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Studies on the effects of genotype and relatively cool temperatures on rough fruit production by tomato… Yankson, Mary Figyina 1977

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STUDIES ON THE EFFECTS OF GENOTYPE AND RELATIVELY COOL TEMPERATURES ON ROUGH FRUIT PRODUCTION BY TOMATO (Lycopersicon esculentum, Mill.)  by  MARY FIGYINA YANKSON B.Sc. University of Science and Technology, Kumasi, Ghana, 1973.  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE DEPARTMENT OF PLANT SCIENCE  We accept this thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA May, 1977 (c)Mary Figyina Yankson  In  presenting  this  an a d v a n c e d d e g r e e the L i b r a r y I  further  for  of  this  written  at  agree  for  financial  British  by  for  gain shall  Columbia  the  requirements  Columbia, reference  copying  of  I agree and this  that  not  copying  or  for that  study. thesis  t h e Head o f my D e p a r t m e n t  is understood  of  The U n i v e r s i t y o f B r i t i s h 2075 Wesbrook P l a c e V a n c o u v e r , Canada V6T 1W5  of  for extensive  p u r p o s e s may be g r a n t e d It  fulfilment of  available  permission.  Department  Date  freely  that permission  representatives. thesis  in p a r t i a l  the U n i v e r s i t y  s h a l l make i t  scholarly  by h i s  thesis  or  publication  be a l l o w e d w i t h o u t  my  i  ABSTRACT  Tomato fruits which are misshapen or rough are frequently a problem in the field crop, and sometimes in the greenhouse crop. This horticultural problem has been attributed to the exposure of seedling plants to relatively cool temperatures (below 15°C), but lack of knowledge about conditions causing rough fruit resulted in experiments to explore the influence of genotype and relatively cool temperatures on the production of rough fruit. A field study was carried out at the University of British Columbia in 1975 using 3 cultivars (Bonny Best, Fireball and Immur Prior Beta [IPB]) and 2 reciprocal hybrids of Bonny Best and IPB.  In that season, there  was a substantial quantity of rough f r u i t , and there were highly significant differences among genotypes. Controlled environment studies were used in 3 greenhouse experiments. In the f i r s t , tomato seedlings of 6 cultivars (Bonny Best, Cold Set, Early Red Chief, Fireball, IPB and Vendor) were chilled for either 3 or 7 nights to 10° ± 1°C at each of 4 different ages ranging from 3.5 to 6.5 weeks after seeding.  Control plants were kept at 19° +• 1°C. None  of the cultivars in any treatment produced enough rough fruit to be of any horticultural concern, but there were some highly significant differences (1% level) among the cultivars for the number of rough fruits produced. The second experiment employed more severe chilling conditions. Seedlings from 4 age groups ranging from 3 to 6 weeks were chilled for  ii  2 weeks using a night temperature low of 4.4 C • 0  of 12..8 ? C.  and a day high  Four cultivars (Cold Set, Fireball, IPB and Vendor)  were used, and although there were significant differences (5% level), the numbers of rough fruit did not match the horticultural problem. The third controlled environment experiment employed a regime of hourly changes in temperature to range from a night low of 4.4 °C and a day high of 21.1 °C, using .only 2 cultivars (IPB and Vendor). plants were kept at 20.0 C/23.9°C. U  .  Control  The plants were transferred  to controlled environment chambers 35 days after seeding, and kept in the contrasting temperature regimes until fruit matured.  Although  the IPB had a significantly greater number of rough fruit than Vendor, the magnitude of the numbers of rough fruit were too small to be of practical importance.  Apparently, the rough fruit problem is not caused  by the simple matter of exposure to chilling temperatures, and it is supposed that an interaction, possibly a very complex one, may be the cause of this type of misshapen fruit.  iii  TABLE OF CONTENTS  Paje ABSTRACT  i  LIST OF TABLES  v  LIST OF.FIGURES  viii  ACKNOWLEDGEMENT  ix  INTRODUCTION  1  LITERATURE REVIEW  3  Floral Induction and Initiation  3  Floral Development  8  Fruit Malformation  11  MATERIALS AND METHODS  14  Cultivars/Lines and Source of Seed  14  Soil Mixes  16  Greenhouse Plant Protection  16  A. Field Experiment  16  B. Greenhouse Experiments 1. Experiment la 2. Experiment lb 3. Experiment 2 4. Experiment 3  19 19 22 22 27  RESULTS  29  Field Experiment Pollen Production and Percent Normal Pollen Total Number of Fruit Number of Smooth Fruit Number of Rough Fruit  29 29 30 30 30  Greenhouse Experiments Experiment la Number of Flowers Total Number of Fruit Number of Smooth Fruit Number of Moderately Rough Fruit Number of Rough Fruit Flower Morphology and Fruit Shape  34 34 34 34 37 42 42 42  iv  Page  Experiment lb Flower Initiation  46 46  Experiment 2 Flower Initiation Fruit Set Mean Number of Days from First Flower Bud Appearance to First Fruit Set Total Number of Fruit Number of Smooth Fruit Number of Moderately Rough Fruit Number of Rough Fruit Flower Morphology and Fruit Shape  46 46 52 52 56 56 61 61  Experiment 3  61  5 2  DISCUSSION  69  LITERATURE CITED  75  V  LIST OF TABLES Table  Page  1.  Sources of seed  17  2.  Soil mixes  17  3.  Location of the plants in the 5 treatment groups from pricking-out to transplanting  25  4.  Analyses of variance of the mean percent normal pollen.per. plant on clusters 1 and 2  31  5.  Mean percent normal pollen per plant of each line on clusters 1 and 2  31  6. Analyses of variance of the mean numbers of t o t a l , smooth and rough fruit per plant of each line on clusters 1 and 2  32  7.  Mean number of total, smooth and rough fruit per plant of each line on clusters 1 and 2  33  8.  Analyses of variance of the numbers of flowers, total, smooth,  35  moderately rough and rough fruits per plant 9. 10.  Mean number of flowers per plant of each cultivar  36  Mean total number of fruit per plant of each cultivar on  38  clusters 1 and 2 11.  Mean total number of fruit per treatment age on clusters 1 and 2 39  12.  Mean number clusters 1 Mean number clusters 1 Mean number  13. 14.  of smooth fruit per plant of each cultivar on 40 and 2 of smooth fruit per plant per treatment age on 41 and 2. of moderately rough fruit per plant of each cultivar 43  per treatment age on clusters 1 and 2 15.  Mean number of rough fruit per plant on clusters 1 and 2  44  16.  Mean number of rough fruit per plant of each cultivar  44  17.  Numbers of normal, semi-normal and abnormal flowers and the subsequent smooth, moderately rough and rough fruits observed  45  vi  Table  Page  18. Analysis of variance of mean numbers of days from seeding to appearance of f i r s t flower buds on clusters 1 and 2 of each cultivar  47  19. Mean number of days from seeding to appearance of f i r s t flower buds on clusters 1 and 2 of each cultivar  48  ,20. Analyses of variance for mean numbers of days from seeding to appearance of f i r s t flower buds, and for f i r s t fruit set and days from f i r s t flower bud appearance to f i r s t fruit set on clusters 1 to 4  49  21. Mean number of days from seeding to appearance of f i r s t flower 50 buds on clusters 1 to 4 per plant of each cultivar 22. Mean number of days from seeding to appearance of f i r s t flower 51 buds on clusters 1 to 4 per plant at each treatment 23. Mean number of days from seeding to f i r s t fruit set on clusters 1 to 4 per plant of each cultivar  :  53  24. Mean number of days from f i r s t flower bud appearance to f i r s t fruit set on clusters 1 to 4 per plant at each chilling treatment  54  25. Mean number of days from f i r s t flower bud appearance to f i r s t fruit set on clusters 1 to 4 per plant of each cultivar  55  26. Analysis of variance of numbers of total smooth, moderately rough and rough fruit per plant  57  27. Mean total number of fruit per plant of each cultivar on clusters 1 to 4  58  28. Mean number of smooth fruit per plant of each cultivar and clusters 1 to 4  59  29. Mean number of moderately rough fruit per plant of each  60  cultivar on clusters 1 to 4 30. Mean number of rough fruit per plant of each cultivar  62  31. Mean number of rough fruit per plant of each treatment group 63 on clusters 1 to 4 32. Numbers of normal, semi-normal and abnormal flowers and the 64 subsequent smooth, moderately rough and rough fruits observed  vi i  Table  Page  33. Analyses of variance of the mean total, smooth, moderately rough and rough fruit numbers per plant on clusters 1 to 4  66  34. Mean numbers of total, smooth and moderately rough fruit per plant of each cultivar on clusters 1 to 4 (warm temperature regime)  67  35. Mean t o t a l , smooth, moderately rough and rough fruit per plant of each cultivar on clusters 1 to 4 (cool temperature regime)  68  vi i i  LIST OF FIGURES  Figure 1.  Page Smooth, moderately rough and rough fruits  19  ix  ACKNOWLEDGEMENT The writer wishes to express her thanks to her supervisor of studies, Dr. C A . Hornby, Associate Professor,Horticulture and Plant Breeding, for his encouraging interest and invaluable assistance in the preparation of the thesis. Acknowledgement is given to the other members of the Committee;  Dr.  V.C. Runeckles, Professor and Chairman of the Department of Plant Science, Dr. R.J. Copeman, Assistant Professor, Department of Plant Science and Dr. C.W. Roberts, Professor of Poultry Genetics for reviewing the manuscript. Special thanks are expressed to Dr. G.W. Eaton, Professor, Department of Plant Science, for helping with the statistical analysis of the data. The writer is indebted.to the Canadian International  Development Agency  and the University of Science and Technology, Kumasi, Ghana for financial assistance.  Finally she wishes to express her gratitude to Mr. Ilmars Derics,  Ms. Diane Green and all the other members of the Department of Plant Science, who helped in various ways in the preparation of the thesis.  1  INTRODUCTION  Malformation of tomato fruit is a problem which has caused growers a loss of marketable product and/or revenue for many years.  A badly  misshapen fruit is a problem whether i t is to be used for processing or for the fresh market.  Gould (12) stated that one of the qualities for  a good processing tomato cultivar is the ability to produce smooth fruit because an irregular outline increases the difficulty in peeling, and results in a very high percentage of waste.  Invariably  the exhibition standards of perfection or grade descriptions for the fresh market f r u i t , emphasize  1  smooth, regular shaped fruit.  Rough or deformed  fruits will thus have to be discarded during the grading process.  However,  i f the malformation is not too serious, but i f there is a relatively high proportion of deformed f r u i t ,  the crop will be given a lower grade  resulting in reduced revenue to the grower. Fruit malformation, other than "catfacing" (Knavel and Mohr, 21)- is often prominent in the field crop, especially when plants are started early in the season to obtain an adequate yield in a short growing season.  The  tomato is a warm season crop and reports of the optimum growing temperatures for the production of a high percentage of No. 1 fruit have been given by Abdalla and Verkerk (1), Shoemaker (35), Snyder (36), Stoner (37)> Verkerk (44) and others.  The temperatures range between a nighttime  low of 17°C and a daytime high of 24°C.  During the propagation period and  for some weeks after transplanting to the f i e l d , when the flower buds are being differentiated, temperatures may be cooler than the recommended  2  optimum range.  Thus,there is a common belief that exposure of the  plants to relatively cool temperatures results in misshapen fruits. This belief is supported by the report of Kaname and Itagi (20) that plants exposed to relatively low temperatures (7°-13°C), just before or just after flower bud differentiation, developed more abnormally-shaped fruits than plants exposed at earlier or later stages.  The observation  that the problem tends to be emphasized in relatively cool seasons also supports this belief.  The literature, however, reveals very l i t t l e infor-  mation about the cause of rough fruit. There have also been reports of the problem occurring in the greenhouse crop in some areas of B.C., especially in the spring crop.  The  seedlings for the latter crop are started during the cold winter months. Thus.it is suspected that the plants could be unintentionally chilled during some stage or stages of rough fruits.  their  - development resulting in  This suspicion is supported by the statement of Stoner  (37) in the U.S. Department of Agriculture handbook that "in no case should the night temperature drop below  58°F  during fruit bud develop-  ment, as this may cause misshapen tomatoes of poor quality". Growers also believe that some cultivars are more susceptible than others to the production of malformed f r u i t .  