Combining ability analysis of Cucurbita moschata D. in Cote d'Ivoire and classification of promising lines based on their gca effects.

Abstract

Twelve hybrids and their four parental lines were evaluated for their general performances, combining abilities, potency ratio and heterosis effects. Taller plants and smaller fruits characterized the parental line Long, while the Soubre parent showed favorable fruit and seed traits but with a small number of seeds. The line Zouan-H exhibited performances that are close to Soubre but with a smaller number of fruits per plant, higher number of seeds per fruit and the weight of the fruit is one-half that of the Soubre line. The Oval parent is characterized by a high number of seeds per fruit, smaller fruits and shorter plants. Significant effects of heterosis were observed in different hybrids for different characters. And the computed values of potency ratio indicated that gene(s) expressions were characterized by partial dominance in many cases and super dominance in some other cases. The variance of the effect of the general combining ability of the female parent was highly significant for all the evaluated traits. The variance of the effect of the general combining ability for the male parent was significant for some characters. The variance due to the effect of the specific combining ability was also highly significant for all the traits evaluated. It showed that the effects of additive genes and non-additive genes contributed to the expressions of the characters. However, the general predictive ratio was closer to 1.00 for all the fruit-related traits implying the strong effects of additive genes in the determination of the fruit-related characters. A classification of the parental lines based on the effects of their general combining ability grouped the Soubre lines as promising contributors to fruit yield. The parental lines Long and Oval formed another group likely on the basis of the small size of their fruits, the small pulps, the smaller number of fruits per plant and the high number of seeds per fruit. Long would be a candidate parent for the development of cultivars with longer vegetative growth. The parental line Zouan-H formed the third group and it was mostly characterized by its advantageous seed traits.