Abstract
This study was conducted to determine the impacts of plastic mulch, drip irrigation method and different amount of water and their interactions on yield, water use efficiency (WUE) and quality characteristic of tomato (Mobile cultivar). The study was conducted in Torogh Agricultural Research Station, Razavi Khorasan province. The study was done during 2007-2008. Experimental design was randomized complete blocks (RCBD) in split split plot with three replications. Design treatments included different amount of water (60, 80 and 100% water requirement) in main plot, drip irrigation method (surface and subsurface) in sub plot and mulch (with/without mulch) in sub-sub plot. The combined analysis showed that irrigation water amount, irrigation method and mulch treatments had significant effect on yield and WUE (P≤ 0.01). Yield in 60, 80 and 100% water requirement treatments was 31.141, 54.575 and 62.265 ton/ha, respectively, which showed significant difference. The highest WUE (7.881 kg/m3) was in 80% irrigation treatment, followed by 60 and 100% (with 5.925 and 7.232 kg/m3), respectively. There was significant difference between yield in surface and subsurface drip irrigation (that was 43.380 and 55.274 ton/ha), respectively. Water use efficiency in subsurface drip irrigation was 7.927 kg/m3 that was greater than surface drip irrigation. Yield in mulch and without mulch treatment was 55.641 and 42.714 ton/ha, respectively. Application of mulch increased water use efficiency about 30 percent. Subsurface drip irrigation with 80% water use and using of mulch was the best treatment.

Keywords: Tomato, Deficit irrigation, Drip irrigation, Mulch