NIH WWWWWW\IHWHNW 12 8 H U1\l 403 m r4 E815 LIBRARY Michigan State University ‘- This is to certify that the thesis entitled SINGLE AND 3-WAY CROSS HYBRIDS 0F PICKLING CUCUMBER presented by Mansoor Tasdighi has been accepted towards fulfillment of the requirements for Ph.D. . Horticulture degree in Date April 17, 1980 0-7639 MM FIN£§: 25¢ per day per 1“ RETUMIMS LIBRARY MATERIALS: Place in book return to remove charge from clrculatton records SINGLE AND 3-NAY CROSS HYBRIDS OF PICKLING CUCUMBER By Mansoor Tasdighi A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Horticulture l980 ABSTRACT SINGLE AND 3-wAY CROSSES OF PICKLING CUCUMBER By Mansoor Tasdighi Devel0pment of high-yielding cucumber cultivars adapted to once-over mechanical harvest has received considerable attention in breeding programs. A highly female F] with uniform sex expression is desirable because of the concentration of fruit set necessary for once-over mechanical harvest. However, commercial hybrid cultivars are generally termed predominantly female (PF), with variable per- centages of staminate and female flowers. The present research was undertaken to compare single with 3-way cross hybrids; and also, androecious with monoecious pollen parents for their effects on sex expression and subsequent yield; and finally, to estimate the genetic variance components in pickling cucumbers under open-field conditions for sex expression and yield. The significant correlations between percent female nodes and marketable yield were 0.34 for single cross and 0.45 for 3-way cross hybrids. The use of androecious pollen parents for hybrid cultivars resulted in superior yielding hybrids as compared to the monoecious lines currently being used as pollen parents for commer- cial hybrid seed production. It was speculated that 3—way cross Mansoor Tasdighi might be used in place of single cross hybrid cultivars for the pro- duction of pickling cucumbers for once-over harvest. Additive effects of genes (general combining ability) were found to be relatively more important than non-additive effects (specific combining ability) for both percent female nodes and yield. It may be possible to predict the best 3-way combination for yield from the general performance of the parents in single cross combina- tions. Therefore, cucumber breeders might develop high yielding cultivars based on high general combining ability for yield in paren- tal arrays. ACKNOWLEDGEMENTS I would like to express thanks to all who have made the pursuit of this degree a meaningful experience. Special thanks goes to my guidance committee Drs. L. R. Baker, C. E. Cress, E. H. Everson, J. F. Fobes, R. C. Herner and T. J. Johnston for the time and oppor— tunities they have offered me during my graduate study. I wish to express my deep gratitude to Marja, with whom I have learned and experienced much. Special thanks go to my fellow graduate students: Mike, Gene, Anand, Mary, NC, Jim, Larry for their willing assistance with the many research plots. Thanks also go to all the students particularly Robin who helped from planting to grading during the two years of field works. And my thanks go to Jerry Skeltis of the Clarksville Experiment Station for his help with cultural practices. ii Guidance Committee: This thesis has been condensed into the format suited and intended for publication in the Journal of the American Society for Horticultural Science. TABLE OF CONTENTS Acknowledgements. Guidance Committee . Table of Contents List of Tables PART I. Comparison of single and 3—way crosses of hybrid pickling cucumber for female expression and yield in once-over harvest Abstract Introduction . Materials and Methods . Results and Discussion. Literature Cited. PART II. General and specific combining ability in single and 3-way crosses of hybrid pickling cucumber for female expression and yield intended for once over harvest Abstract Introduction . Materials and Methods . Results and Discussion. Literature Cited. iv Page ii l9 20 22 27 38 LIST OF TABLES Table Page PART I. l Parental lines of pickling cucumber used to produce an array of single and 3-way cross hybrids. . . 