T. Sandeep Kumar
Department of Genetics and Plant Breeding, Sri Venkateshwara Agricultural College Tirupati, AP, India
October, 2011


Eight parents and 28 F1 cross combinations of maize were evaluated in a RBD with three replications during rabi, 2010-2011 so as to identify the best parental genotypes and cross combinations with higher grain yield. Based on both per se performance and gca effects, the inbred lines CM 209, CM 149 and BML 15 were recognized as the best general combiners for most of the traits and hence, could be used in crossing programme for obtaining transgressive segregants for yield and yield components. The highly significant sca effects in addition to high per se performance were identified for most of the traits in the crosses viz., CM 149 x BML 6 (cob length, cob girth, grain yield per plant and 100-seed weight) and CM 132 x BML 7 (days to 50 per cent tasseling and days to 50 per cent silking).These cross combinations showing high sca effects besides high per se performance for yield and yield components could be utilized in recombinant breeding programme. The estimates of components of variance revealed predominance of non-additive gene action for all the traits. In such cases where non-additive gene action played a predominant role in association with additive component, the recurrent selection and reciprocal recurrent selection can be used to exploit simultaneously both the components.
The estimates of heterosis obtained in hybrid combinations revealed considerable genetic divergence among eight parents. The cross combinations CM 149 x BML 6 and CM 148 x BML 15, which recorded high heterobeltiosis for most of the traits could be utilized in heterosis breeding programme to exploit heterotic vigour. Further, based on highly significant heterobeltiosis, standard heterosis and sca effects for grain yield per plant, the promising cross combinations were CM 149 x BML 6, CM 149 x BML 15, CM 148 x BML 15 and CM 133 x BML 7.
Correlation analysis revealed that, number of kernels per row followed by cob length, cob girth and 100-seed weight exhibited maximum positive association with grain yield per plant. Further, the inter-se association among these traits was also highly significant and positive. Path coefficient analysis revealed that, cob length followed by cob girth, number of kernels per row and 100-seed weight exerted highest positive direct effects on grain yield per plant. Hence these characters may be given due emphasis in formulating selection indices in order to evolve high yielding genotypes in maize.