Effects of Nitrogen Forms and Water Stress on Nitrogen Uptake of Rice Plants at the Seedling Stage

By using the method of nutrient solution culture and simulated water stress with PEG6000,the effects of different nitrogen forms(NO3——N,NH4+-N and the mixture of NO3——N and NH4+-N)and water statuses(non-water stress and water stress condition)on N uptake of rice plant at the seedling stage were studied.The results showed that:Under non-water stress,N consumption of NO3——N supplied rice plant was higher than that of NH4+-N supplied rice plant.Under water stress,supply of mixture of NO3——N and NH4+-N significantly promoted N consumption of rice plant,and N consumption of rice plant supplied with NO3——N had a little increase.Water stress had no significant effect on N consumption of NH4+-N supplied rice plant.Under water stress,supply of mixture of NO3——N and NH4+-N increased N content of rice plant,but it had no significant effect on N content of NH4+-N supplied rice plant.Under non-water stress,the nitrogen-use efficiency of rice plants was higher under the supply of mixture of NO3——N and NH4+-N than the other two treatments.After water recovery,supply of mixture of NO3——N and NH4+N significantly promoted nitrogen-use efficiency of rice plants.Water stress had no significant effect on nitrogen-use efficiency of NH4+-N supplied rice plant,but significantly reduced in NO3——N supplied rice plant.Under non-water stress or water stress,the nitrogen-use efficiency of NO3——N supplied rice plant was the lowest among the three nitrogen forms treatments.