Abstract: The effect of different target water content in soil on the photosynthetic property and yield of summer-sowing corn was studied under the rain-proof condition. The results showed that the moisture content in soil was closely related to yield, the critical values of moisture content in soil were 45% of field water capacity at period of yield formation, 80%at period of optimum yield formation, 50% at period of seedling emergence, 70% at period of optimum seedling emergence. Dry or over-wet soil tended to decrease photosynthetic area, potential and rate, the accumulative intension of dry matter, that caused the drop of crop yield with a great scope. The requirement for soil water content differed at the different growing time, the water indices that were useful for the summer-sowing cron photosynthetic property were: 50% to 80% for the seedling stage, 60% to 80% for the jointing stage and after that, and 70% to 80% was the best excellent.

Key words: Summer-sowing corn, Target water content of soil, Photosynthetic property, Yield