Line x testers analysis of tropical maize inbred lines under heat stress for grain yield and secondary traits

Abstract

The combining ability and mode of gene action in tropical maize germplasm is not extensively studied. In the present study, a line x tester analysis involving 290 test-cross hybrids developed by crossing 145 tropical maize inbred lines with two testers and four standard checks was conducted for grain yield and other agronomic traits under heat stress during summer 2013 at B gudi agriculture research station. The main objective of the investigation was to study mode of gene action governing the traits under heat stress along with identification of superior inbred lines based on combining ability to develop heat tolerant hybrids. Analysis of variance showed that mean squares for genotypes was highly significant for grain yield, days to anthesis and silking, anthesis silk interval, plant height and ear height under heat stress. The combining analysis for lines (GCA), tester (GCA) and line x tester (SCA) showed significant difference (P < 0.01) for all the traits under study except ASI for LXT interaction. This indicates that both additive and non additive gene action control the expression of these traits under heat stress. The low GCA variance to SCA variance ratio for all the traits showed preponderance of non-additive gene action in the inheritance of the traits. Among 145 inbred lines used for study, the inbreds L78, L73, and L37 showed good general combining ability for grain yield. The crosses L118 x L2 and L143 x L1 were having good specific combiners ability for grain yield under heat stress. These inbreds can be used in breeding program for development of heat tolerant hybrids through exploitation of dominant gene action.