Abstract: Studies on the physiological performance, dry matter accumulation rate, water utilization efficiency and economic coefficient of millet after drought show that millet had compensation effect after drought, which was a kind of adaptive physiological phenomenon. In the treatment that millet had been drought earlier, millet showed a tendency of extra growth, and its relative daily accumulation rate of dry matter was higher than other treatments at the same water supply level. The dry matter loss could be compensated partly or even completely through extra growth. The physiological impact of earlier drought on millet had the character of continuity. After subsequent increasing water supply, the treatment that had been drought earlier showed a higher net photosynthetic rate and a higher chlorophyll content in leaf. The compensation effect of millet also showed a higher efficiency in utilizing limited water and dry matter to produce grain. In the west semiarid area of China, autumn cropos with the character of extra growth after drought adapt the distribution of natural precipitation, comparing with summer crops.

Key words: Millet, Drought, Compensation effect, Relative daily accumulation rate of dry matter, soybean., derivative spectrum, unmanned aerial vehicle, high definition digital image, nitrogen balance index, hyperspectral data, vegetation index