn Fe Mn B Black Cherry 2.19 0.5 2.77 1.23 0.76 8 22 143 62 14 Pollock 2.21 0.48 3.02 1.19 0.63 8 24 124 92 16 Sufficiency Range* 3.0-5.0 0.3-0.6 3.0-5.0 1.0-2.0 0.3-0.5 5-15 25-40 40-100 30-100 20-40 24  3.5.6 Irrigation and Fertigation A timer-controlled low-pressure drip-irrigation system supplied city water (15 psi) to the crop.  To facilitate fertigation, EcoGrow treatments were supplied via a dedicated ø13 mm header line (Appendix B).  Water was dispensed along treatment beds via pressure compensating drip line (20 cm emitter spacing, 0.91 lph at 15 psi). Irrigation timing was periodically adjusted to account for changes in evapotranspiration over the course of the season.  Irrigation frequency was based on monitored soil moisture content.  The intent was to minimize leaching losses while maintaining an adequate and consistent moisture level.  Irrigation scheduling for the season is presented (Appendix B). Every Monday, from June 14 to September 27 (16 weeks) 400 mL of EcoGrow® 3-3-4 liquid fertilizer was diluted in 100 litres of city water in a large plastic Rubbermaid® tote (Figure 3 and Appendix B).  A submersible pump (Model 1800, Disston, USA) was used to distribute the nutrient solution via drip irrigation lines isolated from other treatments.  An additional 50 L of water was pumped through the system to clear the lines of fertilizer.  Three totes (300 L) of city water were subsequently distributed to the remaining three treatments for an equivalent irrigation rate across treatments and to eliminate extraneous influences of the fertigation procedure. Figure 3. EcoGrow Nutrient Solution Reservoir with Submersible Pump for Fertigation  25  3.5.7 Weed Control The black bio-plastic mulch effectively controlled weeds within treatments beds.  Unmulched pathways were hand-weeded with a hoe approximately every two weeks or as required.  Weeds emerging at the base of tomato plants and through holes in the mulch were removed concurrently with pruning and training. 3.6 Data Collection and Analysis To characterize the growing environment, ambient temperature, humidity, soil temperature and soil moisture data were routinely collected with a series of data loggers.  Soil fertility was analyzed prior to fertilizer applications, at fruit set (July 1) and mid-harvest (August 23). Growth, yield and plant health parameters were monitored for each experimental unit. Vegetative growth parameters monitored every 2-3 weeks included: plant height, number of nodes, and chlorophyll meter readings of the first and fourth leaves from the apex to monitor nutritional status, as well as tagged lower and mid-canopy leaves to evaluate senescence rates. Foliar sampling corresponded with soil sampling and chlorophyll measurements for the purpose of correlating these three metrics.  Above ground vegetative biomass (dry weight) was determined at the end of the season. Yield was quantified by measuring individual fruit fresh weight, largest shoulder diameter, and number of total and marketable fruit.  Total soluble solids content was determined for the first three fruit harvested from each plant.  The following sections describe sampling procedures in detail. 3.6.1 Environmental Parameters 3.6.1.1 Hoop House Ambient Temperature and Humidity Ambient temperature and humidity inside the hoop house were monitored with a Hobo H8-003- 02 data logger (Onset Computer Corp., Bourne MA) mounted to a wooden stake 30 cm above the ground and shielded from direct sunlight with a piece of white, corrugated plastic sheeting. Measurements were collected every 15 minutes from June 16 until August 23 when the instrument failed to reboot after downloading data.  Daily averages as well as minimum and maximum temperatures were determined to characterize the growing environment. 26  3.6.1.2 Soil Temperature Soil temperature was measured every 15 minutes at 10 cm depth for all treatments in Block 2. Data were collected using temperature sensors (model: TMC20-HD, Onset Computer Corp., Bourne MA) connected to a Hobo H8-008-04 outdoor 4 channel external data logger (Onset Computer Corp., Bourne MA).  Measurements were collected from June 16 until August 23 when the instrument failed to reboot after downloading data.  Average daily and seasonal soil temperatures, as well as diurnal minimum and maximum temperatures were determined. 3.6.1.3 Soil Moisture Soil moisture was measured hourly at 10 cm and 20 cm depth for each treatment in Block 2 using Watermark 200SS moisture sensors connected to a Watermark data logger (model: 900M; Irrometer Co., Riverside CA).  In lieu of a temperature probe for continual moisture sensor calibration, a default value of 22oC was used. 3.6.1.4 Outside Temperature and Humidity Atmospheric temperature and humidity data were acquired from the UBC Climate station located at Totem Field, south-west UBC campus, Vancouver Canada.  This meteorological station is approximately 700 m northwest of the research site. 3.6.2 Soil Fertility Monitoring Soil fertility was characterized on May 17th prior to fertilizer amendment, at fruit set on July 1st, and at mid-harvest on August 23rd.  For the May 17th sampling, one composite sample, comprised of 7 discrete subsamples (top 15 cm), was taken from each of the northwest, southwest, northeast and southeast hoop house quadrants.  For the July 1st and August 23rd sampling events, composite samples comprised of 7 discrete subsamples were taken from each treatment replicate.  Subsamples from the top 15 cm were taken along the length of each treatment bed and mixed in a clean bucket before withdrawing the composite sample.  Soil samples were refrigerated at 4oC until delivery for analysis at Pacific Soil Analysis Inc., Richmond, BC. May 17th soil samples were analyzed for pH, total N, ammonium (NH4 +), nitrate (NO3 -), P, K, Ca, Mg, Cu, Zn, Fe, Mn and B.  July 1st and August 23rd samples were analyzed for total N, NH4 +, 27  NO3 -, P, K, Ca, and Mg.  Soil sampling coincided with foliar analyses in order to correlate fertility with crop nutrition metrics. 3.6.3 Vegetative Growth Vegetative growth was evaluated by the following metrics: plant height (cm), number of nodes, and biomass production (dry weight).  Plant height and number of nodes were measured every two to three weeks on: June 10th, June 21st, July 5th, July 26th, August 9th, August 23rd, and September 13th.  Plant height was quantified with a measuring tape and nodes counted at each sampling event.  Above-ground vegetative biomass was determined after trial termination. Tomato plants were cut at soil level and dried along with shoot and leaf trimmings at 60oC. 3.6.4 Foliar Sampling Foliar samples taken on June 11th, July 1st and August 23rd were analyzed at Pacific Soil Analysis Inc. (Richmond, BC) for N, P, K, Ca, Mg, Cu, Zn, Fe, Mn and B concentrations. Samples taken on June 11th characterized seedling health at transplanting.  Composite samples (1 per cultivar) consisted of the second set of leaflets from the apex of the most recently matured leaf on each tomato plant.  The remaining two sampling dates coincided with fruit set and mid-harvest respectively.  Composite samples were collected for each cultivar per treatment replicate (4 treatments x 3 replicates x 2 cultivars = 24 samples per event).  Samples were comprised of the most recently mature leaf, including petiole, (four leaves per sample) as described by Hochmuth et al. (1991).  Samples were stored in sealed plastic bags and refrigerated at 4oC until laboratory delivery. 3.6.5 Senescence Rates and Chlorophyll Measures Chlorophyll status was non-destructively measured using an Opti Science™ CCM-200 chlorophyll meter (Hudson, NH).  Measurements for monitoring plant health were taken from the first and fourth most recently matured leaves.  Senescence was monitored on tagged lower and mid-canopy leaves.  Chlorophyll measurements were taken on the same dates as the vegetative metrics described in Section 3.6.3. 3.6.6 Disease Assessment Qualitative assessment of disease incidence and severity was determined by comparing time series photographs of each plant against a number of print and online resources (Barrett et al., 28  1991; http://5e.plantphys.net; http://vegetablemdonline.ppath.cornell.edu; http://www.agf.gov.bc.ca; http://www.omafra.gov.on.ca). 3.6.7 Yield Tomato fruit were harvested twice weekly at the pink to red-ripe stage (Heuvelink, 2005). Weekly yields were determined by pooling the two weekly harvests.  Measured yield parameters included quantity, fresh fruit weight and the largest shoulder diameter.  All fruit from each experimental unit were individually weighed on a small, portable scale (±0.1 g) periodically calibrated against a laboratory scale (±0.001g; Sartorius, Goettingen, Germany).  Shoulder diameter was measured by ruler (±0.1 cm).  Total and marketable yields were quantified. Marketable fruits were classified as those free of blemishes, cracks, and disease symptoms. 3.6.8 Fruit Quality 3.6.8.1 Total Soluble Solids Total soluble solids content (TSS) was measured for the first three fruit harvested from each plant.  Fruit were first ground with a pestle and mortar before pureeing in a blender.   TSS (oBrix) was measured by placing a few drops of pureed tomato juice in a hand held refractometer. 3.6.9 Statistical Analysis Statistical analysis was conducted using the software JMP 8.0 (SAS, Cary NC).  Treatment and block effects were determined by ANOVA and t-tests using Tukey’s HSD.  Multiple pairwise correlation analysis (Pearson Product Moment Correlations) was used to identify relationships between foliar and soil nutrients and chlorophyll meter readings.  Due to differing growth and yield characteristics of the two tomato cultivars trialed, statistical analysis of genotype x fertilizer interactions was only conducted for foliar nutrition and TSS metrics.     29  4. RESULTS 4.1 Growing Environment The hoop house substantially enhanced growing conditions by more than doubling production season (June 9 to October 12) GDD to 1577 from 728, as measured outdoors.  On average, ambient temperatures were 4.5oC higher in the hoop house (   Table 4 and Figure 4). Depending on irradiance and ventilation, daytime temperatures were typically 10oC to 25oC higher in the hoop house, while nighttime temperature differences were negligible.  The reduced greenhouse effect during August was likely due to increased ventilation by leaving the hoop house sides open during this time.  Daytime relative humidity (RH) was low, ranging between 25% and 35%, while nighttime RH was typically in excess of 90%.    Table 4. Mean Monthly Temperatures (oC) Month Outside Hoop house Difference June 13.9 19.7 5.9 July 17.6 22.3 4.8 August 17.6 20.9 3.3 September 14.7 18.7 4.0 October 13.1 17.6 4.5 Season Average 15.4 19.9 4.5 Figure 4. Hoop house vs. Outdoor Mean Daily Temperatures  0.0 5.0 10.0 15.0 20.0 25.0 30.0 09/06/2010 09/07/2010 09/08/2010 09/09/2010 09/10/2010 Te m p e ra tu re  ( o C ) Outside Temp. Hoop house temp. Predicted Hoop house temp. 30  4.1.1 Soil Temperature Mean hoop house soil temperature (-10 cm) between June 19 and August 23 was 23.6oC (Figure 5), an increase of 4.7oC over outside soils averaging 18.9oC.  This increase is similar to that observed for ambient air temperatures.  On average, minimum and maximum daily soil temperatures were 20.5 and 27.1oC, respectively. Figure 5. Hoop House Soil Temperatures at 10 cm Depth   15.0 17.0 19.0 21.0 23.0 25.0 27.0 29.0 31.0 33.0 So il Te m p e ra tu re  ( o C ) Daily Hhouse Soil Max. Daily Hhouse Soil Mean Daily Hhouse Soil Min. 31  4.1.2 Soil Fertility 4.1.2.1 Pre-treatment Conditions Pre-treatment soil analysis for each hoop house quadrant revealed variable fertility conditions (Table 5).  Total N in quadrant 2 (0.53%) was 32% higher compared to quadrant 1 (0.36%), 26% higher than quadrant 3, and 13% higher than quadrant 4.  Quadrant 1 had the lowest N, P, Ca, Mg and Zn while quadrant 4 was lowest in K.  The pH was adequate and comparable over the entire area, averaging 6.5. Table 5. Pre-Amendment Soil Fertility Quadrant Treatment pH N NH4 NO3 P K Ca Mg Cu Zn Fe Mn B % ppm 1: SW 1PM, 1HV, 2LQ 6.3 0.36 7 33 135 210 3150 310 0.4 19 17 48 0.8 2: NW 1LQ, 1CT, 2HV 6.5 0.53 14 42 189 395 4600 430 0.3 25 14 50 1.4 3: SE 2PM, 3PM, 3HV 6.6 0.39 38 55 195 210 4700 320 0.3 23 11 50 0.6 4: NE 2CT, 3CT, 3LQ 6.6 0.46 14 48 195 130 3350 245 0.4 26 16 50 0.7 Mean 6.5 0.44 18 45 179 236 3950 326 0.4 23 15 50 0.9 *Sampled May 17, 2010.  