EFFECT OF WATER DEFICIT ON SNAP BEAN YIELD AND WATER USE EFFICIENCY UNDER DRIP IRRIGATION SYSTEM

Field experiment was carried out at the Research Farm of Faculty of Agriculture, Suez Canal University, Ismailia, Egypt, during the summer 2016 growing season in a sandy soil with snap bean (Phaseolus vulgaris L.) under drip irrigation system. The main goal of the present work was to study effect of different emitters and water deficit (T_1: 100 %, T_2: 75 % and T_3: 50 % of evapotranspiration (ETc)) on snap bean yield and water use efficiency (WUE). Two different emitters manufactured (in-line ‘Em1’ and on-line ‘Em2’) were evaluated with lateral length 50 m at different operating pressures of 50, 100, 150 and 200 kPa. The obtained results indicated that, the coefficient of uniformity (CU) increased with increasing operating pressure from 50 to 100 kPa and decreased with increasing operating pressure from 100 to 200 kPa. The first treatment produced high yield without significant differences of the second treatment, so, concerning the different irrigation regimes the 75 % ETc treatment gave a remarkable yield and pronounced water saving equal 25 % from applied water of T_1 therefore it is technically and economically recommended and the best one for saving water. Water use efficiency was the highest in 50 % ETc, but 75 % ETc was the best one economically. Yield was the greatest when fresh and adequate irrigation was applied. Snap bean yield was significantly affected in a linear relationship (r^2 ≥ 0.90) by deficit irrigation conditions.