If this is a fact, i t  suggests genetic influence on the expression of the character. The foregoing prompted the initiation of this study to ascertain: a) What conditions of cool temperature and age of plant resulted in the production of rough f r u i t , and b) Whether cultivars  (different genotypes) differed in susceptibility to  the production of abnormally-shaped fruits.  3  LITERATURE REVIEW  The production of rough fruit by tomato plants, which have been subjected to relatively cool temperatures during certain periods of their growth, could be due to a disruption of the normal sequence of physiological and developmental processes, which lead to floral floral development and subsequent fruit set.  initiation,  The disruption could be  caused by the relatively cool temperature conditions or by an interaction of the cool temperatures with a complex of other factors.  Wedding and  Vines (4'5') stated that although field observations might indicate that a period of poor plant growth and the subsequent production of abnormallyshaped fruit might coincide with a period of exposure to relatively low temperatures,it was impossible to be certain of the relationship.  They  pointed out that other factors such as sunlight, humidity, nutrient supply and water could be changing at the same time that the plants are exposed to the relatively low temperatures.  Kaname and Itagi (20) have  since reported that high levels of nutrition and irrigation combined with low temperatures favoured fruit malformation.  Floral Induction and Initiation There are conflicting results reported on the influence of cultivar (genotype), temperature^(both top and root), light, nutrient supply and vegetative growth on floral induction and initiation in the tomato. There is a sensitive phase for flower production in the tomato plant. Lewis (22) reported that the sensitive period for the temperature effect on the f i r s t inflorescence was between the eighth and twelfth day after  4  cotyledon expansion.  Treatments (14°C compared with 25°-30°C) given  from the time of cotyledon expansion to the emergence of the f i r s t inflorescence had effects which sometimes lasted to the f i f t h inflorescence. According to Wittwer and Teubner (48), the sensitive interval for the f i r s t inflorescence formation was the 2-week period immediately following cotyledon expansion. . Similar results were obtained by Calvert (6), who also noted that the sensitive phases for the f i r s t , second and third inflorescences occurred at weekly intervals for the cultivar, and at longer intervals for "Ailsa Craig"..  "Potentate",  Frenz (11) growing 3 tomato  cultivars under 2 day/night temperature combinations (24°/18° and 18°/ 12°C) for 18 days after germination, observed that flower initiation occurred 6 to 8 days'after germination in some cultivars and after 10 to 12 days in others.  However, the end of the sensitive phase, especially  with the higher temperatures, could not be clearly shown 18 days after germination. The relationships among temperature, vegetative growth and flowering were considered by Roodenburg (-29) who stated that the number of leaves preceding the f i r s t inflorescence emergence was minimal at-relatively low temperatures.  Wittwer and Teubner (48) also observed that exposure  of tomato seed!ings to low temperatures (10.0°-12. 8°C), in contrast to growth at 18.3' -21.1 C during the sensitive phase, promoted the devel-. l0  ,0  opment of fewer leaves before the f i r s t flower cluster appeared.  Results  obtained by Alpateve and Polumordvinova (3)< indicated that the initiation of the f i r s t inflorescence began 10 to 20 days after germination during the 2 to 3 permanent leaf stage.  However, they reported that the tem-  perature during germination and daylength and nutrition during early  5  growth did not affect the position of the f i r s t inflorescence in 6 cultivars, and that the number of leaves preceding the f i r s t inflorescence varied from 7 to 10.  Calvert (6), using "Potentate",observed that the  number of leaves produced before the f i r s t inflorescence was minimized with high temperature (26.7'°C day and night).  Later Calvert (7)  reported that the duration from germination to the initiation of the f i r s t flower truss depended on light and temperature conditions.  Temper-  atures above .21.T; °C during the vegetative phase significantly increased the number of leaves whereas temperatures below 12.8 ;°C slowed down the growth rate of the plant.  In further studies, Calvert (8) proposed an  explanation and suggested that the rate of apical enlargement was slow at high temperatures because the developing leaves took a greater share of.the available assimilates at the expense of the growing point.  Thus  the transition from vegetative to reproductive activity was delayed. Phatak et_ al_. (26) stated that exposure of the tops of tomato seedlings to temperatures of 10/0 -12.;8°C significantly reduced the number of nodes o  below the f i r s t inflorescence when compared with plants grown at 15.6J 0  18.3 °C or 18.3:°-21.1 °C.  Aung (4) also observed a relatively  high  correlation between leaf nodes preceding the f i r s t inflorescence and days from seeding to f i r s t anthesis.  Frenz (11) working with 3 tomato  cultivars, which were subjected to 2 day/night temperature combinations (24°/18° and 18°/12°C) for 18 days after germination, concluded that high temperatures, in contrast to relatively low temperatures, resulted in the production of more leaves.  However, independent of temperature,  the sensitive phase for leaf induction prior to the f i r s t inflorescence began 6 days after germination in all cultivars and ended 4 to 6 days  6  later.  Saito and Ito (32) noted that the f i r s t inflorescence was.  differentiated when the stem diameter just below the cotyledon reached 2.4-2.8 mm. According to Grainger (13) the transition from vegetative to floral activity was effected by an adequate supply of carbohydrates to the growing point.  Imanishi and Hiura (19) noted that there were varietal  differences in flowering date for the f i r s t inflorescence. and Stankiewicz (24) made a similar observation.  Litynski  However, reports by  Calvert (7)showed"thatthe length of the period from germination to the initiation of the f i r s t floral truss was dependent on light and temperature conditions.  Lewis (22) stated that a low temperature (14°C),  compared with high temperatures of 25°-30°C, during the period from cotyledon expansion to the appearance of the f i r s t inflorescence, gave an increase in flower number in tomato plants grown under both natural and a r t i f i c i a l light.  Calvert (5) observed similar results.  Verkerk  (44) working in California and in Holland noted that under relatively high light conditions, an increase in the average temperatures resulted in fewer flowers per truss; whereas under lower light intensities, the temperature effects were less pronounced.  However, Calvert (9) observed  that in low light intensities (equivalent to those occurring in midwinter in Great Britain) an i n i t i a l period of high temperature (21.1 °C) followed by low temperature (15.6-°C) induced a greater flowering capacity than a constant low temperature.  Wittwer and Teubner (48, 4-9)  reported that seedlings, exposed to 10°-13°C in contrast to growth at 18°-21°C for 2 to 3 weeks subsequent to cotyledon expansion, produced a significantly greater number of flowers in the f i r s t cluster.  Also,  7  cold treatment of older seedlings increased the flower numbers in later formed clusters.  Howlett (17), using the cultivar "WR 7", observed an  increase in flower numbers when the plants were grown at 10°C night temperature, but the increase was not substantial, and might have been a varietal effect.  Saito and Ito (32,) reported that exposure of tomato  seedlings to a night temperature of 17°C, in contrast to 24° and 30°C, for 3, 5 and 7 weeks resulted in the production of the maximum number of flowers in the f i r s t , second and third inflorescences respectively. In contrast to the above observations, Takahashi et al_. (38) stated that more flowers were produced at 24°C than at 17°C.  They also observed  that floral differentiation was earliest at 30°C and latest at 17°C. Reinken and Struklec (27) also observed earlier flowering at high night temperature (21°C) than at low night temperature (12°C).  Differential  exposure of the tops and roots of tomato seedlings, according to Phatak et al_. (26) showed that top temperatures determined the position bf the f i r s t inflorescence whereas root temperatures influenced flower numbers. Root temperatures of 10.0°-12:."3°C resulted in a significant increase in flower numbers compared with flower production at 15.6;.°-18.3 °C or 18.3. °-21.11°C.  However, Abdelhafeez .et al_. (2) observed no marked  influence of soil temperature on flowering.  Howlett (16) has reported  that floral primordia were differentiated over a photoperiod of 4 to 24 hours.  He obtained no indication that a smaller number of floral  primordia was induced and initiated under the shorter photoperiods. White (47) observed that the number of blossom buds formed was lower in nitrogen starved tomato plants than in those receiving adequate nitrogen. Went (46), however, stated that low night temperatures as well as low  8  light intensities by day, did not materially increase or decrease the number of floral primordia initiated per inflorescence.  He stated that  flower initiation is primarily a morphological process influenced by internal organization and genetic constitution rather than by external factors.  Floral Development Hayward (15) stated that the floral primordium f i r s t appeared as a dome-shaped enlargement directly continuous with the main axis. floral parts (calyx, corolla, stamens and pistils)  The  then developed in  acropetal succession. ' The ontogeny of the pistil may indicate how any disruption during this stage of floral development could possibly result in the production of rough f r u i t .  Hayman (15) reported that, in the  bicarpellate types of tomato, the early development of the carpellary primordia resulted in the formation of conical hood-like structures whose concave faces opposed each other.  Within the carpel primordia  there remained a definite proportion of the axis, which consisted of a more or less concave disc.  This part of the axis elongated and enlarged  to form a conical structure.  Later growth was initiated at the base of  the elongating cone and 2 septa developed involving a portion of the axis to form 2 locules.  At this stage each carpel was open at the top  and its cavity was a pit bordered by the elongated central portion of the axis, the ridge-like septa:; and the curved walls of a carpel. Continued growth resulted in the tip of each carpel being inclined toward the central portion of the axis and finally these tips became so closely appressed to the elongated column of the axis that the 2 structures  9  were no longer recognizable as distinct from each other.  Further  elongation of the terminal portions of the carpels resulted in the formation of a long narrow style.  Continued enlargement and bowing  out of the basal wall of each carpel formed 2 locules in which the central axis developed as a columnar structure from which the ovules arose. The influence of genotype, temperature, light, water and nutrient supply on the development of the tomato flower has been reported. MSskov and Aleksandrova (25) stated that a reduction of night temperature to 17°C retarded bud development.  Saitoand Ito (32) grew tomato plants  under all combinations of day temperatures of 24° and 30° and night temperatures of 17°, 24° and 30°C.  They observed that high temperatures  induced earlier flower bud development.  Calvert (8) also reported that  following floral initiation, an increase in both light and temperature tended to accelerate development of the inflorescence towards anthesis. Later, Calvert (9.) observed that the beneficial effects on flower devel-. opment were greatest when the day temperature was high (21.T :°C). According to Abdelhafeez et al_. (2) flower development was not markedly influenced by soil temperature (20°C) but was retarded by low air temperature (17°C).  Howlett (16), using photoperiods of 4-24 hours,  concluded that supplemental illumination for tomato plants grown under a short photoperiod resulted in more buds reaching anthesis. tended to absciss on plants grown without extra illumination.  Buds  10  Rylski (30) reported that relatively.low temperatures before anthesis caused flower abnormalities. observations.  Sal violi and Martin (34) made similar  Zielinski (50) described fasciation in the perianth,  stamens and p i s t i l s of the tomato flower•.  