氮肥优化管理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

【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/hm^2,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/hm^2,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】OPT_s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,OPT_s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OPT_s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。

【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 Nmanagements 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/hm^2, 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/hm^2, OPT）, the N rate was substituted by 20% N with organic fertilizer base on OPT treatment（OPT1） and the N rate was substituted by20% 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（PFP_N）,N agronomy efficiency（AE_N） and N recovery efficiency（RE_N） in OPTs were increased by 99.4%, 137.6% and70%, 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.