Genetic variability in guinea grass

Abstract

Thirty guinea grass clones were evaluated in a field experiment laid out in an RBD with two replications at the Instructional Farm, College of Agriculture, Vellayani during 1990. Data on nine biometric characters and fodder yield were collected and subjected to analysis of variance and co-variance. Genetic parameters like heritability, genetic advance and correlations were estimated. The path anlysis was done to assess the cause-effect relationship and discriminant function analysis was done to formulate selection index for identifying superior clones. The analysis of variance revealed significant difference with respect to all the characters except dry fodder yield. High genotypic and phenotypic variances were observed for number of panicles per hill, leaf length, and plant height. High phenotypic and genotypic coefficients of variation were observed for number of panicles per hill, weight of seeds per hill and leaf-stem ratio indicating the presence of large amount of genetic variability. High heritability estimates were recorded for the leaf length, number of panicles per hill, protein percentage, leaf-stem ratio, leaf breadth, weight of seeds per hill, number of tillers per hill, plant height and leaf area index. High heritability along with high genetic advance observed for number of panicles per hill, weight of seeds per hill, leaf-stem ratio number of tillers per hill, length, leaf area index and leaf breadth indicates additive gene action and the reliability of these characters during selection. High positive genotypic correlation and significant positive phenotypic correlations of green fodder yield with dry fodder yield, plant height, leaf length and leaf area index indicate that selection based on any one of these characters will result in the improvement of green fodder yield. The yield components showed varying degrees of association among themselves. Correlation studies indicate that selection based on plant height, leaf length and leaf breadth will be effective in the improvement of fodder yield. Path analysis revealed that leaf area index had the maximum direct effect on green fodder yield followed by plant height and leaf-stem ratio. Number of tillers per hill exerted negative direct effect on green fodder yield. Based on the results of variability, correlation and path analysis it can be concluded that selection based on plant height, leaf area index and leaf-stem ratio will be effective for the improvement of fodder yield in guinea grass. A selection index was constructed and by practicing twenty per cent selection, six top ranking clones viz. FR 42, MC 14, FR 559, Mackuenii, FR 550 and MC 16 were identified for use in future breeding programmes.