Effect of brackish water on tomato yield and water consumption under mulched-drip irrigation

Field experiments of brackish water on tomato yield, evapotranspiration ( ET), and water use efficiency(WUE) were carried out in 2003. Tomato was drip irrigated with brackish water( total dissolved solids: TDS = 1.9, 2.4, 3.0 and 3.5 g (.) L-1), and fresh water( TDS = 0.9g (.) L-1). Throughout tomato growing season, the soil matric potential(SMP) at 0.2m under drip emitter was kept to be higher than -20 kPa. Data indicated the weight and size of fresh fruits increased as the salinity levels increased. The maximum weight was about 5% more than the minimum one, and the largest size(diameter x height) was about 50% more than the minimum one. When the TDS of irrigation water was less than -2.5g (.) L-1, the number of fruits produced by a plant and tomato yield increased as the TDS of irrigation water increased and then turned to decrease when the salinity levels were beyond 2.5g (.) L Firstly, the accumulative ET of tomato decreased significantly as the TDS of irrigation water increased, and then the decrease rate became small when salinity level was beyond 3.2 g (.) L-1. On the contrary, WUE increased as the TDS increased, reached the maximum value when salinity level reached to 3.2 g (.) L-1, and then the change trend turned to smooth. As a result, it is feasible to irrigate tomato with brackish water( TDS about 0.9-3.5g (.) L-1) under mulched-drip irrigation system in North China Plain. But as the highest tomato yield was concemed, it is advisable to choose the brackish water with TDS about 2.5g(.)L(-1)