In the perianth there were  exaggerated petal and sepal numbers of up to 80.  Both the petals and  sepals could be developed in more than one whorl in fasciated flowers. Fasciation in the stamens resulted in adhesion of these organs to the corolla or calyx, cohesion of the antheridial filaments and rudimentary anther sacs with aborted pollen.  In the p i s t i l , fasciation  showed as partial to complete distortion of the pistillate parts.  In  the ovary of fasciated flowers, the locules were often increased in number and the ovules were rudimentary and/or aborted.  Sometimes as  many as 7 p i s t i l s were formed in a single flower and frequently at least oneof these pistils was functional.  This fasciation phenomenon resulted  from unfavourable environmental conditions such as relatively low tern-, peratures (7.2°-T2.8°C), high nitrogen level, low light intensity and prolonged drought followed by abundant moisture interacting with certain genotypes.  Later, Saito and Ito (33) made similar observations on  tomato plants exposed to a temperature range of 9°-10°C.  They suggested  that fasciation was due to surplus nutrients becoming available to the flower buds as a result of reduction in vegetative growth at the low temperature.  They, however, observed that this effect was reduced when  the plants were grown at low light intensities or under poor nutrient conditions, notably low nitrogen.  11  Fruit Ma1 forma tion There are reports of relationships between abnormal flowers and malformed tomato fruits, and the influence of genotype, temperature and other external factors on the production of misshapen f r u i t . Shoemaker (35) stated in his book that relatively low temperatures when the fruit clusters were small -.caused;.  , • rough f r u i t .  Ryl ski  (30) observed that low temperatures before anthesis in tomato flowers caused flower abnormalities and subsequent fruit deformation. using sweet pepper cv. ''California Wonder  Also  (a plant with requirements  similar to those for the tomato), Rylski and Halevy (31.) reported that a high temperature (20°C) during flower development was a pre-requisite for the formation of well-shaped elongated fruit.  Kaname and Itagi  (20) also made similar observations, when they exposed tomato seedlings to 4 temperature regimes: 17°-20°C, 7°-10°C, 8°-13°C and cold frame with unregulated temperature during winter in Japan,  They reported  that the lower the growing temperature, the greater was the production of malformed f r u i t .  A short period (3 days) at 2°C did not affect fruit  shape on plants raised as seedlings in normal temperatures^ More malformed fruits were developed when plants were exposed to low temperatures just before.or just after flower-bud differentiation than when exposed at earlier or later stages.  High levels of nutrition and irrigation  combined with low temperatures were also found to favour fruit malformation.  Working in Morocco, Ricada and Honnorat (28) observed that most  of the deformed tomato fruit developed from flowers that were themselves deformed.  They stated that these malformations were not inherited and  did not resemble those caused by growth regulators.  The main cause of  12  the problem was thought to be climatic since the growing period was marked with unfavourable sandstorms and sharp temperature fluctuations, which resulted in periodic checks of growth.  They also suggested that  unbalanced- nutrient supply might have accentuated the problem in some cases. Knavel and Mohr (21) grew seedlings of the tomato  lines  "Pi  244956" and "Floralou" for 5 weeks in growth chambers at 2 temperature regimes, 5.f6 -13.3;°C and 20:0°-26.7°C. ;0  Subsequently the plants were  transferred to a glasshouse at 20.-0°-26.7 C. o  Most.fruits of "Floralou"  appeared normal regardless of seedling temperature treatment whereas plants of the "PI" selection grown at S.s&V^-lS.S.^C bore the most deformed fruit of the "catface" type. Sal violi and Martin (34) reported that the cultivar, "Platense", produced abnormal flowers and excessively large and misshapen fruit.of the "catface" type.  This character was found to.be due to a simple  recessive gene afl with complete penetrance at about 10.5°C during flowering and zero penetrance .at 20.3°C.  Two inherited tomato fruit  abnormalities were also reported by Ekstrand ( 1 0 ) . The.first type was produced from fasciated flowers and such fruits were crinkled and segmented and in some instances had fissures in the pericarp through which the placenta was visible.  In the second type of abnormality, the  plicate portions of the fruit pericarp did.not (as in the f i r s t case) form a circle but were irregularly situated within and on top of the normal pericarp structure like a group of.small tomatoes on top of a larger main f r u i t . It is evident from the foregoing .that there is a dearth of reports  13  giving evidence on the cause of rough f r u i t .  However, i f the condition  is excited by factors similar to those which cause other fruit abnormalities, eg. "catface"  .  rough fruit may be associated  with a complex of factors interacting with certain genotypes to affect vegetative growth and consequently the reproductive capacity and fruitfulness of tomato plants.  14  MATERIALS AND METHODS  Field and greenhouse experiments were carried out in 1975 and 1976 at the University of British Columbia. located on Department of Plant Science land.  The field experiment was. The greenhouse experiments  were located in a house with automatic roof ventilation, which opened when the temperature reached 18.3 :°C.  Most of the greenhouse experiments  required periods of controlled temperature regimes, and these periods Model PGC-78 employed Pereival/growth chambers, each with a capacity of 75 X 168 X 122 cm and illuminated with 16 high output cool white fluorescent light tubes and 10 40-watt incandescent lamps: (42,000 erg/cm /sec).  Cultivars/Lines and Source of Seed A total .of 6 different cultivars and 2 reciprocal. F-j hybrids of 2 of the cultivars were used.(Table 1). 1. "Bonny Best" (BB). Johnson and Stokes.  BB was introduced in Philadelphia in 1908 by  It was obtained from a single plant selection of  "Chalk Early Jewel" cultivar at Jeffersonville, Pa.  It is popular in  regions with short growing seasons and i t is adapted to all tomato growing regions in the U.S.  It is valuable for forcing under glass  and matures 63-73 days after setting the plants.  BB is used for home  and market gardens and i t is late in regions of cool nights.  BB is a  semi-erect indeterminate plant, which grows to a height of 45-55 cm and has a spread of 140-160 cm or 3 times its height. 2. "Cold Set" (CS). in Brantford, Canada.  CS was introduced by the Douglas Seed Company It was obtained from a cross'between "Fireball"  15  X wild-fruited "Filipino" number 2 (Pink Selection) at the Ontario Agriculture College, Guelph. pruning and compact.  It resembles "Fireball" and i t is self-  CS has a wide adaptation between the Peace River  district of Alberta and Texas. with short growing seasons. early (68 days).  It is excellent for the northern areas  CS is used for field culture and matures  There are both hot and cold setting types and the. latter can  be seeded direct at soil temperatures as low as 10°C. 3. "Early Red Chief" (ERC). 65 days after setting. harvest season.  ERC is an early cultivar, which matures  It is a vigorous compact plant with a long  The early pickings are shipped and the later harvest  is canned. 4. "Fireball" (FB).  FB was introduced by.the Joseph Harris Company  and was announced in the 1952 Harris seed catalogue.  It was obtained  from "Harris' Round" X "Valiant" and resembles the tomato cultivar "Victor".  FBiis ideal for field growing in areas with short growing  seasons and i t is recommended for the Great Lakes region, New England and Canada.  The plant is determinate with small vines, l i t t l e foliage  and matures 60-65 days after, field-setting.  FB produces very smooth  globe-shaped fruits and gives large cluster sets even in cold weather. 5. "Immur Prior Beta" (IPB).  IPB is an indeterminate tomato cultivar  with potato leaves and leafy inflorescence.  It produces small fruits  with green shoulders and can set fruit at temperatures as low as 7.2 °C. 6. "Vendor" (VR). VR is one.of the.best fal 1 staking or greenhouse tomato cultivars,. sturdy.  It is slightly shorter than most greenhouse types and is very  The fruit clusters are closer together than most cultivars.  7. The two reciprocal F-, hybrids used were IPB X BB and BB X IPB.  16  Soil Mixes The soil mixes used to raise all the seedlings are given in Table 2.  Greenhouse Plant Protection, The greenhouse was fumigated every 2 weeks with either "Plantfume" containing Bis-0,0-diethylphosphorothionic anhydride or "Pyrethrum" to control insect pests.  The latter fumigant was used whenever i t was  necessary to avoid flower drop.  A. Field Experiment  The objective of the field experiment was to obtain a quantitative measure of rough fruit production in the different cultivars and F-j hybrids under field conditions.  Cultivars BB, FB, IPB and F-j hybrids  of BB X IPB and IPB X BB were used.  Plant Production Seeds were sown in flats on April 1,1975.  Seventeen days later  the seedlings were pricked-out into 10-cm peat pots.  The plants were  kept in the greenhouse for another 15 days and then placed in cold frames for hardening for 15 days.  The frames were, covered at night to  guard against frost damage for the f i r s t 10 nights, and thereafter only when i t was raining.  17  Table 1.  Sources of seed.  Source  Cultivar/Line Bonny Best (BB)  U.B.C, stock  BB X IPB  U.B.C. stock  Cold Set (CS)  Plant Genetics and Germplasm Inst., Agricultural Research Centre, Beltsville, Maryland 20705. (USDA)..  Early Red Chief (ERC)  Stokes Seeds Ltd., St. Catharines, Ontario.  Fireball  (FB)  U.B,C. stock  Immur Prior Beta (IPB)  U.B.C. stock  IPB X BB  U.B.C. stock  Vendor (VR)  Stokes Seeds Ltd., St. Catharines, Ontario.  2  University of British Columbia  Table 2.  Soil mixes.  Type of mix  Description  Seed  2 parts screened steam-sterilized s o i l : 1 part sphagnum moss.  Pricking-out  3 parts screened steam-sterilized s o i l : 1 part sphagnum moss, plus 1,87 kg "Osmocote" 14-14-14 slow release f e r t i l i z e r to 1.00 .m^ of the soil-moss mixture.  18  Planting and Management Practices The seedlings were transplanted to the field on May 18, 1975 using a randomized complete block design.  There were 5 blocks with single row  plots, each consisting of 4 plants of one cultivar or hybrid. spacings were 1.8 1.2  The  m between adjacent blocks and adjacent plots, and  m within plots. Immediately after transplanting, the seedlings were protected from -1  arthropod pests with "diazinon" 50EC at the rate of of water.  1 ml 1  Each plant was watered 3 times a week for the f i r s t 3 weeks  when the plants were getting established and thereafter overhead irrigation was used once a week.  The plots were weeded fortnightly.  A tri-weekly  fertilizerplacement programme with a 13-16-10 compound f e r t i l i z e r at the rate of  277 g  to a plant, was started 6 weeks after transplanting.  The  plants were neither pruned nor trained. Collection and Treatment of Data Data on pollen production and fruit shape were collected from the f i r s t and second clusters on the main stem. 1. Pollen production. selected.  Two of the 4 plants in each plot were randomly  The day after the flowers opened, the f i r s t 4 flowers of each  inflorescence were collected for visual estimation of the amount of pollen  produced. Then following acetocarmine (0.5%) staining, the percentage of normal pollei was obtained for each inflorescence. 2. Fruit shape.  After randomly selecting the plants for pollen  studies, the 2 remaining plants in each plot were used for fruit shape  19  evaluation.  When the flowers opened, each of the 2 clusters was pruned  to leave the f i r s t 4 flowers to set fruit.  The ripe fruits were then  graded as: i)  Smooth - symmetrical with no irregularities such that fruits are not noticeably ridged, angular or indented, and marketable (-Fig. 1), or  i i ) Rough - seriously misshapen or deformed, asymmetrical and unmarketable (Fig. 1) The pollen and fruit shape data were subjected to standard analyses of variance and the means compared using the Newman-Keuls (SNK) multiple range test when the F-test showed significance at the 1% level.  B. Greenhouse Experiments  1. Experiment la The objective of experiment la was to study fruit shape as affected by exposing tomato seedlings to chilling night temperatures.  Six cultivars,  BB, CS, ERC, FB, IPB and VR were used. Growing Plants.  