关中平原冬小麦临界氮稀释曲线和氮营养指数研究

Critical Nitrogen Dilution Curve and Nitrogen Nutrition Index of Winter Wheat in Guanzhong Plain

在整理分析关中平原7年氮肥大田试验的基础上,分析比较了不同氮肥处理下冬小麦的氮浓度稀释曲线,并构建了关中平原主栽品种小偃22地上部生物量的临界氮浓度稀释曲线模型。结果表明：不施氮、氮肥不足、氮肥适宜和过量施氮4组处理的平均产量分别为4 263、5 097、6 023、6 203 kg/hm2,氮肥不足处理显著降低了小麦产量,过量施氮与氮肥适宜处理相比产量没有显著差异。植株氮浓度均随生物量增加而降低,较高的施氮量导致较高的植株氮浓度。关中平原冬小麦临界氮浓度与地上部最大生物量符合幂函数关系。利用氮营养指数NNI（植株实际测定的氮浓度与临界氮浓度的比值）和2010—2011年冬小麦季的独立试验资料对建立的临界氮稀释曲线进行检验,结果表明：不施氮、氮肥不足、氮肥适宜和过量施氮4组处理的NNI值分别为0.70、0.89、1.01和1.25;关中平原各试验地土壤肥力差异较大,冬小麦适宜施氮量为75～180 kg/hm2,平均为137 kg/hm2。该研究建立的临界氮稀释模型的准确性较高,所得出的分析结果可靠,可以用于诊断和调控冬小麦氮素营养。

The critical nitrogen concentration in plant was defined as the minimum nitrogen concentration required for maximum plant above-ground biomass. By collecting and analyzing seven-site-year field experiments with various nitrogen application rates according to certain criteria,the critical nitrogen concentration dilution curve was constructed for the main winter wheat variety ＂Xiaoyan 22 ＂ in Guanzhong Plain. The relationship between maximum above-ground biomass and critical nitrogen concentration of winter wheat could be described by a negative power function. The nitrogen dilution curves affected by different nitrogen treatments were evaluated and compared. Results showed that increased nitrogen supply generally resulted in a greater nitrogen concentration. The winter wheat yield with zero,deficient,suitable and excess nitrogen were 4 263,5 097,6 023 and 6 203 kg / hm2,respectively. Nitrogen deficiency would reduce wheat yield,however,there was no significant difference between the yield of excessive and suitable nitrogen application treatments. The dilution curve was validated with independent experiment data（ 2010—2011） through nitrogen nutrition index（ NNI）,which was defined as the ratio of measured to critical nitrogen concentrations. The results showed that theNNI value with zero,deficit,suitable and excess nitrogen application treatments were 0. 70,0. 89,1. 01 and 1. 25,respectively. Wheat would get nutrition imbalance when nitrogen was used only as a base fertilizer and even reduce crop yield with excess nitrogen application. The suitable nitrogen application rate was 75 ～ 180 kg / hm2（ averagely 137 kg /hm2） for winter wheat in Guanzhong Plain due to the variety of soil productivity. The critical nitrogen dilution curve could be used as a diagnostic tool to detect wheat nitrogen nutrition,and it also provides a key technical approach for guiding nitrogen fertilization practices and management in wheat production in Guanzhong Plain.