5 2 Hybridization for single and 3-way cross hybrids of pickling cucumber to test for femaleness and yield in once-over harvest system. . . . . . . . 6 3 ANOVA for the effect of year on femaleness and yield of pickling cucumber for once-over harvest. . . 9 4 ANOVA for effect of hybrid cross on femaleness and yield of pickling cucumber for once-over harvest. ll 5 Means of parental lines and different hybrid crosses for sex expression and yield of pickling cucumber for once-over harvest. . . . . . . . . . 12 PART II. l Parental lines of pickling cucumber used to produce an array of single and 3-way cross hybrids. . . 23 2 ANOVA model used to study combining ability in single and 3-way cross hybrids of pickling cucumber grown over 2 years under open-field conditions for once- over harvest. . . . . . . . . . . . . 26 3 Femaleness and yield of single cross hybrids of pickling cucumber with one parent in common in l978 and l979 field trials for once-over harvest. . . 28 4 Femaleness and yield of 3-way cross hybrids of pick- ling cucumber with two parents in common and of common parents in l978 and l979 field trials for once-over harvest . . . . . . . . . . . 29 Table Page 5 Estimates of relative GCA and SCA effects for femaleness and yield based on single cross hybrids of pickling cucumbers grown over 2 years in open- field conditions for once-over harvest. . . . . 3O 6 Estimates of relative GCA and SCA effects for femaleness and yield based on 3-way cross hybrids of pickling cucumbers grown over 2 years in open field conditions for once-over harvest. . . . . 32 7 Estimates of the components of variance for GCA and _ SCA and their interaction with year calculated for the l978 and l979 combined F1 data of single and 3-way crosses of pickling cucumber . . . . . 35 vi SINGLE AND 3-NAY CROSSES OF PICKLING CUCUMBER I. COMPARISON OF SINGLE AND 3-WAY CROSSES OF HYBRID PICKLING CUCUMBER FOR FEMALE EXPRESSION AND YIELD IN ONCE-OVER HARVEST. SINGLE AND 3-NAY CROSSES OF PICKLING CUCUMBER I. COMPARISON OF SINGLE AND 3-WAY CROSSES OF HYBRID PICKLING CUCUMBER FOR FEMALE EXPRESSION AND YIELD IN ONCE-OVER HARVEST. ABSTRACT An array of single and 3-way cross hybrids of pickling cucum- bers were evaluated over two years under open-field conditions for female expression and yield. The significant correlations between percent female nodes and marketable yield were 0.34 for single cross and 0.45 for 3-way cross hybrids. Highest yields were obtained from the gynoecious by androecious, gynoecious by hermaphrodite, and gynoecious by hermaphrodite by androecious parental combinations, in that order, on the basis of either total or marketable fruits per plant. Androecious and monoecious pollen parents were compared for their influence on the yield and female expression of their hybrid combinations. Androecious lines were superior pollen parents as their hybrids were more female and produced higher yields than those with monoecious pollen parents. The possible use of any of the above mentioned parental sex combinations; and the use of 3-way crosses as hybrid cultivars in place of conventional single crosses of gynoecious by monoecious, for the production of pickling cucumbers for once-over mechanical harvest is suggested. INTRODUCTION Pickling cucumber production in Michigan was estimated at an on-farm value of $l5 million for l978 (USDA Statistical Reporting Service). Most of the cr0p is produced for once-over mechanical harvest (USDA Statistical Reporting Service). Production of pickling cucumbers for mechanical harvest differs greatly from that for hand- harvest (8). The entire crop is harvested when the greatest number of fruits is judged marketable (6). Thus, the success of once-over mechanical harvest is based on inherent yield potential and unifor- mity which in turn depends upon