GENETIC-ANALYSIS OF YIELD COMPONENTS IN CUCUMBER AT LOW PLANT-DENSITY

Plant architecture can be manipulated in cucumber (Cucumis sativus L.) to provide an array of phenotypes. Determinate, multiple-lateral plan ts are unique because they afford an opportunity to increase fruit yie ld per plant. Estimates of genetic variances, numbers of genetic facto rs, and genotypic and phenotypic correlations between traits were made in a population, segregating for sex expression, leaf size, and plant habit at low plant density (approximate to 19,000 plants/ha). Replica ted evaluation of 100 F-3 families derived from an initial mating betw een a gynoecious, determinate, moderately branched line (G421) and a m onoecious, indeterminate, multiple lateral branching line ('H-19') ind icated that mainstem length and multiple lateral branching exhibit mos tly additive genetic variance. For sex expression, additive and domina nt genetic variances were important. The minimum number of genetic fac tors controlling sex expression, number of lateral branches, and mains tem length were estimated at five, four, and eight, respectively. Phen otypic and genotypic correlations between trails indicated that relati ve leaf size may influence fruit mass while having only limited influe nce on the number of fruit produced per plant. The amount and type of genetic variation suggests that the development of an array of determi nate, multiple-lateral branching plant types with varying sex expressi on and plant stature is possible.