Australian mungbean yields are constrained by a range of biotic (major diseases and insects pests), and abiotic (flooding/waterlogging, drought, heat, salinity, and nutrient deficiency) stresses. In this thesis, several mungbean genotypes were compared for their response to drought, waterlogging, Mn toxicity, and nodulation under varying levels of nitrate in growing medium. Four AgriVentis Mungbean genotypes (AVTMB#1, AVTMB#2, AVTMB#3 and AVTMB#4), as selected from prior evaluation by CQU cropping research group for high yields in field conditions of central Queensland, were compared with the current leading mungbean variety (Jade-AU) in Central Queensland, Australia. When drought stress was imposed at the flowering stage (R1), two chlorophyll a fluorescence parameters, excitation pressure (1-qP) and effective quantum yield of photosystem II (ФPSII) measured at R1, were decreased in proportion to the final yield decrease, and are therefore recommended for use in screening programs for drought tolerance. Significantly higher yield performance under the drought stress conditions and higher Instantaneous water use efficiency (iWUE) was achieved by AVTMB#1 and AVTMB#4, with a 39 and 38% higher seed yield, respectively, than Jade AU. When plant roots were waterlogged at the pod filling stage (R4), gas exchange and chlorophyll a fluorescence measured 30 days after stress imposition decreased in proportion to the decline of final yield. The chlorophyll a fluorescence parameter, excitation pressure (1-qP), and photosynthetic rates (Asat) were correlated with seed yield, hence recommended for use in screening programs for waterlogging tolerance. Genotype Jade-AU and AVTMB#3 experienced the lowest yield penalty under waterlogging among the five genotypes, with a 13.6 and 21.7% yield decline, respectively, relative to non-waterlogged conditions. Waterlogging of poorly draining soil types resulted in increased levels of manganese (Mn) in the soil solution. In a 15-day seedling trial in hydroponic culture involving the five genotypes, Mn concentrations as low as 284 μM resulted in a decline in plant growth, leaf chlorophyll contents and chlorophyll a fluorescence of dark-adapted leaves (Fv/Fm), while causing a significant increase in total antioxidant in leaves. Furthermore, the uptake of Mn in shoots and roots was investigated at a 284 μM level and results revealed that more Mn was accumulated in roots than in shoots, however, it did not discriminate among genotypes. At Mn levels of 284 μM and 1136 μM, genotypes Jade-AU and AVTMB#3 maintained greater leaf chlorophyll content and dark-adapted leaf chlorophyll a fluorescence (Fv/Fm) than other genotypes. Furthermore, genotype AVTMB#3 exhibited significantly higher shoot and root lengths. However, shoot and root dry weights were not significantly different between genotypes.