Seeds were sown on May 16, 1975 and seedlings pricked-  out into 10- 'cm plastic pots 11 days later. started on June 11 , 1975, and -"  Chilling treatments were  17 days later the seedlings were trans-  ferred to 15 - cm pots and chilling treatments were continued for a further 14 days. Chilling Treatment.  The chilling treatments were intended to simu-  late the growing conditions under which tomato plants are alleged to develop rough f r u i t , that is chilling at night, whether the plants be in protected structures or in the f i e l d .  Thus,during the treatment period,  Fig. 1. Smooth, moderately rough and rough fruits.  20  the plants were placed in the growth chambers each day from 2000 h to .0800 h . j and returned to the greenhouse for the remainder of the day.  The night temperatures employed were 10°±1°C (cool chamber) for  the chilling treatment and 19°±1°C (warm chamber) for the control or non-chilling conditions. The possible relationship between age of plant and vulnerability to chilling treatment was studied by choosing : 4- different ages for the test plants.  Thus treatment of different age lots began at 3.5, 4.5, 5.5  and 6.5 weeks after seeding.  Each age group was subjected to 3 durations  of exposure to the chilling temperature: a) No chilling - 7 nights in the warm chamber; b) Short chilling - 3 nights in the cool chamber and 4 nights in the warm chamber; c) Long chilling - 7 nights in the cool chamber. Six plants of each cultivar were chosen at random for each duration of exposure for each age-of-plant lot.  Over the 7-day treatment period,  the seedlings were moved around in the growth chambers so that no plant occupied the same position for 2 successive nights.  Plants belonging to the same  age. lot ..were-.placed together-, randomly at one place on a greenhouse bench at the end of the treatment period. Planting and Management Practices.  Four uniform seedlings out of the  6 treatecha-t each age were selected for each cultivar and each duration of treatment at the end of the last treatment age (7.5 weeks after seeding). The plants were then potted in sterilized s o i l .  9 1- / plastic buckets f i l l e d with steam-  Four greenhouse benches were used as replications with  21  72 single plant plots.  The table of random numbers (23) was used to  position plots within each replicate. The plants were trained to a single stem and watered daily.  A  fortnightly f e r t i l i z e r programme with "Hi-sol" 20-20-20 soluble plant food at  2 g per .. plant, ,  v  ~  . ...  .was started 2 weeks .after  potting. Collection and Treatment of Data.  Data were collected separately  for the f i r s t and second inflorescences.. 1. Number of flowers. The total number of flowers was counted when the last floral bud in each inflorescence became visible. 2. Relationship between flower morphology and fruit shape. An attempt was made to relate the flower appearance to the shape of the fruit which would subsequently develop from i t .  Ninety-four plants from the 4 r e p l i -  cations (26, 27, 21 and 20 plants from replications 1 to 4 respectively) were randomly selected 5 to 6 weeks after seeding.  All the flowers which  were open within this period were classified and tagged as: i) normal:- anther cone symmetrical and all other floral parts not fasciated, expected to produce smooth f r u i t ; i i ) semi-normal:- anther cone slightly misshapen and/or enlarged, some of the other floral parts fasciated, expected to produce moderately rough f r u i t , and iii)  abnormal:- anther cone asymmetrical and fasciated, and most or  all the other floral parts fasciated, expected to produce rough f r u i t . 3. Fruit number and shape. The total number of fruits retained in each cluster was counted at maturity.  The ripe fruits were then graded as  22  rough, moderately rough, or smooth. Data on flower and fruit numbers and on fruit shape were subjected to standard analyses of variance and the means compared using the SNK test when the F-test showed significance at the 1% level.  2. Experiment lb. The trial was intended as a supplement to experiment la to estimate;:, the number of days taken for the f i r s t and second inflorescences to appear in the different cultivars. (  Growing Plants.  for experiment l a .  Plants were taken from the same seedling lot raised The plants were set on a greenhouse bench using 3  replications in a completely randomized block design.  No chilling treat-  ments were given and all other cultural practices were the same as those used in experiment l a . Collection and Treatment of Data. Flower Initiation.  The number of  days from seeding to the f i r s t flower bud emergence was noted for the f i r s t and second clusters.  The means of 2 plants per cultivar per r e p l i -  cation were subjected to the standard analysis of variance.  The cultivar  and cluster means were each compared with thecSNK test when the F-test showed significance at the 1% level.  3. Experiment 2 The results from experiment la indicated that the chilling treatments employed had l i t t l e effect on fruit shape.  Some surplus young plants for the  23  field experiment had been placed in cold frames for 3 weeks in May, 1 9 7 5 , and were !then  :  returned to the greenhouse where they subsequently produced a  considerable number of. rough fruit on early clusters.  This contrast  suggested that a more severe chilling treatment might beaassociated with production of rough f r u i t , and that the age of plant or stage of development might be important.  Thus,experiment 2 was designed to study  the effect of exposing tomato seedlings at different ages to relatively severe chilling temperatures below 1 2 . 8 ° C continuously for a period of 2 weeks, thereafter placing the plants in normal greenhouse growing temperatures of 20°C and above.  Four cultivars were chosen for test in  this experiment, namely, CS, FB, IPB and VR. Growing Plants.  Seeds were sown on May 4 , 1976 and seedlings pricked-  out into 10. -.' cm square plastic pots 8 days later.  The plants were kept  in the greenhouse for another week to recover from the shock of pricking-out and then placed in the growth chambers.  There was a total of 25 plants  per cultivar and each plant was numbered to indicate the position i t was to occupy in the growth chamber using the table of random numbers (2i3). Chi 11ing Treatment.  The chilling treatment was exposure of plants  to a diurnal temperature range of 4.4^° to 1 2 . 8 ^ ° C weeks.  : for a period of 2  The control plants were kept on a diurnal temperature range of 20^0°  to 23v<9 C." ;0  When the plants were in the controlled environment  chambers, a 14-hour photoperiod was supplied as follows: 0600 h  to  07)0.0.hi, - all incandescent lamps on;!  0700 h ,  to ";0930 n  all incandescent and half fluorescent lamps on;  0930 h ,  to  all incandescent and fluorescent lamps on;  1700 h  24  1700 h •., to • 1830 h  - all incandescent and half fluorescent lamps on;  1830 h  to  2000 h  - all incandescent lamps on;  2000 h  to  0600 h •., - all lights off.  A total of 3 growth chambers, 2 programmed to give normal temperatures (20:0 -23.9°C ':,) and a third set to give cool temperatures (4.4 °-12.8 °C) o  .were used.  Diurnal changes in temperature from hour to hour were  gradual. One week after pricking-out, when the plants were assumed to have recovered from the shock of pricking-out, the seedlings were transferred to one normal-temperature growth chamber for one week to enable them to adjust to the growth chamber growing conditions. were then begun.  The chilling treatments .  There were 5 treatment groups which included 4 groups  of chilling treatments and a f i f t h group was the unchilled control.  Each  chilling treatment group was placed in the.cool-temperature growth chamber for a 2-week period of continuous c h i l l i n g .  Thus the treatment groups  were:. 1) Chilling started at 3 weeks from seeding; 2) Chilling started at 4 weeks from seeding; 3) Chilling started at 5 weeks from seeding; 4) Chilling started at 6 weeks from seeding; 5) No chilling - control. The order in which the plants were placed in the 3 growth chambers is shown in Table 3. The same number of seedlings was-kept in all the chambers at any given time by the use of f i l l e r plants in order to eliminate border effects and to ensure the same chamber area for each plant.  Thermographs and  J  25  Table 3.  Location of the plants in the 5 treatment groups from prickingout to tr a h s p 1 a n t i n g .  Growth chamber Weeks After .prickingout  M  I  N p r m a 1  1  2  Cool  0  All plants in greenhouse  1  trt  2  trt 2,3,4,5  -  trt 1  3  trt 3,4,5  -  trt 1,2  4  trt 4,5  trt 1  trt 2,3  5  trt 5  trt 1,2  trt 3,4  6  trt 3,5  trt 1,2  trt 4  7  All plants in greenhouse  2,  1,2,3,4,5  Treatment .group .as listed on page 24.  minimum and maximum thermometers were kept in the growth chambers to check the temperatures. Planting and Management Practices.  The chilling treatments were  ended on July 1, 1976 and all the plants returned to the greenhouse, then 4 uniform plants were selected out of the 5 plants per cultivar in each treatment group and planted in '9^1  plastic containers f i l l e d with  steam-sterilized soil on July 2, 1976. The same randomization order which  26  was kept in the growth chambers was maintained in the greenhouse. Each plant was grown to a single stem and staked.  Plants were  watered daily and fed with approximately 1,g "Hi-sol"'20-20-20 per plant: once a week starting from 2 weeks after potting. Collection and Treatment of Data.  Data were collected on the f i r s t  4 clusters. 1. Flower initiation. The number of days from seeding to the appearance of the f i r s t floral bud was noted for each of the 4 inflorescences. 2» Fruit set. The number of days taken for the f i r s t fruit to set on each cluster was recorded.  The flower was considered to have set fruit when  the ovary developed to.the size of a pea.  Two sets of data were recorded:.  i) days from seeding to f i r s t fruit set; and i i ) days from f i r s t flower bud appearance to f i r s t fruit set. 3. Relationship between f 1 ower morphology and frliit shape. An attempt was made to relate the flower appearance to the shape of the fruit which would subsequently develop from i t .  The flowers were classified as normal,  semi-normal or abnormal based on the criteria used in experiment l a . 4. Fruit number and shape. The total number of fruits retained in each cluster was counted at maturity.  The ripe fruits were then graded as  smooth, moderately rough or rough. All data were evaluated as outlined for experiment 1.  It was intended  to test the relationship between flower morphology and subsequent f r u i t shape, but the proportions of flowers in the semi-normal and abnormal  2  groups were comparatively too low to warrant using the X' test.  27  4. Experiment 3 The objective of the greenhouse experiment 3 was.to study fruit shape as affected by exposing tomato plants to temperatures which fluctuated in contrast to the uniform or gradually changing temperature regimes employed in previous experiments. Growing Plants.  Two cultivars, IPB and VR, were used.  Seeds were sown on August 23, 1976 and seedlings  pricked-out-8 days later into 10 ,-": cm plastic pots.  The plants were  kept in the greenhouse and transferred to the growth chambers on September 27, 1976, 35 days from seeding, after the plants were potted into '.JM ' . . plastic buckets f i l l e d with steam-sterilized soil-. Temperature Treatment and Management Practices.  Two temperature  regimes were used: i) warm regime - gradual change in temperature with a day high of 23.9\°C _ at noon and a night low of 20.0.°c at midnight; ;  i i ) cool regime - sharp hourly fluctuations of temperature between a day high of 21.1 °C '  at noon and a night low of 4.4.,.?£at  14-hour photoperiod from 0600 h  .to  0100 h. > A  200.0 h . was given as done in  experiment 2. There were 4 plants per cultivar, arranged randomly in each growth chamber.  The plant positions were changed each week to minimize position  effects on growth.  Each plant was fertilized with 14.2 -g "Hi-sol" 20-20-20  f e r t i l i z e r before being placed in the growth chamber.  Three weeks after  treatment was started, each plant was fertilized with 28.4 .g of a f e r t i l i z e r mixture made up of equal volumes of KN0 and Superphosphate (KN0 : N=l3.5%, 3  1^0 = 46%, and Superphosphate = 18% ^2^5^' every 3 weeks.  3  a n c  ' ' t  1 1 s  i™*"  1 6 1 1  The plants were trained to a single stem.  *  w  a  s  repeated  Collection and Treatment of Data.  The total number of fruits  were counted at maturity in clusters 1 to 4,  The fruits were then  graded as smooth, moderately rough and rough.  Data were evaluated  for the previous experiments.  29  RESULTS  In general, with the exception of the field data, the number of malformed fruit produced was comparatively too few for any significance between lines to be of real value.  