many factors including the cultivar, environment and management (7, 8). The average yield of pickling cucumber by once-over mechanical harvest is respectable at T93 bu/A (USDA Statistical Reporting Service), but the yield potential is likely higher. An arbitrary goal of 400 to 600 bu/A of seeded pick- ling cucumber by once-over harvesting has been speculated by various researchers. Female expression of hybrid varieties is an important econo- mic trait, as a high concentrated fruit-set is needed for once-over mechanical harvest. Commercial hybrid cultivars are predominantly female (PF) with various percentages of staminate and pistillate flowers. Improvement in the percentage and stability of pistillate flowering (femaleness) of these hybrids under field conditions should subsequently improve the uniformity of fruit-set and yield for once- over harvest. Two possibilities have been put forward to enhance the ”femaleness" of cultivars as compared to the current PF hybrid cultivars. Recent attention focused on the use of hermaphroditic, bisexual flowers only, (9, l3) and androecious, only male flowers, (l4) lines, in place of the commonly used monoecious lines (l0, l2), for hybrid seed production of pickling cucumber. Compared to mono— ecious, androecious pollen parents usually produced hybrids with a higher percent of gynoecious (female) plants (l4). It is not known whether all-female, gynoecious cultivars would yield higher than the PF cultivars used for once-over harvest, or if increased femaleness would be necessarily associated with subsequent increased yield. The objectives of this study were to compare single and 3-way cross hybrids of pickling cucumbers; to evaluate androecious and monoecious pollen parents for their effects upon hybrid sex expression and subsequent yield; and to determine the association of sex with yields from a hybrid array for once-over harvest. MATERIALS AND METHODS Plant materials An array of parental lines was selected from publically released and Michigan State University (MSU) germplasm (Table l). In January l978, appr0priate stock seeds were sent to Linda Vista near Cartago, Costa Rico, to produce all the hybrid seeds (Table 2) for experimental purposes. Plants were grown using standard cul- tural practices in plastic houses with screened sides to exclude pollinating insects; seeds were produced by hand-pollination. Field trials Seeds were sown at the Clarksville Horticultural Experiment Station (near Grand Rapids, MI.) in a sandy loam soil during_the l978 and l979 growing seasons. The plots were arranged in a par- tially balanced triple lattice design. Each plot was 6 m long on a 4-row flat bed with 45 cm between rows. The seedlings were blocked to 30 cm between plants in the row, which approximated 65,000 plants per hectare. Standard cultural practices (8) were used including sprinkler irrigation and bees for pollination. The seed lots of single crosses with '5804A', germinated very poorly; and therefore, these plots were eliminated from the data analysis. A random sample of l2 plants per plot was classified for sex expression by recording the sex of individual flowers on the first m<_ x awe camama_aae _mp:me_amaxm 3m: L:= cowsaau _:: :omEm_u _c: __acaou upmm Afi=mm_a>poam= x ummvx m-m_kv x mew _aecms_aaaxm 2m: awom m—mZm x mam nmmmewm .>_:: :OmEm_u qpxo mzowowoczo :_mwco msumum muczom m:w_ qupocmza xmm paucmcmm .muaaa»; mmocu xmzam use mpmcwm do hence cm moacocq op new: consaozo m:w_xowg to moan. _mocmcmml-._ m4mchccweoumcm z x w m:o_omo:oz x m:o_omo:>o m m_w5md zppcmcwsonmcm < x c mzowomocuc< x msowowoczw N_ mzowumocxw I x u mawnocsamscmz x msowomoczw merge»: mmoco m_m:wm mu_ca»; u_ca>; do xmm mmoco mommocu we mmxmm Pangaea; .02 do maxe .Empmxm umw>cag Lm>olmoco cw cpmw» ucm mmm: -mFmEmw cow ammo cu consauso mew—xo_a to maven»; mmocu >c2-m cam mchwm Low :owpmeuwcozz--.m m4m 5.l cm diameter) to estimate once-over harvest yields. This grade size distribution was suggested to be the