Effect of Year, spacing and Generation on General and Specific Combining Ability in Barley

Evaluation of seven varieties of barley and F₁ progenies of their half-diallel set, at 5⋅0 cm plant to plant spacing in 1973 and of the parents, F₁’s and F₂’s at 5⋅0 and 15⋅0 cm spacings in 1974 revealed that both years as well as spacings had significant effect on yield and other characters. The year interaction was significant for ears/plant, 1000-grain weight and plant height. The spacing interaction was significant for ears/plant (in F₁ and F₂ both) and 1000-grain weight (in F, alone). Partitioning significant interaction variances into general and specific combining ability components indicated that GCA effects were no less susceptible to the environmental interactions than SCA effects. The F₁ and F₂ generations were also significantly different for yield, ears/plant, 1000-grain weight and plant height. Each generation progenies showed significant variance regarding most of the characters. In general a decrease in the relative magnitude of SCA variance was observed in F₂ generation.

On the basis of estimates of GCA effects of parents and SCA effects of crosses it was concluded that HD-37 × NP-21 is a potential cross to breed for higher grain yield following conventional breeding programme.