Water use and productivity of drip irrigated wheat under variable climatic and soil moisture regimes in North-West, India

In North-Western India, wheat is normally irrigated at an IW: CPE of 0.9, with 75 mm depth of irrigation water (conventional irrigation practice, CP) resulting in wastage of water. An effective irrigation strategy is required that will save irrigation water without compromising yield penalty. So, an experiment was conducted at Punjab Agricultural University, Ludhiana during 2014-15 and 2015-16 in split plot design, keeping four sowing dates {25th October (D-1), 10th November (D-2), 25th November (D-3) and 10th December (D-4)} in the main plots and five irrigation schedules {irrigation at 15 (FC15), 25 (FC25), 35 (FC35) and 45 (FC45)% depletion of soil moisture from field capacity (FC) and a conventional practice} in sub plots. The objectives of the study were to evaluate the effect of drip irrigation amounts on field water balance, yield and water productivity of wheat. The results revealed that mean grain yield decreased by 8.3 & 8.7, 10.7 & 10.6 and 13.1 & 13.4% from D-1 to D-2, D-2 to D-3 and D-3 to D-4 during 2014-15 and 2015-16, respectively. Pooled grain yield decreased by 29% with delay in sowing from D-1 to D-4. Reduction in ETc was 10% in D-4 as compared to DJ. during 2014.15 and 24% during 2015-16. The highest grain yield was obtained with irrigation applied at 15% depletion from FC. The pooled grain yield decreased by 30%, ETc by 21% and water productivity by 29% in FC45 as compared to FC15. The water saving in drip irrigation during 2014-15 was 62, 70, 77 and 83% in FC15, FC25, FC35 and FC45 respectively as compared to CP. The respective values during 2015-16 were 38, 44, 54 and 60%. The results demonstrate that irrigating wheat at 15% depletion of FC using drip method of irrigation as a novel concept that saves irrigation water in addition to higher grain yield.