optimum harvest-time for once-over harvest (6, 7). Since the time required for l0% over-sized was not uniform, each plot for a given hybrid entry was harvested individually. The fruits were then size-graded according to PCIC§/ standards as follows: Grade No. l 2 3 4 Fruit diam. (cm) < 2.7 2.7-3.8 3.8—5.l > 5.l The number and weight of each grade were recorded for each plot. The data were statistically analyzed using plot yields adjusted to a per plant basis. Homogeneity of the variances over years was tested by using a two-tailed F test (l6) and found homo- geneous; therefore, data were pooled over the two years. g/Pickling Cucumber International Committee, St. Charls, IL 60l74. RESULTS AND DISCUSSION The interaction of year with many of the parental lines and hybrids was significant (Table 3) for sex expression and for total and marketable number of fruits per plant. The test of homogeneity for variances was not significantly different; therefore, the data were averaged over the two years of study. The hybrids of gynoecious (G) by hermaphroditic (H) crosses were stable from year to year for sex expression as measured by percent female nodes. This agreed with previous works (2, 5, 9, l3) which concluded that the use of herma- phroditic pollen parents improved and stabilized the gynoecious expression of hybrids with gynoecious seed parents. The parental gynoecious and hermaphroditic lines were also stable across years, although more variation was observed for gynoecious parents as com- pared to their hybrids with hermaphroditic pollen parents (Table 3). Estimation of yield by weight is biased by the time-of- harvest due to rapid changes in fruit size and weight; and most strongly by the proportion of over-sized, unmarketable fruits. Accordingly, yield was estimated by the number of fruits per plant as suggested previously (l5) for once-over harvest yields. However, we did find a correlation of 0.74 between total fruit number and total weight of fruits per plant and 0.77 between marketable fruit number and marketable weight of fruits per plant. These correlations were highly significant, probably due to the timeliness of the harvest 8 TABLE 3.~-ANOVA for the effect of year on femaleness and yield of pickling cucumber for once-over harvest. Mean squareX/ Total Marketable _ . . z/ fruit/plant fruits/plant Source or variation- d.f. Sex expression (No) (No) G x H Fi's 11 10.832 l.483** l.434** Year 1 78.648 0.332 1.456** G x H Fi's x Year 11 10.627 1.514** l.391** G x A Fi‘s 5 643.635** 4.930** 4.082** Year 1 11392.921** 8.054** 12.005** G x F1's x Year 5 768.460** 1.430** 1.445'* G x M Fi‘s 8 l346.053** 0.527** 0.443* Year l 24257.266** 2.279** 6.468** G x M Fi‘s x Year 8 1234.158** 0.879** . O.910*' (G x H) x A Fi's 35 1018.88S** 0.934'* 0.948** Year 1 16079.595** 6.222** 10.700** (G x H) x A Fi’s x Year 35 549.262** 0.344** 0.685** (G x H) x M Fi's 35 1295.076** O.791** 0.969** Year 1 67478.479** 32.321** 45.426** (6 x H) x M Fi‘s x Year 35 836.852** O.366** 0.428" G 2 112.287 0.098 0.264 Year 1 2.571 1.839** 1.475** G x Year 2 1.926 l.208** 0.858** H 3 14.071 15.754** 28.033** Year 1 2.299 2.991** 10.147** H x Year 3 22.582 3.165** l.169*' M 2 215.083** 1.900** 0.970** Year 1 7.661 2.534*' O.739** M x Year 2 219.493** l.OO3** 0.108** Pooled error 450 41.955 0.207 0.175 / G ' gynoecious; H = hermaphrodite; A ' androecious; M a monoecious / * = significant at 5% level; ** a significant at l: level. ID of individual plots according to their size grade distribution; i.e., 10% over-sized by weight (6). Among the array of parental means for yield and associated traits (Table 5) gynoecious lines exhibited the highest percent female nodes (94%) as compared to monoecious, M, (12%) and hermaphroditic (0%, only bisexual nodes) parental lines. Of course, androecious (A) lines bear only staminate flowers with no pistillate flowers. The means of gynoecious and monoecious parental lines did not differ for total yield, but there was a