GENETIC VARIABILITY, HERITABILITY, CORRELATION AND PATH COEFFICIENT ANALYSIS FOR GRAIN YIELD AND ITS CONTRIBUTING TRAITS IN WHEAT CROSSES UNDER DIFFERENT ENVIRONMENTS

Abstract

Seven parents of bread wheat were crossed in 2013-14 in a half diallel pattern. In 2014-15 season, 7 parents and their 21 F1 crosses were grown at two sowing dates , viz. 15th of November (Recommended sowing date) and 5th of December (late sowing date). A field experiment was devoted for each sowing date and laid out in a randomized complete blocks design with three replications. The results revealed that the additive (VA) and dominance (VD) variances were significant for all studied traits at both sowing conditions and their combined data, except VD for flag leaf area at late sowing date. However, the magnitude of VA was larger than that of VD under the two sowing dates and their combined data. High narrow sense heritability values were obtained for days to heading and plant height under both sowing dates as well as number of spikelets spike-1 and grain yield plant-1 under late sowing conditions. Moderate heritability values were detected for number of kernels spike-1 at both sowing dates as well as number of spikelets spike-1, flag leaf area and grain yield plant-1 at normal sowing date. On the other hand, low heritability values were found for 1000-kernel weight and number of spikes plant-1 under both environments as well as flag leaf area at late sowing conditions. These results indicated the importance of choosing the favorable environmental conditions for exhibiting the best expression of genes for different traits. Significant and positive correlations were found between grain yield plant-1 and each of days to heading, flag leaf area, plant height, number of spikelets spike-1 and number of kernels spile-1 at both sowing dates as well as number of spikes plant-1 at late sowing date. Results of path coefficient analysis illustrated that number of kernels spike-1, flag leaf area and plant height under both environments followed by number of spikelets spike-1 under late sowing conditions proved to be the major contributors in grain yield variation. Thus, these traits should be considered as selection criteria for wheat yield improvement under the target environments.