氮肥优化管理协同实现水稻高产和氮肥高效

【目的】 研究不同氮肥管理方式对水稻生长、氮累积分配和产量的影响，为通过氮肥优化管理提高水稻产量和氮肥利用率提供理论依据。 【方法】 以江苏省如皋市农业科学研究所的长期定位田间试验（2008 年至今）为研究平台，以江苏省沿江及苏南地区主推水稻品种‘镇稻 11 号’为供试材料，设 3 种氮肥管理模式，即:不施氮肥对照（CK）、农民习惯施氮（N 350 kg/hm2，氮肥运筹为基肥∶分蘖肥∶促花肥 = 4:4:2，FFP）和氮肥优化管理（氮肥运筹为基肥∶分蘖肥∶促花肥:保花肥 = 4:2:2:2，OPTs），其中氮肥优化管理包括优化施氮处理（N 240 kg/hm2，OPT）、优化替氮处理（OPT 施氮基础上，有机肥氮替代 20% 化肥氮，OPT1）和优化减氮再替氮处理（OPT 施氮基础上，先减氮 20% 再用有机肥氮替代 20%化肥氮，OPT2），通过在水稻最大分蘖期、拔节期、开花期和成熟期采集地上部植株样品，分析生物量、产量、氮累积和氮转运及其相互关系的差异。 【结果】 OPTs 处理较 FFP 处理平均增产 8.4%，其原因是提高了水稻花后的氮累积和生物量，进而提高了水稻的穗粒数、结实率和千粒重。水稻氮累积和转运的结果表明，FFP 处理主要是通过增加花后植株体内氮转运来提高籽粒氮累积，而 OPTs 处理则主要是通过提高花后水稻植株氮累积来增加籽粒氮累积。同时，水稻氮肥利用率随施氮量的增加而降低，与 FFP 处理相比，OPTs 处理的氮肥偏生产力（PFP_N）、氮肥农学效率（AE_N）和氮肥回收效率（RE_N）分别平均提高 99.4%、137.6% 和 70.0%；且优化替氮处理（OPT1）在稳定增产的基础上仍可进一步提高水稻的氮肥利用率。另外，分析不同氮肥管理模式对水稻的产量贡献阶段可知，相较于 FFP 处理与 CK 处理间的氮肥低产低效阶段，氮肥优化管理则可实现从 FFP 提升到 OPTs 的高产高效阶段。 【结论】 利用氮肥总量控制、分期调控和适量有机替代的氮肥优化管理措施，可协同实现水稻高产和氮肥高效。

Nitrogen optimize management achieves high grain yield and enhances nitrogen use efficiency of rice

Objectives]In order to provide theoretical basis for improving rice yield and N use efficiency, we studied the effect of different nitrogen (N) management models on rice growth, N accumulation and distribution, and yield formation.[Methods]‘Zhendao 11’, a widely planted rice in Jiangsu Province, was used in this study to investigate the biomass, yield, N accumulation, N transport and their relationships under different N managements at four growth stages of rice, including tillering, shooting, flowering and maturity. The experiment was conducted in the long-term fertilizer experiment field from 2008 in the Agriculture Science Research Institute of Rugao, Jiangsu Province. The three N fertilizer management models were designed as follows: free N fertilizer control (CK), farmer’s N fertilizer practices (N 350 kg/hm2, N application of basal:tillering: shooting was 4 : 4 : 2, FFP), and optimum N fertilizer managements (N application of basal: tillering:shooting: flowering was 4 : 2 : 2 : 2, OPTs) that including optimal N treatment (N 240 kg/hm2, OPT), the N rate was substituted by 20% N with organic fertilizer base on OPT treatment (OPT1) and the N rate was substituted by 20% N with organic fertilizer after reducing 20% N base on OPT treatment (OPT2).[Results]The average yield of optimum N managements (OPTs) increased by 8.4% compared with FFP. In OPTs, the kernels per spike, seed setting rate and 1000-grain weight were higher than FFP treatment through improving the accumulation of biomass and N after anthesis. Grain N accumulation in FFP treatment was mainly resulted due to the increased amount of remobilized N from plant N absorption before anthesis, while in OPTs, it was mainly resulted from the increased amount of N uptake after anthesis. Furthermore, the N use efficiency of rice was decreased with increasing application levels of N fertilizer. Compared with FFP treatment, partial factor productivity of N (PFPN), N agronomy efficiency (AEN) and N recovery efficiency (REN) in OPTs were increased by 99.4%, 137.6% and 70%, respectively, and the N use efficiency was further increased in OPT1 treatment. Additionally, the results also showed that the rice yield contribution stages of different N managements, high yield and high efficiency stage from FFP to OPTs was more effective for improving yield than low yield and low efficiency stage from CK to FFP.[Conclusions]The optimum N managements can be coordinated to achieve high yield and high N use efficiency of rice plants by regulated the amount of N fertilizer with side dressing and substituted chemical fertilizer-N through organic fertilizer-N.