significant difference for market- able number of fruits per plant (Table 4). Single cross hybrids Hybrids of G x H crosses produced the highest percent female nodes (Table 5) and were phenotypically stable for gynoecious expres- sion as the difference between years was not significant. However, all other parental sex combinations used for hybrids were signifi- cantly different over years for percent of female nodes. The dif- ferences for yield between the hybrids made by the parental crosses of G x H, G x A, and G x M were significant (Table 4). The first years means for yield, both total and marketable, were highest for G x H hybrids. However, the G x A hybrids outyielded the other two sets of single cross hybrids in the second year. Overall, the G x A hybrids were higher yielding than either G x H or G x M hybrids. Regression analysis calculated a significant correlation coefficient of 0.25 between percent pistillate nodes and total yield and of 0.34 between the former and marketable yield. The higher correlation of TABLE 4.--ANOVA for effect of hybrid cross on femaleness and yield of pickling cucumber for once-over harveSt. Mean squarggl Tetal Marketable z/ fruit/plant fruit/plant Source of variation— df Female nodes (3) (No) (No) Between G parents 2 224.58 0.20 0.5 M Parents 2 430.17** 3.80** 1.94** Single crosses 2 25100.24** 21.80** 17.21*' 3-way crosses 1 9111.65** 32.29** 46.10** G vs. M l 369396.10** 0.02 1.40* G vs. G x H 1 402.18** 23.36'* 27.42** G vs. G x A 1 7649.24** 48.93** 34.12** G vs. G x M 1 14195.59** 5.94*' 3.83** G vs. (G x H) x A 1 6280.46** 22.89** 22.05** G vs. (G x H) x M l l3515.39*' 6.53" 4.13*' H vs. G x H l 311135.48** 14.96** 22.59** H vs. G x A 1 215768.63** 25.46** 26.61** M vs. G x M 1 190912.56** 6.28** 11.64** H vs. (G x H) x A l 278677.87** 12.20** l9.90*' H vs (6 x H) x M l 202853.68** 7.35** 13.28** G x H vs. G x A 1 26109.19** 7.73** 1.41* G x H vs. G x H 1 43884.73** 17.80** 21.90** G x H vs. (G x H) x A 1 8450.63" 0.58 0.52 G x H vs. (G x H) x M 1 15609.48** 16.28** 20.75** G x A vs. G x M 1 2007.87** 42.88" 30.16** G x A vs. (G x H) x A 1 321.74** 23.04** 8.28** G x A vs. (G x H) x M 1 1004.60" 70.45” 53.42" G x M vs. (G x H) x A 1 7285.11** 12.13'* 16.56** 0 x H vs. (G x H) x M 1 624.33** 0.01 0.05 Error 540 93.43 0.26 0.22 z/ G = gynoecious; H = hermaphrodite; A = androecious; M = monoecious. to 2/ . significant at 5% level; **: significant at 1% level. I 12 .mmuwnoczamEcm; co Pmowazu .mamzm mcopno ow nczoc mew: merged N1>513| \ .mmuoc co mcwzope Fmsxmmwn __< \ .mcmms esp co :owumcmamm as“ Low w m_awe mom \ o.~ _.N mm mecca»; co came agate w.~ o.m mm mzowomocoz x AmwwuoczamEcwI x mzowomocaov _.m N.m om m:o_omocu:< x Ampwuoccamscm: x mzowomocxwv m._ o.N Fm m:o_umocoz x maowomocxo m.m m.m mm mzowomocuc< x macromoczo N.N m.m Am ou_uocsac5cm: x mzowomocxo 3m.m zo.¢ zo mpwuocgameLmI ¢.P N._ m_ mzowomocoz o._ N._ am msowoooczo Aozv Aozv ARV mono: mmoco eacaxc\a=as Hempaxngc» acmpa\uw:cw mpm_Pwomwa opacpmxcmz PGHOP ~.umo>cm: cm>oumuco Loy cmaszoso mcwpxuwa co w_mw> new cowmmmchm xmm co» mummoco even»; “cmcmwewu use mmc__ Poacmcma co mcmwz--.m womqp l3 marketable yield with pistillate nodes indicates that there may be more differences between the hybrids for marketable yield than for total yield. Three-way cross hybrids The androecious pollen parent crosses of (G x H) x A, pro- duced more female nodes and yielded more than those utilizing mono- ecious pollen parents, (G x H) x M, over the two years of testing (Table 5). The correlation coefficient of 0.35 between pistillate nodes (%) and total yield and of 0.45 between the former and market- able yield for the 3-way cross hybrids were highly significant at the 1% level. These values are higher than those calculated for single cross hybrids which indicated more variation among 3-way cross hybrids for yield. The correlations between the same traits for single and 3-way cross hybrids were less for the second year than the first