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20171
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Subject: Genetics and Plant Breeding × Author: Amadabade, Jairam × Start date: 2016 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Determination of gene action and heterotic response across the environments for yield and yield contributing traits in short duration maize (Zea mays L.)
    (G.B. Pant University of Agriculture and Technology, Pantnagar (Uttarakhand), 2017-01) Amadabade, Jairam; Singh, N.K.
    The present investigation was undertaken on experimental materials derived through crossing ten inbred lines in half diallel mating design. The evaluation experiments on 10 inbred lines their 45 single crosses and a hybrid check PSM1 were conducted in RCBD with two replications under two plant population densities namely optimum plant density and high plant density during Rabi, 2014-15 and Kharif, 2015 seasons at N. E. Borlaug Crop Research Centre, Pantnagar, Uttarakhand, India. The objectives of the investigation were (i) to estimate combining ability (ii) to determine the extent of heterosis and parental and heterotic contribution to the per se performance of hybrids (ii) to identify superior single cross hybrids (iii) to assess the response of hybrids across the environments in maize. Observations were recorded on grain yield and other related traits and data were analyzed using appropriate statistical and biometrical models. Analysis of variance indicated sufficient amount of variability in the experimental material for all the characters across the environments except canopy temperature in E1 and E4 and tassel length under all four environments. Mean performance of parents and hybrids for traits namely ear length, ear diameter, number of kernel rows per ear, number of kernels per row and 100 kernel weight was noted to be maximum in E1 environment, whereas for grain yield it was maximum in E2 environment. Analysis of variance for combining ability revealed significant GCA and SCA variances for most of the characters indicating the importance of both additive and non-additive genetic effects for expression of the traits. Estimates of σ2 SCA were greater than the σ2 GCA for all the characters across the environments indicating pre-dominance of non-additive variance. The inbred lines P4, P6, P9 and P10 had good GCA effects for most of the characters across the environments; these may be utilized as parental lines in breeding programmes. Promising crosses for grain yield with highest SCA effects were P3×P8 in E1, P3×P10 in E2 and E4, P4×P9 in E3 and pooled environment. The cross P4×P9 also had high SCA effects for ear length and number of kernels per row in pooled environment. The most promising hybrids exhibiting significant MPH, BPH and SH for grain yield were P4×P7 and P4×P9 in E1; P1×P8 and P1×P5 in E2; P4×P7 and P4×P9 in E3; P4×P7 and P3×P10 in E4 and P4×P7 and P4×P9 in pooled over environment. Inbred parents contributions to the per se performance of the crosses were found to be higher than heterosis contribution for yield and yield contributing traits. AMMI analysis of variance indicated considerable effects of environment, genotype and genotype x environment interaction on total variability for all the characters. The best adapted genotypes with high per se performance for grain yield were P7×P10 in E1, P1×P8 in E2, P6×P9 in E3, P6×P9 in E4. Further, the comparative assessment of grain yield stability of genotypes through regression, AMMI and GGE biplot statistics identified P4×P7 as the most stable cross with high per se performance for grain yield across the environments.