Estimates of Combining Ability and Gene Action in Maize (Zea mays L.) Under Water Stress and Non-stress Conditions

Abstract

Combining ability and gene action for grain yield and other traits in maize were estimated under water stress and non-stress conditions at the Institute for Agricultural Research farms located at Samaru (11^o11'N; 07^o38'E) and Kadawa (11^o39'N; 08^o02'E) using North Carolina mating design II. Seven drought susceptible maize inbred lines used as females were crossed to six drought tolerant maize inbred lines used as males. The experiment was laid out using 7 x 8 simple lattice design with two replications under each condition at each location. Results of the combining ability analysis revealed that both additive and non-additive gene actions were responsible for the control of grain yield and other traits studied under water stress and non-stress conditions. However, the values of dominance genetic variance were greater than additive genetic variance for all traits which depicts the importance of non-additive gene action for controlling these traits. The low narrow sense heritability estimates also indicate the importance of non-additive gene action. The study showed that the female parents S1, S6 and S7 and the male parents P2, P7 and  P8 could be considered as good combiners for grain yield and other traits under the water stress and non-stress conditions. The crosses S1 x P2, S6 x P7 and S7 x P8 were the best among the hybrids for grain yield under water stress and non-stress conditions. Considering the dwindling amount of annual rainfall in the area where the study was carried out, these hybrids show potential for exploitation of grain yield and other desirable traits.

Keywords: Combining ability, gene action, water stress, non-stress, heritability