棉花高光谱植被指数与LAI和地上鲜生物量的相关关系研究

Relationships between Hyperspectral Vegetative Index,LAI and Aboveground Fresh Biomass of Cotton

通过测试棉花关键生育阶段350～2500nm波段的冠层高光谱数据，用近红外波段760～850nm及红光波段650—670nm的2个范围内的波段，组成了高光谱归一化植被指数（NDW）和800和670nm两个波段组成修改型二次土壤调节植被指数（MSAVI2），分别与棉花叶面积指数（LAI）和地上鲜生物量进行相关分析，结果表明，棉花NDVI和MSAVI2与LAI和地上鲜生物量两个参数均以幂指数相关关系为最佳（RNDVI—LAI=0．7291^＊＊，RMSAVI22—LAI=0．7436^＊＊，n=81；RNDVI-鲜生物量=0．7426^＊＊，RMSAVI2-鲜生物量=0．7911^＊＊，n=59），MSAVI2与LAI和地上鲜生物量的相关性均高于NDVI与LAI和地上鲜生物置的相关性，说明MSAVI2较NDVI能更好的消除土壤背景对反射光谱造成的影响，能较精确的提取反映棉花生长状况的叶面积指数和生物量信息。

This hyperspectral reflectance （350 to 2 500 nm） data were recorded at the cotton key growth stages in a field experiment, utilizing cotton leaf area index at near infrared band 760 - 850 nm and red region band 650 - 670 nm, combining the two bands range reflectance into vegetation indices NDVI （Normalized Vegetation Index）, and near infrared band 800 nm and red region band 670 nm, combining two bands range reflectance into MSAVI2 （Modified Second Soil - Adjusted Vegetation Index）. Analyzing the correlation between NDVI and MSAVI2 and cotton leaf area index（LAI） , aboveground fresh biomass respectively, it was found that there were all the highest power function relationship among them（ RNDVI-LAI = 0. 729 1^＊ ＊, RMSAVI2-LAI = 0. 743 6^＊ ＊, n = 81; RNDVI- Fresh biomass = 0. 742 6 ^＊＊ , RMSAVI2 - Fresh biomass =0.791 1 ^＊＊ , n = 59 ）, power function of MSAVI2 and LAI , aboveground fresh biomass have the higher precision than NDVI does, it shows that MSAVI2 can eliminate the effects of the soft background on the reflectance , it is better to extract cotton canopy LAI, aboveground fresh biomass.