Genetic analysis of heat adaptive traits in tropical maize (Zea mays L.)

Abstract

Studies were conducted to determine the gene action for heat adaptive traits and grain yield under heat stress condition by using the hybrids generated in L×T and NCD-II. The results revealed predominance of non-additive gene action for heat stress adaptive traits in both the experiments. Among the parents, ZL135005 and CAL1730 of L×T experiment and ZL132088 and CZL0522 of NCD-II were good general combiners for heat tolerance component traits like leaf firing, tassel blast and also for yield contributing traits and hence these lines could be used for generating pedigree crosses for deriving second cycle in-breds. Hybrids viz., ZL134989×CML470 and ZL135003×CML 470 of L×T; VL1010963× ZL132070 and VL062655×CAL1427 of NCD-II showed desirable specific combining ability effects for maximum number of traits. These hybrids could be taken forward for multi-location testing under heat stress condition. Association studies revealed that plant height (0.199, 0.286) and number of grains per cob (0.458, 0.453) were positively associated with grain yield and ASI (-0.113, -0.107) leaf firing (-0.163) and tassel blast (-0.165) were associated negatively with grain yield. Tassel blast and leaf firing could be considered as negative traits for selection of tropical maize lines /hybrids under heat stress condition.