Correlation and D2 analysis in forage sorghum (Sorghum bicolor L. Moench)

Abstract

The present investigation entitled “Correlation and D2 analysis in forage sorghum (Sorghum bicolor L. Moench)” involving thirty nine genotypes was undertaken to examine the genetic variability, heritability, genetic advance, correlation, path coefficient analysis and genetic divergence. All the thirty nine 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), leaves per plant, total soluble solids (%), leaf area (cm2), stem girth (mm), leaf stem ratio and green fodder yield per plant (g). Analysis of variance observed considerable differences among the genotypes for all the traits viz., days to 50% flowering, plant height, leaf breadth, leaf length, leaf area, stem girth, leaves per plant, leaf stem ratio, total soluble solids and green fodder yield per plant, which indicates that wide spectrum of variation among the genotypes. Genotypic and phenotypic coefficient of variation were showed high (more than 25%) for leaf length and stem girth, indicating that scope of importance with respect to these characters through selection. High heritability (> 60%) estimates were recorded for days to 50% flowering, leaf breadth, leaf length, leaf area, stem girth, leaves per plant, total soluble solids and green fodder yield per plant, indicated that these traits may be most potential for further improvement in sorghum. High heritability coupled with high genetic advance were revealed for leaf area, total soluble solids and green fodder yield per plant, which indicates that preponderance of additive gene effects for these attributes and hence may prove useful for effective selection. Green fodder yield recorded significant and strong positive correlation with days to 50% flowering, leaf breadth, leaf length, leaf area, stem girth, leaves per plant and leaf stem ratio at both genotypic and phenotypic level. Therefore, this character is useful to the breeders in selecting suitable plant type. Path coefficient analysis exhibited high positive and direct influence of leaf breadth, stem girth, plant height and leaf area towards green fodder yield. These attributes are to be considered in sorghum improvement programme and direct selection for these characters would be fruitful. The analysis of genetic divergence through Mahalanobis D2 statistics exhibited considerable genetic diversity among genotypes. The thirty nine genotypes were grouped into 6 clusters. The cluster I and III (10 genotypes) having the maximum number of genotypes. This envisaged that the genotypes grouped within a particular cluster were more or less genetically similar to each other and apparent wide diversity was mainly due to the remaining genotypes distributed over rest of the other clusters. Percent contribution and expression of characters towards the genetic divergence play an important role in selecting the superior genotypes among diverse genotypes. Plant height had maximum contribution towards the genetic divergence followed by green fodder yield per plant, leaf stem ratio, leaves per plant, leaf area and stem girth while remaining characters noted very low contribution percent towards the genetic divergence. Maximum intra cluster distance was recorded in cluster V, indicating greater genetic divergence between the genotypes belonging to these clusters and crosses involving genotypes viz., Rajasthan Chari-2, UP Chari-4, HC-171 and HC-260 are suggested. Crosses in the above combinations are expected to provide enough genetic variability to select high green fodder yield and stable segregates in the segregating generations. Genetic divergence study suggested that crosses between the genotypes cluster V (Rajasthan Chari-2, UP Chari-4, HC-171 and HC-260) and genotypes of cluster VI (SSG 59-3, IC-0568396, HC-136, IC-0347570) for getting better hybrid vigour in F1 or better hybrids and also for good recombinants in segregating population.