Water and Radiation Use Efficiencies in Drip-irrigated Pepper (Capsicum annuum L.): Response to Full and Deficit Irrigation Regimes

Bell pepper (Capsicum annuum L., cv. 'Mercury') response to full and deficit irrigation was studied during the 2005 growing season at Tal Amara research station in the Central Bekaa valley of Lebanon. Treatments were (C) well-watered treatment receiving 100 % of crop evapotranspiration (ET(crop)), and three water-stressed treatments receiving irrigation at 80 (WS(1)), 60 (WS(2)) and 40 % (WS(3)) of ET(crop). Pepper seasonal evapotranspiration varied from a low of 275 mm in the more stressed treatment (WS(3)) to a high of 478 mm in the well irrigated control, while in WS(1) and WS(2) seasonal ET accounted for totals of 427 and 360 mm, respectively. Relative to plants grown in WS(1) treatment (31.9 t ha(-1)), marketable fruit yields of C, WS(2), and WS(3) were reduced by 11.3, 12.2, and 38.2%, respectively. WS(1) and WS(2) treatments enhanced fruit quality (dry matter and total soluble solids contents) compared with C. Water use efficiency at dry yield basis (WUE(y)) of the control was 0.35 kg m(-3) while WS(1), WS(2) and WS(3) treatments had WUE(y) higher by 22, 35 and 39 %, respectively. Radiation use efficiency (RUE) observed in the C and WS(1) treatments (avg. 2.20 g MJ(-1)) was higher by 13 % in comparison to WS(2) and WS(3) treatments (avg. 1.96 g MJ(-1)), with no significant differences between C-WS(1) and WS(2)-WS(3). We concluded that WS(1) treatment is recommended for drip irrigated bell pepper under field conditions in order to obtain higher yield and optimized WUE under the Mediterranean dry climate of the Central Bekaa Valley.