Genetic variability, correlation coefficient and path analysis for quantitative characters under rainfed ecosystem in the native landraces of rice

A study to find out the genetic parameters, correlation coefficients among yield and yield components, direct and indirect effects of yield components on the yield in the native landraces of rice under Rainfed ecosystem was carried out. 124 rice landraces collected from Bolangir district of Orissa were transplanted in two replications and the data was recorded on ten competitive plants in each accession. The estimates for PCV were higher than GCV for all the traits indicating the effect of environment on the manifestation of traits. The flag leaf width showed the highest estimate followed by panicle length, number of primary branches/panicle, yield/plant and number of effective tillers/plant. From the study of PCV and GCV, the flag leaf width, panicle length, number of primary branches/panicle, yield/plant and number of effective tillers/plant were found to be the important characters. Both the heritability and genetic advance were found high for the number of grains/panicle, number of primary branches/panicle and 1000-grain weight, which indicated the governance by additive gene action. The panicle length, 1000-grain weight, harvest index, biological yield, flag leaf length and its width had high heritability but low genetic advance suggesting that these traits had greater influence of the non-additive gene action with a big role of non-genetic factors in their expression. Moderate heritability estimates associated with moderate genetic advance for some traits suggested that additive and non-additive gene effects were equally important in the inheritance of these characters. The coheritability estimates were highest between harvest index and 1000-grain (48.71) followed by yield/plant and number of grains/panicle (44.71), flag leaf length and plant height (43.15), and number of grains/panicle and panicle length (41.72). A negative coheritability was found between biological yield and harvest index (−39.41), 1000-grain weight and number of grains/panicles (−33.31), 50% flowering and panicle length (−2.74) and 50% flowering and number of primary branches/panicle (−2.94). The yield/plant had positive association with plant height, number of effective tillers, panicle length, primary branches/panicle, number of grains/panicle and 1000-grain weight, harvest index, biological yield, flag leaf length and its width and days to 50% flowering. The path coefficient analysis at phenotypic level revealed that 1000-grain weight had the maximum direct effect on the grain yield followed by number of primary branches, harvest index, number of effective tillers and flag leaf length. Plant height though showed the positive correlation with grain yield but had negative direct effect and contributed indirecdy through harvest index. At the genotypic level, panicle length had maximum direct effect on the grain yield followed by number of grain/panicle, 1000-grain weight, harvest index and flag leaf width.