| Popis: |
The present investigation was carried out to understand the interrelationship and degree of dependence of grain yield on its components and gall midge incidence and to elucidate their relative importance. The experiment was conducted using 42 rice hybrids developed by crossing 6 CMS lines and seven testers in Line X Tester mating design, their parents and four checks. Observations were recorded on gall midge incidence, grain yield and fourteen component characters. Correlation coefficient analysis suggested that grain yield per plant had highly significant and positive association with panicle length (rp = 0.4600**, rg = 0.5545**) followed by number of grains per panicle (rp = 0.4219**, rg = 0.5125**) and number of productive tillers per plant (rp = 0.4006**, rg = 0.4942**) and negative non significant association with gall midge incidence (rp =-0.1154, rg =-0.1430). Panicle length had the highest positive direct effect (0.9688) followed by the number of grains per panicle (0.5748). Gall midge incidence showed a negative direct effect at the phenotypic level and a positive direct effect at the genotypic level on the grain yield per plant. Further, it showed indirect negative effects via plant height, number of productive tillers per plant, number of grains per panicle, spikelet fertility, hulling percentage, milling percentage, kernel length and kernel breadth as revealed from path analysis. The result of multiple linear regression exhibited that only the number of productive tillers per plant and the number of grains per panicle contributed significantly towards grain yield per plant. The step-wise regression analysis revealed that the panicle length, number of grains per panicle and number of productive tillers per plant were the most important characters having R=0.6505 and thus, could explain 42.31% of the total variation of grain yield. Gall midge incidence contributed to only 0.95% of the variation for grain yield, which might be due to the low incidence or resistance of the hybrids to the gall midge. |
