Studies on Genetic Variability for Yield, Yield Components and Resistance to Kalahasti Malady in Groundnut (Arachis Hypogaea L.)..

Twenty one crosses of groundnut derived from 7×7 diallel set without reciprocals were evaluated during rabi 2010-11 for variability, heritability and genetic advance. Analysis of variance for thirteen traits revealed highly significant differences among the F2 populations tested. The estimates of GCV and PCV were high for number of secondary branches per plant, kernel yield per Plant (g), total phenols content (mg/g), pod yield per plant (g), number of kernels per plant and harvest index. High heritability coupled with high genetic advance as percent of mean for traits viz., days to 50% flowering, total phenols, number of secondary branches per plant, harvest index, kernel yield per plant and number of kernels per plant indicate that these are predominantly influenced by additive gene action and the possibility of phenotypic selection in early generations. High heritability coupled with moderate genetic advance as percent of mean for number of primary branches per plant and moderate heritability coupled with moderate genetic advance as per cent of mean for 100-kernel weight indicate the role of both additive and non additive gene action with preponderance of additive genetic variance and selection would be effective to some extent.

Correlation Between Traits and Path Analysis Coefficient for Grain Yield and other Components in Rice (Oryza Sativa L.) Genotypes.

Current research was conducted out at the Wet land farm of S.V. Agricultural College, Tirupati during kharif, 2011 and rabi, 2011-12 crop seasons. The objective was to establish the nature of relation between grain yield and yield components by partitioning the correlation coefficients between grain yield and its components into direct and indirect effects by using simple correlation and path analysis. A correlation coefficient and path analysis study was conducted with six parents and their 15 F1 crosses for eleven component characters including grain yield. The obtained results indicated that number of grains per panicle, total number of productive tillers per plant, harvest index, kernel L/B ratio, milling percentage and panicle length showed highly significant positive association with grain yield per plant. In the path coefficient analysis, number of grains per panicle and total number of productive tillers per plant should be considered as the main yield components because these traits showed the highest positive direct effects towards increasing grain yield with the values of +0.773 and +0.572, respectively. Depending on the findings of present study, number of grains per panicle and total number of productive tillers per plant may be used an effective selection criterion to improve genetic yield potential of rice genotypes.

Targeting of traits through assessment of interrelationship and path analysis between yield and yield components for grain yield improvement in single cross hybrids of maize (Zea mays L.).

In an attempt to study the association of different quantitative traits in improving grain yield in maize hybrids, correlation and path studies were conducted between yield and yield contributing characters. Association studies revealed that, ten out of fifteen characters exhibited highly significant positive correlation with yield per plant. However, the highest correlation was evident for number of kernels per row (rp= 0.8784**). While, the traits viz., days to 50 per cent silking and days to 50 per cent tasseling displayed highly significant negative correlation with yield per plant. Path analysis revealed that, eight traits exerted positive direct effects on yield per plant. However, the trait cob length exerted maximum positive direct effect on grain yield per plant. On contrary, some of the characters viz., days to 50 per cent silking, anthesis-silking interval, leaf area index, days to 50 per cent maturity, SPAD chlorophyll and number of branches per tassel exerted negative direct effects on yield per plant. The present study revealed that, direct selection for number of kernels per row, cob length, cob girth and 100-seed weight might be rewarding for the improvement of yield using the present elite inbreds and their F1 hybrids.