Effect of Irrigating Slightly Acidic Electrolyzed Water on Lettuce Photosynthesis under Mild Water Stress

Abstract: To investigate the mechanism of how slightly acidic electrolyzed water (SAEW) alleviate the mild water stress of plant, we compared the influence of irrigating SAEW with tap water on growth, chlorophyll content, chlorophyll fluorescence and photosynthetic characteristics in lettuce (Lactuca sativa L. cv. Italy lettuce) growth under mild water stress. The available chlorine concentration, pH and ORP of SAEW were 27.75 mg/L, 5.0 and 819 mv. After 50-days growth, for the treatments of SAEW, the stem diameter, roots length, and the ratio of transverse diameter to vertical diameter of leave significantly increased by 23.81%, 26.28% and 9.68% (p < 0.05) compared to tap water treatments, respectively. Meanwhile, the Pn increased by 57.44% and Ci decreased by 23.95% (p < 0.05), respectively. However, the WUE of lettuce treated with SAEW significantly increased by 56.37% (p < 0.05), showing that the lettuce kept the water by reducing the stomatal aperture of leave to decrease the transpiration finally. In addition, the chlorophyll content increased in the treatments of SAEW, showing that the efficiency of photosynthesis under the same light conditions was improved. The quality of lettuce was also investigated, and there were no big differences between two different treatments with VC. Therefore, the irrigation of SAEW on lettuce could enhance the photosynthetic efficiency and alleviate the impact of water stress on lettuce growth without destroying the nutrition of lettuce.