基于高光谱数据的棉花叶绿素密度定量提取研究

Estimating chlorophyll density of cotton canopy in North of Xinjiang by using hyperspectral date

利用ASD FieldSpec FR野外光谱仪,测试了棉花(2个品种4水平种植密度)各生育时期的光谱数据及对应的叶绿素密度(CH.D),分析了它们随生育期的变化规律,并对棉花冠层光谱数据与CH.D进行了回归分析。结果表明:用归一化植被指数(NDVI)建立的幂指数模型的相关系数最大(r=0.722**,n=30),可用以较好地提取棉花CH.D;红边斜率与棉花群体CH.D的线性相关达到1%极显著水平(rdλred=0.679**,n=30),用棉花新陆早19号729 nm波段的一阶微分光谱值与群体CH.D建立的线性回归模型,估测棉花新陆早13号的CH.D,实测CH.D与预测CH.D的相关系数r=0.8818**(n=30),估计精度为82.3%,RMSE为0.254 g/m2,说明可以用高光谱遥感数据对棉花冠层CH.D进行遥感定量监测。

Using the ASD Fieldspec FR spectrometer, the cotton spectrum and CH. D were measured at cotton key growth stages（two varieties and four levels of plant density,in North Xinjiang）. Analyzing the variant rule of the spectrum and chlorophyll density （CH. D） of cotton canopy with growth stages. The results showed that the NDVI exponential index model has the highest correlation coefficient（ r = 0. 722^＊＊, n =30）between Normalized Difference Vegetation Index （NDVI） and the CH. D, it can be used to extracted chlorophyll density of cotton canopy. There is a significantly correlation between red-edge slope and CH. D at 729 nm band of the first derivative （ r = 0. 8499^＊＊ , n = 30）. Then based on the first derivative data at band 729 nm of cotton Xinluozao No. 19, established the linear regression model to estimate the CH. D of cotton Xinluozao No. 13, The relationship between true CH. D value and estimative CH. D value is significant correlation （ r = 0. 8818^＊＊ , n = 30）. The estimated precise is 82.3 %, RMSE is 0. 254 g/m^2. The study indicates that it can be quantificationally monitored cotton canopy CH. D by hyperspectral remote sensing data in Xinjiang.