Studies on Path Analysis and Genetic Divergence in Forage Sorghum (Sorghum Bicolor L. Moench)

Abstract

The present investigation entitled “Studies on path analysis and genetic divergence in forage sorghum (Sorghum bicolor L. Moench)” involving thirty five genotypes was undertaken to examine the genetic variability, heritability, genetic advance, character association, path coefficient analysis and genetic divergence. All the thirty five forage sorghum genotypes were tested in randomized block design with three replications during Kharif 2022. Observations were recorded for days to 50% flowering, plant height (cm), leaf breadth (cm), leaf length (cm), number of leaves per plant, total soluble solids (%), leaf area (cm2), stem girth (mm), leaf stem ratio and green fodder yield per plant (g). On the basis of ten characters, the thirty five genotypes were grouped into five clusters. Cluster IV was the largest, comprising of ten genotypes followed by Cluster I with nine genotypes, Cluster III represented by eight genotypes and Cluster II have six genotypes, which concluded that in general, there was parallelism between genetic and geographic diversity. Cluster V with two genotypes which independently diverged from others. The magnitude of D2 values suggested considerable diversity among the genotypes. The formation of solitary clusters may be due to the total isolation preventing the gene flow or intensive natural/human selection for diverse adaptive complexes. These genotypes may be very unique and useful in breeding point of view. Ten genotypes grouped under Cluster IV which indicated their proximity and narrow genetic base. The maximum intra cluster distance (2.194) was recorded for Cluster II followed by Cluster I (2.181), Cluster III (1.893) and Cluster IV (1.844) while the minimum intra cluster distance (1.325) was noted in case of cluster V. Genotypes belonging to cluster II (MP Chari, CSV-15, SSV-84, UP Chari-4, Pratap Chari-1080 and CSV-17) observed maximum genetic diversity within the cluster as compared to the genotypes belonging to other clusters. Hence, the presence of high genetic diversity in a population will be useful to take up hybridization programme for isolating good recombinant genotypes. Lowest intra cluster distance was found for cluster V (1.325) suggesting that this cluster genotypes have same genetic constitution i.e., homogeneous are less divergent. Maximum inter cluster distance revealed between Cluster I and V (7.401) followed by Clusters II and V (6.616), Cluster IV and V (5.275), Cluster II and III (4.573), Cluster I and III (4.275), Cluster III and V (3.817), Cluster II and IV (3.231), Cluster I and IV (3.023) and Cluster III and IV (2.934) and the minimum inter cluster distance was recorded between cluster I and II (2.417). Maximum inter cluster distance was observed among the clusters which indicates that crosses among the genotypes included in these clusters may give high heterotic response and thus better segregants to generate new material in forage sorghum. Minimum inter cluster distance was found between cluster I and II, indicated close relationship between the genotypes which is not desirable for hybridization programme. Major percent contribution of green fodder yield per plant followed by plant height, leaf stem ratio, days to 50% flowering, number of leaves per plant and leaf breadth and low contribution of character towards genetic divergence was recorded for stem girth. Green fodder yield per plant, plant height, leaf stem ratio, days to 50% flowering, number of leaves per plant and leaf breadth showing the possibility for selection of these attributes. On the basis of high inter cluster distances, hybridization programme could be taken up between the varieties of HC-260, UP Chari-1, MP Chari, CSV-15, SSV-84, UP Chari-4, Pratap Chari-1080 and CSV-17. Hence, identified these eight genotypes as potential parents will be considered for selection to achieve the best result of the breeding programme. Green fodder yield per plant was found highly significant positive association with leaf breadth, stem girth, leaf area, leaf length, number of leaves per plant, plant height and leaf stem ratio at both genotypic and phenotypic level, indicated that selection of these attributes may be helpful to increase fodder yield in sorghum. Genotypic and phenotypic path coefficient analysis of green fodder yield per plant and its contributing characters showed that stem girth had high positive direct effect on green fodder yield per plant followed by leaf breadth and number of leaves per plant at both genotypic and phenotypic level, suggested that the improvement of these attributes would lead to increase fodder yield. Analysis of variance exhibited high significant differences among the genotypes for all the characters i.e., days to 50% flowering, plant height, leaf breadth, leaf length, number of leaves per plant, total soluble solids, leaf area, stem girth, leaf stem ratio and green fodder yield per plant, indicated wide spectrum of variability among the genotypes. Genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were observed high (>25%) for green fodder yield per plant which indicates that there is a greater scope for selection of superior genotypes for these attributes. High heritability (>60%) in broad sense was revealed for all the traits namely, days to 50% flowering, plant height, leaf breadth, leaf length, number of leaves per plant, total soluble solids, leaf area, stem girth, leaf stem ratio and green fodder yield per plant which indicating that the genotypic control for as above attributes. Estimated of genetic advance expressed as percent of mean was high (>20%) for leaf breadth, leaf length, number of leaves per plant, total soluble solids, leaf area, stem girth, leaf stem ratio and green fodder yield per plant, indicated that good response for selection based on per se performance for these traits. High heritability coupled with high genetic advance as percent of mean recorded for leaf breadth, leaf length, number of leaves per plant, total soluble solids, leaf area, stem girth, leaf stem ratio and green fodder yield per plant which indicates that these characters are associated with additive gene action and selection for these attributes will be more effective.