Rough fruit production was not shown  to be influenced by relatively cool temperatures in the controlled experiments.  Field Experiment There were several occurrences which affected the data collected. 1. Bonny Best (BB).  The tops of 2 plants (one each from blocks 1 and  5) died before fruit set.  The remaining plants had either no set or only  1 fruit set instead of the expected 4 in cluster 1.  Fruit set was,  however, improved on the second cluster with only 1 plant not setting any fruit.  The means of percentage set were 15.6% on cluster 1 and 50%  on cluster 2. 2. Fireball (FB).  Two of the total of 10 plants did not set any fruit  on cluster 2, but cluster 1 set some fruit on all plants.  Mean percen-  tage fruit sets were 67.5% and 52.5% on clusters 1 and 2 respectively. 3. Both inflorescences set fruit in the other lines. on both trusses.  IPB averaged 100%  BB X IPB had means of 87.5% and 92.5% fruit set respec-  tively on the f i r s t and second clusters.  IPB X BB had 97.5% set on  cluster 1 and 100% set on cluster 2. Pollen Production and Percent Normal Pollen.  Pollen production by  FB was relatively poor; however, the other lines produced relatively large  30  quantities of pollen and there were no apparent differences among them. The percentages of normal pollen showed no significant differences among the lines (Table 4).  There was, however, an indication that IPB  and IPB X BB produced the lowest proportions of normal pollen.  The per-  centages of normal pollen produced by BB, BB X IPB and FB were very similar (Table 5). Total Number of Fruit.  The total number of fruits produced on both  the f i r s t and second clusters showed significant differences among lines (Table 6).  The highest yields on cluster 1 were obtained from IPB, IPB  X BB and BB X IPB but the differences between them were not significant. FB gave an.average fruit yield, which was not significantly  different  from the yield of BB X IPB, but significantly different from IPB and IPB X BB (Table 7).  BB produced significantly fewerfruits in cluster 1  than any of the other lines. IPB, IPB X BB and BB X IPB as a group produced significantly more fruit on cluster 2 than either FB or BB.  The difference between the  latter 2 lines was not significant, and differences among the former lines were also not significant. Number of Smooth Fruit.  Yields of smooth fruit showed significant  differences for cluster 2 but not for cluster 1 (Tables 6 and 7).  There  were no smooth fruits on either cluster of IPB and cluster 1 of BB (Table 7).  The only significant difference in yields of smooth fruit  was that between IPB and BB X IPB on cluster 2. Number of Rough Fruit.  There were significant differences among  lines in rough fruit numbers on both clusters (Table 6).  Only the differences  31  Table 4. Analyses of variance of the mean percent normal pollen per 2  plant on clusters^! and 2.  Mean squares Source  Df  Cluster 1  Cluster 2  Rep  4  77.86  102.52*  Lines*  4  131.69  94.82*  Error  16  85.26  29.07  Total  24  Mean of 2 plants per line per replication.  2  •^Each cluster analyzed separately. Lines indicate 3 cultivars and 2 F-, reciprocal hybrids. * Significant, • ; o 5% level. x  w  Table 5. Mean percent normal pollen per plant of each lihe^ On clusters 2  1 and 2.  Lines (% normal pollen) Cluster  BB  1  85.6  2  87.4  BB X IPB W  IPB  IPB X BB  FB  83.3  77.9  73.4  84.4  86.8  77.8  81.1  87.1  Mean of 10 plants in all lines except BB (8 plants).  2  •^Line indicates 3 cultivars and 2 F] reciprocal x  hybrids.  Each cluster analyzed separately.  w  The SNK test was not carried out after the analysis of variance showed no significance^ l% level. N  32  Table 6. Analyses of variance of the mean numbers of total, smooth and rough fruit per plant of each l i n e  2  on clusters^ 1 and 2.  Mean Squares Cluster 1 Source  Cluster 2  Df  Total  Smooth  Rough  Total  Smooth  Rough  Rep (R)  4  0.125  2.178**  1.917  0.632  0.295  0.839  Lines (V)  4  17.870** 3.167  14.128**  9.729** 2.220** 10.228-  R XV  16  0.406  1.518**  1.633**  0.811  0.464  0.846  Error  23  0.283  0.435  0.500  1.022 • 0.587  1.565  Total  47  z  Line indicates 3 cultivars and 2 F-j reciprocal  •^Each cluster analyzed separately. ** Significant, 1% 1evel.  hybrids.  33  Table 7. Mean number of total, smooth and rough fruit per plant of 2  each line^on clusters* 1 and 2 •  Total fruit number Line  Cluster  1  Smooth fruit number  2  1  2  Rough fruit number .1  2  BB  0.5c  W  2.0b  0.0  0.5ab  0.5b  1.5b  BB X IPB  3.5ab  3.7a  1.2  1.2a  2.3ab  2.5b  IPB  4.0a  4.0a  0.0  0.0b  4.0a  4.0a  IPB X BB  3.9a  4.0a  1.1  l.Oab  2.8a  3.0ab  FB  2.7b  2.1b  0.5  0.5ab  2.2ab  1.6b  Mean of 10 plants in a l l lines except BB (8 plants).  z  •^3 cultivars and 2 F-j reciprocal x  hybrids.  Each cluster analyzed separately.  Mean separation within columns by SNK test, 1% level.  w  Absence of a  letter shows the test was not carried out after the analysis of variance showed no significance,,1% level.  34  between BB and each of IPB and IPB X BB were significant on the f i r s t cluster (Table 7).  The differences between IPB and every other line  but IPB X BB were significant in cluster 2. One hundred percent of the IPB fruits were rough on both clusters. BB produced 100% rough fruit on cluster 1 but 25% less rough fruit on cluster 2.  With IPB as the maternal parent, the F-j hybrid with BB had  71.8% and 75.0% rough fruit respectively on the 2 clusters.  The reciprocal  hybrid gave about 65.7% rough fruit on cluster 1 and about 1.9$. more on cluster 2.  FB produced about 81.5% rough fruit on the f i r s t cluster  and 76.2% on the second cluster.  Greenhouse Experiments. Experiment la Number O f Flowers.  The number of flowers produced differed sig-  nificantly among cultivars (Table 8).  IPB and BB produced the most  flowers and the difference between them was significant (Table 9),  The  differences between each of these 2 cultivars and the other cultivars were also significant.  However, the differences ! among  the number of  flowers produced by CS, ERC, FB and VR were not significant. Neither the age at which the plants were chilled nor the duration of the chilling treatment had any significant effects on the number of flowers produced (Table 8).  Cluster 1 produced more flowers than cluster  2 but the difference was not significant.  Also, there were no significant  interactions = among., a'lany>tofin the main effects. Total Number of Fruit.  Considering total fruit number, the cultivars  Table 8. Analyses of variance of the numbers of flowers, total, smooth, moderately rough and rough fruits per plant.  Mean squares  Source Replications Age (A) Cultivars (C) Treatments (T) A X C A XT C XT A X C XT Error (A) Clusters (P) P XA P XC P XT P XA X C P X A XT P X C XT P X A X C XT Error  3 3 5 2 15 6 10 30 213 1 3 5 2 15 6 10 30 216  Total •  575  Flowers  Total fruit  3.590 5.682 116.160** 0.866 3.884 1.922 3.637 2.157 3.402 10.293 0.354 6.239 1.616 1.560 1.440 2.450 2.910 2.958  9.557 2.997 209.390** 2.314 2.380 4.428 4.062 3.542 3.291 77.293** 17.650** 17.685** 0.283 4.097 1.938 2.206 3.483 2.433  *Significant,  5% level  **Significant,  : 1% level  Smooth fruit 7.150 9.243 244.970** 0.470 2.976 5.748 4,268 4.596 4.781 26.694** 11.745** 13.336** 0.137 3.587 1 .632 2.473 3.068 2.332  Moderately rough fruit 2.447 0.271 3.794* 0.825 1.264 0.929 0.625 0.768 1 .267 4.340* 1.419 0.919 0.116 1.604** 0.619 0.458 0.59.9 0.682  Rough fruit 0.928 1.660 4.261** 0.049 1.069 0.674 0.184 0.790 0.797 2.778** 0.199 0.490 0.028 0.445 0.463 0.234 0.311 0.264  36  Table 9. Mean number of flowers per plant of each cultivar. 2  Cultivar  Number of flowers  BB  8.35M  v^CS  6.98c  ESC. ERC-.F1  FB  IPB  VR  6.64c  7.28c  9.40a  6.68c  Mean of clusters 1 and 2. .  2  Mean separation within row by SNK test, ~\% level.  y  37  could be separated into 3 significantly different groups (Table 10). BB and'IPB gave the highest yields and the poorest were obtained from ERC and VR.  Fruit yields of CS and FB were intermediate between the  previous groups and the differences within groups were not significant. Mean fruit number on cluster 1 was significantly greater than on cluster 2, but mainly in IPB and VR (Tables 8 and 10).  Although the age  at which the plants were chilled did not significantly influence fruit number, there was a significant interaction between age and cluster (Table 8).  The differences between the 2 clusters of plants chilled at  5.5 and 6.5 weeks of age were significant (Table 11). Duration of exposure to cold temperature did not significantly affect yield and there were no interactions between treatment duration and the other main effects (Table 8). Number of Smooth Fruit.  There were significant differences in the  number of smooth fruit among cultivars (Table 8).  IPB and BB respectively  had the highest and the second highest mean numbers of smooth fruit per cultivar, and the,difference between them was significant (Table 12). The lowest numbers of smooth fruit were obtained from ERC and VR but the difference between them was not significant. The mean number of smooth fruit was greater on cluster 1 than on cluster 2, and the difference was significant (Table 12).  There was a  significant cultivar X cluster interaction but only the differences between the clusters on IPB and VR were significant (Tables 8 and 12). Age at treatment initiation did not affect numbers' of smooth fruit but an age X cluster interaction resulted in significant differences between clusters on plants chilled at 5.5 and 6.5 weeks of age (Tables 8 and 13).  38  Table 10. Mean total number of fruit!' per plant of each cultivar on clusters 1 and 2.  Cultivar Cluster  BB  CS  ERC  FB  IPB  VR  1  6.31abu  3.81cd  3.08de  3.85cd  7.10a  3.85cd  4.67a*  2  5.62b  3.75cd  2.44e  4.27c  5.38b  2.17e  3.94b  5.9?al  3.78b  2.76c  4.06b  6.24a  3.01c  Cultivar mean  Mean separation within and between columns by SNK test, 1% level.  z  •^Mean separation within row by SNK test, Mo level. Mean separation within column by SNK test, 1% level.  x  CIuster .mean  39  T a b l e l l . Mean total number of f r u i t ' per plant per treatment age  z  on clusters 1 and 2.  Treatment age (weeks) Cluster  z  3.5  1  4.43bc  2  4.11bc  5.5  6.5  Cluster mean  4.24bc  4.75ab  5.26a  4.67a  4.25bc  3.62c  3.76c  3.94b  4.5 y  Age (from seeding) at which chilling treatment was initiated.  Mean separation within and between columns by SNK test, 1% level.  y  Mean separation within column by SNK test, 1% level.  x  x  40  Table 12. Mean number of smooth fruit per plant of each cultivar on clusters 1 and 2.  Cultivars Cluster  BB  CS  ERC  IPB  FB  VR  CIuster mean  1  4.67 b' ' 2.56cd  1 .35e  6.02a  2.73cd  2.31d  3.27a <  2  4.23b  2.60cd  1 .04e  4.71b  3.38c  1.10e  2.84b  Cultivar mean  4.45b  2.58c  1 .20d  5.36a  3.05c  1.71d  2  y  x  Mean separation within and between columns by SNK test, \% level.  z  Mean separation within row by SNK test, 1% level.  y  Mean separation within column by SNK test, 1% level.  x  41  Table 13. Mean number of smooth fruit/ per plant per treatment age on clusters 1 and 2.  Treatment age (weeks) Cluster  z  3.5  1  3.21 ab  2  3.08ab  4.5 y  5.5  6.5  Cluster mean  2.92bc  3,18ab  3.79a  3.27a :  3.14ab  2.28c  2.88bc  2.84b  x  Age (from seeding) at which chilling treatment was initiated.  Mean separation within and between columns by SNK test, 1% level.  y  Mean separation within column by SNK test, 1% level.  x  2  42  Number of Moderately Rough Fruit.  The analysis of variance  showed no dependence of moderately rough fruit production on any of the main effects, namely, cultivar, cluster, age at chilling and duration of the chilling treatment (Table 8).  There was, however, a  significant third order interaction effect among cultivar, cluster, and age at chilling (Table 14). Number of Rough Fruit.  Rough fruit number indicated significant  differences among cultivars and between clusters (Table 8).  Cluster 1  had more rough fruit than cluster 2 (Table 15). BB had the most rough fruit and the differences between that cultivar and ERC and VR were not significant (Table 16).  The smallest  number of rough fruit was given by CS but only the differences with BB and VR were significant., The analysis of variance (Table 8) showed that the chilling treatments did not result in any significant differences in the numbers of rough fruit on the several cultivars. Flower Morphology and Fruit Shape.  It was intended to test the  relationship between flower appearance and subsequent fruit shape, but the proportions of flowers in the semi-normal and abnormal groups were 2 comparatively too low to warrant using the X  test.  