Studies on Gene Action and Character Association Among Quantitative Traits in Forage Sorghum (Sorghum Bicolor L. Moench)

Abstract

The present investigation entitled “Studies on gene action and character association among quantitative traits in forage sorghum (Sorghum bicolor L. Moench)” was conducted to carried out the genetic analysis of breeding material through components of variance, nature and magnitude of gene effects, genetic variability, heritability, genetic advance, correlation coefficients, general and specific combining ability effects and heterosis among yield and it components in parents and F1’s hybrids. Ten diverse parents i.e., HC-171, Pratap Chari-1080, MP Chari, HJ-513, CSV-21, Gwalior Local, HC-260, Pant Chari-7, Pusa Chari-23 and Varsha, germplasm selected from MPUA&T, Udaipur, Rajasthan. Ten parents diallel set excluding reciprocals was made during the season of kharif 2017 by raising the crop at Crop Research Centre of Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut. All the 45 crosses and their ten parents were grown during kharif season 2018. All the 45 F1’s hybrids along with ten parents were sown in randomized block design with three replications. Observations were recorded on 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.Analysis of variance for parents and crosses showed highly differed significantly for all the ten 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. Parents vs crosses were found highly significant for all the traits, indicated that wide genotypic differences among the parental lines and F1’s hybrids.High heritability coupled with high genetic advance as percent of mean was observed for the characters i.e., days to 50% flowering, plant height, leaf breadth, leaf length, stem girth, leaf area, total soluble solids and green fodder yield, suggesting that the genes governing these characters may have additive effect.Green fodder yield exhibited significant stable and positive correlation with plant height, leaf length, stem girth, leaves per plant and leaf area at genotypic and phenotypic level, suggesting that selection of these characters may be practiced for gain higher fodder yield in forage sorghum.Stem girth displayed high order of direct effect on green fodder yield per plant followed by leaf stem ratio, leaf breadth, leaves per plant and days to 50% floweringat phenotypic and genotypic level, indicated that these characters may contribute for increased fodder yield in forage sorghum.Estimates of additive genetic variance D was noted positive significant for plant height, leaf breadth, leaves per plant and green fodder yield, indicated predominance of additive gene action in the inheritance of these attributes. Dominance components H1 and H2 recorded highly significant and positive for all the characters except leaf stem ratio in F1 generation. The estimates of H1 values were higher than the values of H2 for all the characters, indicated that unequal allelic frequencies at relevant loci in the population.Value of F was observed highly significant and positive for all the characters except leaves per plant in F1 generation, which indicates the excess of dominant and positive allele in the parents for governing these attributes. Estimates for degree of dominance (H1/D)½ exhibited to be more than unity in F1 generation for all the ten characters except leaf area, suggested that the existence of over dominance for these attributes.Ratio of gene with positive and negative effects in the parents H2/4H1 was found less than unity theoretical value (0.25) for days to 50% flowering, leaf breadth and leaves per plantin the F1 generation, which indicated that dissimilar distribution positive and negative alleles. Proportion [(4DH1)½+F/(4DH1)½-F)] indicates the ratio of dominant and recessive alleles among the parents. It was recorded more than unity for days to 50% flowering, plant height, leaf breadth, leaf length, stem girth, leaves per plant, leaf area and green fodder yield, which indicated accumulation of dominant alleles in the parents for these traits, whereas, this ratio was less than unity for leaf stem ratio and total soluble solids, reflecting more recessive alleles in the parents. Ratio h2/H2 is an important measure of the group (s) of the genes controlling the character and exhibiting dominance. The value of this ratio was found more than unity for days to 50% flowering and plant heightin F1 generation, indicated that more than one major gene groups are responsible for governing these characters and rest of the characters observed the proportion of h2/H2 less than one unity, indicating the presence of at least one major gene or gene group is controlling these traits.The mean degree of dominance (σ2g/σ2s)1/2 was estimated greater than unity for leaf breadth, stem girth, leaf stem ratio and green fodder yield, indicated the involvement of over dominance for this trait, whereas it was less than unity for days to 50 % flowering, plant height, leaf length, leaves per plant, leaf area and total soluble solids, indicating that the involvement of partial dominance for these attributes. On the basis of overall gca effects and per se performance among the lines, MP Chari, HJ-513, Gwalior Local and Pant Chari-7 were identified as good general combiners for maximum 9 traits including green fodder yield and, Pant Chari-7 for 8 attributes., suggested that these parents may be used in the hybridization programme aimed devolvement of superior genotypes in forage sorghum. On the basis of overall results and fodder yield performance the crosses viz., Pant Chari-7 x Varsha, Pusa Chari-23 x Varsha, CSV-21 x Varsha, Gwalior Local x HC-260, Gwalior Local x Pant Chari-7, CSV-17 x Pusa Chari-23, HJ-513 x Gwalior Local, HC-171 x CSV-21 and HC-171 x Gwalior Localwere identified as best specific combiners for maximum attributes including green fodder yield for 8 to 10 other contributing traits, which may be utilized for obtaining transgressive segregants in the next generation. On the basis of overall findings and per se performance the manifestation of high degree of heterosis over better and mid parent in certain cross combinations i.e., Pratap Chari-1080 x HJ-513, Pant Chari-7 x Varsha, HC-171 x HJ-513, Pratap Chari-1080 x HC-260, MP Chari x Pusa Chari-23, HC-171 x Pratap Chari-1080 and HC-171 x MP Chari, suggested that great possibility to produce higher fodder yield varieties.