D2 Analysis in Forage Sorghum (Sorghum Bicolor L. Moench)

Abstract

The present investigation entitled “D2 analysis in forage sorghum (Sorghum bicolor L. Moench)” comprising thirty seven genotypes was undertaken to examine the genetic divergence, character association, path coefficient analysis, genetic variability, heritability and genetic advance. All the thirty seven forage sorghum genotypes were tested in randomized block design with three replications during Kharif 2021. Observations were recorded for days to 50% flowering, plant height (cm), leaf breadth (cm), leaf length (cm), stem girth (mm), leaves per plant, leaf area (cm2), leaf stem ratio, total soluble solids (%) and green fodder yield per plant (g). 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, stem girth, leaves per plant, leaf area, leaf stem ratio, total soluble solids and green fodder yield per plant which indicated wide spectrum of variability among the genotypes. Genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) were observed high (>25%) for leaves per plant, leaf stem ratio and green fodder yield per plant. High magnitude of GCV and PCV indicated that there is a greater scope for selection of superior genotypes for these attributes. High heritability coupled with high genetic advance as percent of mean recorded for leaf breadth, stem girth, leaf area, leaf stem ratio, total soluble solids and green fodder yield per plant which indicates that these characters are associated with additive gene action and therefore, phenotypic selection for these traits will be more effective. Green fodder yield per plant was found highly significant positive association with stem girth, leaf area, leaves per plant, leaf breadth, plant height, total soluble solids and days to 50% flowering 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 leaf breadth had high positive direct effect on green fodder yield per plant followed by leaf area, stem girth, leaf length and leaves per plant at both genotypic and phenotypic level, which shown that these traits were related with green fodder yield and therefore, improvement of these attributes would lead to increase fodder yield as well. Based on D2 values thirty seven genotypes of sorghum were grouped into six clusters using ten component characters. Cluster I was the largest, comprising of fourteen genotypes followed by Cluster V with eight genotypes, Cluster III represented by six genotypes, Cluster VI have five genotypes, Cluster II with three genotypes, which concluded that in general, there was parallelism between genetic and geographic diversity. Cluster IV have one genotype which independently diverged from others. 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. Fourteen genotypes grouped under Cluster I which indicated their proximity and narrow genetic base. The maximum intra cluster distance (2.38) was recorded for cluster I followed by cluster II (2.32), cluster V (2.25), cluster III (2.03), cluster VI (1.91) while minimum intra cluster distance (0.02) was noted in case of cluster IV. Genotypes belonging to cluster I (G-48, Pratap Chari-1080, Varsha, IC- 0347570, UP Chari-2, CSV-17, Pant Chari-7, Pant Chari-4, IC-056030, IC-0568396, IC-0597651, IC-0597651, UP Chari- 4 and UP Chari-1) observed maximum genetic diversity within the cluster as compared to the genotypes belonging to other clusters. Hence, hybridization could be taken up among these genotypes for obtaining desirable segregants for the fodder yield and yield contributing characters. Lowest intra cluster distance was found for cluster IV (0.02) suggesting that this cluster genotypes have same genetic constitution i.e., homogeneous are less divergent. Maximum inter cluster distance revealed between cluster II and cluster IV (5.81) followed by cluster III and V (5.25), cluster IV and cluster VI (5.21), cluster II and cluster III (4.95), cluster I and cluster IV (4.79), cluster IV and cluster V (4.74), cluster III and cluster VI (3.93), cluster I and cluster V (3.85), cluster III and cluster IV (3.81), cluster I and cluster II (3.70), cluster II and cluster VI (3.63), cluster II and Cluster V (3.60), cluster V and cluster VI (2.87), cluster I and cluster III (2.86) and the minimum inter cluster distance was found between cluster I and cluster VI (2.71). Maximum inter cluster distance was observed among the clusters, indicated 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 indicating close association between the genotypes which is not desirable for hybridization programme. Major percent contribution of green fodder yield per plant was the maximum contributor towards genetic diversity (27.07) followed by leaf length (12.78), leaves per plant (12.27), plant height (11.45), leaf breadth (10.40), stem girth (10.11), total soluble solids (9.36), leaf stem ratio (9.33) and leaf area (8.92) whereas minimum contribution of character towards genetic divergence was recorded for days to 50% flowering (8.32). Green fodder yield per plant, leaf length, leaves per plant, plant height, leaf breadth and stem girth were identified as high contributors towards genetic diversity which could be used as parameters while selecting diverse parents in hybridization programme for further improvement in fodder yield. On the basis of high inter cluster distances, hybridization programme could be taken up between the varieties of MP Chari, CSV-21, Pant Chari-8, IC0597638, UP Chari-3, HC-260, Pant Chari-5, HC-136 and Pusa Chari-9. Hence, identified these nine genotypes as potential parents can be utilized in further breeding programme in which the as above attributes will be considered for selection to achieve the best result of the breeding programme