Analyzed by Pacific Soil Analysis Inc., Richmond BC. 4.1.2.2 Treatment Effects on Soil Fertility Soil from each plot was analyzed again at fruit set (July 1, 2010) and mid-harvest (August 23, 2010).  All nutrients were similar across treatments, except Ca, which was highest in the control and lowest in poultry manure plots (Table 6).  The mean NH4 to NO3 ratio of 1:7.3 was favourable for tomato growth (Adams, 1999).  The only significant block effects observed were for N at fruit set, where levels were highest Block 3 and lowest in Block 2.  Block 1 N levels were intermediate. Table 6. Soil Nutrient Status at Fruit Set Treatment N NH4 NO3 P K Ca Mg % ppm Control 0.34 a* 7.7 a 74.0 a 142 a 207 a 3417 a 310 a Hairy Vetch 0.33 a 7.7 a 38.9 a 124 a 182 a 3250 a,b 293 a EcoGrow 0.34 a 9.3 a 68.3 a 131 a 235 a 3350 a,b 333 a CPM 0.33 a 7.7 a 55.7 a 112 a 200 a 2767 b 278 a *Column values with different letters indicate significant treatment differences (α 0.05) Mid-harvest total N, NO3, NH4, and P levels were similar to concentrations observed at fruit set, while available K and Ca declined (Table 6 and Table 7).  Treatment effects on soil P and Ca 32  were significant at mid-harvest.  Highest levels were in the control, followed by hairy vetch (HV), EcoGrow and composted poultry manure (CPM), respectively.   Table 7. Soil Nutrient Status at Mid-Harvest Treatment N NH4 NO3 P K Ca Mg % ppm Control 0.34 a* 5.8 a 62.7 a 150 a 122 a 2767 a 285 a Hairy Vetch 0.33 a 6.7 a 40.0 a 138 a,b 97 a 2650 a,b 248 a EcoGrow 0.31 a 6.2 a 90.3 a 135 a,b 143 a 2667 a,b 280 a CPM 0.32 a 7.1 a 56.3 a 120 b 158 a 2250 b 288 a   *Column values with different letters indicate significant treatment differences (α 0.05) 4.2 Vegetative Growth 4.2.1 Height and Nodes Height of both cultivars followed a characteristic sigmoidal growth curve (Heuvelink, 2005). Growth of cv. Pollock declined after August 9th (Figure 7), while strong linear growth of cv. Black Cherry continued until August 23rd (Figure 6).  Growth rates were not affected by fertilizer treatments in either cultivar.  Growth of cv. Black Cherry exceeded that of cv. Pollock over the entire season (    Table 8).     Table 8. Growth Rate (cm day-1) by Cultivar Period Black Cherry Pollock June 10 to June 20 1.2 0.3 June 21 to July 5 2.3 0.6 July 6 to July 26 2.7 1.7 July 27 to August 9 3.5 1.7 August 10 to August 23 3.4 0.7 August 24 to September 13 1.5 0.2 33  Figure 6. Cumulative Growth of cv. Black Cherry  Figure 7. Cumulative Growth of cv. Pollock  The growth habit of the two tomato cultivars differed substantially.  Indeterminate growth of cv. Black Cherry continued throughout the season, while growth of cv. Pollock appeared semi- determinate, with little growth observed after week 10.  There were no treatment effects on plant height or number of nodes in either cultivar (Table 9).  Total plant height of cv. Black Cherry was 0 50 100 150 200 250 1 2 3 4 5 6 7 8 9 10 11 12 13 14 H e ig h t (c m ) Week Control Hairy vetch EcoGrow Poultry manure 0 50 100 150 200 250 1 2 3 4 5 6 7 8 9 10 11 12 13 14 H e ig h t (c m ) Week Control Hairy vetch EcoGrow Poultry manure 34  on average 232 cm, while cv. Pollock averaged 103 cm.  Cv. Black Cherry produced on average 28 nodes compared to 18 in cv. Pollock. In mid-July, the terminal growing point on a number of cv. Pollock plants was inadvertently pruned, restricting further vegetative growth.  Pruning of cv. Pollock plants reduced plant height by 30 cm on average. Table 9. Cumulative Plant Height and Nodes Treatment Plant Height (cm) Nodes Black Cherry (s.d.*) Pollock (s.d.) Black Cherry (s.d.) Pollock (s.d.) Control 230 (16.8) 102 (17.8) 27.4 (2.6) 18.0 (3.2) Hairy vetch 237 (21.2) 103 (14.5) 29.0 (3.0) 18.1 (2.5) EcoGrow 238 (18.6) 98 (12.3) 27.8 (2.8) 17.7 (2.5) Poultry manure 224 (25.3) 110 (15.0) 28.3 (3.6) 18.8 (3.3) *s.d.: standard deviation Above ground vegetative biomass, including shoots, leaves and trimmings, was determined on a dry weight basis.  Cv. Black Cherry yielded substantially more biomass compared with cv. Pollock due to its’ different growth habit described previously.  Biomass accumulation was equivalent across treatments in cv. Black Cherry (Figure 8).  However, in cv. Pollock, EcoGrow produced more biomass compared to other treatments, which were similar. Figure 8. Vegetative Biomass  Pruning of cv. Pollock had a deleterious effect on biomass production by either delaying or completely terminating further vegetative growth (Figure 9).  Reductions were significant in Control and HV treatments where pruning reduced biomass production by 31.3% and 18.3%, respectively. 151.5 161 206.2 129.7 265.6 312.2 315.8 286.6 0 50 100 150 200 250 300 350 Control Hairy vetch EcoGrow CPM V e ge ta ti ve  D ry  W e ig h t (g ) Pollock Black Cherry * 35  Figure 9. Pruning Effects on cv. Pollock Dry Matter Accumulation  4.2.2 Foliar Nutrient Status Foliar nutrient levels at fruit set and mid-harvest are presented (Table 10 and Table 11).  In cv. Black Cherry, K was highest with EcoGrow and lowest in the CPM treatment at fruit set. Manganese was lowest in the EcoGrow treatment at mid-harvest.  For cv. Pollock, Ca was significantly lower in the CPM treatment at fruit set and in the HV treatment at mid-harvest. Boron was highest in the control at fruit set, and similar to EcoGrow and CPM at mid-harvest. Foliar Mn was highest in control and HV treatments at fruit set, with no treatment differences by mid-harvest.  Mid-harvest K levels were highest in EcoGrow and HV treatments for cv. Pollock. At fruit set, foliar levels of N, P, K, Ca, and Mg were significantly higher in cv. Pollock compared to cv. Black Cherry.  By mid-harvest only Ca, Mg, and Fe were higher in cv. Pollock.  No significant correlation was identified between foliar nutrient levels and yield in either cultivar. According to sufficiency ranges at fruit set (Hochmuth et al., 1991), all nutrients were adequate to high except for Mn (deficient) in cv. Black Cherry.  By the mid-harvest sample, P, K, and Zn deficiencies were observed in both cultivars.  A minor Mn deficiency was noted in cv. Black Cherry treated with EcoGrow.  Phosphorus was deficient in all cv. Pollock plants by mid-harvest, while K and Zn deficiencies occurred in control and CPM treatments.  For both cultivars, K was highest when treated with EcoGrow. 151.5 161 206.2 129.7 104 131.5 201.7 140.9 140 153.6 205.4 137.2 0 50 100 150 200 250 Control Hairy Vetch EcoGrow CPM V e ge ta ti ve  d ry  w e ig h t (g ) Unpruned Pruned All plants 36  Table 10. Foliar Nutrient Concentrations at Fruit Set Treatment N P K Ca Mg Cu Zn Fe Mn B % ppm B la c k  C h e rr y  Control 4.29 a* 0.42 a 3.03 a,b 2.37 a 0.44 a 15 a 42 a 108 a 26 a 27 a HV 4.35 a 0.39 a 3.25 a,b 2.14 a 0.44 a 14 a 45 a 112 a 28 a 25 a EcoGrow 3.93 a 0.38 a 3.44 a 2.47 a 0.51 a 14 a 37 a 92 a 26 a 27 a CPM 4.41 a 0.39 a 3.01 b 2.13 a 0.46 a 14 a 45 a 92 a 27 a 23 a  P o ll o c k  Control 4.62 a 0.46 a 3.47 a 3.53 a 0.65 a 15 a 43 a 92 a 31 a,b 32 a HV 4.62 a 0.40 a 3.81 a 3.21 a,b 0.68 a 14 a 45 a 101 a 35 a 29 b EcoGrow 4.58 a 0.44 a 3.84 a 3.41 a 0.68 a 15 a 45 a 90 a 30 b 29 b CPM 4.53 a 0.41 a 3.57 a 2.97 b 0.64 a 13 a 42 a 90 a 30 b 27 b Sufficiency †  2.5-4.0 0.2-0.4 2.5-4.0 1.0-2.0 0.25-0.5 5-10 20-40 40-100 30-100 20-40 *Letters indicate significant treatment effects (α 0.05) within each cultivar, but not between cultivars. † (Hochmuth et al., 1991); Colour indication: Yellow = deficiency; Green = sufficient; Red= High. Table 11. Foliar Nutrient Concentrations at Mid-Harvest Treatment N P K Ca Mg Cu Zn Fe Mn B % ppm B la c k  C h e rr y  Control 2.72 a 0.20 a 1.41 a 3.14 a 0.39 a 14 a 19 a 94 a 38 a 44 a HV 2.60 a 0.22 a 1.49 a 2.63 a 0.34 a 14 a 23 a 88 a 35 a,b 40 a EcoGrow 2.48 a 0.21 a 1.71 a 2.63 a 0.30 a 13 a 21 a 78 a 29 b 36 a CPM 2.50 a 0.19 a 1.22 a 2.86 a 0.37 a 16 a 19 a 94 a 31 a,b 41 a  P o ll o c k  Control 2.69 a 0.19 a 1.01 b 4.50 a 0.58 a 14 a 18 a 122 a 56 a 66 a HV 2.66 a 0.16 a 1.60 a 3.64 b 0.55 a 12 a 21 a 121 a 58 a 48 b EcoGrow 2.77 a 0.19 a 1.54 a 4.07 a,b 0.54 a 13 a 21 a 123 a 54 a 53 a,b CPM 2.76 a 0.19 a 1.32 a,b 3.87 a,b 0.42 a 16 a 17 a 96 a 42 a 60 a,b Sufficiency †  2.0-3.0 0.2-0.4 1.5-2.5 1.0-2.0 0.25-0.5 5-10 20-40 40-100 30-100 20-40 *Letters indicate significant treatment effects (α 0.05) within each cultivar, but not between cultivars. † (Hochmuth et al., 1991); Colour indication: Yellow = deficient; Green = sufficient; Red= High. Multiple pairwise correlation analysis found no significant relationships between soil and foliar nutrients when separated by treatment and sampling event.  Combining treatment and sampling event data for each cultivar exposed significant relationships between several foliar nutrients (correlation coefficients >0.65) (Table 12).  Calcium was the only soil nutrient found to be correlated with foliar nutrients. Strong positive correlations between foliar N, P and K were found in both cultivars.  These same nutrients were positively correlated with available soil Ca, but not with their own respective soil levels.  Foliar Mg was positively correlated with N in both cultivars and with K in cv. Black Cherry.  Boron was negatively correlated with foliar N, P, and K, which was likely due to metabolic changes between growth phases.  Remaining correlations were inconsistent between cultivars. 37  Table 12. Soil and Foliar Nutrient Correlations by Cultivar Nutrient Correlations Cv. Black Cherry Cv. Pollock N:P 0.89 0.95 N:K 0.88 0.96 N:Mg 0.72 0.68 N:Mn N/S -0.69 N:Zn 0.94 N/S N:B -0.80 -0.82 N:Casoil 0.67 0.69 P:K 0.92 0.93 P:Fe N/S -0.71 P:Mn N/S -0.73 P:Zn 0.90 N/S P:B -0.76 -0.73 P:Casoil 0.66 0.68 K:Zn 0.88 N/S K:Ca N/S -0.70 K:Mg 0.67 N/S K:Mn N/S -0.68 K:B -0.84 -0.90 K:Casoil 0.69 0.69 Ca:B N/S 0.72 Fe:Mn N/S 0.79 N/S = not significant Nutritional status based on DRIS norms (Caron & Parent, 1989) at fruit set revealed treatment effects on K:P ratios in cv. Black Cherry (Table 13).  For both sampling dates, concentrations of all nutrients except Ca and Mg were lower than DRIS norms.  Deviation from DRIS norms was substantially greater by mid-harvest, indicating a greater nutrient imbalance at this time.  This is supported by low N, P and K levels.  The use of DRIS nutrient ratios is claimed to overcome changes in nutrient partitioning between developmental stages (Sumner, 1979). However, the application of generalized DRIS norms across cultivars, under different environmental conditions and between developmental stages is still a matter of debate (Amundson & Koehler, 1987; Beverly, 1991; Caron & Parent, 1989).  Thus, comparisons should be considered with caution.  38  Table 13. Cv. Black Cherry Nutrient Ratios by Treatment and Sampling Event Nutrient Ratio Fruit Set Mid Harvest DRIS CV Control HV EcoGrow CPM Control HV EcoGrow CPM %N* 4.29 a 4.35 a 3.93 a 4.41 a 2.72 a 2.60 a 2.48 a 2.50 a 4.5 14.8 %P 0.42 a 0.39 a 0.38 a 0.39 a 0.20 a 0.22 a 0.21 a 0.19 a 0.75 25.6 %K 3.03 a 3.25 a 3.44 a 3.01 a 1.41 a 1.49 a 1.71 a 1.22 a 4.36 19.2 %Ca 2.37 a 2.14 a 2.47 a 2.13 a 3.14 a 2.63 a 2.96 a 2.86 a 1.72 20 Mg 0.44 a 0.44 a 0.51 a 0.46 a 0.39 a 0.34 a 0.30 a 0.37 a 0.34 22.9 N:P 10.45 a 11.15 a 10.74 a 11.47 a 13.68 a 12.29 a 12.01 a 13.42 a 6.3 23.9 N:K 1.42 a 1.34 a 1.16 a 1.49 a 1.99 a 1.78 a 1.52 a 2.04 a 1.06 18.8 N:Ca 1.82 a 2.08 a 1.59 a 2.17 a 0.91 a 0.99 a 0.89 a 0.88 a 2.71 25.3 10Mg:N 1.03 a 1.00 a 1.30 a 1.04 a 1.44 a 1.30 a 1.22 a 1.47 a 0.76 23.1 K:P 7.36 b 8.34 a,b 9.21 a 7.79 a,b 7.00 a 7.22 a 8.04 a 6.52 a 6.14 28.1 Ca:P 5.82 a 5.48 a 6.72 a 5.52 a 16.08 a 12.39 a 14.79 a 15.35 a 2.45 31.8 10Mg:P 10.82 a 11.20 a 13.73 a 11.93 a 19.96 a 15.93 a 14.68 a 19.59 a 4.74 30.7 10Ca:K 7.84 a 6.56 a 7.23 a 7.02 a 23.78 a 18.14 a 18.80 a 23.29 a 4.02 18.8 100Mg:K 14.64 a 13.40 a 14.83 a 15.37 a 29.22 a 23.53 a 18.60 a 29.89 a 8.00 27.2 10Mg:Ca 1.87 a 2.07 a 2.07 a 2.22 a 1.29 a 1.28 a 1.09 a 1.29 a 2.04 32.3 Row means per sampling date not followed by the same letter are significantly different (α 0.05). *dry weight basis Plants are considered to have optimal nutrition when the nutrient imbalance index (NII), the absolute sum of individual indices, equals zero.  