Combining ability studies for physiological and grain yield traits in maize at two temperature regimes.

The F1 generation obtained from a 6×6 diallel cross was evaluated for combining ability effects at normal and high temperature regimes for various physiological and grain yield parameters. The mean squares due to genotypes, general combining ability (GCA), specific combining ability (SCA) and reciprocal effects were highly significant for all the traits at both temperature regimes while GCA effects were non–significant for stomatal conductance and transpiration rate at high temperature. The GCA: SCA variance ratio exhibited that all traits were controlled by the non-additive genes except for growing degree-days to 50% maturity that was predominantly under the control of additive genes at both temperature regimes. The inbred line 935006 was found to be the best general combiner with better mean performance for grain yield plant -1 with lesser growing degree days to 50% silking growing degree days to 50% physiological maturity and higher turgor potential at normal and high temperature regimes. The best single cross hybrid was 935006 × R2304-2 and its reciprocal followed by F165-2-4 × R2304-2 and F165-2-4 × 935006 for good specific combining ability, reciprocal effects, better grain yield plant -1 and some other desirable traits.