Estimation of the spring wheat water and chlorophyll content inRainfed Agriculture Areas of Loess Plateau based on the spectralabsorption feature of the liquid water and chlorophyll

摘要

Because of the high water content of vegetation, water absorption feature dominate spectral reflectance of vegetation inthe near-infrared region of the spectrum, and chlorophyll dominate the visible region . Previous studies have primarilyrelated water band indices (WI) to vegetation water content .But the similar studies are vacancy in Rained AgricultureAreas of Loess. Two observation tests were carried out in arid and semi-arid area in Loess Plateau in order to find outthe best preferential sensitively spectral index to water content and chlorophyll for the spring wheat and to monitor cropsdrought in this area. The results indicated that at leaf level the NDVI and EVI are the highest sensitive indices to theFMC and Chlorophyll, and for the leaf EWT,SAVI is the best index((r=0.738,P<0.01)); at canopy level, the red edge(?red) and the water content have the best relationship, and the sensitivity for WII180 and NDWI are better . And the Xred isalso the best indictor for the chlorophyll at canopy level, the second is R670/R440, Furthmore, If considered thepotential for atmospheric interference when data are collected from aircraft or satellite plarforms, So Wli i8o ,W11450 andNDWI may be the feasible for satellite remote sensing of vegetation water content at the canopy level. Meanwhile theNDVI and EVI may be the best index for satellite remote sensing of vegetation water content at leaf level for the aridand semiarid Rainfed Agriculture Areas of Loess Plateau.