基于叶片干物质的滴灌玉米临界氮稀释曲线构建

Development of critical nitrogen dilution curve based on leaf dry matter for maize under drip irrigation

建立宁夏引黄灌区滴灌玉米临界氮浓度稀释曲线,采用临界氮浓度模型对滴灌玉米氮营养状况进行分析,探讨基于此模型推导的氮营养指数用于诊断氮营养的可行性,为实现滴灌玉米氮肥精准管理和生态环境保护提供理论参考。试验以‘天赐19’玉米为材料,设置6个氮素水平(0、90、180、270、360和450 kg·hm^-2),在2年田间定位试验的基础上构建基于叶片干物质(LDM)的滴灌玉米临界氮浓度(Nc)稀释曲线和氮营养指数模型。结果表明:1)滴灌玉米叶片干物质和氮浓度之间呈负幂函数关系,其模型表达式分为2部分:当LDM<1.15 t·hm^-2时,Nc=3.2%;当LDM≥1.15 t·hm^-2时,Nc=3.29LDM^-0.29;2)拟合模型的评价指标均方根误差(RMSE)和标准化均方根误差(n-RMSE)分别为0.203、8.0%,年度间具有较好的稳定性;3)不同氮素处理下,氮营养指数(NNI)在0.47~1.44。不同生长阶段NNI与产量呈显著正相关,与氮肥农学利用效率呈显著负相关,故NNI可进一步解释滴灌玉米在限氮和非限氮条件下的产量变化。本研究基于叶片干物质构建的临界氮浓度稀释曲线可在滴灌玉米拔节期至吐丝期提供准确的氮素营养状况估测。

To provide a theoretical reference to nitrogen fertilizer management for maize and eco-enviromental protection in the irrigated area of Ningxia,we established the critical nitrogen concentration(Nc)dilution curve of maize under drip-irrigated condition.The nitrogen nutrition index(NNI)was deduced from the established Nc curve model,to diagnose feasibility of nitrogen nutrition.Six levels of nitrogen application rates including 0,90,180,270,360 and 450 kg·hm^-2 were conducted in field with maize variety‘Tianci 19’.During two-year field study,the Nc dilution curve and NNI model of maize were established based on leaf dry matter(LDM).The results showed that:1)There was a negative power function relationship between LDM and Nc,which presented as two parts,if LDM<1.15 t·hm^-2,Nc=3.2%,while if LDM≥1.15 t·hm^-2,Nc=3.29LDM^-0.29.2)The root mean square error(RMSE)and standardized root mean square error(n-RMSE)of the model were 0.203 and 8.0%,respectively,with fine stability among years.3)The NNI ranged from 0.47 to 1.44 with different nitrogen application rates.In addition,NNI was positively correlated with yield and negatively correlated with agronomic utilization efficiency of nitrogen fertilizer at different growth stages of maize.Therefore,NNI could be used to explain maize yield changes with and without nitrogen limit under drip-irrigated system.In conclusion,the critical nitrogen dilution curve established from leaf dry matter could be applied to accurately estimate nitrogen nutrition status throughout the whole growing stages from the jointing stage to silking stage of maize under drip irrigated system.