year, but in both years 3-way crosses displayed higher correlation coefficients than single cross hybrids. Moreover, market- able yields were more closely correlated with percent pistillate nodes than total yield. This high correlation between percent pis- tillate nodes and marketable yield indicated that hybrids with more pistillate flowers would be more likely to produce the highest market- able yields. Single versus 3-way cross hybrids The ranking for sex expression (Table 5) among single and 3-way crosses was somewhat consistent over both years. The G x H l4 crosses produced the highest percent pistillate nodes. The other combinations of parental sexes produced hybrids in the following descending order; (G x H) x A, G x A, (G x H) x M, and G x M for % pistillate nodes which agreed with earlier work (14). The various hybrid combinations displayed a comparable ranking for yield as measured by total and marketable fruit counts per plant. By obser- vation, the descending order of parental sex combinations was G x A, G x H, (G x H) x A, (G x H) x M, and G x M hybrids for yield. The difference between (G x H) x M and G x M hybrids for yield was not significant and neither was G x H from (G x H) x A hybrids (Table 4). By observation, the average mean for marketable number of fruits of G x A was some 9% higher than (G x H) x A hybrids (Table 5). On a 1-year basis, however, the mean of (G x H) x A was slightly higher than G x A in 1978; the converse was observed in 1979. As expected, hybrid vigor for yield was expressed, as measured by the grand mean of all hybrids for total (2.1) and marketable (2.0) numbers of fruits per plant, when compared to the gynoecious and monoecious parental lines (Table 5). Previous researchers found similar hybrid vigor for yield of F1 hybrids over parental means in cucumber (3, 4). Of course, the all-male, androecious lines do not produce fruit due to the absence of pistillate flowers. Based on these data, the use of androecious lines as pollen parents for single and 3-way crosses resulted in more female and superior yielding hybrid cultivars as compared to the mono- ecious lines currently being used as pollen parents for commercial 15 hybrid seed production (1, ll, 12). Therefore, we would suggest the use of androecious pollen parents for 3-way cross hybrids in place of single and 3-way cross hybrid cultivars with monoecious pollen parents for the production of pickling cucumbers for once-over har- vest. However, the eventual adOption of androecious in place of monoecious pollen parents for hybrid seed production can only be proposed as was suggested previously (14). The parental combinations giving more female expression did result in a higher yield potentials than the current G x M hybrid cultivars. High female expression contributes to both more and uniform, concentrated fruit-set necessary for maximum yields in once-over mechanical harvest as exhibited by the G x A, G x H, and (G x H) x A experimental hybrid crosses. 10. 11. 12. LITERATURE CITED Barnes, w. G. 1961. A male sterile cucumber. Proc. Amer. Soc. Hort. Sci. 77: 415-416. El-Shawaf, I. I. 5., and L. R. Baker. Inheritance of partheno- carpic yield in gynoecious pickling cucumber (Cucumis sativus L.). I. Performance of hermaphroditic pollen parents in top crosses with gynoecious. (In press). Hayes, H. K. and D. F. Jones. 1916. First generation crosses in cucumbers. Ann. Rep. Conn. Agric. Expt. Sta. pp. 319-322. Hutchins, A. E. 1938. Some examples of heterosis in cucumber, C. sativus L. Proc. Amer. Soc. Hort. Sci. 36: 660-664. Kubicki, B. 1965. New possibilities of applying different sex types in cucumber breeding. Genetica Polonica 6: 241-250. Miller, G. H. and G. R. Hughes. 1969. Harvest indices for pick- ling cucumbers in once-over harvest system. J. Amer. Soc. Hort. Sci. 94: '485-487. Morrison, F. D. and S. K. Ries. 1968. Cultural requirements for once-over mechanical harvest of cucumbers for pickling. Proc. Amer. Soc. Hort. Sci. 91: 339-346. Motes, J. E. 1977. Pickling cucumbers; production-harvesting. Michigan State University Ext. Bull. E-847. 