夏玉米不同部位干物质临界氮浓度稀释曲线的构建及对产量的估计

Construction of critical nitrogen dilution curve based on dry matter in diffe rent organs of summer maize and estimation of grain yield

准确和动态地诊断营养生长阶段植株氮状况,对于评估植物氮需求、预测玉米产量以及优化氮素管理至关重要。基于植物的氮诊断工具可优化夏玉米生产中氮素的管理,本研究旨在开发和验证基于玉米地上部不同部位干物质的临界氮浓度稀释曲线,并建立玉米相对产量(relative yield,RY)与不同生长阶段氮素营养指数(nitrogen nutrition index,NNI)和累积氮素亏缺(accumulated nitrogen deficit,AND)的关系。本文以2个不同氮效率的品种为试验材料进行连续4年的田间定位试验,设置4个氮素水平(0、150、225和300 kg hm^−2),分析不同施氮量对2个玉米品种营养生长阶段干物质的影响,基于叶干物质(leaf dry matter,LDM)、茎干物质(stem dry matter,SDM)和植物干物质(plant dry matter,PDM),构建不同的临界氮浓度稀释曲线。结果表明,基于LDM、SDM和PDM建立的临界氮浓度稀释曲线,均能很好地诊断玉米氮营养状况;3条临界氮浓度稀释曲线对产量进行预测比较发现,RY与NNI和AND在不同生长阶段之间的相关性均达到显著水平,相关系数R2值均大于0.65,其中R2值在V12−VT时期最大,同时回归模型的验证结果表明,在V12−VT时期模型显示出可靠性。R2值大于0.92,RMSE值小于10%,证实了模型在V12和VT两个时期关系的稳定性。总的来说,一定的条件下,基于LDM和SDM建立的临界氮浓度稀释曲线可以对基于PDM建立的临界氮浓度稀释曲线进行代替。在V12−VT阶段,RY与NNI和AND的稳定关系很好地说明了在受氮素限制和非氮素限制下RY的变化,并对夏玉米产量进行准确的估计。本研究为花前玉米的氮肥管理提高粮食产量提供理论依据。

It is essential to accurate and dynamic diagnosis of plant nitrogen status at vegetative growth stage for the assessment of plant nitrogen demand and the prediction of crop yield as well as the optimization of nitrogen management in maize.Plant-based nitrogen diagnostic tool can be used to optimize nitrogen management in summer maize production.The aim of this study was to develop and verify critical nitrogen concentration dilution curves based on dry matter in different tissue of the plant,and to establish the relationship between relative yield(RY)nitrogen nutrition index(NNI),and accumulated nitrogen deficit(AND)at different growth stages in maize.We conducted a 4-year field study using four nitrogen application rates(0,150,225,and 300 kg N hm^−2)and two maize cultivars(Zhengda 12 and Shaandan 609)to analyze the effects of nitrogen on dry matter at the vegetative growth stage,and based on leaf dry matter(LDM),stem dry matter(SDM),and plant dry matter(PDM),different critical nitrogen concentration dilution curves were developed.The results showed that the critical nitrogen concentration dilution curves based on LDM,SDM and PDM can well diagnose the nitrogen nutrition status of corn.The yield prediction results of three critical nitrogen concentration dilution curves showed that the relationship between RY and NNI,AND at different growth stages was highly significant,and the values of R2 were all greater than 0.65,where R2 was the largest at V12–VT,and the verification of the regression model showed reliable model performance during the V12–VT period,with R2 values greater than 0.92 and RMSE values less than 10%,which confirmed the stability of the relationship between V12 and VT.Generally,under certain conditions,the critical nitrogen concentration dilution curve based on LDM and SDM can be used to replace the critical nitrogen concentration dilution curve based on PDM.The stable relationship between RY and NNI,RY and AND in V12–VT stage can well explain the change of RY under restricted and unrestricted nitrogen and estimate the yield of summer maize.This study provides the basis for nitrogen management of pre-anthesis to improve maize grain yield.