Nirala, R. B. P.Chaurasia, Niranjan Kumar2023-04-092023-04-092021https://krishikosh.egranth.ac.in/handle/1/5810196169The present investigation entitled, “Combining ability and yield stability in maize (Zea mays L.)” was carried out with seven inbred lines, twenty one F1’s which were developed through diallel matting scheme (Method II Model I) and three hybrid checks at three locations during Kharif 2019 and Rabi 2019-20. The locations were (i) Bihar Agricultural College, Sabour (Zone-IIIA of Bihar); (ii) Bhola Paswan Shastri Agricultural College, Purnea (Zone-II of Bihar) and (iii) Pulse Research Centre, Mokama (Zone-IIIB of Bihar). The mean data of fourteen characters viz., days to 50 per cent anthesis, days to 50 per cent silk, anthesis-silking interval, days to 50 per cent physiological maturity, plant height, ear height, ear length, ear diameter, kernel rows per ear, kernels per row, grains per plant, 1000-kernel weight, shelling per cent and grain yield per plant were analyzed using statistical methods (i) to study general and specific combining ability of inbred lines and crosses, respectively, (ii) heterotic responses of maize hybrid, and (iii) G x E interaction and stability parameters of yield and component characters. The pooled analysis of variance for design of experiment over six environments indicated highly significant mean squares due to environments, genotypes and genotype x environment interactions (GEI) for all the fourteen quantitative traits under study. The pooled analysis of variance for diallel analysis (Method II Model I) revealed highly significant mean squares due to environments, genotypes, parents, hybrids, parents vs hybrids, genotype x environments, parent x environments, hybrid x environments and parent vs hybrids x environments for all the characters under study except due to hybrids x environments for ear length, kernel rows per ear and shelling per cent. The pooled analysis of variance for combining ability reveled highly significant mean squares due to general combining ability (GCA), specific combining ability (SCA), environments, GCA x environment interactions and SCA x environment interactions for all the characters under study. The magnitude of mean squares due to GCA x environment interactions were greater than respective SCA x environment interactions for all the character studied except days to 50 per cent anthesis, ear length and 1000-kernels weight. The pooled estimate of variance components for various parameters showed a lower ratio of σ2gca/σ2sca for all the characters studied except anthesis-silking interval revealed preponderance of non-additive gene effects in expression of characters. The pooled estimates of GCA effects of seven parents revealed the parents, namely, P1, P6 and P7 were good general combiner for grain yield per plant and its component traits. The pooled estimates of SCA effects revealed the hybrids, namely, P3 x P6, P4 x P5, P2 x P5, P2 x P3, P2 x P4, P3 x P4, P2 x P6, P3 x P5, P1 x P5, P1 x P6, P3 x P7, P4 x P7, P1 x P7, P1 x P2, P6 x P7, P1 x P3, P5 x P6 and P1 x P4 were good specific combinations for grain yield per plant. These hybrids were also found to be good specific combinations for three or more yield component traits. The hybrids, P1 x P4, P2 x P5, P3 x P6, P4 x P5 and P6 x P7 were found to be good specific combinations for early days to 50 per cent anthesis, early days to 50 per cent silk, shorter anthesis-silking interval and early days to 50 per cent physiological maturity. The pooled estimates of mid parent, better parent and standard heterosis over the best check, DMRH-1308 (C1) for grain yield per plant revealed the hybrids, namely, P1 x P7, P2 x P5 and P3 x P6 exhibited significant to highly significant positive heterotic responses for this trait. Analysis of variance for stability of fourteen quantitative traits in maize over six environments revealed mean squares due to genotypes, Env. + (G x Env.), environment (linear) and pooled deviations were highly significant for all the characters under studied. The significant to highly significant mean squares due to G x E (linear) were observed for all the traits under study except for days to 50 per cent anthesis, days to 50 per cent silk, plant height, ear length, kernels per row and grains per plant. The higher magnitude of mean squares due to environment (linear) than the G x E (linear) were recorded for all the studied traits indicated that linear response of environment accounting for major part of the total variance. The estimates of environmental indices revealed the environment, E4 (Rabi 2019-20, BAU, Sabour) had highly positive environmental indices for all the traits under study. Hence, E4 was considered as the most favorable environment amongst the six environments for expression of all the studied characters. The estimates of stability parameters for grain yield per plant revealed nine hybrids, namely, P1 x P2, P1 x P4, P1 x P5, P2 x P4, P2 x P5, P3 x P4, P3 x P5, P4 x P7 and P5 x P6 had high mean grain yield, unit regression coefficient (bi=1) and non-significant deviation from regression (S2di=0) indicating these hybrids were stable for this trait over the test environments. Based on estimates of high GCA (at least for female parents), SCA, standard heterosis and stability parameters for grain yield per plant two hybrids, namely, P1 x P5 and P1 x P2 were identified as promising stable experimental hybrids over test environments. Hence these hybrids may be exploited commercially under test environments for the high grain yield.EnglishThesis