Biological Response of Rice Plants to N Form Under Condition of Partial Root Water Stress at Tillering Stage

Effects of different nitrogen forms(NO_3~——N,NH_4~+-N and the mixture of NO_3~——N and NH_4~+-N) and partial-root water stress on biological response of rice plants were studied by using the method of nutrient solution culture in a split-root system with simulated water stress(by adding PEG,6000).The results obtained are listed as follows: Under non-water stress,NO_3~——N nutrition increased the roots growth of rice plants,while NH_4~+-N nutrition increased the shoot growth;under partial-root water stress,the increase of biomass of rice plants were about 31.7% and 37.7% higher in the mixture supply of NO_3~——N and NH_4~+-N than either sole supply of NO_3~——N and NH_4~+-N,respectively,and the increase of biomass in shoots were about 33.5% and 33.2% higher under the supply of mixture of NO_3~——N and NH_4~+-N than either sole supply of NO_3~——N and NH_4~+-N,respectively.The increase of one part root biomass under non water stress was significantly higher than both of the other part of root grown under water stress and all of the roots grown under non water stress when NO_3~——N was supplied as the nitrogen source.There was no significant difference between the increase of biomass of two parts of roots either grown under non water stress or grown under water stress when NH_4~+-N or the mixture of NO_3~——N and NH_4~+-N was supplied as the nitrogen source,which was higher than the increase of dry biomass of both of the roots grown under non water stress.Therefore it was concluded that ammonium nutrition might enhance the resistance to drought stress of rice plants and practical maintain of certain amount of ammonium in soil can significantly alleviate the reduction of rice plants caused by drought stress.