Genetics of heat tolerance traits in spring maize (Zea mays L.)

High temperature or heat stress at the time of pollination is the main problem faced in the cultivation of spring maize under Punjab conditions. The genetic analysis of heat tolerance traits in maize during two spring environments revealed that both additive and dominance variances were significant for the heat tolerance traits studied viz. plant height, ear height, days to 50% anthesis, days to silking, leaf firing, tassel blast, seed setting, chlorophyll a & b, total chlorophyll content and membrane thermostability. Over dominance was observed for all the traits except proline content. Epistatic interactions were involved in leaf firing, shelling percentage and membrane thermo stability only. Non additive gene action was predominant in the inheritance of majority of the heat tolerance traits. Thus, development of resistant! tolerant hybrids would be a viable breeding strategy in spring environments.