The degree of deviation from optimal indicates the severity of nutrient imbalance.  For cv. Black Cherry, the greatest nutritional imbalance at fruit set was with EcoGrow followed by CPM, control and HV respectively (Table 14).  Between sampling dates, NII increased 2.4, 3.1, 3.5 and 3.6 fold for EcoGrow, HV, CPM and control, respectively.  At this time, NII were greatest in control and CPM treatments and least in EcoGrow and HV treatments.  While still insufficient, EcoGrow and HV were better suited to Black Cherry nutritional demands compared to CPM and the control. Table 14. Cv. Black Cherry M-DRIS Indices Nutrient Index Control Hairy vetch EcoGrow CPM Fruit Set Mid Harvest Fruit Set Mid Harvest Fruit Set Mid Harvest Fruit Set Mid Harvest N 1 -13 4 -15 -7 -20 6 -16 P -30 -88 -33 -69 -41 -75 -34 -86 K -23 -102 -15 -78 -15 -68 -22 -107 Ca 27 115 19 86 29 100 20 111 Mg 20 46 19 32 29 22 23 46 NII 101 364 90 279 121 285 104 366 Individual nutrient indices in the optimal range are between -15 to 15 (Barker & Pilbeam, 2007). Values less than -15 indicate deficiency and those above 15 potential excess.  At fruit set, all cv. Black Cherry plants were most deficient in P, followed by K (        Table 15). Nitrogen was sufficient in all treatments (Table 14).  Magnesium was most abundant with CPM 39  and equivalent with Ca for HV and EcoGrow.  By mid-harvest, K was the most limiting nutrient in all treatments except EcoGrow.  Potassium, P and N were deficient in all treatments, while Ca and Mg were in excess.  Deficiencies were greatest with CPM and in the control.         Table 15. Cv. Black Cherry Nutrient Requirement Ranking Fruit Set Control P > K > N > Mg > Ca Hairy vetch P > K > N > Ca = Mg EcoGrow P > K > N > Ca = Mg CPM P > K > N > Ca > Mg Mid Harvest Control K > P > N > Mg > Ca Hairy vetch K > P > N > Mg > Ca EcoGrow P > K > N > Mg > Ca CPM K > P > N > Mg > Ca  Limiting  Sufficient  Similar to cv. Black Cherry, treatment effects on cv. Pollock were related to K ratios (Table 16). At fruit set, treatment effects were observed for N:K and K:P ratios.  With respect to DRIS norms, K and P levels were lower, Ca and Mg higher, and N comparable.  By mid-harvest, treatment differences in K:DM, N:K and Ca:K ratios were noted.  Hairy vetch and EcoGrow had the highest K content followed by CPM and control, respectively.  In all treatments, N, P and K were lower than DRIS norms, while Ca and Mg were higher.  This is consistent with cv. Black Cherry. Table 16. Cv. Pollock Nutrient Ratios by Treatment and Sampling Event Nutrient Ratio Fruit Set Mid Harvest DRIS CV Control HV EcoGrow CPM Control HV EcoGrow CPM %N* 4.62 a 4.62 a 4.58 a 4.53 a 2.69 a 2.66 a 2.77 a 2.76 a 4.5 14.8 %P 0.46 a 0.40 a 0.44 a 0.41 a 0.19 a 0.19 a 0.19 a 0.19 a 0.75 25.6 %K 3.47 a 3.81 a 3.84 a 3.57 a 1.01 b 1.60 a 1.54 a 1.32 a,b 4.36 19.2 %Ca 3.53 a 3.21 a 3.41 a 2.97 a 4.50 a 3.64 a 4.07 a 3.87 a 1.72 20 %Mg 0.65 a 0.68 a 0.68 a 0.64 a 0.58 a 0.55 a 0.54 a 0.42 a 0.34 22.9 N:P 10.03 a 11.87 a 10.51 a 11.00 a 14.83 a 15.07 a 14.61 a 14.44 a 6.3 23.9 N:K 1.33 a 1.22 a,b 1.19 b 1.27 a,b 2.68 a 1.66 b 1.80 a,b 2.20 a,b 1.06 18.8 N:Ca 1.32 a 1.44 a 1.35 a 1.53 a 0.60 a 0.74 a 0.69 a 0.72 a 2.71 25.3 10Mg:N 1.40 a 1.47 a 1.49 a 1.43 a 2.18 a 2.07 a 1.95 a 1.50 a 0.76 23.1 K:P 7.52 b 9.73 a 8.81 a,b 8.68 a,b 5.66 a 8.98 a 8.15 a 6.77 a 6.14 28.1 Ca:P 7.64 a 8.25 a 7.81 a 7.22 a 25.58 a 21.24 a 21.47 a 20.30 a 2.45 31.8 10Mg:P 14.03 a 17.58 a 15.66 a 15.80 a 33.10 a 31.76 a 28.44 a 22.14 a 4.74 30.7 10Ca:K 10.17 a 8.46 a 8.91 a 8.33 a 45.23 a 22.81 b 26.52 a,b 30.92 a,b 4.02 18.8 100Mg:K 18.65 a 17.94 a 17.75 a 18.09 a 58.22 a 34.46 a 35.23 a 34.48 a 8.00 27.2 10Mg:Ca 1.84 a 2.12 a 2.01 a 2.19 a 1.29 a 1.52 a 1.33 a 1.09 a 2.04 32.3  Row means per sampling date not followed by the same letter are significantly different (α 0.05).*dry weight basis 40  NII values indicate nutrient imbalances at both growth stages for cv. Pollock.  Indices were similar across treatments at fruit set, though slightly lower with CPM (Table 17).  NII values increased threefold between sampling dates for fertilized plants compared to a fourfold increase in the control, suggesting significant nutrient imbalances in all treatments. Table 17. Cv. Pollock M-DRIS Indices Indices Control Hairy vetch EcoGrow CPM Fruit Set Mid Harvest Fruit Set Mid Harvest Fruit Set Mid Harvest Fruit Set Mid Harvest N -8 -26 -6 -27 -9 -27 -5 -17 P -37 -132 -51 -123 -43 -118 -43 -104 K -30 -206 -20 -95 -22 -109 -22 -130 Ca 49 216 42 132 45 148 37 157 Mg 37 104 44 80 41 73 40 53 NII 161 684 162 457 159 475 147 461 For all treatments, N was sufficient at fruit set and deficient by mid-harvest in cv. Pollock (Table 17).  However, mid-harvest N deficiency was minor with CPM.  For both sampling events, P and K were the most limiting nutrients, with substantially higher imbalances by mid-harvest (Table 18).  At mid harvest, K was most limiting in control and CPM treatments.  Both sufficiency range and DRIS diagnostics revealed positive effects of HV and EcoGrow fertilizers on K nutrition in cv. Pollock.    Table 18. Cv. Pollock Nutrient Sufficiency Ranking Fruit Set Control P > K > N > Mg > Ca Hairy vetch P > K > N > Ca > Mg EcoGrow P > K > N > Mg > Ca CPM P > K > N > Ca > Mg Mid Harvest Control K > P > N > Mg > Ca Hairy vetch P > K > N > Mg > Ca EcoGrow P > K > N > Mg > Ca CPM K > P > N > Mg > Ca  Limiting  Sufficient  4.2.3 Chlorophyll Status and Senescence Rates Fertilizer treatments did not preferentially affect first or fourth leaf chlorophyll meter measurements (Figure 10 thru Figure 13).  Cultivar differences were noted, however.  First leaf chlorophyll meter readings in cv. Black Cherry decreased between the first two sampling dates, 41  then remained constant or increased slightly for the remainder of the season (Figure 10). Powdery mildew infection darkened leaves late in the season, which may explain the increasing values.  In contrast, first leaf chlorophyll content in cv. Pollock steadily decreased over the season (Figure 11).  Fourth leaf fluorescence readings only declined slightly over the season in cv. Black Cherry (Figure 12).  In cv. Pollock, fourth leaf chlorophyll readings increased from July 1st to 26th, then remained stable until August 23rd before declining over the remainder of the season (Figure 13).  Cultivar differences in leaf greenness were visually apparent, coinciding with higher instrument readings for cv. Black Cherry, confirming the need for cultivar specific reference crops. Figure 10. Cv. Black Cherry First Leaf Chlorophyll Readings   15 20 25 30 35 40 1/7/10 26/7/10 9/8/10 23/8/10 13/9/10 C C I Control Hairy vetch EcoGrow Poultry manure 42  Figure 11. Cv. Pollock First Leaf Chlorophyll Readings   Figure 12. Cv. Black Cherry Fourth Leaf Chlorophyll Readings  15 20 25 30 35 40 1/7/10 26/7/10 9/8/10 23/8/10 13/9/10 C C I Control Hairy vetch EcoGrow Poultry manure 0 5 10 15 20 25 30 35 40 1/7/10 26/7/10 9/8/10 23/8/10 13/9/10 C C I Control Hairy vetch EcoGrow Poultry manure 43  Figure 13. Cv. Pollock Fourth Leaf Chlorophyll Readings  Chlorophyll measurements were not sensitive to treatment effects on foliar nutrients, likely because K was the only nutrient significantly affected.  Pooling treatment and sampling event data for each cultivar exposed correlations between first leaf chlorophyll readings and several foliar nutrients; these correlations were not consistent between cultivars.  Chlorophyll readings from cv. Black Cherry were correlated with foliar N (r=0.89), P (r=0.80), K (r=0.82), Zn (r=0.90) and B (r=-0.86).  In cv. Pollock, correlations were found with K (r=0.65) and B (r=-0.78). Chlorophyll measurements were neither correlated with soil nutrient status nor yield metrics. Fertilizer treatments did not affect lower canopy senescence rates in either cultivar. Senescence rates for each cultivar are defined by the following polynomial equations (where y = fluorometer reading; x = time): Equation 1. Black Cherry Lower Canopy Senescence Rate y = 0.0022x2 – 177.54x + 4E6 (R2 = 0.86) Equation 2. Pollock Lower Canopy Senescence Rate y = 0.0025x2 – 200.13x + 4E6 (R2 = 0.98) No mid-canopy senescence was observed in cv. Black Cherry, while in cv. Pollock, CPM induced accelerated senescence compared to the other treatments which were not different 0 5 10 15 20 25 30 35 40 1/7/10 26/7/10 9/8/10 23/8/10 13/9/10 C C I Control Hairy vetch EcoGrow Poultry manure 44  (Figure 14).  Cv. Pollock mid-canopy senescence rates for control, EcoGrow and HV treatments were defined by Equation 3 while Equation 4 was used for CPM. Equation 3. Cv. Pollock Mid-Canopy Senescence for Control, EcoGrow and HV Treatments y = -1.6033x2 + 1.862x + 33.693 (R2 = 0.99) Equation 4. Cv. Pollock Mid-Canopy Senescence for CPM y = 33.396x-0.825 (R2 = 0.99) Figure 14. Cv. Pollock Mid-Canopy Senescence  4.2.4 Yield 4.2.5 Yield Summary Harvest of cv. Black Cherry fruit began 53 days after transplanting on August 2, 2010 and continued for eleven weeks until trial termination on October 11th, at which point abundant green fruit remained on all plants.  All three fertilizers produced similar yield increases over the control (  Table 19 and  Table 20).  Pre-treatment soil fertility appears to have been adequate until week 6 when harvests from HV and CPM treatments began to exceed the control (Figure 15). EcoGrow began out-yielding the control by week 8, eventually matching the other fertilizers by 10 15 20 25 30 35 40 26/7/10 9/8/10 23/8/10 13/9/10 C C I Control Hairy vetch EcoGrow Poultry manure 45  trial’s end.  EcoGrow fertilized plants continued to yield well through the final weeks of the season, while yields diminished in all other treatments. Harvest of cv. Pollock fruit began 60 days after transplanting on August 9, 2010 and continued for 10 weeks.  Yields and harvest distribution from cv. Pollock were similar in all treatments ( Table 21 and     Table 22).  Pre-treatment soil fertility may have been sufficient for cv. Pollock with its’ shorter, semi-determinate lifecycle.  This is supported by fertilizer yield effects in cv. Black Cherry after week 6, by which time the entire fruit load in cv. Pollock had set. 4.2.6 Cumulative Fruit Yields Average fertilizer yield response in cv. Black Cherry was 23% over the control (  Table 19). Mean shoulder diameter was comparable in all fertilized treatments, and significantly greater than the control in EcoGrow and CPM treatments.  Fruit counts did not differ significantly across treatments.  Cull rate of harvested fruit was low and did not differ between treatments, averaging 1.2%.  On average, 1.5 kg of unripe fruit remained on fertilized cv. Black Cherry plants compared to 1.1 kg in the unfertilized control.  This equates to approximately 29% of total yield in both cases.  Marketable yield trends did not differ from total yields in cv. Black Cherry ( Table 20).  Mean seasonal fruit weight was similar across treatments.  However, week-by-week analyses revealed treatment effects (Section 4.2.7).   Table 19. Cv. Black Cherry Total Yield Per Plant Treatment Yield (g) No. Fruit Dia. (cm) Control 4043.6 b 161.3 a 3.3 b Hairy Vetch 5323.0 a 199.1 a 3.4 a,b EcoGrow 5324.3 a 195.3 a 3.5 a CPM 5112.0 a 187.3 a 3.5 a Column values not followed by the same letter are significantly different (α 0.05)  Table 20. Cv. Black Cherry Marketable Yield Per Plant Treatment Yield (g) No. Fruit Weight (g) Control 2888.7 b 159.8 a 25.7 a Hairy Vetch 3721.0 a 197.1 a 25.9 a EcoGrow 3702.8 a 192.6 a 26.0 a CPM 3669.7 a 184.6 a 27.2 a Column values not followed by the same letter are significantly different (α 0.05) None of the fertilizers trialed stimulated a yield response in cv. Pollock (     Table 21).  On average each cv. Pollock plant yielded a total of 4734 g comprised from 28 tomatoes.  Cull rate 46  was equivalent across treatments, averaging 1.3% which is similar to cv. Black Cherry.  Un- harvested green fruit averaged 400g, or 8.4% of total yield; significantly lower than cv. Black Cherry.  Due to low cull rates, marketable yield relationships did not differ from total amounts ( Table 22).      