Inheritance of Parthenocarpic Yield in Gynoecious Pickling Cucumber for Once-over Mechanical Harvest by Diallel Analysis of Six Gynoecious Lines1

Abstract

Six gynoecious inbred lines of cucumber ( Cucumis sativus L.) were evaluated for parthenocarpic yield by using 2 diallel analysis programs. A complete diallel of F 1 and half-diallel of F 2 generations, including parents, was used to study the genetics of parthenocarpic yield. Highly significant differences for GCA and SCA effects were found for all yield characters, suggesting that both additive and non-additive gene action were important. Reciprocal differences or maternal effects were not significant for any of the yield characters. Diallel analysis suggested that recessive genes were acting in the direction of higher yields. Accordingly, the development of a parthenocarpic hybrid cultivar with high yield potential would require that both parents possess genotypes with high yield potentials. Heritability estimates varied from nearly 0 to 32% for 3 different yield measurements with number of fruits on the main stem most heritable. Significant ratios for heterosis and heterobeltiosis were obtained for all yield measurements. However, only fruit number on the main stem was affected by an inbreeding depression. Breeding improvement programs for parthenocarpy might include recurrent selection for fruit number on the main stem of gynoecious seed parent lines combined with backcrossing of the gene for hermaphroditic expression into gynoecious parthenocarpic lines for pollen parents.