Crop water productivity (CWP) is a measure of crop yield per unit of water consumed and plays a crucial role in evaluating the role of alternate management practices for sustainable production. This study investigates the crop water and yield dynamics of rice (Oryza sativa L.) subjected to three (low, moderate, and high water stress) deficit irrigation scenarios. Factorial experiments were conducted in four paddy fields in a command area of south India during the 2017–18 growing seasons with farmers’ current irrigation practice used as the control (T1). Seasonal total and irrigation water application of rice was ranged from 803 and 175 mm for high stress to 978 and 350 mm for T1 conditions. Cumulative potential evapotranspiration (ETo) for the growing seasons was observed to be 326.65 ± 2.51 mm. The FAO-56-based SIMDualKc model was parameterized to partition the evapotranspiration (ET) fluxes and to obtain site-specific crop coefficients for each scenario. Model-simulated root zone soil moistures were in agreement with the observations for all irrigation treatments (R2 > 0.80, RMSE < 0.04 cm3 cm−3, n = 20). Stage-specific single (Kc) and basal crop (Kcb) coefficients for rice with T1 are, respectively, 1.1, 1.09, 0.79, and 0.9, 0.97, 0.57, which are slightly lower than FAO tabulated values. The calibrated soil–water balance model was further applied to simulate crop yield using a simple crop growth algorithm. Our results conclude that crop yield is sensitive to water stress during vegetation (ky = 1.14 ± 0.10) followed by transplantation (ky = 1.07 ± 0.16) and reproduction stages (ky = 1.02 ± 0.17). We observed a marginal increase in CWP (12% in 2017 and 3% in 2018) and a reduction in deep percolation losses (29% in 2017 and 14% in 2018) through controlled water-saving strategies.

中文翻译：

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亏缺灌溉策略对印度南部半干旱热带地区水稻 ET 分配和作物水分生产力的作用

作物水分生产率 (CWP) 是衡量单位用水量的作物产量，在评估替代管理实践对可持续生产的作用方面起着至关重要的作用。本研究调查了水稻 (Oryza sativa L.) 在三种（低、中和高水分胁迫）亏缺灌溉情况下的作物水分和产量动态。在 2017-18 生长季节期间，在印度南部一个指挥区的四个稻田中进行了因子试验，以农民当前的灌溉方式作为对照（T1）。水稻的季节性总用水量和灌溉用水量从高胁迫的 803 和 175 毫米到 T1 条件的 978 和 350 毫米不等。观察到生长季节的累积潜在蒸散量 (ETo) 为 326.65 ± 2.51 毫米。对基于 FAO-56 的 SIMDualKc 模型进行参数化以划分蒸散 (ET) 通量并获得每个场景的特定地点作物系数。模型模拟的根区土壤水分与所有灌溉处理的观察结果一致（R2 > 0.80，RMSE < 0.04 cm3 cm−3，n = 20）。T1 水稻的阶段特定单一 (Kc) 和基茬作物 (Kcb) 系数分别为 1.1、1.09、0.79 和 0.9、0.97、0.57，略低于粮农组织列表值。使用简单的作物生长算法，进一步应用校准的水土平衡模型来模拟作物产量。我们的结果得出结论，作物产量对植被 (ky = 1.14 ± 0.10) 然后是移植 (ky = 1.07 ± 0.16) 和繁殖阶段 (ky = 1.02 ± 0.17) 期间的水分胁迫敏感。