Table 21. Cv. Pollock Total Yield Per Plant Treatment Yield (g) No. Fruit Dia. (cm) Control 4866.7 a 29.3 a 7.2 a Hairy Vetch 4725.7 a 27.9 a 7.2 a EcoGrow 4694.7 a 28.1 a 7.2 a CPM 4662.5 a 25.5 a 7.4 a      Table 22. Cv. Pollock Marketable Yield Per Plant Treatment Yield (g) No. Fruit Weight (g) Control 4829.4 a 29.1 a 156.8 a Hairy vetch 4657.3 a 27.6 a 161.2 a EcoGrow 4589.0 a 27.4 a 162.9 a CPM 4399.1 a 24.5 a 174.0 a  Pruning of cv. Pollock reduced yields by 23.2%, 19.6%, 13.7% and 7.4% in control, HV, EcoGrow and CPM treatments, respectively (Table 23).  The absence of treatment effects permitted pooled analysis of pruning effects on yield distribution (Section 4.2.8.1). Table 23. Pruning Effects on cv. Pollock Marketable Yield Per Plant (g) Treatment All plants Pruned Unpruned Yield loss Control 4564.8 a 3708.4 a 4829.4 a 23.2 Hairy Vetch 4425.0 a 3742.4 a 4657.3 a 19.6 EcoFert 4483.9 a 3958.3 a 4589.0 a 13.7 CPM 4182.3 a 4073.9 a 4399.1 a 7.4 4.2.7 Cv. Black Cherry Harvest Distribution Yields from cv. Black Cherry were comparable across treatments for the first five weeks, after which all fertilizers stimulated yield increases over the control (Figure 15 and Table 24). Composted poultry manure and HV out yielded EcoGrow in week six and seven, respectively. The delayed yield response with EcoGrow was overcome by high yields in weeks ten and eleven, resulting in equivalent cumulative yields for all fertilizer treatments (Figure 15). 47  Composted poultry manure yields dropped sharply after week eight, offsetting strong early season production.  Analysis of fruit counts did not disclose any additional treatment effects. Table 24. Treatment Effects on cv. Black Cherry Weekly Per Plant Marketable Yield (g) TRMT Week 1 2 3 4 5 6 7 8 9 10 11 Control 18.6 a 64.0 a 268.9 a 383.6 a 354.1 a 396.3 b 306.6 c 415.9 b 338.7 a 171.1 b 170.9 b,c HV 26.9 a 43.8 a,b 207.4 a 415.6 a 349.8 a 535.5 a,b 573.0 a 659.4 a 416.0 a 239.9 a,b 253.8 b EcoGrow 13.7 a 24.5 b 238.0 a 367.3 a 292.9 a 473.8 a,b 431.3 b,c 630.5 a 533.2 a 319.3 a 378.3 a CPM 17.2 a 53.7 a,b 243.3 a 408.7 a 335.5 a 588.0 a 490.8 a,b 713.3 a 462.2 a 244.3 a,b 112.7 c Column values not followed by the same letter are significantly different (α 0.05) Figure 15. Cv. Black Cherry Cumulative Marketable Yield  Fruit weight was similar across treatments up to harvest week six, after which EcoGrow fruit weight exceeded the control (with the exception of week eight).  Tomato fruits harvested from HV and CPM treatments had intermediate weights, similar to both EcoGrow and control treatments ( Table 25).  Moderate early season fruit mass increases were following by a steady decline from week five onward (Figure 16).  For all treatments, fruit weight peaked on week 4. EcoGrow produced the largest fruit from week seven until the end of season.  Final week average fruit weight averaged 13.5 g for EcoGrow compared to 10.8 g in the control. 0 500 1000 1500 2000 2500 3000 3500 4000 1 2 3 4 5 6 7 8 9 10 11 M ar ke ta b le  Y ie ld  P e r P la n t (g ) Harvest Week Control Hairy vetch Ecofert Poultry manure 48  Figure 16. Seasonal Changes in cv. Black Cherry Fruit Weight by Treatment   Table 25. Treatment Effects on cv. Black Cherry Fruit Weight (g) Treatment Week 1 2 3 4 5 6 7 8 9 10 11 Control 22.7 a 22.6 a 27.4 a 28.0 a,b 24.1 a 20.7 a 18.2 b 16.5 a 13.4 b 12.0 b 10.8 b Hairy vetch 24.6 a 21.8 a 27.1 a 27.4 b 25.0 a 22.0 a 20.0 a,b 17.5 a 14.3 a,b 12.4 a,b 12.0 a,b EcoGrow 24.5 a 24.2 a 26.6 a 27.9 a,b 24.7 a 23.0 a 21.5 a 19.0 a 15.9 a 13.8 a 13.5 a CPM 25.8 a 24.6 a 27.7 a 29.7 a 25.3 a 23.1 a 21.4 a,b 18.6 a 15.1 a,b 12.4 a,b 12.7 a Column values not followed by the same letter are significantly different (α 0.05) Fruit size changes based on largest shoulder diameter matched fruit weight data ( Table 26). Shoulder diameter at season’s end was 2.8 cm for all fertilizer treatments and 2.6 cm in the control.  Table 26. Cv. Black Cherry Fruit Diameter (cm) Treatment Week 1 2 3 4 5 6 7 8 9 10 11 Control 3.8 a 3.7 a 3.9 a 3.9 a 3.7 a 3.5 a 3.2 b 3.1 b 2.9 b 2.8 a 2.6 b Hairy vetch 4.0 a 3.7 a 3.9 a 3.9 a 3.7 a 3.6 a 3.4 a,b 3.3 a,b 3.0 a,b 2.9 a 2.8 a EcoGrow 3.8 a 3.8 a 3.9 a 3.9 a 3.8 a 3.7 a 3.4 a 3.3 a,b 3.1 a 2.9 a 2.8 a CPM 4.0 a 3.9 a 3.9 a 4.0 a 3.7 a 3.7 a 3.5 a 3.3 a 3.0 a,b 2.8 a 2.8 a Column values not followed by the same letter are significantly different (α 0.05) 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 1 2 3 4 5 6 7 8 9 10 11 Fr u it  W ei gh t (g ) Harvest Week Control Hairy vetch EcoGrow Poultry manure 49  4.2.8 Cv. Pollock Harvest Distribution Harvests from cv. Pollock began one week later than cv. Black Cherry on August 9.  Hairy vetch plots began to yield one week after the other treatments.  Yields increased rapidly from weeks three through five (Figure 17 and Table 27).  Control, HV and CPM yields were highest in week five.  EcoGrow weekly yields never reached the peak observed in other treatments, but remained consistent during weeks five through eight.  In contrast, CPM yields decreased steadily after week five.  Hairy vetch yields followed that of EcoGrow with the addition of the high week five harvest.  Harvests from all treatments declined sharply after week seven. Weekly fruit counts matched yield distribution (Table 28).  No significant changes in shoulder diameter were observed over the season.  The irregular shape of many Pollock fruits suggest that shoulder diameter was a poor indicator for this cultivar.   For all treatments average shoulder diameter was 7.2 cm. Figure 17. Cv. Pollock Weekly Marketable Yield Distribution  Table 27. Cv. Pollock Weekly Yield Per Plant (g) Treatment Week 1 2 3 4 5 6 7 8 9 10 Control 8.89 a 91.5 a 376 a,b 684 a 1195 a 1018 a 488 b 585 a 127 a 0 b Hairy vetch 0 a 81.5 a 232 a,b 483 a 1140 a 889 a 911 a 603 a 71.1 a 14.9 b EcoGrow 13.5 a 71.1 a 415 a 609 a 915 b 921 a 885 a 535 a 116 a 2.91 b CPM 7.81 a 109 a 216 b 586 a 1219 a 972 a 594 a,b 314 a 94.7 a 70.3 a Column values not followed by the same letter are significantly different (α 0.05)  0 200 400 600 800 1000 1200 1400 1 2 3 4 5 6 7 8 9 10 Y ie ld  P e r P la n t (g ) Control Hairy vetch EcoGrow Poultry manure 50  Table 28. Cv. Pollock Weekly Harvested Fruit Count Per Plant Treatment Week 1 2 3 4 5 6 7 8 9 10 Control 0.1 a 0.8 a 3.0 a,b 4.2 a 7.4 a 5.3 a 3.1 a 3.8 a 1.0 a 0 b Hairy vetch 0 a 0.6 a 1.9 b 3.3 a 6.4 a,b 5.3 a 4.8 a 3.6 a 0.7 a 0.1 b EcoGrow 0.1 a 0.6 a 3.3 a 4.0 a 4.8 b 5.1 a 4.5 a 3.7 a 0.8 a 0.1 b CPM 0.1 a 0.6 a 1.7 b 3.6 a 6.3 a,b 5.3 a 3.4 a 2.1 a 0.8 a 0.4 a Column values not followed by the same letter are significantly different (α 0.05) Fruit weight increased during the first five weeks and was greatest in weeks five through seven before diminishing back to early season values by week 9 (Table 29).  End of season fruit weight increases in CPM and HV treatments may be skewed by the low number of fruit harvested in the final week. Table 29. Seasonal Changes in cv. Pollock Fruit Weight (g) Treatment Week 1 2 3 4 5 6 7 8 9 10 Control 106.7   116 a 132 a 173 a 163 b 195 a 142 b 137 a 140 a Hairy vetch     142 a 119 a 142 b 178 a,b 155 b 183 a,b 160 a 105 a 179 a EcoGrow 162.5   120 a 127 a 154 a,b 191 a 190 a 206 a 147 a 157 a 34.9 b CPM 93.7   131 a 139 a 165 a,b 187 a,b 183 a,b 178 a,b 150 a 115 a 166 a Column values not followed by the same letter are significantly different (α 0.05) 4.2.8.1 Pruning Effects on cv. Pollock Yield Distribution Pruning accelerated fruit ripening and condensed the harvest period, which peaked on week six (September 6-12) for both pruned and un-pruned plants (Figure 18).  This peak was almost 200 g more in pruned plants.  Yields dropped sharply after week six for pruned tomato plants, compared to a more gradual decline in un-pruned plants up to week 9.  Harvests from all plants were similar during the final two weeks.  Yields from pruned tomatoes averaged 3943 g plant-1; over 700 g less than un-pruned specimens averaging 4652 g plant-1 (Figure 19). 51  Figure 18. Pruning Effects on cv. Pollock Harvest Distribution  Figure 19. Pruning Effects on cv. Pollock Marketable Yields  4.3 Fruit Quality 4.3.1 Total Soluble Solids Total soluble solids (TSS) was significantly higher in cv. Black Cherry compared to cv. Pollock ( Table 30).  For cv. Black Cherry TSS were highest in CPM and EcoGrow treatments and lowest in HV and control treatments.  In cv. Pollock, TSS was highest with EcoGrow, and lowest in the control. 0 200 400 600 800 1000 1200 1400 1 2 3 4 5 6 7 8 9 10 11 M ar ke ta b le  Y ie ld  ( g)  Week Pruned Unpruned 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 1 2 3 4 5 6 7 8 9 10 11 M ar ke ta b le  Y ie ld  ( g)  Week Pruned Unpruned = -700 g 4652g g 3943g g 52    Table 30. Tomato Soluble Solids Content (oBrix) Treatment Black Cherry Pollock Control 5.4 b 4.0 b Hairy vetch 5.7 b 4.1 a,b EcoGrow 5.9 a 4.2 a Poultry Manure 5.9 a 4.1 a,b Column values not followed by the same letter are significantly different at α 0.05 4.4 Physiological, Pest and Disease Symptoms A number of physiological and disease symptoms were present on both cultivars, while few pests were encountered.  A few outer row plants were temporarily attacked by flea beetles shortly after transplanting, but disappeared after a couple weeks.  Apterous black aphids appeared early July but again, pest presence was temporary and no colonies developed. Physiological leaf curl first appeared on July 5th in both cultivars.  Leaf curl first affected lower leaves, progressing upwards over time.  In late July, irregular shaped interveinal necrotic spots appeared on cv. Black Cherry (Figure 20).  These spots first appeared as greasy, water soaked areas and may have been the first symptoms of late blight (Phytophora infestens).  At the same time, both cultivars began wilting in the heat of the day but regaining turgidity at night.  This indicates the presence of a wilt disease, possibly bacterial canker (Clavibactor michiganensis) or verticillium wilt.  Later evolution of spores emanating from necrotic tissue suggests the latter, but may have also been from a secondary fungal pathogen.  Characteristic of verticillium wilt was V-shaped necrotic areas surrounded by chlorotic tissue in cv. Pollock.  Necrosis originated at leaf margins and tapered proximally (Figure 21 and Figure 22).  Upon trial termination, necrotic vascular tissue was apparent in most plants near the soil line. 53  Figure 20. Irregular Interveinal Necrotic Spots in cv. Black Cherry (July 30)   54  Figure 21. Verticillium Wilt on cv. Pollock (August 24)  Figure 22. Verticillium Wilt in cv. Pollock (August 24)  55  Definitive symptoms of late blight appeared on August 10th in cv. Black Cherry (Figure 23). Symptoms first appeared on plants closest to an adjacent, outdoor crop of blight infected potatoes and tomatoes.  Symptoms were first restricted to leaves and petioles, but extended to stems and fruit in both tomato cultivars in late August (Figure 24). Figure 23. Late Blight in cv. Black Cherry (August 10)  Figure 24. Late Blight Infected cv. Pollock Fruit (August 24)  56  Symptoms of powdery mildew (Leveillula taurica) appeared in late August on both cultivars. This disease progressed rapidly, with extensive infection of cv. Black Cherry by September 28th (Figure 25).  Cv. Black Cherry appeared more susceptible to powdery mildew compared to cv. Pollock.  From September 20th onward grey mould began infecting a number of fruit and stems (Figure 26).  Initially localized, disease incidence worsened by the end of the season. Figure 26. Gray Mold on cv. Black Cherry (September 20)  Sept. 28, 2010 Aug. 24, 2010 Sept. 20, 2010 Figure 25. Powdery Mildew Disease Progression in cv. Black Cherry 57  By mid-July, older leaves exhibited interveinal chlorosis, which was more apparent in cv. Pollock.  Typically indicative of Mg deficiency, this is not supported by the high foliar concentrations in tested samples.  However, as a mobile nutrient, translocation of Mg to new tissues may have induced deficiency.   In early August, marginal necrosis along with interveinal necrotic spots appeared in new growth of cv. Black Cherry (Figure 27).  Leaf margins and tips curled upwards.  This was combined with reduced growth, leaf size and blotchy fruit ripening, all symptoms of K deficiency, which is supported by foliar analyses discussed previously. Figure 27. Potential Potassium Deficiency in cv. Black Cherry (August 10)   58  5. DISCUSSION 5.1 Growing Conditions The June through August average hoop house temperature of 21oC was within the 20 to 25oC optimal range (De Koning, 1994; Heuvelink, 2005).   