夏玉米冠层反射光谱与植株水分状况的关系

通过不同夏玉米品种生育期内冠层叶片含水率与不同波段组成的比值指数(RVI)和归一化植被指数(NDVI)进行线性、指数、对数、幂函数以及多项式回归分析,研究不同品种夏玉米的冠层叶片和植株水分状况与反射光谱之间的相关关系。结果表明,冠层叶片和植株含水率与460～670nm范围内波段反射率均成负相关,与730～1260nm范围内波段反射率均成正相关。其中冠层叶片含水率与460、500、600、650、670nm范围内波段反射率均呈显著相关,而植株含水率与460、500、600、650、670、780、800、850、900、950、1050nm范围内波段反射率相关性也较高。冠层叶片含水率与归一化植被指数(NDVI)相关性均达到极显著水平,与比值指数(RVI)相关性中只有RVI(950,550)、RVI(850,730)、RVI(800,730)和RVI(780,730)4个波段呈极显著正相关。RVI与叶片含水率相关性以RVI(850,730)最优,NDVI与叶片含水率相关性以NDVI(1050,550)最优。植株含水率也与RVI和NDVI呈正相关,相关性均较好,但NDVI优于RVI。RVI与植株含水率相关性以RVI(800,500)最优,决定系数为0.8490;NDVI与植株含水率相关性以NDVI(780,650)最优,决定系数为0.8645。

Relationships Between Canopy Reflectance and Plant Water Status of Summer Maize

The study on the relationship between canopy reflectance characteristics and plant water status of summer maize showed that the water contents of canopy leaf and plant all had a negative correlation with the spectral reflectance of 460 - 670 nm and had a positive reflectance of 730 -1 260 nm, indicated that the water contents of canopy leaf had a significant correlation with the spectral reflectance of 460, 500, 600, 650, 670 nm , but the plant had a higher correlation with the spectral reflectance of 460, 500, 600, 650, 670, 780, 800, 850, 900, 950, 1 050 nm. In addition, the canopy leaf water contents all had a significant correlation with NDVI, and only had a significant positively related to the ratio vegetation index RVI(950, 550), RVI(850, 730), RVI(800, 730), RVI(780, 730). Also, the water contents of canopy leaf could be a best correlation with the ratio vegetation index RVI (850,730) and the normalized difference vegetation index NDVI (1050, 550). Otherwise, the water contents of plant all had a positive correlation with RVI and NDVI, and the NDVI was better than RVI, in which the ratio vegetation index RVI (800, 500) whose coefficient of determination was 0.849 0 could be a best correlation with the and the normalized difference vegetation index NDVI (780, 650) whose coefficient of determination was 0.864 5 also could be a best correlation.