ROJA, VMALLIKARJUNA, SANIKOMMU2020-02-282020-02-282019http://krishikosh.egranth.ac.in/handle/1/5810143865D5907The present investigation was carried out during kharif 2018-19 at Agricultural Research Station, Peddapuram with the prime objective of categorizing 49 genotypes of maize (Zea mays L.) into distinct classes based on their genetic diversity. Other parameters like mean, genetic variability, heritability, genetic advance as per cent of mean, character association and the magnitude of direct and indirect effects of yield component traits on grain yield were also studied. The analysis of variance demonstrated significant differences among 49 genotypes for all the traits investigated. The traits, days to 50 per cent tasseling, days to 50 per cent silking, days to maturity, plant height and ear placement height recorded a slight difference between Phenotypic Coefficient of Variation (PCV) and Genotypic Coefficient of Variation (GCV) indicating less influence of environment on these characters whereas traits like anthesis silking interval, kernels row-1, cob yield plant-1, grain yield plant-1 and protein content registered wide variation between PCV and GCV suggesting more influence of environment on the expression of these traits. High heritability coupled with high genetic advance as per cent of mean was observed for ear placement height whereas anthesis silking interval, cob yield plant-1 and grain yield plant-1 registered low to moderate heritability and high genetic advance as per cent of mean was observed for the trait implying additive gene action. Futher, the traits days to 50 per cent tasseling, days to 50 per cent silking, days to maturity and plant height recorded high heritability coupled with low to moderate genetic advance as per cent of mean implying non-additive gene action in the expression of these traits. Genotypic correlations in general were higher than phenotypic correlations indicating associations are largely due to genetic reasons. The traits, cob length, cob girth and cob yield plant-1 were found to possess significant positive association with grain yield plant-1 at both phenotypic and genotypic levels. xi Path analysis revealed that cob yield plant-1 showed true relationship with grain yield plant-1 by establishing significant positive association and positive direct effect. Considering the nature and quantum of trait associations and their direct and indirect effects, it can be inferred that plant height, cob length, cob girth and cob yield plant-1 could appear as key traits in selection programme for picking up high yielding genotypes for the utilization in the breeding programme. The multivariate analysis indicated considerable genetic divergence among the 49 genotypes studied. D2 analysis grouped the 49 maize genotypes into nine clusters and cluster I was largest with 24 genotypes while clusters IV, VI, VII, VIII, IX are smallest with single genotype in each. Maximum inter cluster distance (110.57) was observed between clusters II (KDML-115, PDML 15, VM 51, ADL 1619, PDML7470, CAL 1784, CAL 17834, VM 45, AL8127) and cluster VIII (CML 1505) indicating presence of maximum diversity among the genotypes falling within these clusters. Principal component analysis revealed first five principal components recorded eigen value more than one explained 75.39 per cent of the total variability. 2D, 3D scatter diagram of principal component analysis demonstrated that genotypes like ADL8070, PDML 19-39, VM 51 and CML 1505 are away from other genotypes which is also evident from tocher‟s method proving that these genotypes are more divergent and indicating their usefulness in hybrid breeding programmes. Hence, the crosses VM51 × CML1505 and ZL161032 × PDML19-44 are having good chance of producing heterotic hybrids or transgressive segregants. Further, these genotypes should be tested for their combining ability and gene action using different mating designs to produce hybrids based on the type of gene action involved.en-USnullThesis