While main season mean temperature was ideal (Table 4), diurnal minimum and maximum temperatures, typically below 15oC and above 30oC respectively, are the most likely cause of the observed physiological leaf roll in both tomato cultivars (Anonymous, 2011c) and fruit scalding in July (Barrett et al., 1991; De Koning, 1994).  Similarly, daytime relative humidity (RH), averaging 35%, may partially explain daytime crop wilting observed from late July onwards (Heuvelink, 2005; Taiz & Zeiger, 2010).  High daytime temperatures and low RH produced vapour pressure deficits (VPD) far in excess of the 0.1 to 0.8 kPa optimal range (OMAFRA, 2001), prompting stomatal closure to conserve moisture at the expense of photosynthesis (Bunce, 2000; Dorais, Papadopoulos, & Gosselin, 2001; Taiz & Zeiger, 2010).  In addition to reduced crop growth, high VPD can exacerbate other environmental and disease stressors (Barrett et al., 1991; Hoffman, 1979; Picken, 1984). Disease (see: below & Section 5.8) and K deficiency (Section 5.4) symptoms encountered in this study are thought to have been exacerbated by these growing conditions. Low nighttime temperatures (<15oC), combined with RH often in excess of 90% facilitated crop infection by several fungal pathogens, including powdery mildew, late blight, and verticillium wilt (Barrett et al., 1991; De Koning, 1990; Heuvelink, 2005; Morgan, 1984).  Incidence and severity of these pathogens was initially slow, but accelerated rapidly in late August, coinciding with increasing humidity and diminishing temperatures, which were on average 18.7oC and 17.6oC, for September and October, respectively (Table 4).  Grey mould also appeared late in the season with increasing incidence, reflective of differing environmental conditions required by these fungal pathogens (Barrett et al., 1991; Morgan, 1984).  Late season cooling along with diminishing irradiance may also explain an almost 60% reduction in shoot growth rate of cv. Black cherry after August 23 (Table 8) (Heuvelink, 1995; Heuvelink & Marcelis, 1989).   Ho (1996) found these same conditions induced floral abortion, which is consistent with observations made in this study.  Late season floral abscission did not affect yield as insufficient time remained for fruit maturation from these flowers. The environmental extremes discussed above are partially a result of inefficient hoop house ventilation.  When unventilated, daytime hoop house temperatures increased rapidly as a 59  function of irradiance, affecting growth, pollen viability, floral abortion, and fruit scalding (Heuvelink, 2005).  When exposed directly to sunlight, fruit temperatures can be up to 9oC higher than ambient (De Koning, 1994).  On at least one sunny day, without sufficient ventilation, temperatures exceeded 40oC causing fruit scalding, primarily in south facing cv. Black Cherry fruit.  Conversely, ventilation is also an important tool for disease management under low temperature and high RH occasions (Morgan, 1984).  This highlights the need for attentive management of hoop houses without automated ventilation systems.  In greenhouse systems, roof ventilation should be at least 15% and ideally 25% of the floor area (Tite, 1983). For hoop houses, Coleman (2009) recommends a maximum length to width ratio of 2.5 to maintain adequate ventilation throughout the structure. The hoop house used in this study had a length to width ratio of 2.1:1. Soil temperatures (-10 cm) varied between 20oC and 27oC, with an average of 23.6oC, for the period between June 19th and August 23rd (Figure 5).  For hydroponic greenhouse production, root zone temperatures exceeding 23oC can have deleterious effects (Adams, 1999).  In contrast, 20oC to 30oC is optimal for soil based production systems (Harssema, 1977).  Thus, soil temperatures at -10 cm are not suspected of adversely affecting crop growth.  However, due to low thermal conductance associated with this coarse textured, sandy soil, surface temperatures were likely much higher, especially with the use of black plastic mulch (Brady & Weil, 2000).  Placement of soil temperature sensors across the width and over the length of the hoop house, as opposed to clustering in Block 2 (Figure 28), would have been a better strategy for assessing variability between blocks and adjacent treatments. Tomato roots may penetrate to a depth of 2 m, but approximately 60% of the root mass is typically found in the top 30 cm (Rendon-Poblete, 1980).  Root distribution was not measured in this study; however, few roots were seen near the surface, which might have been due to high surface temperatures.  In addition to suspected high surface temperatures, the soil surface was usually dry on inspection, both of which directly impact root distribution and nutrient mineralization (Brady & Weil, 2000; Marschner, 2012).  The wetting zone from drip irrigation emitters is affected by soil texture, where lateral movement and moisture holding capacity is reduced in sandy soils with large pore size distribution (Weil & Brady, 2002).  In this study moisture tension at -10 cm and -20 cm increased rapidly above 3 kPa, which is characteristic of a sandy loam with few micropores and low clay content.  While these conditions may have favoured deeper rooting, nutrients near the surface, such as P, would have been inaccessible to the plant.  A second drip line would have improved moisture distribution, while soil temperature 60  fluctuations can be moderated with organic mulches (Teasdale & Abdul-baki, 1995).  Excavating plant roots at the end of the season as well as monitoring lateral and vertical soil temperature and moisture gradients would be valuable for better understanding environmental factors affecting root distribution and proliferation. While the hoop house improved environmental conditions and more than doubled growing degree days (GDD), the system could be improved with more attentive ventilation management or with circulating fans and automated vents.  Planting around May 21st as opposed to June 9th, as is typical in this region, would have increased growing degree days, resulting in a longer and earlier harvest.  This is especially relevant for cv. Black Cherry where 29% of the total fruit load remained immature upon trial termination.  With an additional 2.5 weeks up to 50% of this fruit load may have matured, depending on temperature (Heuvelink, 1995).  Use of organic mulches (i.e., straw or hairy vetch) in lieu of black plastic would moderate soil temperatures and potentially improve soil moisture distribution.  Several studies have revealed increased disease resistance, delayed senescence, and improved yields when hairy vetch mulches are used for tomato production (Abdul-baki et al., 1996; Campiglia et al., 2010; Kumar et al., 2005, 2004; Mills et al., 2002; Teasdale & Abdul-baki, 1995).  The limiting factor in this region is whether these mulches permit sufficient soil warming. 5.2 Fertilizer Characteristics Application rates of 100 kg-N ha-1 resulted in P (P2O5) amendments of 10 (23), 66 (151) and 71 (163) kg ha-1 and K (K2O) amendments of 74 (89), 137 (165) and 85 (102) kg ha -1 for HV, EcoGrow and CPM, respectively.  Composted poultry manure thus provided the most P, while EcoGrow was highest in K.  Despite the greatest P contribution from CPM, foliar concentrations of P were not different from other treatments (Table 10 and Table 11), suggesting existing soil P was likely sufficient.  This is further supported by slightly increasing soil P levels between fruit set and mid-harvest (Table 6 and Table 7), which may reflect increased mineralization due to more biologically favourable soil conditions (Barker & Pilbeam, 2007).  For other nutrients, plant uptake would have likely depleted a portion of the available nutrient pool, as is supported by decreasing soil concentrations of K, Ca and Mg between sampling dates and increasing nutrient imbalances interpreted by both sufficiency range and DRIS analyses.  Total N remained relatively unchanged and is thought to have been adequate across treatments up to at least the mid-harvest sampling event. 61  The composted poultry manure smelled strongly of ammonia and was still producing heat at the time of amendment; confirmed by analyses revealing 3840 ppm NH4 + versus 173 ppm NO3 -. Amending soils with immature compost stimulates soil biota, resulting not only in immobilization of applied nutrients, but also a portion of the existing soil pool (Weil & Brady, 2002).  Gale et al. (2006) found that composted broiler manure decomposed rapidly during the first 30 days, and over a 70 day period approximately 40% of plant available nitrogen (PAN) had mineralized. Other studies have reported growing season PAN release rates of 18% to 64% for fresh and 3% to 9% for composted broiler manure (Gilmour, Koehler, Cabrera, Szajdak, & Moore, 2004; Kirchmann, 1990; Preusch et al., 2002; Tyson & Cabrera, 1993).  However, Gale et al. (2006) found inconsistent decomposition rates between ‘composted’ and ‘un-composted’ products due to process inconsistencies and may explain the higher release rates reported. The ammonium content, which is toxic to plants in high concentrations (Jones, 1998; Marschner, 2012), had dissipated by fruit set.  By this time, NH4:NO3 and total N were similar to the other treatments (Table 6).  Most likely, ammonium levels would have diminished adequately by transplanting since NH4 is a transient, short-lived phase in the dominant nitrification process in soils with near neutral pH (Brady & Weil, 2000). Additionally, a percentage of the N in the surface applied manure was probably lost directly through ammonia volatilization.  Even at the highest reported release rates, PAN from the composted poultry manure was estimated at 63 kg ha-1.  In contrast to composting effects on PAN from poultry manure, P availability is similar for both fresh and composted products (Preusch et al., 2002). As stated previously, the absence of P related treatment effects on soil and foliar metrics suggests that fertility levels were adequate, except that by mid-harvest foliar P levels were near the critical threshold (Table 11).  The composted poultry manure was also much higher in the micronutrients Cu, Zn, Fe, Mn, and B compared to the other fertilizer treatments (Table 1), but this did not translate into higher foliar concentrations. Of the fertilizers trialed, EcoGrow was highest in K (3.9%), which positively affected K nutrition. Foliar K levels were highest in EcoGrow treatments for both cultivars across sampling times, with significant differences seen in cv. Black Cherry at fruit set (Table 10) and cv. Pollock at mid-harvest (Table 11).  Cultivar differences related to K nutrition are likely due to source-sink relationships.  A small vegetative sink in cv. Pollock at mid-harvest, combined with continuous EcoGrow application may have permitted more K partitioning to developing fruit, reducing translocation demands from leaves, and thus explaining the higher foliar concentrations in this treatment.  In cv. Black Cherry, the large vegetative and generative sink size would have diluted 62  the effects of additional K application from EcoGrow, especially if the dose was insufficient to meet crop demand.  With 3% available N, it is expected that most of the N applied with EcoGrow would have been available to the tomato crop.  Even though existing soil N appears to have been adequate, application rate and timing unmatched to crop demand may explain the absence of treatment effects. Hairy vetch is suspected of having cytokinin-like activity similar to sea kelp, especially when applied as a mulch (Mattoo & Abdul-baki, 2006).  Nitrogen mineralization rates from incorporated hairy vetch residues are initially rapid, releasing approximately 50-60% during the first 28 days (Lawson et al., 2012).  Subsequent release is much slower, totalling 70-80% over a growing season, depending on conditions.  Denitrification losses can also be high when mineralization is rapid (Rosecrance, Mccarty, Shelton, & Teasdale, 2000).  