不同土壤水势与氮素营养对杂交水稻生理特性和产量的影响

以超级杂交水稻“两优培九”为试验材料，研究了不同土壤水势和氮素营养对其生理特性和产量及氮肥利用率的影响。结果表明， 1）同一土壤水势下，植株地上部分干重与总干重随氮肥水平的提高而提高，而根冠比则降低。2）在同一氮肥水平下，叶片净光合速率、叶绿素a和叶绿素b及其总含量、SPAD值及叶片水势随着土壤水势的降低而降低，而叶绿素a/b、丙二醛的含量和过氧化物酶的活性随之而增加；同一土壤水势下，叶绿素a和叶绿素b及其总含量、SPAD值均随氮肥水平的提高而提高，而叶片水势、叶绿素a/b和丙二醛的含量随之降低。3）在同一氮肥水平下，水稻产量随土壤水势的降低而降低；土壤轻度干旱时，水稻产量高低顺序为高氮中氮低氮；而当土壤水分充足或土壤重度干旱时，则表现为中氮高氮低氮。随着土壤水势的降低，中、高氮处理的氮肥农学利用率降低。试验结果还表明，225 kg/hm2施氮水平在0 kPa土壤水势下有明显的增产效果，过度增施氮肥并不利于水稻增产与氮肥利用率的提高。

Effect of different nitrogen nutrition and soil water potential on physiological parameters and yield of hybrid rice

Super hybrid rice “Liangyou Peijiu” was used as experimental material to study the effect of different nitrogen nutrition and soil water potential on physiological characteristics, yield and agronomic efficiency of nitrogen. The results showed that: 1)Dry weight of shoot and total dry weight of plant increased as nitrogen levels increased at the same soil water potential, but root-shoot ratio was the opposite. 2) Net photosynthetic rate, chlorophyll a, b and total content, leaf SPAD readings and leaf water potential decreased as soil water stress strengthened at the same nitrogen level, while chlorophyll a/b, MDA content and activities of peroxidase were enhanced. Chlorophyll a, b and total content, leaf SPAD readings increased with nitrogen level at the same soil water potential, but leaf water potential and MDA content decreased. 3) Yield decreased with soil water potential at the same nitrogen level. When soil water potential was medium, yield was HN NNLN, while yield was NNHNLN under the conditions of well-watered soil or severe soil drought. Nitrogen agronomy efficiency of rice under NN and HN conditions decreased with soil water stress. The result indicated that rice yield increased significantly at 225 kg/hm2 and 0 kPa soil water potential, and there was negative effect on grain yield and nitrogen agronomy efficiency under excessive nitrogen conditions.