Genetic diversity and association studies for yield attributing traits in bread wheat [Triticum aestivum (L.) em. Thell]

The present study was conducted to assess the variability parameters, diversity, correlations and path coefficient for eight metric traits in 44 diverse genotypes of bread wheat. Significant genotypic differences were observed for all the traits studied indicating considerable amount of variation among genotypes for each character. The highest genotypic and phenotypic coefficient of variation was observed for harvest index (%), biological yield per plant (g), tillers number per plant and grain yield per plant (g). Similarly, high heritability and genetic advance were also observed for these traits indicating the scope for their improvement through selection. Positive and significant correlation of grain yield/plant was recorded with harvest index (%), biological yield per plant (g) and tiller number per plant. Biological yield per plant (g) showed the highest direct effect on grain yield which was followed by harvest index (%). Based on Euclidean cluster tree analysis the 44 bread wheat genotypes were grouped in five clusters in such a way that genotypes within each cluster had higher similarity than between clusters i. e. the genotypes within the cluster had much smaller distance than the genotypes belonging to different clusters. Maximum divergence was present between clusters I and IV (5.826) followed by IV and V (5.288) followed by clusters III and IV (4.992). Cluster I was highly desirable as it consisted of genotypes which were good in respect to one or more characters and atleast comparable in respect to other characters. These genotypes can be used for success of breeding programme as divergent parents can lead to recovery of transgressive segregants with high genetic yield potential. Selection of genotypes with better mean yield coupled with optimum harvest index (%) should result in progenies with high grain yield potential in wheat.