Effects of Waterlogging at Vegetative and Reproductive Growth Stages on Photosynthesis, Leaf Water Potential and Yield in Mungbean

Abstract

The effects of short-term waterlogging on mungbean and recovery from the damage were studied in a plastic greenhouse. Pot-grown plants of two mungbean cultivars, KPS l and CNXP-49 were waterlogged for eight days, at the vegetative and reproductive growth stages. Photosynthetic rate (P), transpiration rate (T_r), diffusive resistance (r_s) and leaf water potential (Ψ_l) were measured at the 1st, 4th and 8th day of the 8-day waterlogging treatment and at the 4th and 8th day after the end of waterlogging. P was reduced significantly by waterlogging. It was reduced by 58 and 64% at the 8th day of waterlogging at the vegetative and reproductive stages, respectively, in KPSl and, by 76 and 82%, respectively, in CNXP49. T_r was reduced by 48 and 66% in KPSl and CNXP-49 respectively, at the 8th day of waterlogging at both stages. The diffusive resistance at the 8th day of waterlogging was increased by 79 and 83%, in KPSl and CNXP-49, respectively, at the vegetative stage, and by 76 and 79% at the reproductive stage. AU these physiological parameters of both cultivars recovered to almost normal values within 4 days after the end of waterlogging at the reproductive stage and within 8 days at the vegetative stage. Waterlogging did not affect Ψ_ι, indicating that the decrease in P and T_r was not associated with leaf dehydration. Waterlogging at the vegetative and reproductive stages significantly reduced the dry matter accumulation during and after the waterlogging in both KPSl and CNXP-49. Final seed yield in KPSI and CNXP-49 was reduced by 16 and 19%, respectively, by the waterlogging at the vegetative stage and by 23 and 30%, respectively, by that at the reproductive stage. Although even short-term waterlogging markedly affected P, T_r and r_s of mungbean, the damage particularly in P and leaf growth was quickly recovered after the end of waterlogging and the reduction of seed yield was less than that expected from the damage in the physiological characteristics. These results, suggest that mungbean has an ability to recover from the short-term waterlogging damage and that the response to^^- waterlogging varies with the cultivar.