However, the deep placement of HV residues would have minimized denitrification losses, but decomposition may have been inhibited at this depth since microbes are most active near the soil surface (Weil & Brady, 2002).  Ignoring N losses, PAN from hairy vetch applications was potentially 70 to 80 kg ha-1 over the season, with 50 to 60 kg ha-1 released over the first month. At an application rate of 23 kg P2O5 ha -1, P contribution from HV was minimal in comparison to the other fertilizers, which contained up to 5.5 times this concentration.  While K content in HV was 2.40%, actual applied rate was lowest at 89 kg K2O ha -1.  Across sampling dates and cultivars, foliar K levels for HV and EcoGrow treatments were similar, despite lower total K content in the HV fertilizer.  The depth of HV incorporation (-20 cm) was below soil sampling depth, which may explain the apparent absence of treatment effects on soil fertility.  Observed K nutrition benefits may be due to root growth stimulation in a zone with more favourable temperatures, moisture, and nutrient supply. Fertilizer N response may have been suppressed by K limitations, or sufficient pre-existing levels of soil N.  Targeting a uniform N application rate is challenging with organic fertilizers due to the many factors influencing inorganic N mineralization rates and the emerging understanding that organic N can make a significant contribution to crop nutrition (Gale et al., 2006; Grubinger, 2012; Nasholm et al., 2000; Zhai et al., 2009).  Fertility effects on crop production are discussed further in the following sections. 63  5.3 Cultivar Effects on Fertility and Crop Performance Both determinate and indeterminate tomatoes are truly sympodial, where the apical meristem terminates in an inflorescence after seven to eleven leaves.  New apices develop from the axillary bud of the last formed leaf, displacing the terminal inflorescence laterally  (Heuvelink, 2005).  Thus, the ‘indeterminate’ nomenclature is a misnomer.  In determinate cultivars, genetics limit the number of inflorescences produced along each axis.  Indeterminate varieties develop dominant apices from lateral shoots along the primary axis indefinitely, resulting in monopodial appearance (Heuvelink, 2005).  Semi-determinate morphology is intermediate, producing 19-21 nodes before losing apical dominance (Scholberg et al., 2000). Cv. Black Cherry is indeterminate, exhibiting strong apical growth through week 11 (August 23rd; Figure 6), after which the 60% reduction in growth rate is believed to have been caused by diminishing day length, irradiance, temperature and possibly limiting nutrient supply (Langton & Cockshull, 1997; Scholberg et al., 2000).  Cv. Black Cherry produced 18 nodes by week eight (August 4th) and a total of 28 cumulatively.  In contrast, growth of cv. Pollock tapered off significantly after developing fourteen nodes by week 8, after which only four additional nodes developed by the end of the season.  Visible morphological changes in cv. Pollock coincided with this decrease in growth, where additional shoots above the terminal inflorescence failed to exert apical vigour; retaining the appearance of axial lateral shoots.  This is an important distinction when considering crop nutrition (Section 5.4). Vegetative growth reductions in cv. Pollock after August 9th (Figure 7) were indicative of assimilate partitioning shifts from vegetative to generative sinks.  By this time, almost the entire fruit load had set and generative sink strength would have equaled the assimilate demand of the existing fruit load.  As fruit mature, their assimilate demand decreases and plants are able to partition more resources to the remaining immature fruit (Heuvelink, 2005).  For an indeterminate cultivar such as cv. Black Cherry, both vegetative and generative sink sizes increase throughout the season; only pruning and fruit maturation offset these increases.  Thus, it is reasonable to expect nutrient source limitations in the second half of the season to have a greater impact on yields from cv. Black Cherry than on cv. Pollock. 5.4 Tomato Crop Nutrition Depending on cultivar and production system, an outdoor tomato crop yielding 40 to 50 ton ha-1 absorbs 100 to 150 kg N ha-1, 20 to 40 kg ha-1 P2O5 and 150 to 300 kg ha -1 K2O (Halliday & 64  Trenkel, 1992).  Recommended fertilization rates, depending on background fertility, range between 75 to 180 kg N ha-1, 120 to 240 kg P ha-1, and 110 to 340 kg K ha-1 (Diver, Kuepper, & Born, 1999; Papadopoulos, 1991; Teasdale & Abdul-baki, 2007; Ward, 1964).  At fruit set, total soil N was on average 0.34% across all treatments (Table 6), which equates to approximately 7650 kg Ntotal ha -1 in the plough layer (top 15 cm).  Many factors determine N mineralization rates (Grubinger, 2012; Zhai et al., 2009).  However, Brady and Weil (2000) suggest that approximately 1.5% to 3.5% can be expected to mineralize over season.  This equates to 115 to 268 kg N ha-1, which would have been sufficient for crop growth.  To further support this claim, no foliar N response was measured in either cultivar and N concentrations were sufficient across treatments at both sampling dates (Table 10 and Table 11).  At fruit set, cv. Pollock leaves from all treatments contained more N compared to cv. Black Cherry.  It is plausible that cv. Pollock had greater N demand at fruit set, or a higher N use efficiency, which is genetically determined (Chardon, Barthélémy, Daniel-Vedele, & Masclaux-Daubresse, 2010).  It is also likely that cv. Pollock had a larger source to sink ratio due to its slower vegetative growth rate, smaller stature and fewer, albeit larger fruit. The yield response observed in cv. Black Cherry (  Table 19) might be related to N partitioning to other plant parts, most notably the fruit.  It is difficult to comment on late season nutrient supply as the mid-harvest sampling event was relatively early, corresponding with harvest week four of eleven.  An additional foliar analysis from cv. Black Cherry in mid-September may have revealed subsequent differences in N nutrition.  Regardless, the observed yield response was equal across fertilizer treatments, indicating that cv. Black Cherry does not respond preferentially to different N sources.  Existing soil fertility was considered adequate for cv. Pollock, which did not exhibit a yield response (Table 21).  This is encouraging for producers who can take comfort in using a variety of fertilizer sources as long as they are of high quality with sufficient nutrient content and in the proper ratios to meet crop demand. Chlorophyll meters measuring leaf greenness are a rapid, non-destructive method for monitoring leaf chlorophyll and N status by (Knighton & Bugbee, n.d.; Sandoval‐Villa et al., 2000; Shaahan, El-Sayad, & Abou El-nour, 1999).  Good correlation has been found between chlorophyll meter readings and leaf N in tomato (Güler & Büyük, 2007).  No treatment effects were identified at fruit set or mid-harvest for first and forth leaf chlorophyll readings (Figures 10 thru 13) since N levels were adequate and did not differ between treatments.  However, data pooling of treatments and sampling dates identified positive correlations between chlorophyll readings and foliar N, P, K, and Zn in cv. Black Cherry and with K in cv. Pollock (Table 12).  The 65  instrument was not sensitive enough to identify subtle treatment effects or as a yield response indicator in cv. Black Cherry, but did identify developmental shifts in nutrient partitioning and/or increasing nutrient imbalances between fruit set and mid-harvest.  Consistently higher chlorophyll readings from cv. Black Cherry compared to cv. Pollock, which had higher foliar N levels at fruit set (Table 10), emphasizes the interpretive value of cultivar specific reference crops (Fontes & de Araujo, 2006; Sandoval‐Villa et al., 2000; Shapiro & Francis, 2006).  The only observed treatment effect on senescence was accelerated mid-canopy rates for cv. Pollock treated with CPM (Figure 14).  Mattoo and Abdul-baki (2006) suggest that high early season fertility may prematurely constrain root cytokinin activity, initiating early senescence.  Thus it is possible that CPM nutrient dynamics affected mid-canopy senescence in cv. Pollock.  However, this theory is not supported by foliar analyses that failed to identify relevant treatment effects on N uptake. During vegetative growth, tomato plants require K and N in equal amounts.  The K:N uptake ratio increases to 2:1 with increasing fruit load (OMAFRA, 2001).  By formation of the ninth truss, K:N ratio is 2.5:1 (Heuvelink, 2005).  Potassium fertilization increases yield and by increasing the K:N ratio, fruit production is encouraged over vegetative growth (Adams, 1999). At fruit set, K content was greater in cv. Pollock (Table 10), but by mid harvest, cultivar differences disappeared (Table 11).  The higher K content in cv. Pollock at fruit set was probably related to source to sink relationships described previously.  While EcoGrow and HV treated cv. Pollock plants had higher K levels at mid-harvest, concentrations were close to the critical level and may have been insufficient for optimum yields.  Without additional fertilization, it is assumed that K would have become increasingly deficient as the season progressed.  The benefit of weekly EcoGrow applications was apparent in cv. Black Cherry with increased late season yields and larger fruit.  The yield lag in cv. Black Cherry treated with EcoGrow (Table 24) indicates that a higher early season application rate or pre-planting amendments may have been required.  Late season yield responses to EcoGrow, along with foliar status at mid-harvest suggest that K was the most limiting nutrient affecting crop performance. Under conditions of K deficiency, fruit quality suffers from blotchy ripening, blocky fruit, puffiness, softness, green shoulders, irregular shape and low acidity (Barrett et al., 1991; Jones, 2008; Lune & van Goor, 1977; Rooda van Eysinga & Smilde, 1981).  Green shoulders also result from suboptimal temperatures and/or sun exposure and is thus related to leaf cover and seasonal conditions (Jones, 2008).  The number of cv. Pollock fruit with green shoulders and unfilled locules increased late in the season.  Green shoulders were also noted in cv. Black 66  Cherry, but was less apparent due to characteristic black shoulders masking symptoms.  Cooler growing conditions and K deficiency would have affected fruit development from pollination through ripening, both directly through assimilate shortages and indirectly through reduced leaf area (Heuvelink, 1995). Potassium supply in sandy soils, such as those encountered in this study, is restricted to organic matter exchange complexes and the soil solution (Brady & Weil, 2000).  Low cation exchange capacity (CEC) in these soils limit exchangeable K, justifying periodic fertilization, especially during fruiting.  Potassium uptake can also be inhibited by high Ca and Mg, which compete for uptake pathways and exchange sites in the root apoplasm (Brady & Weil, 2000; Jones, 1998; Marschner, 2012).  While this is more typically a concern in calcareous soils, insufficient K supply, compounded by high soil Ca and Mg may have affected uptake.  In addition, K moves through soils predominantly by diffusion, a much slower process compared to Ca movement via mass flow (Brady & Weil, 2000; Marschner, 2012) and thus moisture and temperature stress may have influenced K mobility and root foraging. If root growth (foraging capacity) was inhibited due to disease or nutrient deficiencies, then K deficiency could have been induced despite adequate soil levels.  If this was the case, then Ca nutrition should also be affected since it is mostly absorbed proximal to the root tip.  However, foliar Ca status may not indicate root inhibition since an almost equal amount of Ca absorbed by mature root sections is translocated to shoots (Marschner, 2012).  Across sampling dates, both cultivars had very high foliar Ca and Mg levels (Table 10 and Table 11).  Since Ca is not translocated to developing fruit and blossom end rot (BER) was almost non-existent, Ca nutrition was considered adequate.  Jones (2008) suggests that the ratio of foliar Ca to K is more important than individual nutrient concentrations.  Furthermore, mature leaf Ca and K contents should be almost equal in fruiting tomato plants for optimum growth and yield.  