Shading effect on photosynthetic rate and gas exchange characteristics of mungbean and blackgram

Abstract

Abstract : Effect of four different shading on quantum yield and leaf gas exchange of mungbean and blackgram was evaluated. Mungbean plants grown under full sunlight and 25% sun gave similar quantum yield while 25% sun treated blackgram showed a markedly higher quantum efficiency than control plants. The light-photosynthetic response of shade grown mungbean and blackgram presented a typical shade-leaf pattern characterized by photosynthetic reduction and low light saturation point. The light limiting condition resulted in a reduction in net photosynthesis (Pn) rate, stomatal conductance (gs) and mesophyll conductance (gm). The reduction of Pn rate in all light intensities at flowering and pod filling stages was higher in mungbean than in blackgram. The decrease in mesophyll conductance may be attributed to the increase of intercellular C02 concentration (Ci).