Heterotic expression and combining ability analysis for yield and yield components over environments in yellow maize (Zea Mays L.)

Combining ability over environments was studied for twelve yield and yield related traits in maize involving 66 F₁ crosses produced in line x tester design. Pooled analysis of variance over environments revealed significant differences among lines, testers and line x tester crosses. The performance of lines, tester and crosses were significantly different in all the environments for all the traits except testers for number of leaves per plant and ear girth. Inbred lines L2, L3, L4, L19, L22 and L22 and L21 were good general combiners for most of the traits. Inbred lines L15, L4 and L13 for earliness; L19, L1 and L2 for higher number of ears plant; L2, L3, L1 and L5 for higher plant height were identified. On the basis of SCA and per se performance hybrid L2 x T1, L17 x T2, L6 x T3 identified as early in maturity. Twenty one crosses revealed significant and positive SCA effects for grain yield per plant. Among these L14 x T3, L7 x T1, L1x T2, L6 x T2, L22 x T2, L8 x T1, L17 x T2, L9 x T1 and L19 x T1 and L19 x T1 were found to be promising for again yield. Three types of cross combinations were resulted due to high x high, high x low and low x low GCA effects when one or both the parents were poor general combiners, they resulted into a hybrid having highly significant SCA effects upon crossing. This is exemplified by hybrid L21 x T3 and L9 x T1 for grain yield per plant, biological yield per plant and 100 kernel weight; L5 x T3 for kernels per row. Cross combination L1 x T2. L7 x T1, L22 x T2, L14 x T3, L8 x T3, L9 x T1, L19 x T1 and L21 x T3 resulted good heterotic expression and performed well across the environments.