Forty black gram [Vigna mungo (L.) Hepper] genotypes were evaluated using principal component analysis to estimate the extent of genetic diversity for ten different yield and its component traits. The first three principal components viz., PC I, PC II and PC III with eigen values more than one contributed around 80% of the variability for the genotypes studied. PC I contributed 46.834% towards variability and the traits responsible for its contribution are viz., number of clusters per plant, grain yield per plant, number of branches per plant and number of seeds per pod. The second axis (PC II) contributed 18.951% variability and variation at this axis is due to the accumulated genetic variation of traits viz., days to 50% flowering, days to maturity, grain yield per plant and number of clusters per plant. While PC III and PC IV accumulated 13.807% and 5.765% respectively. Therefore on a cumulative note, first four axes contributed about 85.357% of total variance among 10 characters for all the forty genotypes under study. In the current investigation, four lines (TU 94-2, PU 31, IPU 94-1 and LBG 623) are identified from the depicted 2D & 3D figures as diverse genotypes, which may yield transgressive segregants or heterotic F1s based on nature of gene action of the trait in question.

Background: Yellow mosaic disease (YMD) caused by Mungbean Yellow Mosaic Virus (MYMV) is one of the most destructive biotic constraints for production in urdbean. Development and introduction of resistant cultivars with high seed yield is considered as the most economical and eco-friendly option to manage YMD, for which understanding the gene action controlling the inheritance of different traits along with YMD resistance is an important requirement. Methods: Material comprised of four diverse genotypes (TU 94-2, PU 31, IPU 94-1 and LBG 623), six F1s, six BC1s and six BC2s and six F2s. These six generations of all the six crosses were evaluated for various yield related traits in rabi, 2020-21 and phenotyped for YMD in summer, 2021 at Lam, Guntur, Andhra Pradesh which is hotspot for YMD. Result: Inadequacy of additive-dominant model for all most all traits including YMD except for test weight was observed. It was found that, [l] type of non-allelic interaction was observed to be predominant for majority of the traits. Further, the existence of duplicate type of epistasis in the inheritance was evident at least in few crosses for all the traits (except days to maturity). The duplicate epistasis will reduce the variation in F2 and subsequent generations, thereby hinder the pace of the progress through selection.

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