8 pp. Mulkey, w. A. and L. M. Pike. 1972. Stability of gynoecism in cucumber (Cucumis sativus L.) as affected by hybridization with the hermaphrodite 'TAMU 950'. HortScience 7: 284-285. Peterson, C. E. and D. J. DeZeeuw. 1963. The hybrid pickling cucumber, 'Spartan Dawn'. Mich. Agric. Expt. Sta. Quart. Bull. 46: 267-273. , and J. L. Neigle. 1958. A new method of producing hybrid cucumber seed. Quart. Bull. Mich. Agric. Expt. Sta. 40: 960-965. Pike, L. M. 1974. ‘TAMU Triple Cross' pickling cucumber. HortScience 9: 83. 16 17 Pike, L. M. and N. A. Mulkey. 1971. Use of hermaphrodite cucum- ber lines in development of gynoecious hybrids. HortScience 6: 339-340. Scott, J. N. and L. R. Baker. 1976. Sex expression of single and 3-way cross cucumber hybrids with androecious pollina- tors. HortSCIence 11: 243-245. Smith, 0. S. and R. L. Lower. 1978. Field plot techniques for selecting increased once-over harvest yields in pickling cucumbers. J. Amer. Soc. Hort. Sci. 103: 92-94. Steel, R. G. D. and J. H. Torrie. 1960. Principles and Proce- dures of Statistics. McGraw-Hill, New York. pp. 481. SINGLE AND 3-NAY CROSSES OF PICKLING CUCUMBER II. GENERAL AND SPECIFIC COMBINING ABILITY IN SINGLE AND 3-NAY CROSSES OF HYBRID PICKLING CUCUMBER FOR FEMALE EXPRESSION AND YIELD INTENDED FOR ONCE-OVER HARVEST SINGLE AND 3-NAY CROSSES OF PICKLING CUCUMBER II. GENERAL AND SPECIFIC COMBINING ABILITY IN SINGLE AND 3-NAY CROSSES OF HYBRID PICKLING CUCUMBER FOR FEMALE EXPRESSION AND YIELD INTENDED FOR ONCE-OVER HARVEST ABSTRACT Single and 3-way cross hybrids of 13 parental lines of pick- ling cucumber were used to estimate general and specific combining ability for percent female nodes and yield. Parental lines 'SSlF', '3688', '581H', and '5802A' exhibited the highest general combining ability effects in both single and 3-way crosses for total yield and marketable yield. Additive effects of genes were found to be rela- tively more important than nonadditive effects for both percent female nodes and yield. Cucumber breeders might develop high yielding cul- tivars based on high general combining ability for yield in parental arrays; moreover the general performance of the parental lines in single crosses might be used to predict high yielding 3-way hybrid CY‘OSSGS . INTRODUCTION Information on the relative importance of general (GCA) and specific combining ability (SCA) is of value in breeding programs for species which are amenable to the development of F1 hybrid cul- tivars. Such basic information on combining ability in CUCUmber would aid the breeder in developing improved hybrid cultivars. Sprague and Tatum (26) used the term "general combining ability” to designate the average performance of a line in hybrid combinations. They used "specific combining ability" to designate those cases in which certain combinations do relatively better or worse than would be expected on the basis of the average performance of the lines involved. Genetically, GCA is associated with additive genetic variance and SCA is generally considered to be a function of dominance variance and epistatic variance (22). The relative impor- tance of GCA and SCA have been reported by several workers in cross— pollinated (2, 8, 9, 13, 14, 22, 26) and self-pollinated (4, 7, 12, 21) crops. The GCA is relatively more important than SCA in pre- viously unselected materials, but SCA, on the other hand, is rela- tively more important in populations previously subjected to testing and selection for GCA (22). Only limited data have been reported from combining ability studies on cucumber. El—Shawaf and Baker (5) made a combining abil- ity study involving 4 gynoecious lines crossed with 5 hermaphroditic 20 21 cucumber lines. They reported that additive genetic variance was greater and more important than that for nonadditive effects for parthenocarpic yield and associated