To test the applicability of critical nitrogen dilution curve for estimating nitrogen (N) nutrient status of winter wheat in central Henan area, we carried out a site-fixed experiment from October 2011 to June 2014 using the large-spike variety Zhoumai 16 and the multi-spike variety Yumai 49-198. Five N application levels, namely pure N 0, 120, 180, 240, and 360 kg ha-1, were designed to build the critical N concentration dilution curve of shoot biomass and N nutrition index model. The aboveground biomass increased obviously with rising N level and then tended to a mild level. The relationship between critical N concentration and shoot biomass of wheat fit the power function with R2 of 0.8203 for Yumai 49-198 and 0.7981 for Zhoumai 16 (P<0.01). These models showed good stability across years. The N nutrition index estimated by the model could be used for evaluating the N nutrition situation of wheat plants, and a significant linear correlation was observed between the N nutrition index and the ni-trate concentration in wheat stem base. These results indicate that the critical N concentration dilution model is applicable in di-agnosing N nutrient status of wheat plants in central Henan area.%为了验证小麦临界氮稀释曲线在豫中地区的适用性,选择大穗型品种周麦16和多穗型品种豫麦49-198进行了连续3年(2011年10月至2014年6月)的田间定位试验,设置5个氮水平(纯氮0、120、180、240、360 kg hm-2),分别构建了小麦地上部生物量临界氮浓度稀释曲线模型和氮营养指数模型。结果表明,地上部生物量随着施氮量增加显著提高,而后趋于平缓；小麦临界氮浓度与地上部生物量符合幂函数关系,其 R2分别为0.8203(豫麦49-198, P<0.01)和0.7981(周麦16, P<0.01),且模型在年度间具有较好的稳定性。根据模型得到的氮营养指数可以较好地评价小麦植株氮营养状况,且小麦氮营养指数和相对茎基部硝酸盐之间具有显著的线性相关。说明本文所构建的小麦临界氮浓度稀释模型适用于本地区,且可以用来估测小麦植株氮素盈亏水平。
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