Responses of Tomato Yield and Water Consumption to Water Quality and Drip Irrigation Technical Parameters

Abstract

Scarcity of freshwater in arid and semi-arid regions makes treated wastewater from domestic and industrial sources an indispensable alternative water source for irrigation. However, concern exists over the unfavorable effects of sewage effluent on water uptake and production of crops. The objectives of this study were to utilize field experiments to investigate the effects of water quality and drip irrigation technical parameters (irrigation frequency and lateral depth) on tomato yield, quality and water consumption. The types of irrigation water used in the experiments were groundwater, secondary sewage effluent, and blend water that was obtained by mixed the secondary sewage effluent and the groundwater at one to one ratio. Three irrigation intervals of four days, eight days, and sixteen days were tested. Three lateral depths including 0 cm, 15 cm, and 30 cm in study. Stevens HydraProbes were used to measure water content continuously to estimate crop water consumption. During the harvest season, several fruit quality parameters, including ascorbic acid (Vc), soluble solids, soluble sugar, and water soluble acid, were measured. The results demonstrated that sewage irrigation could cause a decrease in water consumption of tomato. The decrease in water consumption was more considerable for the treatments with higher irrigation frequencies and lower lateral depth, the largest decrease was 3.7% and 5.5 % than that irrigated with the blend water and the groundwater, respectively. Sewage application could increase tomato yield apparently. Lower irrigation frequency is unfavorable to increase crop yield. An increasing trend of yield was found with increase of lateral depth. Neither water qualities and the irrigation frequencies (lateral depths) nor the interactions between the two significantly influenced yield and fruit quality of soluble sugar, soluble acids, and soluble solids. The levels of ascorbic acid (Vc) increase with the decrease of irrigation frequencies, and the difference between four-day irrigation and sixteen-day irrigation reached a significance level of 0.05. Sewage application increase water use efficiency (WUE) apparently. WUE could increase with the increase of irrigation frequencies and lateral depths. These results suggest that sewage irrigation could increase crop yields and influence water consumption negatively, higher irrigation frequencies and deeper lateral depths was recommended for increasing yield and saving water.