By using the method of nutrient solution culture and simulated water stress with PEG6000,the combination effects of nitrogen forms,water stress and exogenous gibberellic acid(GA3)on physiological attributes and growth of rice( Oryza sativa L. cv. , Jinyou 402) were studied. The trials had 15 treatments of three water conditions ( non-water stress, water stress, water stress and GA3 ) and five nitrogen nutrients conditions ( NH4+ -N/NO-3 -N of 0/100,25/75,50/50,75/25,100/0). The results obtained were as follows: Water stress reduced the leaf area, leaf relative water content ( RWC ) , chlorophyll concentration, but it increase proline accumulation in rice plant. GA3 largely enhanced the above physiological parameters to levels similar to control. Exogenous application of GA3 improved the water stress tolerance in rice plant by maintaining membrane permeability, enhancing chlorophyll concentration,leaf relative water content( RWC)and leaf area. Mixture of 25% NH4+ -N and 75% NO-3 -N was the best nitrogen nutrition condition for rice plant to relieve the water stress under water stress condition, but it was the nitrogen nutrition condition of 50% NH4＋ -N and 50% NO-3 -N in mixture of water stress and GA3 condition.%以水稻品种金优402为研究材料,采用营养液培养,聚乙二醇模拟水分胁迫的方法,研究不同形态氮素营养和水分胁迫条件下,外源激素赤霉酸对水稻生理特性和生长的影响.试验设置3种水分条件和5种氮素营养(NH4+-N/NO3--N为0/100,25/75,50/50,75/25,100/0)条件,共15个处理:即正常水分处理,作为试验的对照；水分胁迫处理和水分胁迫加赤霉酸处理.结果表明,水分胁迫抑制水稻叶面积扩展,降低叶片相对含水量和叶绿素含量,增加脯氨酸的积累；添加赤霉酸则将除脯氨酸外的上述水稻的各项生理参数显著地提高到接近对照的水平.添加外源赤霉酸可以通过维持水稻膜渗透、增加叶面积、提高叶片相对含水量和叶绿素含量等生理机制,改善水稻幼苗对水分胁迫的适应能力.在水分胁迫下,NH4+-N/NO3--N为25/75的氮素营养最有利于缓解胁迫的影响,水分胁迫添加赤霉酸后,则以NH4+-N/NO3--N为50/50的氮素营养效果最佳.
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