水氮互作下水稻氮代谢关键酶活性与氮素利用的关系

以杂交稻冈优527为材料，设“淹水灌溉”(W₁)、“前期湿润灌溉+孕穗期浅水灌溉+抽穗至成熟期干湿交替灌溉”(W₂)和“旱种”(W₃)3种灌水及不同的施氮量处理，研究对水稻氮代谢酶活性及氮素吸收利用的影响，并探讨各生育期水稻氮代谢酶活性与氮素吸收利用及产量间的关系。结果表明，水与氮对水稻各生育期氮代谢酶活性及氮素吸收利用有显著互作作用，W₂相对于其他灌水处理有助于拔节至抽穗期水稻吸氮量的增加，提高氮素干物质生产效率及稻谷生产效率，而且与施氮量为180 kg hm^-2 耦合能达到提高氮代谢酶活性、增产、提高氮肥利用效率的目的，为本试验最佳的水氮耦合运筹模式；施氮量达270 kg hm^-2 时水氮互作优势减弱，不利于3种灌水方式下硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸合酶(GOGAT)活性的提高，还会导致产量及氮效率的下降。相关分析表明，水氮互作下各氮代谢酶活性与氮素利用特征及产量间存在显著或极显著的相关性，据此可将各生育期功能叶GS活性作为准确判断水稻各生育期氮素积累量的指标；并可将抽穗期剑叶中NR、GS、GOGAT及内肽酶(EP)活性作为综合评价水稻产量及氮效率的指标。

Relationship of Activities of Key Enzymes Involved in Nitrogen Metabolism with Nitrogen Utilization in Rice under Water-Nitrogen Interaction

Hybrid rice Gangyou 527 was used to investigate the effects of three irrigation regimes (submerged irrigation, W_1; dry cultivation, W_3; and damp irrigation before booting stage plus shallow irrigation at booting stage plus wetting-drying alternation irrigation from heading stage to mature stage, W_2) and different amounts of N application on activities of N metabolism enzymes and N absorption and utilization in rice, and the correlation of the N metabolism enzymes activities in functional leaves with N absorption and utilization and yield at different growth stages. The results showed that there was an obvious interaction between irrigation regime and amounts of N application. Compared with other irrigation treatments, the treatment W_2 promoted the N up-take from tillering to heading, N dry matter production efficiency (NMPE) and N production efficiency (NPE). W_2 and suitable Napplication amount (180 kg ha~(-1)) enhanced activities of N metabolism enzymes, yield, and nitrogen use efficiency, being the best model in this paper referred as the water-nitrogen coupling management model. Applying nitrogen 270 kg ha~(-1) resulted in nega-tive effect of water-nitrogen interaction, slowing down the increase of activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT), decreasing N agronomy efficiency (NAE), N recovery efficiency (NRE), and yield. Correlation analysis indicated that there existed significantly or highly significantly positive correlations of activities of N me-tabolism enzymes with indices of N uptake and utilization and yield, with different correlation coefficients of different growth stages. According to the conditions above, GS activity in function leaves might be a candidate indicator for N uptake and accu-mulation at different growth stages, and activities ofNR, GS, GOGAT, and endopeptidase (EP) in flag leaves at heading stage for rice yield and NMPE, NPE, NAE, NRE.