Heterotic performance and combining ability in a diallel cross among spring wheats (Triticum aestivum L.)

Abstract

Levels of hybrid vigour for earliness, plant height, four components of yield, and yield were examined in the F1 generation of a diallel cross of eight cultivars of spring wheat. Kernel weight and kernels per spike exhibited high levels of heterosis effects. The analysis for general combining ability indicated that a large part of the total genetic variation observed for six out of seven traits was associated with genes which were additive in their effects. The estimates for specific combining ability were highly significant for five out of seven traits. These estimates were lower than those of general combining ability for six out of seven traits. The combining ability analysis helped in classifying the parents in terms of their hybrid performance and in gaining greater understanding of the nature of quantitatively inherited traits. The importance of genetic diversity in relation to heterosis was also assessed.