Genetic analysis for earliness and yield traits in maize

摘要

Five white kernel maize inbred lines with distinct genetic make-up were crossed in a 5 × 5 complete diallel fashion during spring season 2011 at Cereal Crops Research Institute (CCRI), Pirsabak - Nowshera, Pakistan. The resulting 20 F 1 hybrids, their five inbred lines and two checks hybrids (OPV 'Jalal' and 'Pioneer hybrid 30K08') were further evaluated during subsequent summer season 2011 at four locations. Present research was designed to study the genetic mechanisms controlling various earliness and yield traits through Hayman’s diallel approach. Genotypes, locations and genotype by environment interactions (GEI) showed significant ( p≤0.01 ) differences for all the traits studied. Significant genotypic differences for various traits justified to carryout the Hayman's genetic analysis. For adequacy, the additive-dominance model was adequate / partially adequate for various traits at all the locations. According to genetic analysis, the key components of genetic variances i.e., additive (D) and dominance components (H1, H2) and average degree of dominance revealed that dominance components were predominant and overdominance type of gene action played an important role in the inheritance of all the traits at different locations. Genetic analysis further revealed unequal proportion of positive (U) and negative (V) alleles in the loci (H2H1) with asymmetrical distribution of genes in the parental genotypes (H2/4H1 0.25) for majority of the traits. Broad sense heritability values were higher for days to 50% tasseling (0.89 to 0.97), days to 50% silking (0.91 to 0.97), ear length (0.86 to 0.99), 1000-grain weight (0.92 to 0.97) and grain yield (0.98 to 0.99), respectively at all the locations. Narrow sense heritability for above traits was low to medium ranging from 0.12 to 0.23, 0.17 to 0.33, 0.13 to 0.36, 0.10 to 0.51 and 0.07 to 0.11, respectively at all the locations. Desirable high genetic gain values were observed for yield traits while for earliness the values were moderate. Due to non-additive genes controlling various traits and high broad sense heritability estimates, the promising F 1 hybrids could be developed in future breeding programs for production of early maturing and high yielding maize hybrids and cultivars through selection from later segregating generations.