Abstract: According to the field experiments on Changwu tableland of southern Loess Plateau,the function of corn yield response to water could be described as: Pw=1.00-5.293(1-k)² ,where Pw is the potential productivity index of dryland corn, and k is the water stress index, a ratio of water consumption to water requirement during the entire growth period of dryland corn under high soil fertility conditions.The k value varies from 0.78 to 1.10,and its theoretical upper limit is related to the local potential evapotranspiration.The average Pw was 0.87 from 1985 to 1988.Its long term value has a similar fluctuating trend with the short term one over the four years.The former was 11247 kg·hm^-2,and the latter was 7696 kg·hm^-2.The actual yields in the field experimental region during recent years approach to the short term value,due to the high input of fertilizers and the improvement of crop varieties.

Key words: Potential productivity of dryland crop, Corn, Loess Plateau, PROSAIL model, leaf area index, vegetation isoline, tasseled cap triangle, WorldView 3