Effect of Irrigating with Slightly Acidic Electrolyzed Water on LettucePhotosynthesis under Mild Water Stress

Abstract

Abstract. To investigate if slightly acidic electrolyzed water (SAEW) can alleviate mild water stress on plants, we compared the influence of irrigating with SAEW and tap water on growth, chlorophyll content, and photosynthetic characteristics in lettuce (Lactuca sativa L. cv. Italy lettuce) under mild water stress. In this study, lettuce was irrigated with SAEW and tap water at different times. The available chlorine concentration, pH, and oxidation-reduction potential (ORP) of SAEW were 27.75 mg/L, 5.0 and 819 mV, respectively. Both SAEW treatments (long time watering before water stress and re-watering after water stress) showed increases in stem diameter, root length, and biomass accumulation in lettuce when compared with tap water treatments, which meant that inhibition in plant growth was greatly alleviated. Besides, lettuce treated with SAEW maintained a relatively high gas exchange and significantly increased water use efficiency (WUE), showing the better adaptation to water stress. The quality of lettuce was also investigated, and the vitamin C (VC) content in lettuce was not evidently different between these two treatments. Therefore, irrigation with SAEW on lettuce may enhance the photosynthetic efficiency and alleviate the impact of water stress on lettuce growth without destroying VC content of lettuce. Taking the disinfection effect of SAEW into consideration, this work provided a feasible way to lower the risks of pesticide residues in lettuce and alleviate the water stress at the same time.