Evapotranspiration and water productivity of wheat under different hydrothermal regimes

A field experiment was conducted during rabi 2013–14 with three dates of sowing, D₁(29^th October), D₂ (12^th November) and D₃ (28^th November) and four irrigation levels, I₁ (Irrigation at CRI stage), I₂ (irrigation at CRI and Flag leaf emergence stage), I₃ (irrigation at crown root initiation, flag leaf emergence and soft dough stage) and I₄ (recommended 4 post sowing irrigations) in randomized block design. Evapotranspiration computed with soil moisture depletion method and Papadakis method was higher under D₁ (374.9 mm and 492.7 mm) as compared to D₂ (352.7mm and 480.2mm) and D₃ (346.5 mm and 443.0 mm) whereas with USDA open pan evaporimeter and modified Jenson and Haise method, it was higher in D₂ (340.2 mm and 423.5 mm) as compared to D₁ (326.6 mm and 409.8 mm) and D₃ (334.2 mm and 409.4 mm). Water productivity was higher under D₁ followed by D₂ and D₃. The crop coefficient was also higher under D₁ (1.16) as compared to D₂ (1.04) and D₃ (1.03). Higher water productivity with regard to grain and straw yield was observed in D₂I₃ (14.02 kg/ha/mm) followed by D₂I₂ (13.85 kg/ha/mm) and lowest in D₃I₄ (9.77 kg/ha/mm).