水氮管理模式对不同氮效率水稻氮素利用特性及产量的影响

以高产氮高效品种(德香4103)和中产氮低效品种(宜香3724)为材料,通过"淹水灌溉+氮肥优化运筹(W1N1)"、"控制性交替灌溉+氮肥优化运筹(W2N1)"、"旱种+氮肥优化运筹(W3N2)"3种水氮管理模式处理,研究其对氮素利用及产量的影响及其生理特性,并探讨氮素利用及产量与生理响应间的关系。结果表明,氮效率品种间的差异与水氮管理模式对水稻氮素利用特征、灌溉水生产效率、生理特性及产量均存在显著影响;不同氮效率品种间在氮肥利用效率方面的差异明显高于水氮管理模式的调控效应;而水氮管理模式对灌溉水生产效率、总吸氮量、氮素干物质生产效率及稻谷生产效率的调控作用显著。W2N1相对于W1N1及W3N2水氮管理模式能促进不同氮效率水稻拔节至抽穗期、抽穗至成熟期氮素的累积,提高功能叶谷氨酰胺合成酶(GS)活性、光合速率(Pn)及根系活力,进而提高稻谷产量及氮肥利用率,且对中产氮低效品种的调控效应显著高于对高产氮高效品种,为本试验最佳的水氮管理模式。高产氮高效品种的平均总颖花数、拔节至抽穗期稻株氮累积量、功能叶GS活性、Pn及根系活力均显著高于氮低效品种,尤其结实期高产氮高效品种更有利于维持叶片及根系的代谢同化能力,利于氮素转运、再分配到籽粒中提高稻谷生产效率及氮肥利用效率,是氮高效品种相对于氮低效品种高产、氮高效利用的重要原因。相关分析表明,水氮管理模式下不同氮效率水稻主要生育时期功能叶GS活性、Pn及根系活力与氮素利用及稻谷产量均存在显著或极显著的正相关;尤其以水稻抽穗期剑叶GS活性及根系活力与氮素利用及稻谷产量的正相关性最高。

Effects of Water-Nitrogen Management Patterns on Nitrogen Utilization Characteristics and Yield in Rice Cultivars with Different Nitrogen Use Efficiencies

The optimal water-nitrogen (N) managements and the selection of genotypes with high nitrogen utilization efficiency (NUE) play a vital note in rice production aiming at high yield, high NUE and water-saving irrigation. In order to elucidate effects of water-nitrogen management patterns on N utilization characteristics, grain yield and its physiological basis in rice cultivars with different NUEs. Two different NUE rice cultivars with high-yield and high N-efficiency (Dexiang 4103) as well as medium-yield and low N-efficiency (Yixiang 3724), were used with three water-nitrogen management patterns, including standing irrigation and optimized N application (W1N1), alternate irrigation and optimized N application (W2N1), and dry cultivation and optimized N application (W3N2). The relationship between yield or N utilization characteristics and glutamine synthetase (GS) activity, photosynthetic rate (P_n) and root activity was investigated. The results showed that rice cultivars with different NUEs and water-nitrogen management patterns significantly affected N utilization characteristics, irrigation water use efficiency, physiological characteristics and grain yield. The regulation effects of water-nitrogen management patterns on NUE indexes (physiological efficiency, agronomy efficiency, and N recovery efficiency) were lower than those of rice cultivars with different NUEs, while theeffects of water-nitrogen management on irrigation water use efficiency, total N accumulation, N dry matter production efficiency, and N production efficiency were significant. Compared with W1N1 and W3N2, W2N1 could promote the N uptake from elongation to maturing stages, enhance activity of GS, P_n, and root activity, and then improve grain yield and NUE of two different NUE rice cultivars, being the best model in this experiment. Moreover, the regulation effects of water-nitrogen management patterns on the cultivar with medium-yield and low N-efficiency were significantly higher than these with high-yield and high N-efficiency rice cultivars. The results also showed that average total spikelet number, N accumulation from elongation to heading stages, GS activity and P_n of leaves, and root activity of high N-efficiency rice cultivar were higher than those of low N-efficiency rice cultivar. Especially, during filling stage compared with medium-yielding and low N-efficiency cultivar, the high-yielding and high N-efficiency rice cultivar was more beneficial to higher metabolism and assimilation capacity of leaves and roots, which is the important reason for high-yielding and high N-efficiency rice cultivar further to increase yield and NUE. Correlation analysis indicated that there existed significantly positive correlations of GS activity and P_n of leaves, and root activity in the two N-efficiency rice cultivars with indices of N uptake and utilization and yield, furthermore, the maximum correlation coefficients of GS activity of leaves and root activity with yield or NUE were observed at heading stage.