作物水分利用及产量形成对水分胁迫的响应模拟与亏缺灌溉精确调控

Deficit irrigation (DI) shows great water-saving potential under experimental conditions, but with some limitations to controlling water deficit precisely, applying for the different climate and soil conditions correctly, and deeply understanding on the theory and approach of DI. Agricultural system model can cover the shortage of experimental results but has lack of evaluating and improving the key simulation processes with detailed experimental data sets. In this project, using field experiment and agricultural system model methods, we first evaluate and improve the key model processes of simulating crop water use and grain yield in response to various water stress levels using multiple field experimental data sets, and enhance the model' performance under various water stress conditions. Combining experimental and model simulation results, we analyze the responses of crop water use and grain yield to water deficits at the different growth stages, and determine the most reasonable crop water stress levels and the corresponding irrigation water requirements at different growth stages. Based on the above analysis, detailed DI scenarios are designed with the improved model for the long-term simulation at multiple sites in the Northern China, which are used to quantify the relationships between crop yield, irrigation requirement and water deficit levels, and their controlling factors across the different climate and soil conditions. The optimal DI modes and regulating index are refined and established for the different sites. These results will extend the field experimental results, benefit on the deep understanding of DI regulating theory, and provide useful guidelines on precisely regulating DI management .

亏缺灌溉在试验条件下取得显著的节水效果，但在水分精确控制、应对不同气候和土壤条件时存在不足，缺乏对其调控原理和技术指标的量化分析。农业系统模型在一定程度上可弥补试验研究的不足，但对模型关键过程的改善工作不够深入，模型的可靠性有待加强。本项目结合田间试验与农业系统模型的研究优势，利用多站点试验数据详细评价、改善作物水分利用及产量形成等关键模拟过程，提高模型在水分胁迫条件下的适应性和可靠性，为模型的应用提供支持。结合试验和模拟数据分析作物水分利用及产量形成对不同生育期水分亏缺的响应规律，明确作物最适水分胁迫程度及其与灌溉指标的数量关系。利用改进的模型在不同气象站点进行情景模拟，系统分析不同气候、土壤条件下水分亏缺程度与作物产量及灌溉需水量的量化关系和主要控制因素，建立不同区域优化亏缺灌溉模式和调控指标，进一步扩展、深化试验结果、明确亏缺灌溉的调控原理，为亏缺灌溉的精确调控提供理论和技术支持。

作物水分精确管理是水资源短缺地区农业可持续发展的关键，目前多数作物水分管理在应对不同气候和土壤条件时存在明显不足，也缺乏对作物水分关系调控原理和技术指标的量化分析。我们利用农业系统模型和水分精确控制试验相结合进行深入研究，主要结果如下：（1）滴灌条件下不同灌溉制度对冬小麦产量和水分利用效率有明显影响，并显著高于常规灌溉处理，表现出明显优势和较高的应用潜力；（2）结合滴灌试验和多站点水分控制试验详细验证、评价了RZWQM-CERES（根系水质模型和CERES结合模型），结果表明该模型能够较好的模拟不同灌溉制度对作物产量、水分利用的影响。在此基础上对比分析了模型中不同分胁迫估算方法对模拟结果的影响（如不同的潜在蒸散计算方法或考虑作物蒸腾和土壤蒸发分开等），初步筛选出了最优算法。同时评价或改善了作物氮素吸收、冠层温度对不同水分亏缺的响应模拟效果。针对模型的不确定性来源（如作物参数和实验数据等）进行了量化评价，发现选择合适的参数优化方法和校正数据可以提高模型的可靠性。这些研究结果显著提高了该模型的适应性和应用潜力。（3）在以上结果基础上，结合历史气象资料和模型模拟结果在国内外不同区域进行了最优灌溉制度研究，包括华北地区冬小麦-夏玉米两熟系统、北方马铃薯系统以及美国北部大平原玉米生产系统等，初步建立了适合不同土壤和气候条件的灌溉制度或策略及相关灌溉指标，这些研究结果为作物精确灌溉提供了重要理论和技术支持。