The relationship between normal flowers and subsequent smooth fruit yield may be considered to be quite high by inspection of the data (Table 17), whereas that between abnormal flowers and rough fruit production is fair.  43  Table 14. Mean number of moderately rough fruit.vper plant of each cultivar per treatment age on clusters 1 and 2. z  Cultivar Age (weeks)  Cluster  3.5  1  0.417ab 1.667a  2 4.5  5.5  6.5  Cultivar means  z  BB  CS  ERC  FB  IPB  VR  1.417ab  0.583ab 1.167ab 0.500ab  0.917ab  0.750ab 1.250ab  0.917ab 0.250ab 0.833ab  1  1.167ab  0.500ab 1.250ab  1.333ab 0.250ab 1.083ab  2  1.167ab  1.OOOab 1.333ab  0.833ab 0.500ab 0.750ab  1  1.167ab  1.083ab 1.250ab  1.167ab 0.750ab 0.833ab  2  1.250ab  1.250ab 0.667ab  1.OOOab 0.833ab 0.667ab  1  0.750ab  1.083ab 1.750a  1.OOOab 0.917ab 1.417ab  2  0.583ab  1.333ab 0.917ab  0.417ab 0.833ab 0.083b  0.927  1.083  0.906  y  x  1.229  0.688  0.771  Age (from seeding) at which chilling treatment was initiated.  Mean separation within and between columns by SNK test, 1% level.  y  SNK test was not carried out after the analysis of variance showed  X  no significance , 1% level.  44  Table 15. Mean number of rough fruit per plant on clusters 1 and 2.  Cluster  Number of rough fruit  1  0.385a  2  0.246b  z  Mean separation within column by SNK test, 1% level  z  Table 16. Mean number of rough fruit  Culti var Number of rough fruit  CS  BB 0.594a  z  0.115c  -  ERC 0.333abc  .". -per plant of each cultivar.  FB 0.125c  Mean separation within row by SNK test, 1% level.  z  IPB 0.188bc  VR 0.542ab  45  Table 17. Numbers of normal , semi-normal and abnormal* flowers and 2  y  the subsequent smooth, moderately rough and rough fruits observed.  Number %  „°Ik^ number  tal  Normal flower  Smooth fruit  Semi-normal flower  Moderately rough fruit  Abnormal Rough flower fruit  196.00  180.00  39.00  65.00  28.00  8.00  74.52  68.44  14.83  24.71  10.65  6.84  Normal flower expected to yield smooth fruit.  z  ^Semi-normal flower expected to yield moderately rough fruit. Abnormal flower expected to yield rough fruit.  x  46  Experiment lb Flower Initiation.  Differences between the days from seeding to.  the appearance of the f i r s t and second inflorescences and also d i f f e r - , ences among cultivars were shown to be significant (Tables 18 and 19). IPB was the earliest and ERC and VR were the latest to show floral buds.  The differences between v .  were significant (Table 19). significant.  IPB and each of the latter cultivars  The difference between CS and VR was also  The difference between ERC and VR and the difference$,among  BB, CS and FB were not significant.  There was an indication at the 5%  level that the cultivar X cluster interaction had an effect on the period required for flower bud appearance (Table 18).  Experiment 2 Flower Initiation.  There were significant differences among c u l t i -  vars for the period required from seeding to appearance of the f i r s t floral buds (Table 20).  Means in Table 21 show FB and CS were the  earliest but the difference between them was not significant.  IPB was  significantly later than FB and CS and in turn VR was significantly later than IPB.  Also there were significant differences in the cultivar X  cluster interaction effects (Tables 20 and 21). Earliness or lateness of flower bud appearance was significantly affected by the age at chilling (Table 22).  Chilling (treatment) at 3  and 4 weeks from seeding significantly delayed floral bud appearance compared to the control and treatment at 5 and 6 weeks of age.  Some,  treatment X cultivar interaction effects were shown to be significant (Tables 20 and 22).  The cluster X treatment X cultivar interaction effects  47  Table 18. Analysis of variance of mean numbers of days from seeding 2  to appearance of f i r s t flower buds on clusters 1 and 2 of each cultivar.  Source  Df  Mean square  Replication  2  0.0625  Cultivars  5  46.2125**  10  3.3375*  Clusters (P)  1  925.1736**  P X C  5  4.3569*  Error  12  0.9309  Total  35  (C)  Error (c)  Mean of 2 plants per cultivar per replication * Significant, '5% level. ** Significant,. 1% level. 2  48  Table 19. Mean number of days from seeding to appearance of f i r s t flower buds on clusters 1 and 2 of each cultivar.  Cultivar (days) CIuster  BB  1  30.2  2  39.8  Cultivar means  CS  Z  35.0bc  y  ERC  FB  IPB  VR  CIuster means  29.5  33.5  29.8  27.2  32.7  30.5 b*  37.7  46.2  38.3  38.3  43.3  40.6a  35.6c  39.8a  34.1bc  32.8c  38.0ab  Absence of a letter shows the SNK test was not carried out -after the  z  analysis of variance showed no significance, 1% level. Mean separation within row by SNK test, 1% level.  y  Mean separation within column by SNK test, 1% level.  x  49  Table 20. Analyses of variance for mean numbers of days from seeding to appearance of f i r s t flower buds, and for f i r s t fruit set and days from f i r s t flower bud appearance to f i r s t fruit set on clusters 1 to 4.  Mean squares First flower bud appearance to f i r s t fruit set  First flower bud appearance  First fruit set  3  2356.80**  1210.70*  263.18  4  416.48**  659.22  1012.40**  C XT  12  68.85  435.69  130.06  Pl/C X T  59  38.27**  371.19  115.46  Cluster (P)  3  8973.60**  2500.10**  1352.90**  P XC  9  352.60**  1281.70**  434.48**  P XT  12  54.94**  442.89  198.37*  P X C XT  36  16.56**  439.83*  107.22  286.20  97.22  Source Cultivar  Df (C)  Treatment (T)  Error  177  Total  315  z  Plants  * ~ 5%level Significant, ** Significant*. •1% level  8.81  50  Table 21. Mean number of days from seeding to appearance of f i r s t flower buds on clusters 1 to 4 per plant of each cultivar.  Cultivar Cluster  CS  FB  IPB  VR  Cluster means  28.8h  27.6h  33.2g  29.8d  1  29.4h  2  38.3c  35.2g  41. If  44.6e  39.8c  3  43.0ef  41.2f  51.8d  53.4d  47.4b  4  45.8e  45. Oe  61.4b  65.8a  54.6a  Cultivar means  39.1c  37.6c  45.5b  49.2a  z  y  Mean separation within and between columns by SNK test, 1% level.  z  Mean separation within row by SNK test, 1% level.  y  Mean separation within column by SNK test, 1% level.  x  x  51  Table 22. Mean number of days from seeding to appearance of f i r s t flower buds on clusters 1 to 4 per plant at each treatment  2  Cluster Treatment (weeks)  1  3  35.4e  4  2  3  4  Treatment means  43.6d  50.1c  55.2a  46.1a  29.If  44.5d  50.8bc  56.5a  45.2a  5  27.5f  36.2e  46.9d  54.7a  41.3b  6  28.7f  37.5e  44.6d  53.2ab  41 .Ob  Control  27.9f  37. Oe  44.3d  53.5ab  40.7b  Cluster means  29.8d  39.8c  47.4b  54.6a  y  x  Age (from seeding) at which chilling treatment was initiated.  2  Mean separation within and between columns by SNK test, 1% level.  y  Mean separation within row by SNK test, 1% level,  x  Mean separation within column by SNK test, 1% level.  w  w  52  were also significant. Fruit Set.  Differences between the number of days from seeding to  f i r s t fruit set on the f i r s t 4 clusters were significant (Table 23). However, only the differences between the f i r s t cluster and each of clusters 3 and 4 were shown to be significant. There was an indication (5% level) that earliness or lateness of f i r s t fruit set depended on the cultivar (Table 20).  However, cultivar X  cluster interaction effects were shown to be significant (Table 23). The number of days from seeding to f i r s t fruit set was unaffected by chilling at any age (Table 20). Mean Number of Days from First Flower Bud Appearance to First Fruit Set.  The effect of chilling at.the different ages on the number of  days required between f i r s t floral bud appearance and f i r s t fruit set was significant (Table 20).  Chilling at 5 and 6 weeks, in contrast to the  control and treatment at 3 and 4 weeks, significantly delayed fruit set (Table 24). The time required for the f i r s t fruit to'set after f i r s t floral bud appearance showed significance among clusters (Table 20).  The period  for the f i r s t cluster was significantly greater than for clusters 2, 3 and 4 and the differences among the latter 3 clusters were not significant (Table 24).  There was an indication at the 5% significance level of  treatment X cluster interaction effects on the number of days required to set the f i r s t fruit after f i r s t floral bud appearance (Table 20). This period was not affected by cultivar but there was a significant cultivar X cluster interaction effect (Tables 20 and 25). Total Number of Fruit.  The total numbers of fruit per plant showed  53  Table 23. Mean number of days from seeding to f i r s t fruit set on clusters 1 to 4 per plant of each cultivar.  Cultivar Cluster  CS  IPB  58.2b  66. 9ab  64.2ab  61.0b  63.9ab  59.4b  70. 6ab  69.0ab  65.8ab  69.8ab  69.8ab  72. 6ab  81.2a  73.4a  74.2ab  73.8ab  84. 5a  53.6b  71.5a  65.6  65.3  73. 6  67.0  54.5b  Cultivar  y  Z  VR  Cluster means  FB  x  Mean separation within and between columns by SNK test, 1% level.  z  ^Absence of a letter in row shows the SNK test was not carried out after the analysis of variance showed no significance, 1% level. Mean separation within column by SNK test, 1% level.  x  54  Table 24. Mean number of days from f i r s t flower bud appearance to f i r s t fruit set on clusters 1 to 4 per plant at each chilling treatment  2  Cultivar Treatment (weeks)  i " ^  z  3  4  Treatment means  22.9  21.6  23.7  23.8b  2  3  27.1  4  36.1  23.2  21.4  21.1  25.4b  5  40.9  34.1  30.5  22.6  32.0a  6  33.1  34.6  33.4  27.6  32.2a  29.8  23.3  26.3  22.6  25.5b  27.7b  26.6b  23.5b  Control C  1  6  r  Y  33.4a  x  W  Age (from seeding) at which chilling treatment was initiated.  ^Absence of a letter shows the SNK test was not carried out after the analysis of variance showed no significance, 1% level. Mean separation within row by SNK test, 1% level.  x  Mean separation within column by SNK test, 1% level.  w  55  Table 25. Mean number of days from f i r s t flower bud appearance to f i r s t fruit set on clusters 1 to 4 per plant of each cultivar.  Cultivar Cluster  CS  FB  IPB  VR  Cluster means  30.7c  40.7a  32.6c  33.4a  1  29.6c  2  27.5c  27.5c  29.4c  26.2c  27.7b  3  26.8c  28.6c  23.4c  27.8c  26.6b  4  28.4c  28.8c  23.1c  14.1b  23.5b  Cultivar means  28.1  28.9  29.2  25.2  y  z  x  Mean separation within and between columns by SNK test, 1% level.  z  ^Absence of a letter in row shows the test was not carried out after the analysis of variance showed no significance, 1% level. Mean separation within column by SNK test, 1% level.  x  56  significant differences among cultivars (Table 26).  IPB had the most  fruit and the differences with the other cultivars, CS, FB and VR, were significant (Table 27).  However, none of the differences  among \  the later 3 cultivars was significant. There were indications at the 5% significance level of cluster differences and cluster X cultivar interaction effects on total fruit number (Table 26).  Chilling the plants at the various ages did not sig-  nificantly affect fruit number but there was an indication (5% level) of cluster X cultivar within treatment interaction effect (Table 26). Numbers of Smooth Fruit.  The numbers of smooth fruit per plant  showed significant differences'among cultivars and among clusters (Table 26).  IPB produced the most smooth fruit and the differences between IPB  and the other cultivars, CS, FB and VR, were significant (Table 28).  The  differences J.amongV the latter 3 cultivars were not significant. The second cluster yielded significantly more smooth fruit than the other 3 clusters (Table 28).  The differences among the f i r s t ,  and fourth clusters were not significant.  third  The ciiltivar X cluster inter-  action effects showed significance (Tables 26 and 28), and smooth fruit number was not affected by the chilling treatments (Table 26). Number;- of Moderately Rough Fruit.  The number of moderately rough  fruit significantly depended on the cultivar (Table 26).  The greatest  number was produced by IPB and i t was significantly different from the yields of CS, FB and VR (Table 29). cultivars were not significant.  The differences among the latter 3  Although the differences among clusters  did not show any significance, the cultivar X cluster interaction effects were significant.  Chilling the plants did not significantly affect  57  Table 26. Analysis of variance of numbers of total smooth, moderately rough and rough fruit per plant.  Mean squares Total fruit  Smooth fruit  Moderately rough fruit  3  157. 69**  76..48**  14,.62**  4  4. 07  4..65  1,.42  0..169  C XT  12  4. 57  5..30  1,.20  0..162  Plants/C X T  59  2, 83  2..84  1 . 24**  0..145  Cluster (P)  3  10. 69*  19. 94**  1,.34  0..079  P XC  9  5. 45*  11..65**  2,.78**  0..096  P XT  12  4. 67  4,,54*  1 .53* ,  0..274*  P X C XT  36  4. 24*  2..84  1,.02  0..187  2. 76  2..14  0,.74  0..134  Source Cultivar  Df (C)  Treatment (T)  Error  177  Total  315  *Significant,  5% level.  **Significant,  1% level.  Rough fruit 0..403*  58  Table 27. Mean total number of fruit per plant of each cultivar on clusters 1 to 4.  