| 吴训,石建初,左强.基于作物水分关系改进土壤水分胁迫修正系数的反求方法[J].水利学报,2020,51(2):212-222 |
| 基于作物水分关系改进土壤水分胁迫修正系数的反求方法 |
| Improving the inverse method to estimate the soil water stress reduction function based on crop-water relations |
| 投稿时间：2019-10-05 |
| DOI：10.13243/j.cnki.slxb.20190672 |
| 中文关键词: 冬小麦 根系吸水 土壤水分胁迫修正系数 反求方法 数值模拟 |
| 英文关键词: winter wheat root water uptake soil water stress reduction function inverse method numerical simulation |
| 基金项目:国家自然科学基金项目（U1706211，51790532）；国家重点研发计划课题（2016YFC0501401） |
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| 中文摘要: |
| 土壤水分胁迫修正系数是宏观根系吸水模型的重要组成部分，其所含拟合参数通常基于反求方法予以评估，但传统反求方法未考虑不同胁迫条件下作物生长差异对潜在蒸腾速率的影响，也难以顾及前期水分胁迫对根系吸水或蒸腾带来的滞后影响（常导致复水后作物蒸腾与根区土壤水分变化趋势不同步），从而对参数评估带来较大偏差。鉴于此，本文提出两点相应的改进措施：（1）利用有效叶面积指数对遭受水分胁迫作物的潜在蒸腾速率进行校正；（2）在了解复水后蒸腾变化过程的基础上，仅利用蒸腾与根区水分变化动态基本同步阶段的相关实测数据来优化参数，以尽可能规避或减小滞后影响（即蒸腾与土壤水分变化的不同步过程）。基于不同灌溉处理冬小麦室内土柱栽培试验对改进方法的可靠性进行了评估，结果表明：与传统方法相比，基于改进方法优化参数所建立的根系吸水模型显著改善了冬小麦实际蒸腾速率和相对蒸腾速率的估算精度，使估算值与实测值间的均方根差（RMSE）分别保持在0.07 cm/d、0.04 cm/d以内，而决定系数（R2）则均在0.96以上；模拟的土壤含水量分布也与实测值吻合良好（RMSE ≤ 0.012 cm3/cm3；R2 ≥ 0.83）。因此，所提出的改进方法可有效用于优化土壤水分胁迫修正系数中的拟合参数，为建立合理的根系吸水模型从而准确估算或模拟作物蒸腾耗水动态和土壤水分迁移过程奠定一定基础。但基于优化参数所建立的根系吸水模型仍难以准确再现根系吸水在复水后的缓慢恢复过程，有关复水后根系吸水的水分胁迫滞后效应机制及其定量表征仍需进一步深入研究。 |
| 英文摘要: |
| Soil water stress reduction function is an important component of macroscopic root-water-uptake models,where the fitting parameters involved are often estimated based on the inverse method. Ignoring the effect of the difference in plant growth exposed to various water stress extents on potential transpiration,as well as the hysteresis effect of previous water stress on root water uptake or transpiration that always leads to offset between transpiration and soil water status after re-watering,however,the traditional inverse method often brings significant error. Therefore,two corresponding improvements were carried out in this study,(1) calibrating the potential transpiration rate of stressed plants by introducing effective leaf area index; (2) optimizing the parameter with only the data in post-recovery periods when the change trends of both transpiration and soil water status were basically synchronized by understanding the dynamics of transpiration after re-watering,to avoid or reduce the hysteresis effect of water stress (i.e. the change trend of transpiration was asynchronous with that of soil water status) as possible. A soil column experiment including various water supply treatments for winter wheat was conducted in greenhouse to verify the reliability of the improved method. The results demonstrated that,relative to the traditional method,the root-water-uptake model established with the improvements significantly enhanced the simulation accuracies of actual transpiration rate and relative transpiration rate (RMSE ≤ 0.07 cm/d and 0.04,respectively; R2 ≥ 0.96),as well as soil water content (RMSE ≤ 0.012 cm3/cm3; R2 ≥ 0.83). Thus,the proposed method can enhance the estimation for parameter in soil water stress reduction function,making a solid foundation for establishing reasonable root-water-uptake model and simulating transpiration and soil water accurately. However,the improved root-water-uptake model still fails to reflect the gradual recovery processes of root water uptake,and thus further study in mechanism and quantification of hysteresis effect is necessary. |
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