Morphological and agronomic traits variations for mungbean variety selection and improvement in Uganda.

Mungbean ( Vigna radiata L. Wilczek ), is a pulse species that is widely  cultivated in sub-tropical and tropical regions of the world. Unfortunately, the yield of mungbean in Uganda is very low mainly due to inherent genotype failures and losses due to pests and diseases. To achieve a gain in yield through breeding requires collection, characterisation, and evaluation of germplasm, as the first step in identifying genotypes with the desired characteristics. The objective of this study was to describe the nature and extent of genotypic variation among mungbean collections for a range of traits of potential agronomic and adaptive interests in Uganda. A total of 35 mungbean accessions acquired mainly from the World Vegetable Centre (AVRDC) in Taiwan, two local ricebean (Vigna umbellata (Thunb.) Ohwi and Ohashi) and one local blackgram genotype (Vigna mungo) were evaluated for several diverse traits for two cropping seasons at two different locations in Uganda. Genotype by environment interaction (GEI) was significant (P < 0.001) for all the traits, indicating inconsistent performance by some genotypes across two locations and two seasons. However, AMMI bi-plot identified stable genotypes for grain yield, while GGE bi-plot identified the best genotypes in a hypothetical environment. The magnitudes of estimated broad sense heritability (H) for the traits used were generally high. However, single link dendogram and Principal  Component Analysis (PCA) revealed narrow diversity in the mungbean collection. The positive relationship between seed size and yield in this sub-set of mungbean germplasm can be used in a breeding programme for a potential gain in selecting large seeded and high yielding genotypes. Key Words : Vigna mungo, Vigna radiata, Vigna umbellata