In this study, Ca levels at mid-harvest were twice that of K (Table 11), indicating potential nutrient antagonism (Jones, 1998; Marschner, 2012). Under nutrient limiting conditions, the K depletion zone around roots would be much greater than under non-limiting conditions (Claassen & Jungk, 1984).  High Mg levels have been implicated with increasing K depletion zone size through competition for adsorption sites.  Clay content is inversely related to the size of K depletion zones, where a larger exchange complex more readily replenishes soil solution K (Claassen & Jungk, 1982); thus a larger K depletion zone is expected in the sandy soils encountered in this study.  This phenomenon may have 67  compounded factors such as insufficient K supply and high Ca and Mg to further limit K uptake. While still insufficient, weekly fertilization with EcoGrow proved an effective means for partially alleviating K deficiency, reflected in foliar analyses of cv. Pollock (Table 11) and increased late season yields from cv. Black Cherry (Table 24). Treatment x sampling event correlation analysis did not reveal any significant relationships amongst foliar and soil nutrients.  This may be due to the small sample size and few treatment effects on foliar nutrition and soil fertility.  Pooling of treatment and sampling event data by cultivar revealed several foliar nutrient correlations indicative of changes in metabolism and nutrient partitioning between developmental stages (Table 12).  Nitrogen, P and K were well correlated, which is to be expected since during reproduction these nutrients are translocated to developing fruit, resulting in lower foliar concentrations (Caron & Parent, 1989; Hochmuth et al., 1991).  Similarly, since Ca and B are immobile (Jones, 1998), negative correlations between these nutrients and N, P, and K reflect a concentration effect due to translocation.  Positive correlations between soil Ca and foliar N, P, and K may be due to decreasing soil Ca availability coinciding with reduced foliar N, P and K levels between sampling dates. Both ‘sufficiency range’ and ‘critical level’ approaches to plant nutrition diagnoses have their limitations.  Assessing sufficiency levels for individual nutrients does not identify hidden hunger, nor does it easily diagnose which nutrients are most limiting (Mourao Filho, 2004; Sumner, 1979).  Additionally, critical levels and sufficiency ranges are specific to cultivar, region, soil type, and production system (Jones, 1998; Sumner, 1979).  The Diagnostic and Recommendation Integrated System (DRIS) was developed to address some of these diagnostic limitations. Nutrient status evaluation using DRIS revealed several nutrient imbalances not exposed by sufficiency range assessments.  This holistic measure is a valuable tool, but should be used with caution when generalized norms from other regions and production systems are used. While the use of nutrient ratios is claimed to overcome metabolic shifts between developmental stages, significant differences between sampling dates for several nutrient ratios have been found (Caron & Parent, 1989; Hartz et al., 1998).  Comparing foliar nutrient values from this study against norms for corresponding developmental stages defined by Caron and Parent (1989) actually revealed slightly greater imbalances.  These researchers developed DRIS norms for Quebec using data from 733 observations consisting of various soil-based and hydroponic systems.  Yields from the top 30% were used to determine DRIS norms, but they did 68  not specify the production systems comprising this sub-population.  It is quite possible that this selection method would have favoured commercial, hydroponic systems.  Thus, these values might not reflect organic production realities in South Coastal British Columbia.  The only other DRIS norms found were for determinate processing tomatoes in Florida (Hartz et al., 1998). Despite these shortcomings, the applied DRIS norms provided a baseline from which to assess crop nutrition and compare fertilizer treatments and cultivar performance.  However, identification of specific nutrient deficiencies relying on these norms should be treated with caution. Despite the limitations of each, all three diagnostic methods as a combined tool set proved useful for assessing nutritional status in this research.  However, establishment of both nutrient sufficiency ranges and DRIS norms for organic production specific to South Coastal British Columbia would be an invaluable resource for local producers and a valuable subject for future research. 5.5 Growth: Biomass Accumulation Tomato biomass production displays a sigmoidal growth curve, such that early exponential vegetative growth rates transition into a long period of strong linear growth.  In determinate cultivars, growth reduction coincides with fruit ripening, due to natural senescence (reduced photosynthesis) and loss of apical dominance, as observed in cv. Pollock.  Diminishing light intensity and temperature under natural conditions restrict late season growth of indeterminate cultivars (Heuvelink, 2005).  In a generative plant, assimilate sink priority shifts from roots and leaves to fruit, resulting in reduced vegetative growth under heavy fruit loads (Ho, 1996). However, when assimilate supply is very limiting, apical shoot growth takes priority over the fruit, showing that a minimum vegetative sink must be maintained (Heuvelink, 1996).  Under ideal growing conditions, assimilate supply governed by nutrient availability determines vegetative growth and fruit production.  Even when nutrients are not limiting, assimilate sink strength is two to three times source availability depending on cultivar (Bertin, 1995; De Koning, 1994; Heuvelink, 2005). The only treatment effect on vegetative dry weight was on cv. Pollock treated with EcoGrow (Figure 8).  It is interesting to note that although not statistically significant, cv. Black Cherry vegetative biomass was greatest with this fertilizer.  Of the major nutrients, only foliar K was higher with EcoGrow, but not different from HV treated plants yielding the second highest 69  biomass.  Interestingly, cv. Pollock grown with EcoGrow yielded the shortest plants with no differences in growth rates observed, meaning the additional biomass was either partitioned to stems or leaves.  Continuous EcoGrow fertigation may have contributed to larger or thicker leaves, especially in the latter part of the season when nutrients became increasingly limiting in the other treatments. 5.6 Yield Mid-harvest foliar analyses coincided with harvest week three and four in cv. Pollock and cv. Black Cherry, respectively.  Fruit harvested in weeks one through four would have been influenced by nutrient status at fruit set, whereas fruit yields in the following weeks were affected by nutritional status at mid-harvest and later.  Potassium and P deficiencies and increasing nutrient imbalances at mid-harvest (Table 14 and Table 17), which was still relatively early in the harvest season, would have further increased in all but the EcoGrow treatment as the season progressed.  Availability of nutrients from pre-plant amendments (CPM and HV) would have continued to decrease later in the season as readily mineralized nutrients were depleted. However, weekly fertigation with EcoGrow would have continued to supply low doses of N, P, and K throughout the season, alleviating nutrient stress in the second half of the harvest season.  This was indicated by higher foliar K in cv. Pollock at mid-harvest and larger cv. Black Cherry fruit from EcoGrow treated plants through the final weeks of the season. Yield distribution in cv. Pollock is characteristic of determinate cultivars with a shorter, more concentrated harvest period.  Yields from cv. Black Cherry were characteristic of indeterminate cultivars, but declining environmental conditions and nutrient limitations restricted late season production.  All fertilizers positively affected cv. Black Cherry yields from week 6 on (Table 24), although there was an initial lag seen in the EcoGrow treatment due to insufficient application rates early in the season.  Continued EcoGrow application positively affected late season yields as discussed previously. Assimilate supply limits yield in all tomato production systems.  Reducing sink size through truss pruning to increase fruit mass, and topping of plants at the end of the season to accelerate ripening are common practices in greenhouse tomato production (Heuvelink, 2005; Papadopoulos, 1991).  Pruning of cv. Pollock plants resulted in accelerated fruit maturation (Figure 18) and reduced yield (Figure 19); fruit size decreased only marginally.  Assimilate production is dependent on both nutrient availability and photosynthesis.  The absence of new 70  leaf growth, as well as diminishing photosynthetic capacity of senescing leaves and nutrient and light limitations may explain why pruning of cv. Pollock did not positively affect fruit weight. Additionally, trusses were not pruned to manage sink strength and the timing of pruning may not have favoured increased fruit size as assimilate demand varies with developmental stage (Heuvelink & Marcelis, 1989). In cv. Black Cherry, fruit size initially increased up to a maximum of 28.3 g fruit-1 (all treatments) at harvest week 4 (August 23rd), after which a steady decline in fruit size was observed (Figure 16).  By season’s end, average fruit weight across all fertilized treatments had diminished 55%, to 12.7 g fruit-1.  Fruit weight reduction from control plants was 61% by season’s end, averaging 10.8 g.  Inconsistent treatment effects on fruit size were observed from harvest week 6 onwards. The largest late season fruit were in the EcoGrow treatment and the smallest were in the control, while HV and CPM fruit sizes were similar to both EcoGrow and control treatments. Fruit size reductions concurrent with increasing fruit loads have been well documented, as a limited assimilate supply is partitioned over an increasing number of fruit (Bertin, 1995; Heuvelink, 2005; Ho, 1996).  Fertilizer treatment effects indicate nutrient uptake as a limiting factor in this production system, regardless of reduced irradiance.  Lower late season ambient temperatures did not contribute to reduced fruit size, as fruit size is inversely related to temperature by slowing fruit development, allowing more time for fruit growth (De Koning, 1994). However, high, mid-season diurnal maximum temperatures would have negatively affected fruit size by increasing developmental rates. 5.7 Fruit Quality Fruit development period is typically 45 to 60 days depending on growing conditions, especially temperature (Heuvelink, 2005).  Fruit size also increases at lower temperatures due to lower developmental rates allowing more time for assimilate accumulation (De Koning, 2000).  Once tomatoes begin ripening they, cease to accumulate assimilates (Atherton & Rudich, 1986; De Koning, 1994); thus conditions determining fruit quality would have coincided with nutrition at fruit set.  Regardless of cultivar, foliar N, P, or K was not related to differences in TSS of the first three fruit harvested in early August.  At fruit set, only Ca was affected by treatment, while higher levels of Ca in control and EcoGrow treatments were not correlated with more or less TSS in harvested fruit.  It is possible that foliar nutrient status was not a relevant metric for measuring treatment effects on fruit assimilate supply.  While treatment effects on cv. Black Cherry yield did not occur until week 7, all fertilizers increased TSS over the control in both 71  cultivars (  Table 30).  This indicates that fertilization had an overall positive effect fruit dry matter accumulation.  Monitoring changes in TSS over the season, as nutrients became increasingly limiting and growing conditions deteriorated, may have been more relevant strategy for assessing season long fertilizer performance. 5.8 Nutrition and Plant Defense Resistance to individual diseases is genetically conferred (Marschner, 2012).  Cv. Pollock is claimed to have good blight resistance (Salt Springs Seeds, Salt Spring Island, BC), while cv. Black Cherry does not have any advertised disease resistance (West Coast Seeds, Ladner, BC).  