Variability of biological nitrogen fixation traits and yield components in blackgram

Abstract

A research programme was carried out at the Department of Agricultural Botany, College of Horticulture, Vellanikkara, Trichur during October – March 1993 -94, with the objectives of assessing the genetic variability for biological nitrogen fixation traits and yield components in blackgram as a preliminary step to develop high yielding varieties with good biological nitrogen fixation capacity. Thirty three varieties of blackgram were evaluated, adopting a randomised block design with two replications. Data on thirteen characters were collected and subjected to analysis of variance. The genotypic and phenotypic coefficients of variation, heritability, genetic advance and genotypic and phenotypic correlations were estimated. Analysis of variance revealed significant differences among the varieties for all the characters except number of pods, number of seeds per pod and harvest index. High heritability coupled with high genetic advance was recorded for weight of nodules in the secondary roots and number of secondary roots suggesting the reliability of these characters during selection programmes for the improvement of the nitrogen content of this crop. Grain yield recorded high positive genotypic correlation with most of the yield components, biological yield and harvest index ; and negative genotypic correlation with nitrogen content in the plant at 50 per cent flowering. High positive genotypic correlation of number of pods per plant and number of seeds per pod with grain yield per plant, indicating that selection based on one or more of the above components may result in the improvement of grain yield. Weight of nodules in the secondary roots, which had high variability, heritability, genetic advance and genotypic correlations with nitrogen content in the plant at 50 per cent flowering and harvest index may be considered during selection programmes for identifying blackgram genotypes having high nitrogen fixation capacity.