Water use efficiency and yield responses of cotton to field capacity-based deficit irrigation in an extremely arid area of China

The objectives of present investigation were to test the effects on water use efficiency (WUE) and cotton yield of implementing a range of deficit irrigation regimes triggered at specific fractions of root zone soil moisture, field capacity (θfc) and different crop phenological stages. The study was conducted on southern oasis of the Taklamakan desert, China. The cotton crop’s WUE was quantified, as were leaf photosynthesis and yield. From a photosynthetic perspective, deficit irrigation resulted in 16.8%, 10.3% and 2.2% increases in leaf WUE under θfc-based regulated deficit irrigation (T1, T2, and T3), compared to the control, respectively. Cotton yield and its components were significantly affected by irrigation depths (p≤0.05). A relatively high seed yield (0.65 kg/m3) and the highest WUE were achieved, under T3 (70% θfc at seedling stage, 60% θfc at squaring, 50% θfc at full-bloom, 70% θfc at boll, 70% θfc at boll cracking stage), showing it to be the most effective and productive irrigation schedule tested. As the application of θfc-based deficit irrigation in surface-irrigated cotton fields showed great potential in saving water, maintaining a high WUE, and improving cotton seed yield, a management strategy consisting or irrigation thresholds of 70% θfc in the root zone at the seedling, boll and boll cracking stages, and of 60% θfc at the squaring stage, and 50% θfc at the full-bloom stage, would be recommended for this extremely arid region. Keywords: regulated deficit irrigation, evapotranspiration, seed cotton yield, water use efficiency, Qira Oasis DOI: 10.25165/j.ijabe.20191206.4571 Citation: Li H F, Qi Z M, Gui D W, Zeng F J. Water use efficiency and yield responses of cotton to field capacity-based deficit irrigation in an extremely arid area of China. Int J Agric & Biol Eng, 2019; 12(6): 91–101.