Comparative Study of Selection Indices Based on Different Weights in Forage Sorghum [Sorghum bicolor (L.) Moench]”.

Abstract

Selection indices are constructed using different weights viz. equal weight, genotypic correlation, phenotypic correlation and path coefficient (direct effects) with all possible combination of traits in forage sorghum (Sorghum bicolor (L.)Moench.) based on six biometrical characters viz. plant height at 50 % flowering (cm), number of tillers per plant, number of leaves per plant, leaf length (cm), leaf width (cm) and green fodder yield per plant (g plant-1) along with their genetic gain and percent relative efficiency relative to fodder yield. The data were collected from a set of forty genotypes of sorghum grown in randomized complete block design with three replications at Main Forage Research Station, Anand Agricultural University, during kharif 2013. Higher relative efficiency of selection indices is observed when equal weight is assigned to the biometrical characters. The index (I134) consisting of plant height at 50% flowering, number of leaves and leaf length has the highest relative efficiency in all the weight methods. Rank correlations between different weight methods in construction of selection index without green fodder yield per plant are highly significant and positive. Also, the genotypes are ranked on the basis of their selection score value. Rank correlations between different weight methods without green fodder yield per plant were highly significant and positive. Thus, they indicated that the ranking of genotypes based on the selection index I134 with highest percent relative efficiency with using equal weight, genotypic correlation, phenotypic correlation and path coefficients taken as weight were more or less similar for all the genotypes on an average. The index with equal weight is finally suggested I134 = 1.0761 X1 - 0.6539 X3 + 6.5097 X4 Where, X1 = plant height at 50% flowering, X3 = number of leaves per plant and X4 = leaf length.