Crop and water productivity and profitability of broccoli (Brassica oleracea L. var. italica) under gravity drip irrigation with mulching condition in a humid sub-tropical climate

Strategic irrigation planning and soil water conservation measure can be rewarding for increasing agricultural productivity in a humid subtropical climatic environment. Field experiments were conducted to evaluate broccoli yield response to crop water productivity (CWP), irrigation water productivity (IWP) and economics under varied irrigation regimes and mulching. Four levels of irrigation: surface irrigation at 1.0 IW/CPE (irrigation water to cumulative pan evaporation, I(1)), drip irrigation at 0.6 (I(2)), 0.8 (I(3)) and 1.0 (I(4)) of crop evapotranspiration (ETc) and three mulches: none (M(0)), black polythene mulch (BPM, M(1)) and paddy straw mulch (PSM, M(2)) were examined. Among these treatments I(3)M(1) produced the higher yield (19.17 t ha(-1)), CWP, IWP and maximum benefit-cost ratio (BCR), being almost competitive with I(3)M(1). Under scarcity of water, I(2)M(1) was an alternative. Drip irrigation could save 21.2–52.7% water over surface irrigation which accommodated 17.1 to 53.3% additional area under irrigation. Yield response factor and water-yield production function suggested the potential yield decrease in relation to increased deficit irrigation. However, a deficit drip irrigation scheduling with 0.8 ETc at a 3-day interval is optimum for increased curd yield, water productivity and economics of broccoli.