traits, except for gynoecious expression where nonadditive effects were most important. The objective of the research reported herein was to esti- mate the GCA and SCA from a group of 13 parental lines of pickling cucumber for female expression, total yield and marketable yield in single and 3-way cross combinations. MATERIALS AND METHODS Three gynoecious (G), 4 hermaphroditic (H), 3 monoecious (M), and 3 androecious (A) lines (Table l) were used to produce an array of 30 single cross and 72 3-way cross hybrids of pickling cucumber. The seed lots of single crosses with '5804A', germinated very poorly; and therefore, these plots were eliminated from the data analysis. The parental lines were considered genetically diverse as they repre- sented breeding lines from Cornell University, Clemson University, and Michigan State University. The single cross hybrids were pro- duced by methods described earlier (18, 19) and the 3-way crosses by methods already reported (20, 24). The hybrids and parental lines, excluding the androecious parental lines, were grown in 1978 and 1979 growing seasons on the Clarksville Horticultural Experiment Station (near Grand Rapids, Mich). A partially balanced triple lattice design was used. The plantings were made in 4-row, 6.m beds with 45 cm between rows. After emergence, the seedlings were thinned to a spacing of 30 cm between plants. The following traits were studied: Sex expression The flower sexes on the first 10 nodes of the main runner were recorded from a random sample of 12 plants from each plot. Nodes with either pistillate and/or pistillate and staminate flowers 22 23 m<_ x awe :oocmmpnae _macaeataaxm :mz <¢omm _<_ x geomamz _ae:oawcmaxw 3m: amomm N<_ x mammamz _ap:oewaaaxu 3m: a:: seaso_u (mmum czocxc: FaucwEwLwaxm .>.:.5 COmEm—U <©mom msowumocoz Armo_e x Geomamzv .aucas_cmaxm :mz I_mm INkaamz x (oeum _aa:oewcoaxw 3m: Imam Iwopesmz x oeemsmz _apcaeecoaxw 3m: Imam :em_k:mz x a=: __occoo a_mm AA=am_L>uoam. x ammvx m-m_kv x mew Peoaasacaaxm :mz amem m_m2m x mam nmmmmpma .>_:: :omsm_u qpxw macromocxw cwmwco mzpmpm wocsom m:w_. maxuocmza xmm _mw:mcma .meaanxz mmoco xmzlm new m_mcwm co chca cm moznoca og com: conszoau m:w_xowa to meWF Faacmcma--.. mom 5.1 cm diameter) to estimate mechanical harvest yeilds (15, 17). The analysis of variance for each year and for the pooled data were computed. The variances for years were homogenous; there- fore, the data were pooled. The mathematical model used for the analysis of variance was; ijkp = U+ 91' + gj + $1,]. + yk + rkp + (gy)1k+ (gy)jk + (S‘Y)1jk+ eIJkp where, ..< ll i'k the obseryation on the hybgid between the ith female 3 p and the j h male in the p' replication of the experiment conducted in the kt year. p = an effect common to all hybrids in all replications, 9i = an effect common to all progenies of the ith female line, 9. = an effect common to all progenies of the jth male 3 line, Sij = an effect common to the progeny of mating the ith female and the jth male line. yk = the effect of the kth year, = the effect of the pth replication in the kth year, 25 (9y)1k = the interaction effect of the ith female and the kth year, (gy)jk = the interaction effect of the jth male and the kth year, (Sy)i’k = the effect of the second interaction of the ith female 3 and the jth male and the kth year, = the effect of the plot which had the hybrid between the ith female and the jth male in the pth replication con- ducted in the kth year. eiikp The analysis of variances were calculated for both single and 3-way cross hybrids (Table 2). The OZJ. estimates the genetic 1 variance component of the female lines; andcyzg , the genetic variance J component of the male parents. Hence, small values of' $91 or 0293 indicate genetically similar female or male parents, respectively. Similarly, (Esij is a measure of SCA variance where low values indi- cate a performance as expected on the basis of their GCA. 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