秸秆全量还田与氮肥运筹对机插粳稻产量及氮素吸收利用的影响

Effects of Total Straw Returning and Nitrogen Application on Grain Yield and Nitrogen Absorption and Utilization of Machine Transplanted Japonica Rice

以常规粳稻南粳5055、南粳46为材料,在总施纯氮量为300 kg hm–2条件下,设置9∶1、8∶2、7∶3、6∶4、5∶5、4∶6共6种基蘖肥与穗肥比例,探讨秸秆全量还田条件下不同氮肥运筹对机插粳稻产量及氮素吸收利用特征的影响。结果表明,与秸秆不还田相比,秸秆全量还田具有显著的增产效应,南粳5055、南粳46平均增产5.04%、4.64%;随着基蘖氮肥占总施氮量比例的下降,秸秆全量还田机插粳稻产量呈先增后减的趋势,基蘖氮肥与穗氮肥比例为7∶3时,水稻产量最高。相同氮肥运筹模式下,秸秆全量还田处理水稻拔节期及移栽至拔节阶段的群体干物质积累量均低于秸秆不还田处理,抽穗期、成熟期及拔节至抽穗、抽穗至成熟阶段的群体干物质积累量则高于秸秆不还田处理。氮肥运筹间表现为随基蘖氮肥占总施氮量比例的下降,拔节期及移栽至拔节阶段的群体干物质积累量下降,而抽穗期、成熟期及拔节至抽穗、抽穗至成熟阶段的群体干物质积累量呈现先增后减的趋势。当基蘖氮肥与穗氮肥比例为7∶3时,秸秆全量还田条件下的水稻群体干物质积累量最高,经济系数也最高。秸秆全量还田水稻拔节前的氮素积累量低于秸秆不还田处理,拔节至抽穗、抽穗至成熟阶段的氮素积累量则高于秸秆不还田处理,秸秆全量还田处理的氮肥表观利用率、氮肥农学利用率和氮肥偏生产力均高于秸秆不还田处理。不同氮肥运筹间表现为随基蘖肥占总施氮量比例的下降,氮肥表观利用率、氮肥农学利用率、氮肥生理利用率及氮肥偏生产力均呈现先增后减的趋势,当基蘖氮肥与穗氮肥运筹比例为7∶3时最高。

Two regular japonica rice cultivars in Jiangsu(Nanjing5055and Nanjing46)were adopted in this study.The aim ofthis study was to discuss the influence of different nitrogen fertilizer applications on yield nitrogen absorption and utilization inmechanical transplanted japonica rice,under the condition of total straw returning.Total amount of nitrogen fertilizer was300kgN ha–1,with treatments of different basal-tillering/panicle fertilizer ratios,including9:1,8:2,7:3,6:4,5:5,and4:6.The yield wassignificantly affected by total straw returning as compared with non-application of straw,that of Nanjing5055and Nanjing46increased by5.04%and4.64%reapectirely.The yield of machine transplanted japonica rice with straw returned to the field firstincreased and then decreased with decreasing basal-tillering-fertilizer proportion,and the treatment with7:3of basal-tillering/panicle fertilizer ratio had the highest yield.With the same nitrogen application,dry matter accumulation of total straw returningtreatment was lower than that of the control during the elongation stage and the transplantation to elongation stage,but higher atheading stage,mature stage,elongation to heading stage and heading to maturity stage.With the decrease of basal-tilleringfertilizerproportion,dry matter accumulation was decreased at elongation stage and transplantation to elongation stage,but firstincreased and then decreased during the heading,mature,elongation to heading and heading to maturity stages.In the treatment of7:3of basal-tillering/panicle fertilizer ratio,the dry matter accumulation,and economic coefficient were the highest in wholestraw returning treatment.In the whole straw returning treatment,compared with the control,the nitrogen accumulation was lowerbefore elongation,but higher at elongation to heading and heading to maturity stages.In addition,the nitrogen apparent efficiency,nitrogen agronomic efficiency and nitrogen partial factor productivity were also higher than thase of the treatment without strawapplication.In different nitrogen fertilizer applications,with the decrease of basal-tillering-fertilizer proportion,the nitrogenapparent efficiency,nitrogen agronomic efficiency,nitrogen physiological efficiency and nitrogen partial factor productivity werefirst increased and then decreased,reaching the highest point when the application proportion of base-tiller nitrogen fertilizer toearing nitrogen fertilizer was7:3.