Generation Mean Analysis for Yield, its Components and MYMV Disease Resistance in Greengram [Vigna radiata (L.) Wilczek]

Background: Greengram or mungbean is a diploid (2n=22) autogamous leguminous crop. The average global yield is low and stagnant over years in the entire tropical and subtropical Asia. Any improvement in the yield is hard, predominantly because of pest infestation and diseases. Viral diseases result in significant financial losses due to drop in seed yield and quality in many important crops including greengram. Mungbean yellow mosaic disease (MYMD) can lead to yield loss up to 85% in greengram in epidemic conditions.Methods: The present study was conducted at Department of Genetics and Plant Breeding, Faculty of Agriculture, Annamalai University during the period August-October 2020 in three crosses of greengram viz., PLM 506 x IC 76417, PLM 506 x IC 76381 and IC 398746 x IC 76417. The mean data of five basic generations viz., P1, P2, F1, F2 and F3 of three crosses were evaluated. Populations were screened for MYMV disease resistance by employing infector row method. Scaling test was done using the mean values of various generations for the characters. Significance of scale C suggested dominance x dominance (l) type of gene interaction, whereas the significance of scale D showed additive x additive (i) type of gene interaction. The significance of any of the scaling tests proposes inefficacy of simple additive-dominance model. Five genetic effects viz., mean effect (m), additive (d), dominance (h), additive x additive (i) and dominance x dominance (l) was estimated.Result: Hundred-seed weight showed additive-dominance model in the cross PLM 506 x IC 76417. The additive as well as additive x additive type of gene action were in control of number(s) of clusters per plant, percentage of disease infection and most of yield components in the cross PLM 506 x IC 76417. Hence, selection at a later generation is effective to improve these traits. Pod length was controlled by additive gene action in the cross PLM 506 x IC 76381, whereas percentage of disease infection showed additive dominance model. The additive as well as additive x additive type of gene action were in control of plant height and most of yield components in the cross PLM 506 x IC 76381. In the case of other traits, epistatic model was evidenced. Hence, selection needs to be postponed to a later generation. Based on gene action, these crosses may be employed to evolve high yielding plants with MYMV disease resistance.