基于红边参数的棉花冠层叶片氮积累量之估算研究

测试了棉花2个品种4水平种植密度的4个关键生育时期冠层反射光谱,应用微分技术处理棉花冠层反射光谱,提取了红边(680～750nm)波段范围的最大一阶微分值(Dr)和红边面积(SDr)参数。分析了棉花冠层红边参数在不同生育期的变化特征和棉花吐絮期的两种生长类型的冠层红边状况,表明红边位置可以指示它们的氮素状况。以新陆早8号的SDr为自变量与对应的LNA为因变量进行相关分析,SDr与冠层LNA达1%极显著相关(R=0.9186**,n=32),利用其构建的模型方程估算新陆早6号的LNA,实测LNA和估测LNA的估计标准差为0.8909g/m2,估算精度为88.1%(R=0.9277**,n=32),说明采用高光谱提取的红边参数信息是无损实时、快捷评价棉花氮素状况的有效方法。

Study on Estimating Leaf Nitrogen Accumulation in Cotton Canopy Based on the Red Edge Parameter

Hyperspectral reflectance data were recorded at four main growth stages of cotton in a field experiment including two cultivars with four plant densities, and derived the maximum value (Dr) of derivative spectral and area of Red Edge (SDr) from 680 nm to 750 nm wavelength by using Spectral Derivative technique, then analyzed the variant characteristics of Red Edge parameters of cotton canopy in different growth stages, the Red Edge position can show cotton canopy two kinds of nitrogen status in open boll stage. Area of Red Edge is positively correlative with the amount of canopy leaf nitrogen accumulation in Xin Luzao No.8, correlative coefficient is 1% significant (R=0.9186**, n=32), established model function were used to estimate Leaf Nitrogen Accumulation (LNA) in Xin Luzao No.6, the model standard error is 0.8909g/m2, estimation precision is 88.1 % (R=0.9277**, n=32). The result shows that it is an effective, non-destructive, real-time and rapid method to evaluate cotton canopy leaf nitrogen accumulation status by using hyperspectral Red Edge parameters.