Cultivar Cluster  CS  1  2.42  2  FB  IPB  Cluster Means  VR  2.75  5.25  3.10  3.39  3.16  2.45  6.40  3.40  3.86  3  2.84  2.50  5.75  2.30  3.35  4  2.95  2.70  4.55  1.65  2.96  2.60b  5.49a  2.61b  Cultivar Mean.  z  2.84b  x  y  '^Absence of a letter shows the SNK test was not carried out after the analysis of variance showed no significance, y/ level. 0  Mean separation within row by SNK t e s t ,  1% level.  59  Table 28. Mean number of smooth fruit per plant of each cultivar on clusters 1 to 4.  Cultivar Cluster  CS  1  1.84d  2  FB  IPB  Cluster means  VR  2.25cd  3.95bc  2.25cd  2.58b  2.74cd  2.15d  5.85a  2.65cd  3.35a  3  2.53cd  2.40cd  4.40b  1.55d  2.72b  4  2.63cd  2.45cd  2.30cd  1.20d  2.14b  2.43b  2.31b  4.12a  1.91b  z  y  Mean separation within and between columns by SNK test, 1% level.  z  Mean separation within row by SNK test, 1% level.  y  f  Mean separation within column by SNK test, 1% level.  x  60  Table 29. Mean number of moderately rough fruit per plant of each cultivar on clusters 1 to 4.  Cultivar Cluster  CS  FB  VR  Cluster means  0. 579bc  0. 450bc  1.05bc  0. 750bc  0.,709*  0. 368bc  0. 300bc  0.50bc  0. 550bc  0. 430  0. 158c  0. 100c  1.25b  0. 550bc  0. 519  0. 210bc  0. 200bc  2.00a  0. 250bc  0. 671  0. 329b  0. 262b  1.20a  0. 525b  Z  Cultivar means  IPB  y  Mean separation within and between columns by SNK test, 1% level. Mean separation within row by SNK test, 1% level. Absence of a letter i n ; : column shows the test was not carried out after the analysis of variance showed no significance, 1% level.  61  moderately rough fruit number. Number of Rough Fruit.  Number of rough fruit was not significantly  dependent on cultivar, although there was an indication of a possible cultivar effect at the 5% level of significance (Tables 26 and 30).  Also  there was an indication of the possibility of cluster X treatment interaction effects at the 5% level of significance (Tables 26 and 31).  The  differences among clusters and among the chilling treatments were not significant (Table 26). '.  4  •' :'  vAtt  the same time that Experiment 2  was underway, some VR plants which were grown in another house and were expected to produce good quality fruits, produced a high proportion of rough f r u i t . Flower Morphology and Fruit Shape.  It was intended to test the  relationship between flower appearance and subsequent fruit shape (Table 32); however, the proportions of flowers in the semi-normal and abnormal 2 groups were comparatively too low to warrant a X test. inspection of the data showed ".relatively  Nevertheless,  high relationships between  normal flowers and smooth f r u i t and abnormal flowers and rough fruit (Table 32).  There was no:apparent relationship between semi-normal flowers  and moderately rough f r u i t . Experiment 3 The cool temperature regime did not have any marked effect on the production of rough fruit (Table 35). There was a significant difference between the total fruit numbers of the 2 cultivars in the warm regime and an indication of significance  62  Table 30. Mean number of rough fruit per plant of each cultivar.  Cultivar  z  Number of rough fruit  CS  0.079  FB  0.025  IPB  0.163  VR  0.175  2  The SNK test was not carried out after the analysis of variance showed no significance.,  _  < V/o level.  63  Table 31. Mean number of rough fruit per plant of each treatment  2  group on clusters 1 to 4.  Treatment (weeks) Cluster Cluster  3  4  5  6  Control  1  0. 312  0. 062  0. 062  0. 000  0. 067  0. 101  2  0. 312  0. 062  0. 000  0. 000  0. 000  0. 076  3  0. 062  0. 000  0. 250  0. 250  0. 000  0. 114  4  0. 000  0. 250  0. 250  0. 188  0. 067  0. 152  0. 094  0. 141  0. 109  0. 033  Treatment Means  0. 172  y  X  M e a n s  w  z  Age (from seed ing) at which chilling treatment was initiated  y  ' ' S N K tests werei not carried out after • the analyses of var iance showed x  w  no significance,'  1% level.  64  Table 32. Numbers of normal , semi-normal and abnormal f!owers and 2  y  x  the subsequent smooth, moderately rough and rough fruits observed.  Number %  nSmbe?  t a l  Normal flower  Smooth Semi-normal fruit flower  1005.00  854.00  9  5  -  2  6  8  0  -  9  5  16.00 1  >  5  2  Moderately rough fruit  Abnormal Rough flower fruit  175.00 1  6  -  5  9  34.00 3  '  2  2  Normal flower expected to yield smooth fruit.  z  y  Semi-normal flower expected to yield moderately rough f r u i t . Abnormal flower expected to yield rough fruit.  x  26.00 2  A  6  65  at the-5% level between the same cultivars grown under the cool regime (Tables 33 and 34).  The IPB plants had more fruit than VR, and there  were more.fruit on both cultivars in the cool than in the warm regime (Tables 34 and 35). The numbers of smooth fruit paralleled the results for numbers of total fruit for both cultivars in the 2 regimes (Tables 34 and 35).  The  numbers of moderately rough fruit showed no significant difference between cultivars (Table 33).  By inspection i t can be seen that there  were more moderately rough fruit in the cool regime (Table 35) than in the warm (Table 34) and also that IPB had less moderately rough fruit in the warm regime, but more such fruit in the cool regime than VR.• There was no rough fruit on the plants in the warm regime (Table 34); however, under cool conditions, the difference in the number of rough fruit between cultivars is reflected in a mean square which indicates a significant difference (Table 33). fruit whereas VR had none (Table 35).  IPB had a small number of rough  Table 33. Analyses of variance of the mean total, smooth, moderately rough and rough fruit numbers per plant on clusters 1 to 4.  Mean Squares Warm temperature regime^'* Source Cultivar  Df (C)  1  Total fruit  Smooth fruit  16.53**  21.12**  Moderately rough fruit  2  Cool temperature regime Total fruit  0.281  50.00*  Smooth fruit  Moderately rough fruit  Rough fruit  7.03*  6.12  3.78*  Plants/C  6  0.74  0.96  0.156  6.50  0.61  2.06  0.62  Cluster (P)  3  11.86*  8.12  0.365  19.75  18.28*  0.75  0.36  P XC  3  1.62  1.46  0.281  3.58  8.61  1.04  0.36  Error  18  2.74  2.62  0.240  5.17  5.36  0.98  0.53  Total z  y  31  Data for warm and cold temperature regimes analyzed separately.  No rough fruit produced.  Warm temperature regime: day high of 24° ± 1°C and night low 19 ± 1 C.  x  Cool temperature regime with a diurnal cycle from 5° ± 1°C to 21° ± 1°C, *Significant, 5% level. **Significant, \1% level. w  67  Table 34. Mean numbers of total, smooth and moderately rough fruit per plant of each cultivar on clusters 1 to 4 (warm temperature regime)  2  Total fruit Cluster  IPB  VR  CIuster mean  IPB  1  2.50*  2.25  3.38  2.50  2  4.50  2.25  3.38  3  1.25  0.00  4  2.25  0.25  Cultivar means  z  0 2  a n  '  s ,  6 2 a  1  VR  Cluster mean  1.75  2.12  4.25  1.50  2.88  0.62  1.25  0.00  1.25  2.00  0.25  x  ,  1 n J  9  Moderately rough fruit  Smooth fruit  w  IPB  0.500  0.250*  0.250  0.750  0.500  0.62  0.000  0.000  0.000  1.12  0.250  0.000  0.125  0.000  V  2,50a' 0.88b  b  CI uster mean  VR  0.125  u  0.313  q  Day high of 24° ± 1°C and night low of 19° ± 1°C.  y,x,w,v,u,t,q  A b s e n c e  Q  f  Q  1  e  t  t  e  r  s h o w s  t  n  e  S  N  K  t  e  s  t  s  w  e  r  e  n  Q  t  c  a  r  r  i  e  d  out after the analysis of variance showed no significance, 1% level. s  ' Mean separation within rows by SNK test, 1% level. r  Table 35. Mean total, smooth, moderately rough and rough fruit per plant of each cultivar on clusters 1 to 4 (cool temperature regime)  Total fruit  Smooth fruit  VR  Cluster mean  IPB  4.50  6.62  6.75  6.75  4.25  5.50  3  5.50  4.50  4  4.00  1.75  Cultivar means  6.25  Cluster  IPB  1  8.75  2  z  y  q  2  VR  Cluster mean  3.00  4.88  4.75  3.50  4.12  5.00  3.50  4.00  2.88  1.00  1.75  x  3.75  W  4.00  P  3.06  Moderately rough fruit  Rough frui t VR  Cluster mean  0.00  0.25  0.25  0.00  0.12  0.88  0.75  0.00  0.38  0.88  1.25  0.00  0.62  VR  Cluster mean  IPB  1 .50  1.50*"  0.50  1 .75  0.75  1.25  3.75  1.25  0.50  1.38  1.75  0.00  v  IPB 1.50  1.56  u  m  0.69  0.69  s  n  r  0.00  Diurnal cycle from 5° ± 1°C to 21° ± 1°C.  ^""Absence of a letter shows the SNK tests were not carried out after the analysis of variance showed no significance, 1% level.  oo  69  DISCUSSION  When the number of rough fruits is compared with the total number and the number of smooth fruits produced in the field experiment (Table 7), i t is seen that rough fruit production was quite substantial. These results are typical of the horticultural problem of deformed fruit in the tomato crop. The data from the field experiment showed significant differences among  different genotypes (Tables 6 and 7).  the most and BB the least numbers of rough f r u i t .  IPB had  The data for their  2 reciprocal F-j hybrids were intermediate between the parental values. Rough fruit number produced by BB and FB were similar in both clusters whereas the difference between FB and IPB was shown to be significant in cluster 2 only.  The failure of the latter 2 lines to show significance  in cluster 1 could be due to the relatively large variation in rough fruit number which resulted in a relatively large calculated mean square of 14.128 (Table 6).  Thus,a relatively large difference was required for  the 2 lines to be declared significantly different in cluster 1, Accounts of tomato fruit malformations (other than the type investigated in this study) given by workers such as Ekstrand  (10) and  Salvioli and Martin (34) have indicated that these fruit abnormalities are inherited.  To the casual observer, the results on rough fruit pro-  duction obtained in the field experiment (Table 7) would indicate that, i f indeed the character for the production of this type of misshapen fruit has a genetic base, it is partially dominant.  This would then  suggest that the gene or gene complex responsible for the expression of  70  this character is different from that which causes, for example, "catfaced" fruit.  The gene, af1, which is responsible for the latter  tomato fruit disorder has been described as recessive by Salvioli and Martin (34). Inspection of the data for the 2 reciprocal F-j hybrids (IPB X BB and BB X IPB) and their parents, indicated a possibility of the influence of maternal effects on the character in thecluster 2 data (Table 7).  This  should not be surprising since the fruit develops from the ovary, which is a maternal organ. In the partially-controlled environment experiments (Expt, l a , 2 and 3), differences in the number of rough fruit produced by the different genotypes were observed (Tables 16, 30 and 35).  Some of these  differences were significant at the 1% level (Tables 8 and 16) whereas others only approached significance, above 1% but lower than the 5% level (Tables 26 and 33). to be horticulturally  However, these differences cannot be considered  important when the rough fruit numbers are compared  with the total fruit numbers and the numbers of marketable (smooth and moderately rough) fruit (Tables 10, 12, 14, 27, 28, 29 and 35). Although the type of fruit malformation studied is different from others reported by several workers, i t is possible that similar external factors which influence the production of, for example, "catfaced" or "puffy" f r u i t s , could be responsible for rough fruit.  The plants for  the f i e l d experiment were set out in the middle of May, a time when temperatures were relatively low.  Such low temperatures have been reported  to cause other fruit malformations by Kaname and Itagi (20), Knavel and Mohr (21), Saito and Ito (33), Salvioli and Martin (34), and others.  71  Therefore, i t is .'.  X . ) l i k e l y that relatively low temperatures during  the hardening and post-transplanting periods could have contributed to rough fruit production in the f i e l d .  The results of the controlled  experiments (Tables 8 , 26 and 330, however, did not confirm this assumption  nor  "  the reports of Shoemaker (35) and Stoner (37) that  relatively low temperatures caused rough fruit. The relatively cool temperatures and periods of exposure employed in the controlled experiments were similar to those used by Kaname and Itagi (20) to produce abnormally-shaped fruit.  Therefore, the practi-  cally negative results obtained in this study probably indicate that,  if  indeed relatively cool temperatures are responsible for rough fruit production, the low temperature requirements for this type of fruit disorder are different from those reported by Kaname and Itagi (20), Knavel and Mohr (21) and others for other fruit abnormalities.  The temperatures  ( 4 . 4 - ; ? - T ' 2 ; . 8 ; P c ) employed in the growth chambers were possibly either not low enough or the plants were not exposed long enough (3 to 14 days in Experiments la and 2) to the chilling temperatures.  