The spectral characteristics of rice plants subject to water deficiency were analysed and compared with healthy rice plants. Under water deficiency conditions, the reflectance of visible bands of the rice plants increased significantly, while the reflectance of near- and middle-infrared bands decreased. For the early detection of water deficiency, the visible band of Landsat ETM+ is more sensitive than the infrared bands. Band-3 showed the highest reflectance differences between rice under water-deficient and healthy conditions. The use of the vegetation index can distinguish rice under water deficiency more clearly than when only using a single band. The Ratio Vegetation Index (RVI) is the best vegetation index for both early detection of water deficiency and distinguishes the two rice conditions.