In addition to genetic traits, abiotic factors including temperature, humidity and nutrient availability determine a plants ability to resist disease (Marschner, 2012).  Of these, nutrient supply is the most easily manipulated.  Nutrient dependent defense responses include anatomical changes, production of inhibitory compounds, and restriction of nutrient transfer to the invading pathogen (ibid.).  These responses affect pathogen penetration, development and reproduction. Physiological leaf roll and several fungal pathogens infected both tomato cultivars starting in early July.  Physiological leaf roll has been associated with low early season temperatures followed by hot main season conditions and with high N supply (Anonymous, 2011c).  These environmental conditions are characteristic of South Coastal British Columbia and leaf roll is a regular occurrence at the UBC Farm.  Fortunately, physiological leaf roll does not substantially affect crop growth or yield (Anonymous, 2011c).  Nutritional status differentially affects crop immunity depending on whether a disease is obligate or facultative.  The effect of nutrition is minimal in resistant cultivars, but substantial in susceptible cultivars (Marschner, 2012).  In regard to N, high levels favour obligate pathogens (require living tissue), while low levels favour facultative pathogens (prefer senescing tissues) (ibid.).  High N levels can also have a dilution effect, inducing deficiency of other plant nutrients resulting in compromised immunity (Marschner, 2012).  Low N levels have been found to increase susceptibility to grey mould and possibly late blight (Hoffland, Beusichem, & Jeger, 1999; Rooda van Eysinga & Smilde, 1981). Nitrogen nutrition was adequate to high, but not excessive in all treatments at both sampling dates.  While the late season growing conditions were ideal for fungal pathogen development, it is possible that N became limiting late in the season, resulting in greater nutrient imbalances leading to compromised immunity against powdery mildew, late blight and grey mould. 72  Most parasites invade plants apoplastically (Hancock & Huisman, 1981).  Pectolytic enzymes excreted by fungal pathogens dissolve the middle lamella and increase plasma membrane permeability, thus facilitating the efflux of K and other cell contents (Atkinson, Baker, & Collmer, 1986).  Potassium deficiency increases plant susceptibility to both facultative and obligate pathogens by adversely affecting enzymatic activity, resulting in reduced membrane integrity and increased cellular concentrations of sugars and amino acids (Hancock & Huisman, 1981; Marschner, 2012).  These compounds become pathogen food sources once they leak into the apoplasm.  Thus, K deficiency has been linked to powdery mildew and grey mould incidence (Barrett et al., 1991; Hoffland et al., 1999; Marschner, 2012).  These pathogens occurred in both cultivars with increasing prevalence from late August onwards.  Similarly, resistance to powdery mildew in cucumber has been positively linked with P supply (Reuveni, Dor, Raviv, Reuveni, & Tuzun, 2000).  At mid-harvest, K was the most limiting nutrient in Control and CPM treatments, and second to P in EcoGrow and HV treatments in cv. Pollock (Table 18).  In cv. Black Cherry, K was most limiting in all but the EcoGrow treatment at mid-harvest (Table 15).  At this time, both P and K were near the critical level in both cultivars and these deficiencies likely increased as the season progressed, especially in cv. Black Cherry.  While soil P supply was adequate (Table 7), foliar levels at mid-harvest (Table 11) were near the critical limit in all treatments.  It is possible that disease incidence inhibited P uptake and assimilation. Calcium also plays an important role in disease resistance by inhibiting pectolytic enzymes and increasing stability of cellular membranes (Marschner, 2012; Yang, Shah, & Klessig, 1997). Boron also affects membrane permeability and has been associated with powdery mildew resistance in wheat (Stangoulis & Graham, 2007).  High foliar Ca concentrations observed in this study could be attributed to a plant defense response, luxurious uptake, or a concentration effect induced by other nutrient deficiencies and translocation.  High soil availability of Ca combined with K deficiency suggest the latter two theories most probable. Zinc and Mn have also been implicated in plant defense by affecting membrane integrity, as well as synthesis of lignin, phenolics and phytoalexins (Graham & Webb, 1991; Marschner, 2012). By mid-harvest Zn deficiency existed in both cultivars (Table 11).  Early season Mn deficiency may have compromised crop defense later in the season.  Disappearance of Mn deficiency by mid-harvest was either due to greater uptake, or a concentration effect induced by translocation of N, P, and K to developing fruit combined with insufficient P, and K uptake.  Since Mn levels were just above the critical threshold at mid-harvest, the latter is suspected.  The efficacy of these nutrients in plant defense is limited by the availability of other metabolic pathway 73  dependent nutrients.  While environmental conditions favoured fungal disease development late in the season, increasing nutrient imbalances suggest that immunity in both cultivars may have been compromised.  However, since neither of these cultivars is noted as having resistance to these pathogens, nutritional effects on immunity were likely minimal. Cv. Pollock is advertised to have late blight resistance (Salt Springs Seeds, Salt Spring Island, BC).  Cv. Black Cherry appeared to be more susceptible, however from late August onward this pathogen also affected cv. Pollock with increasing incidence.  In general, late blight is managed by cultural practices as breeding for genetic resistance has yet to be effective (Barrett et al., 1991).  Hoop houses are considered necessary in this climate for late blight control, however increased leaf condensation and lower late season temperatures favour pathogen development, regardless of protective cover.  Cv. Pollock plants also became heavily infected with verticillium wilt, which may have affected fertilizer yield responses.  Several resistant cultivars exist and are worthy alternatives when this pathogen is present. 6. CONCLUSION The first research objective was to assess the fertilizer effects of hairy vetch, composted poultry manure, and a commercial kelp product on organic tomatoes grown under protective cover in South Coastal British Columbia.  Regarding this objective, this research project found that: 1. In terms of plant height and number of nodes none of the fertilizers trialed stimulated a vegetative growth response in either cultivar. 2. EcoGrow produced significantly more vegetative biomass in cv. Pollock. 3. All fertilizer treatments stimulated a 23% yield response in cv. Black Cherry. 4. No yield response occurred in cv. Pollock. 5. Fertilizer treatment effects on cv. Black Cherry yield distribution are suspected of being due to timing of application and differences in nutrient mineralization. 6. In both cultivars all fertilizer treatments increased TSS content of the first three harvested fruit. 7. Potassium was found to be the most limiting nutrient, while foliar N, Ca, and Mg were sufficient to high in both cultivars across sampling dates. 8. For both cultivars P nutrition was sufficient at fruit set, but near the critical threshold at mid-harvest, despite adequate soil availability. 74  For the second objective, which was to determine whether genotype x fertilizer source interactions are present for plant growth and yield traits, the following was found: 1. The two tomato cultivars trialed exhibited differing growth, morphology and yield characteristics. 2. All fertilizers stimulated a similar yield increase of 23% in cv. Black Cherry, while no yield response was measured in cv. Pollock. 3. At fruit set cv. Pollock had significantly higher foliar concentrations of N, P, K, Ca, and Mg.  At Mid-harvest only foliar Ca and Mg were significantly higher in cv. Pollock. 4. Composted poultry manure accelerated mid-canopy senescence in cv. Pollock.  No treatment effects on senescence rates were observed in cv. Black Cherry. 5. EcoGrow and hairy vetch improved K nutrition in cv. Pollock at mid-harvest, while at fruit set foliar K levels in cv. Black Cherry were highest with EcoGrow and lowest in the CPM treatment.  Additional key findings relating to cultural management practices and protected tomato production in south coastal British Columbia were that: 1. The hoop house more than doubled growing degree days over outside. 2. Average hoop house temperatures for the period between June and August were within the optimal range, while mean September and October temperatures were below optimal and believed to have adversely affected late season crop growth and yield. 3. Late blight, verticillium wilt, powdery mildew and grey mould infected both tomato cultivars with increasing severity as late season growing conditions diminished. 4. Pruning of the apical growing point in cv. Pollock accelerated fruit ripening and significantly reduced per plant yields by 700 g on average. This research has shown that fertilizer response is cultivar dependent and that these fertilizers sources did not preferentially affect tomato crop performance.  However, a more important result is a better understanding of how these fertilizer sources provided nutrients, most notably N, P, and K, and their effects on yield.  Since organic sources are ‘complete fertilizers’ containing a mix of nutrients with varying release rates, a combination of sources, applied at different times during the cropping cycle may be the best strategy for maximizing yield.  The common practice of periodic fertilization, in addition to pre-plant amendments, is likely best suited to organic tomato production. 75  With respect to the fertilizers trialed, none of the fertilizers were sufficient for optimal crop growth over the entire season under these conditions.  However, a combination of pre-plant amending with CPM or HV, plus subsequent split applications of EcoGrow may produce the best yields.  The EcoGrow split-application fertilization strategy better suited late season yields. The major limitation of this research study was that the results were derived from a single growing season.  To confirm these findings this research trial should be replicated over multiple growing seasons or at multiple locations with similar growing conditions. Further research to assess ideal application rates and mixed source fertilization strategies would be valuable.  A more rigorous disease monitoring strategy would be a desirable addition to this research project, as it is known that nutrient status affects disease incidence.  In addition, assessing alternative cultural practices, such as the use of organic mulches, would be valuable to help determine whether the reported benefits of hairy vetch mulched tomato systems are a valuable production practice in this climate. Lifecycle and higher yields from cv. Pollock suggest that this cultivar is better suited to coastal BC conditions.  However, a longer harvest period with increased late season yields from cv. Black Cherry may be preferred for fresh market distribution.  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Hairy Vetch Moisture Content Determination Sample Fresh Weight (g) Dry Weight (g) Moisture Content (%) 1 19.712 3.136 84.1 2 22.682 3.649 83.9 3 19.407 2.907 85.0 Mean Moisture Content: 84.3      Table A2. Composted Poultry Manure Moisture Content Determination Sample Wet Weight (g) Dry Weight (g) Moisture Content (%) 1 22.2 13.8 37.8 2 22.3 15.7 29.6 3 23.6 16.3 30.9 Mean Moisture Content 32.8  Appendix B Irrigation and Sensor Details Table A3. Irrigation Schedule Period Irrigation Days Duration June 9 – July 9 Monday (fertigation) and Thursday 60 minutes July 10 – August 4 Monday (fertigation),Tuesday, Thursday, Saturday, Sunday 60 minutes August 5 – Sept. 6 Monday (fertigation), Tuesday, Thursday, Saturday 45 minutes Sept. 7 – Oct. 10 Monday (fertigation), Wednesday, Saturday 45 minutes  89  Figure A1. Sensor Locations and Irrigation Layout  

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