It is also possible  that the temperature sensitive period (6, 1 1 , 22 and 48) was missed because the chilling treatments were initiated 26, 22 and 35 days from seeding respectively in Experiments l a , 2 and 3. There is the possibility that the temperature effect (if any) on rough fruit production is not so much a matter of how low the temperature is but how sharply i t fluctuates.  Ricada and Honnorat (28) have suggested  that sharp changes in temperature which caused periodic checks in growth were the probable cause of some tomato fruit malformations in Morocco. It is  .": "likely for such sharp temperature variations to occur during  72  spring and early summer as a result of windy conditions and variable sunny and cloudy periods.  Therefore, i t is possible that sharp  temperature fluctuations were responsible for the rough fruit produced in the field (Tables 6 and 7).  .Plants used in the controlled  experiments la and 2 gave no indication of low temperature effect on rough fruit production (Tables 8 and 26), probably because the temperatures employed were varied gradually between the high and low levels. The cool temperature regime in Experiment 3 was intended to simulate sharp temperature fluctuations comparable to those experienced in the field but the results were not like those in the field (Tables B,' 7_, 33 and 35).  The chilling treatments were probably either applied too late  (35 days after seeding) and/or the temperature fluctuations were not sharp enough.  It is even possible that the condition of the plant prior  to exposure to chilling and/or fluctuating temperatures might be the critical factor because some plants which were less vigorous than those used in the controlled environment Experiment 2 but were used as f i l l e r plants during the treatment period, produced more rough fruit than the plants used in the experiment. The results obtained in the controlled environment studies obviously indicate that production of rough fruit by tomato plants is not simply a result of exposure to low temperature as reported by Shoemaker (35) and Stoner (37).  It is likely that the rough fruit condition is caused by  an interaction of low temperatures with other factors such as sunlight, humidity and nutrient and water supply, as suggested by Kaname and Itagi (20), Ricada and Honnorat (28) and Wedding and Vines (45) for the other tomato fruit shape abnormalities.  The factors could interact in  73  the following manner to produce rough fruit.  Relatively cool temper-  atures are expected to reduce vegetative growth, increase flower numbers, and produce fasciated flowers (18, 33, 48 and 49).  The  reduction in vegetative growth results in a reduced net production of photosynthates.  Flower numbers are also increased with increased  nutrient supply (47).  Thus, i f water is not limiting, under relatively  cool temperature conditions and abundant nutrient supply, a lot of flowers are produced.  Subsequently there would be mass fruit set (14,  18, 27, 41, 42, and 43) using the relatively limited plant reserves. According to Tokarev (40) under conditions of mass fruit production, the plant reduces the rate of fruit development.  Therefore, on the basis  of the ontogeny,of the ovary given by Hayward (15), this could cause differential rates of growth of the different sections of the ovary resulting in non-symmetrical fruits which are largely crinkled at the stem-end and severely grooved.  Photoperiod or light intensity might  affect the availability of photosynthates to the developing fruits and thereby contribute to the development of rough f r u i t .  Sharp temperature  fluctuations might also influence rough fruit production by checking growth of the fruit i f the observation of Ricada and Honnorat (28) can be applied to this problem. According to Tesi and Ferlicca (39) and other workers, application of growth regulators to improve fruit set sometimes resulted in malformed fruit.  Therefore, i t is even possible that complex external factors  could cause particular genotypes to produce endogenous growth regulators, which then act on the developmental processes of the fruit to result in rough fruit.  74  Apparently there are differences in the quantities or numbers of rough fruit produced on different cultivars as shown in both the field and controlled environment studies, although the quantities produced in the controlled environment experiments are not horticulturally significant.  Further studies are, however, needed to develop  a procedure which can be used to test given genotypes' rough f r u i t , production and, hopefully, separate "resistant" forms from the population and then employ such lines in breeding programmes which could be expected to yield cultivars which were highly resistant to the development of malformed fruit.  75 LITERATURE CITED  1.  Abdalla, A.A. and K. Verkerk, 1970. Temperature and nitrogen nutrition in relation to flowering and fruiting in tomatoes. 111-115.  2.  Neth. J . Agr. Sci. 18:  HA 41: 1557.  Abdelhafeez,. A.T., H. Harssema, G. Veri and K. Verkerk. 1971.  Effects of soil  and air temperature on growth, development and water use of tomatoes. J. Agx. Sci. 19: 67-75. 3.  Alpat'ev, A.V. and I.V.  Neth.  HA 41: 9163  Polumordvinova. 1957. ^[Morphological-physiological  differences in tomatoes in relation to variety and growing conditions]. (Russian). 4.  Agrobiologija 3:  Aung, L.H. 1976.  85-89.  HA 28: 1500  Effects of photoperiod and temperature on vegetative and  reproductive responses of Lycopersicon esculentum M i l l . J.Amer. Soc. Hort Sci. 101: 5.  358-360  Calvert, A. 1953. Temperature and truss size in tomatoes.  6.  . 1957.  Effect of the early environment on development of  flowering in the tomato. 1. 7.  Grower 39: 524-525.  Temperature. J_. Hort. Sci. 32: 9-17  . 1962.  Critical phases of tomato plants.  Grower 58: 787-788,  . 1965.  Flower initiation and development in the tomato.  822. 8.  N.A.A.S. quart. Rev. No. 70: 9.  79-88.  HA 36: 3122  . 1969. Studies on the post-initiation development of flower buds of tomato (Lycopersicon esculentum).  J_. Hort. Sci . 4 4 : 117-126  II  10.  Ekstrand, H. 1939. Arftliga missbilningar av tomatfrukter. malformations of tomato fruits]. PBA 10: 575.  [Heritable  Vcixtskyddsnotiser Nos. 4-5: 55-57.  76  11. Frenz, F.-W. 1968. Die "sensitive Phase" fur die generative EntwickVung bei dref;Tomatensorten ('ATlround', Vollendung' und 'Hellfrucht Z 1280').  'Haubners  (The sensitive phase in  the reproductive development of 3 tomatoes varieties,  'Allround , 1  'Haubners Vollendung' and 'Hellfrucht Z 1280'). Gartenbauwiss.chaft 33: 247-271.  HA 39: 4996.  12. Gould, W.A. 1974. Tomato production, processing and quality evaluation. The Avi Publishing Co. Inc., Westport, Connecticut, pp. 445. 13. Grainger, J. 1943. The causes and control of flowering. Chron. Bot. 7: 400-402.  HA 14: 1067.  14. Hallig, V.A. 1971. The effect of a r t i f i c i a l light on the earliness and yield of tomatoes. Acta Horticulture 22: 181-186. HA 42: 4038. 15. Hayward, H.E. 1938. The structure of economic plants. The Macmillan Co. pp. 558-560. 16. Howlett, F.S. 1939. The modification of flower structure by environment in varieties of Lycopersicon esculentum. J_. Agr. Res. 53: 79-117. 17.  . 1958. Effect of temperature upon flower development and fruit set in the greenhouse tomato. 43rd Annu. Proc. Ohio Veg. Potato Grs. Ass, pp. 21-31.  HA 29: 513.  18. Hurd, R.G. and A.J. Cooper. 1970. The effect of early low temperature treatment on the yield of single inflorescence tomatoes. J_. Hort. Sci. 45: 19-27. 19. Imanishi, S. and I.  Hiura. 1972. [Varietal differences in the degree  of leaf rolling in tomatoes.]. J_. Yamagata Agr. For. Soc. 29: 39-41. 20. Kaname, T. and T. Itaga. 1966. [Experiments on controlling fruit malformation in tomatoes. I.  The influence of temperature and seedling  77  vigour on the incidence of misshapen fruits}. Bui 1. Kanagawa Hort. Expt. Stat. 14: 57-64. (Translated by T. Matsumoto, CDA). 21. Knave!, D.E. and H.C. Mohr. 1969. Some abnormalities in tomato fruits as influenced by cold treatment of seedlings. J.Amer.Soc.Hort.Sci. 94: 411-413. 22. Lewis, D. 1953. Some factors affecting flower production in the tomato. J . Hort. S c i . 28: 207-219. 23. Lindley, D.V. and J.C,P. Miller. 1968. Cambridge elementary statistical tables. Cambridge University Press, Cambridge, pp. 12-13. 24. Litynski, M. and Z. Stankiewicz. 1955. Obserwacje nad kwitnieniem i owocowaniem niektorych odmian pomidorow uprawianych w szklarni. (Observations on the flowering and fruiting of some varieties of glasshouse tomatoes). Zesz. nauk. wyz. Szkoly. r o l . Wroclaw Rolnictwo 1: 113-134. HA 27: 523. 25. Moskov, B.S. and L.S. Aleksandrova. 1970. [The productivity of tomatoes in relation to photoperiodic conditions and temperature Sell-hoz. Biol. 5: 26-30.  HA 41: 1486.  26. Phatak, S . C . , S.H. Wittwer and F.G. Teubner. 1966. Top and root temperature effects on tomato flowering. Proc. Amer. Soc. Hort. Sci. 88: 527-531. 27. Reinken, G. and M. Struklec. 1973. [The influence of night temperature on various vegetable crops under glass];. Der Einfluss der Nachttemperatur auf verschiedene GemUsearten unter Glas. Bonn, German Federal Republic. Berichte (Iber Versuche und Untersuchungen, Landwirtschaftskammer Rheinland 1: 7-44. HA 45: 242. 28. Ricada, D. and E. Honnorat. 1951. Note sure deformation des tomates.  78  (A note on deformed tomato fruits). Terre maroc. 25: 299-301. HA 22: 1591. 29. Roodenburg, J.W.M. 1947. The growth and flowering of the tomato. Meded. Dir. Tuinbouw. 10: 296-306. 30. Rylski, I.  1975. Fruit set and development of several vegetable crops  grown under low temperature conditions. In Proceedings of the XIX International 31.  Horticultural  Congress 1974. Warsaw, Poland. 3: 375-385.HA 46:456;  and A.H. Halevy. 1974. Optimal environment for set and development of sweet pepper fruit. Acta Horticulture 42: 55-62. HA 33: 7406.  32. Saito, T. and H. Ito. tomato. I.  1962. Studies on growth and fruiting in the  Effect of the early environment on the growth and fruiting.  1. Thermoperiods. J_. Jap_. Soc_. Hort. Sci. 31: 303-314. HA 33: 7406. 33.  and tomato. XII.  . 1971. (Studies on growth and fruiting in The combined effects of low temperature and nutritional  condition of the seedling on flower development particularly in the ovary and its locule). J_. Ja£. Soc_. Hort. Sci. 40: 354-358. HA 43: 2132. 34. Sal v i o l i , R.A. and G.0. Martfn. 1968. Harencia de flores anormales en Lycopersicon esculentum M i l l . (Inheritance of abnormal flowers in L. esculentum M i l l . ) . Rev. Agron. Noroeste Argent. 6: 1-2: 119-127.PBA39:3716 35. Shoemaker, J.S. 1953. Vegetable growing. 2nd edition. John Wiley and Sons, Inc., N.Y.  p. 372.  36. Snyder, G.B. 1956-1957. Dept. of Olericulture. A.R. Mass. Agric. Expt. Stat. Bull. 503: 43-45. HA 29: 2418. 37. Stoner, A.K. 1971. Commercial production of greenhouse tomatoes. U.S. Agri. Hbk. No. 383: 21. 38. Takahashi, B., T. Eguchi and K. Yoneda. 1973. [Studies on flower formation in tomatoes and eggplants. I.  The effect of temperature  79  regimes and fertilizer  levels on flower bud differentiation in  tomatoes). J. Jap_. Soc_. Hort. Sci_. 42: 147-154. HA 44: 6782. 39. Tesi, R. and A. Ferlicca. 1969. Risultati dei trattamenti per ottenere l'allegagione tetta. (Results of treatments for promoting fruit set in glasshouse tomatoes). Frutticoltura 31: 257-261. HA 39: 6979. 40. Tokarev, V.V. 1972. (The interaction of reproductive organs in tomatoes). In Voprosy Biologii Ratenii. Chelyabinsk, USSR. 4: 66-71. HA 44:4808 41. Torfs, P. 1968. Nachttemperatuur voor stooktomaat. (Night temperature for hothouse tomatoes). Tuinbouwberichten 32: 403-405. HA 39: 6944. 42. Uffelen, J.A.M. Van. 1974. [Some interesting trials with capsicums]. Interessante paprika-proeven. Groenten en Fruit 30: 751, 753. HA 45: 5001. 43. Verkerk, K. 1954. De invloed van temperatuur en licht op de tomaat. (The influence of temperature and light on the tomato). Meded. Dir. Tuinbouw.17: 637-647. 44.  HA 25: 656.  . 1955.[Temperature, light and the tomato]. Meded. La bHoogesch. Wageningen. 55: 175-224. HA 27: 525.  45. Wedding, R.T. and H.M. Vines. 1959. Temperature effects on tomato. Calif. Agr. 13: 13. 46. Went, F.W. 1944. Plant growth under controlled conditions. II.  Thermo-  periodicity in growth and fruiting of the tomato. Amer. J_. Bot. 31: 135-150. 47. White, H.I.  1938. Observations of the effect of nitrogen and potassium  on the fruiting of the tomato. Ann. Appl. Biol. 25: 20-49. 48. Wittwer, S.H. and F.G. Teubner. 1956. Cold exposure of tomato seedlings and flower formation. Proc. Amer. Soc. Hort. Sci. 67: 369-376. 49.  and  . 1957. The effects of temperature and nitrogen  on flower formation in the tomato. Amer, J_. Bot. 44: 125-129. Zielinski, Q.B. 1948. Fasciation in Lycopersicon. I.  Genetic  analysis of dominance modification. Genetics 33: 404-428.  

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