Effect of irrigation with detergent-containing water on foxtail millet shoot biomass and ion accumulation.

Abstract

Water shortage leads farmers to use sewages for irrigation. Sewages contain a large amount of laundry detergent. In this study the impact of irrigation by contaminated water on shoot biomass and seed germination of foxtail millet (Setaria italica) was investigated. The research was conducted as laboratory and pot experiments. Iso-potentials (- 0.042, - 0.077, and - 0.415MPa) of polyethylene glycol (PEG, water deficit treatment) and laundry detergent (contamination treatment) made the laboratory experiment treatments. The pot experiment included contamination factor (0, 0.1, 1, and 10gL-1 of laundry detergent) and deficit irrigation factor (irrigation interval of 1, 2, and 3days). Results of this study showed that at the iso-potential, laundry detergent had more negative effect on seed germination traits when compared with PEG. There was no germination at - 0.415MPa of laundry detergent. Both drought and contamination reduced dry forage yield, plant height, leaf number, leaf area, leaf dry and fresh weight, stem dry, and fresh weight. Detergent concentration of 10gL-1 with irrigation interval of 3days had a forage yield reduction of 63% compared to control (laundry detergent concentration of 0gL-1 with irrigation interval of 1day). Detergent concentration of 10gL-1 with irrigation interval of 1day had a sodium increase of 1847% compared to control. Based on the results of this study, it is recommended not to irrigate foxtail millet farm by contaminated water with laundry detergent higher than 1gL-1.