基于临界氮浓度稀释曲线的小麦氮肥需求量估测研究

Estimation of Nitrogen Fertilizer Requirement of Winter Wheat Based on Critical Nitrogen Dilution Curve

为探究基于临界氮浓度稀释曲线估测小麦氮素需求量的可行性,基于不同生态区开展的不同品种及氮肥水平的小麦试验,结合小麦临界氮浓度曲线(Nc=4.16W^-0.41),构建了拔节期、孕穗期、抽穗期和开花期四个关键生育时期下,小麦氮营养指数(NNI)、氮素需求量(NR)及相对产量(RY)三者间的关系模型,并进行了验证。结果表明,在江苏地区,当总施氮量在120~180 kg?hm^-2时,小麦的氮素需求量最接近于0,氮营养指数最接近于1,为最优的氮素施用量。氮营养指数与氮素需求量(NNI-NR)在小麦生长的各关键阶段存在极强的线性关系(R^2=0.93~0.97);相对产量与氮营养指数(RY-NNI)在各生育时期呈现线性加平台关系,在开花期表现最好,R^2=0.86;相对产量与氮素需求量(RY-NR)的拟合关系在抽穗期表现最好,R^2值为0.72。NNI-NR验证结果与建模结果一致,即在各时期均表现良好,其中拔节期相关关系最强;但RY-NNI和RY-NR验证结果显示两模型分别在开花期和抽穗期预测效果表现最佳。综上,所构建的NNI-NR、RY-NNI和RY-NR三种模型均具有良好的拟合优度和稳定性,运用基于临界氮浓度曲线的小麦氮营养指数和确立的相对产量水平,可以较好地估测当季的小麦氮素需求量,并进行小麦田间氮素精确管理。

In order to explore the feasibility of estimating the nitrogen requirement of winter wheat based on the critical nitrogen dilution curve,field trials were conducted with different wheat varieties and nitrogen rates in different ecological zones.Based on the critical nitrogen dilution curve(Nc=4.16 W-0.41)of winter wheat,predictive models among nitrogen nutrition index(NNI),nitrogen requirement(NR)and relative yield(RY)were built and validated at different key growth stages,including jointing,booting,heading and anthesis.The results showed that,in Jiangsu Province,the nitrogen requirement of wheat was closed to 0 when the nitrogen application rate was 120-180 kg?hm^-2,and the nitrogen nutrition index was closed to 1,which was optimal for nitrogen fertilizing.Nitrogen nutrition index-nitrogen requirement model(NNI-NR)had a strong linear relationship at the critical stage of wheat growth(R^2=0.93-0.97),and relative yield-nitrogen nutrition index model(RY-NNI)performed strong linear plus plateau relationship at each stage.The best stage is anthesis,with R^2 value of 0.86.As for the relative yield-nitrogen requirement model(RY-NR),correlation of heading stage(R^2=0.72)is stronger than that of others.The validation results of NNI-NR were consistent with the modeling results,which means all models performed well in every period and best for jointing stage.The validation results of both RY-NNI and RY-NR models performed best at anthesis and heading stages,respectively.It was found that the three models(NNI-NR,RY-NNI,and RY-NR)have robust relations and can be used to predict the nitrogen requirement of winter wheat for superior nitrogen regulation based on nitrogen nutrition index and relative yield.