Determination of Leaf Photosynthetic Rate and Continuous Cropping Year of Potato in Sunlight Greenhouse

The leaf photosynthetic characteristics of potato variety daxiyang of first-planting and continuous cropping 1year ~4 years were determined in sunlight greenhouse. The results showed that the leaf photosynthetic rate of first-planting treatment are highest(12.97 μmol/(m2·s]from 9:30 to 11:30 at potato full-bloom stage,there was a gradually decreasing trend with continuous cropping years increase,then increased again. there was a gradually decreasing trend of photosynthetic rate with continuous cropping years increase at potato mature stage,photosynthetic rate was increased with continuous cropping gradual decline.maximum concentration of net photosynthetic rate in potato leaves was discovered around 11:00 pm,then continuously decreased,maximum concentration of transpiration rate was discovered in 12:00 to 13:00.