SAVING WATER USED FOR VEGETABLE PRODUCTION BY APPLYING REGULATED DEFICIT IRRIGATION PRACTICES

Water deficit during the growing season is a major factor limiting vegetable production. Therefore, saving water used for vegetable production by applying regulated deficit irrigation (RDI) can be a strategy to reduce water supply. The effects of different RDI levels from irrigation systems on vegetable yields, yield components, water use, and water use efficiency (WUE) of maize, lettuce, and garland chrysanthemum were investigated in a pot experiment. Plants were subjected to four irrigation levels, as follows: full irrigation as a control (RDI-100), 70% of full irrigation (RDI-70), 50% of full irrigation (RDI-50), and 30% of full irrigation (RDI-30). The WUE values of maize and lettuce were significantly higher with RDI-30 than other treatments, yet a significant reduction of WUE in garland chrysanthemum was detected compared to other treatments. There were significant correlations of WUEi with WUEyield and WUEbiomass in maize plants, indicating that WUEi can be a useful nondestructive estimator of yields and biomass contents in maize. Moreover, a significant correlation between WUEi and WUEyield in lettuce plants was observed. This index was correlated with economic production, and can be used to assess fresh weights and as an index of the irrigated water content. These results for evaluating water deficits in plants used nondestructive measurements that are applicable to large-scale water management of vegetable plants, thereby enabling scarce water resources to be conserved.