Effect of Soil Water Stress on Photosynthesis of Different Apple Cultivars

The responses of main photosynthesis,transpiration,water useefficiency and stomata conduct indexes of eight cultivars to soil water stress were studied with one-year-old grafting trees.The physiological indexes were significantly affected by soil water stress but different sensitivity of each index was shown.As stress increases,net photosynthesis rate,transpiration,stomata conduct were gradually decreased but water use efficiency was first increased,and decreased afterward.Different cultivars showed different photosynthesis and transpiration responses to water stress.The net photosynthesis rate,transpiration rate and stomata conduct indexes of cultivars that had stronger drought resistance were all lower than ck under water stress,and the range of descent was significant;water use efficiency of cultivars that had stronger drought resistance was higher than ck under moderate water stress,and the range of ascent was significant.