Abstract:

【Objective】 The objective of the experiment is to study the effects of water-nitrogen management on root traits, nitrogen accumulation and utilization and grain yield in rice with different N use efficiencies, and the relationship between root traits and nitrogen accumulation and utilization and yield.【Method】In this study, two different nitrogen use efficiency (NUE) rice varieties Dexiang 4103 (high NUE) and Yixiang 3724 (low NUE) were used as the trial material to determine the effects of water-nitrogen management on root traits and grain yield in rice with different NUEs, conventional irrigation and controlled alternative irrigation coupled with SPAD-diagnosis N management, optimal N management and farmer’s usual N management were established as treatment factors. During this progress, the relationship between root traits, nitrogen accumulation and utilization and grain yield were analyzed by ridge regression analysis.【Result】There were significant genotypic differences in root traits at heading stage, grain yield, spikelet number per panicle, 1000-grain weight and total spikelet number. The high NUE variety (Dexiang 4103) had more spikelet number per panicle and larger population capacity, with the yield being 0.24%–11.31% higher than that of low NUE variety (Yixiang 3724). Compared with conventional irrigation, the 1000-grain weight under controlled alternative irrigation was significantly larger, while the former was more favorable for improving panicle number, spikelet number per panicle and population spikele number. SPAD-diagnosis-based N management and optimal N management could increase the panicle number and spikelet number per panicle, which increased the population spikelet number, ensuring the grain yield advantage over farmer’s usual N management. Because of the water-nitrogen interaction effect, the gap in 1000-grain weight between N application and zero N treatments under controlled alternative irrigation narrowed considerably compared with that of conventional irrigation, leading to better effect of N application on grain yield under controlled alternative irrigation. The nitrogen use efficiency of Dexiang 4103 was 8.69% higher than that of Yixiang 3724, the nitrogen accumulation of rice under conventional irrigation was higher, as well as the nitrogen recovery efficiency, agronomic efficiency, physiological efficiency under controlled alternative irrigation. SPAD-diagnosis-based N management and optimal N management were more favorable for imroving nitrogen accumulation and utilization efficiency of rice than farmer’s usual N management.The determination coefficient of ridge regression equation between root traits and grain yield of rice at jointing stage, heading stage and maturity stage ranged from 0.4198 to 0.9028. The relationship between root traits at heading stage and grain yield was the most closely related, and the determination coefficients of high NUE and low NUE varieties all exceeded 0.9. At the jointing stage, the rice fine lateral root length had the greatest effect on grain yield. At the heading stage, there was difference between the high NUE and low NUE varieties, and the coarse lateral root length of the former and the fine lateral root surface area of the latter had the greatest effect on grain yield, respectively. In maturity stage, the relationship between adventitious root length and grain yield was the most important. Rice root morphology at heading stage had close relation with the change of nitrogen accumulation, and the determination coefficient of ridge regression equation was close to 0.7. In terms of water and nitrogen management practice, SPAD-diagnosis N management coupled with conventional irrigation or optimal N management combined with alternative irrigation should be applied to achieve grain yield improvement for both high NUE and low NUE varieties.【Conclusion】The root morphology characters of rice at heading stage was closely related to yield and nitrogen accumulation, and the yield and nitrogen accumulation and utilization efficiency of rice could be improved by reasonable water-nitrogen management.

Key words: water-nitrogen management, rice, N use efficiency, root morphology, grain yield

摘要：

目的 探究水氮管理措施对不同氮效率水稻根系构型、氮素吸收利用和产量形成的影响,以及根系性状特征与氮素吸收利用和产量关系。方法 试验采用三因素裂裂区设计,主区为2个不同氮效率水稻品种德香4103(氮高效型)和宜香3724(氮低效型),裂区设置“常规灌溉”和“控制性交替灌溉”2种水分管理方式,裂裂区为SPAD指导施肥、优化施肥以及农民习惯施肥3种施氮模式,运用岭回归分析方法探究根系构型与氮素吸收利用和产量的关系。结果 水稻抽穗期根系性状、产量、每穗粒数、千粒重及总颖花量均存在显著的基因型差异。氮高效品种德香4103每穗粒数多,群体库容量大,产量较氮低效品种宜香3724高0.24%~11.31%;控制性交替灌溉有利于水稻千粒重的增长,常规灌溉则对水稻有效穗数、每穗粒数及群体颖花量提高更为有利;SPAD指导施肥和优化施肥处理能够提高水稻有效穗数和每穗粒数,扩大群体颖花量以保证其对农民习惯施肥的产量优势;由于水氮互作效应的存在,控制性交替灌溉下施氮处理与空白处理水稻千粒重的差距比常规灌溉的大幅降低,使得控制性交替灌溉下施用氮肥的增产效果更佳。德香4103的氮肥生理利用率较宜香3724平均高8.69%,常规灌溉下水稻氮积累量较高,控制性交替灌溉下氮肥回收率、农学利用率、生理利用率均较优;与农民习惯施肥处理相比,SPAD指导施肥与优化施肥模式更有利于水稻氮素吸收利用效率的提高。拔节期、抽穗期和成熟期水稻根系构型与产量岭回归方程的决定系数范围为0.4198~0.9028,其中,抽穗期根系性状与产量关系最为密切,氮高效和氮低效品种的决定系数均超过0.9。在拔节期,水稻细分枝根长对产量影响最大;在抽穗期,氮高效和氮低效品种存在差异,前者是粗分枝根长,后者是细分枝根表面积对产量影响最大;在成熟期,不定根长与产量关系最为密切。水稻抽穗期根系构型对氮积累量变化的解释程度较高,岭回归方程决定系数均接近0.7。就水氮管理措施而言,氮高效和氮低效水稻均应采用常规灌溉配套SPAD指导施肥或控制性交替灌溉结合优化施肥来实现产量的提高。结论 水稻抽穗期根系构型与产量、氮积累量关系密切,采用合理的水氮管理措施能够实现水稻产量和氮素吸收利用效率的同步提高。

关键词: 水氮管理, 水稻, 氮效率, 根系构型, 产量