Integrated Agro-Economic Approach to Deficit Irrigation on Lettuce Crops in Sicily "Italy…

The effect of four different irrigation levels on the marketable yield and economic return of summer-growth lettuce was evaluated during 2005 and 2006 in Eastern Sicily, Italy. The viability of deficit irrigation was evaluated by estimating optimum applied water levels. Actual evapotranspiration ( ETa ) was estimated by combining pan evaporation measures and the Penman–Monteith approach ( ET0-PM ) . The highest marketable yield of lettuce was recorded for plots receiving 100% ET0-PM . For deficit irrigated plots, reductions in crop production were ascribed to a decrease in lettuce weight. Crop coefficients equal to 1 determined maximum crop production values. Crop water use efficiency was maximum at a 100% ET0-PM level of water applied, corresponding to yield of 0.3 t ha−1 mm−1 . Irrigation water use efficiency reached its maximum at a 40% ET0-PM level, with values of 0.54 and 0.44 t ha−1 mm−1 during 2005 and 2006, respectively. Water applied and marketable yield of lettuce showed a significant quadratic ...