Physiological Effects of Elevated CO2 on Loquat Trees (Eriobotrya japonica Lindl.)under Water Stress Effect of elevated CO2 concentration on photosynthesis and antioxidative enzyme activities of wheat plant grown under drought condition Mechanism of Tolerance to Drought in Sugarcane Plant Enhanced by Foliage Dressing of Abscisic Acid under Water Stress Physiological Effects of Elevated CO2 on Loquat Trees (Eriobotrya japonica Lindl.)under Water Stress