Genetic Diversity, Character association and Path-Coefficient study in QPM inbreds
The thirty seven inbreds of quality protein maize of diverse origin, evaluated in RBD showed significant difference among the inbreds in respect of grain yield and its component traits. The characters like days to 50 % tasseling, days to 50 % silking and days to 75% dry husk were less influenced by the environmental factors because of lower differences in magnitudes between GCV and PCV. On the contrary, the characters like cob girth, number of kernels per row, number of kernel rows per cob and grain yield per plant were much influenced by the environmental factors as evidenced from higher differences in magnitude of PCV and GCV. High heritability with low genetic advances for characters like days to 50% tasseling, days to 50 % silking and days to 75 % dry husk indicated the predominance of non-additive gene action whereas high heritability with high genetic advance was reported for cob weight indicating the role of additive gene action. The characters viz., cob weight, 100- kernel weight, plant height, ear height, and no. of kernels per row were highly and positively correlated with grain yield per plant at genotypic and phenotypic levels. Ear height (0.837), days to 50 % silking (0.526) and number of kernels/rows per cob (0.455) in that order had large positive direct effect on grain yield per plant at genotypic level. Similar trend was also observed at phenotypic level. The indirect effects were generally small with only a few exceptions. A close examination of all the direct and indirect effects of the components traits on yield indicated the presence of enough scope for yield improvement through selection for no of leaves per plant, cob length, no. of kernels per row, cob weight and 100-kernel weight. Based on 14 quantitative characters, the 37 quality protein maize inbreds were grouped into13 clusters following D2 analysis and Tocher™s method of grouping. Among the yield traits, days to 50 % silking, days to 50% tasseling, days to 75% dry husk, cob weight, 100 kernel weight and grain yield per plant were found to be the major contributor towards genetic divergence. The overall clustering pattern indicated that QPM 3-7, QPM 9-18, and QPM 1110-7-2 were much divergent from rest of the inbreds in the experiment. Similarly, the inbreds of cluster III and XI and inbreds of clusters IX, III and X were distantly and distinctly related to each other. The pattern of clustering as stated above further indicated that there was no strict association between inbreds developed from diverse base populations.
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