Abstract: A pot experiment was conducted to evaluate the gas exchange, leaf area dynamics and dry matter accumulation of blackgram varieties namely BARI mash 3 and BINA mash 1. The two blackgram varieties did not differ statistically in gas exchange characteristics, leaf area and dry matter accumulation over the growth stages. Blackgram showed highest photosynthesis rate at flowering stage, might be attributed due to higher leaf chlorophyll, higher stomatal and mesophyll conductance and lower intercellular CO₂ concentration, but the highest respiration rate was found at pod filling stage. Leaves of top canopy showed highest gas exchange characteristics followed by the leaves of middle canopy and then bottom canopy. Diurnally, photosynthesis increased gradually with increasing intensity of light and peaked at around noon then decreases. Photosynthesis showed strong correlation with leaf area and dry matter accumulation of blackgram.