Drought is a serious constraint to crop growth and production of important staple crops such as winter wheat and maize. Improved understanding of crops' response to drought can be incorporated into cropping system models to support crop breeding, crop and varietal selection and management decisions to minimize negative impacts. Plants may respond to drought through immediate stomatal regulation as well as possibly altering their morphological characteristics over longer periods. The degree and combination of these short- and long-term responses depends on the intensity and duration of drought as well as crop characteristics. However, field observational evidence for different crop types detailing these at short- and longer term responses and for different organizational levels is still limited. Here we examine the effects of various water supply treatments on short-term changes in leaf water potential (LWP) and gas exchange at the leaf level together with the seasonal changes in canopy photosynthesis, transpiration, and cumulative growth of winter wheat and maize based on field data collected in 2016, 2017, and 2018. Leaf and canopy gas exchange and cumulative growth was varied strongly with the duration and intensity of drought stress as well as growing stages. The longer-term morphological drought responses in winter wheat appeared to have a larger effect on regulating transpiration and assimilation rates than shorter-term responses of stomatal control had. Maize (grown in 2017 and 2018) exhibited different responses, with seasonal variations in minimum LWP and complete stomatal closure at LWP of between -1.6 and -2 MPa. While stomata closed with increasing drought, for maize, the physiological advantages of C₄ photosynthesis as well as morphological adjustments in leaf area size and leaf-rolling strongly determined crop growth and canopy gas exchange in the drought plots as compared with the irrigated plot. Observations highlight that improvements for soil-vegetation-atmosphere models in simulating gas exchange and crop growth should emphasize the dynamic reduction of leaf area under water stress, as well as stomatal regulation.

干旱严重制约着冬小麦、玉米等重要主粮作物的生长和生产。可以将更好地了解作物对干旱的反应纳入种植系统模型，以支持作物育种、作物和品种选择和管理决策，以最大限度地减少负面影响。植物可能通过直接的气孔调节以及可能在较长时期内改变其形态特征来应对干旱。这些短期和长期反应的程度和组合取决于干旱的强度和持续时间以及作物特性。然而，针对不同作物类型在短期和长期响应中以及针对不同组织级别详细说明这些作物类型的实地观察证据仍然有限。在这里，我们研究了各种供水处理对叶水势 (LWP) 和叶片水平气体交换的短期变化以及冬小麦和玉米冠层光合作用、蒸腾作用和累积生长的季节性变化的影响。 2016 年、2017 年和 2018 年收集的田间数据。叶片和冠层的气体交换和累积生长随干旱胁迫的持续时间和强度以及生长阶段的不同而有很大差异。与气孔控制的短期响应相比，冬小麦的长期形态干旱响应似乎对调节蒸腾和同化速率具有更大的影响。玉米（2017 年和 2018 年种植）表现出不同的反应，最小 LWP 的季节性变化和 LWP 完全关闭的气孔在 -1.6 到 -2 MPa 之间。₄ 光合作用以及叶面积大小和卷叶的形态调整强烈决定了干旱地块与灌溉地块相比的作物生长和冠层气体交换。观察结果强调，土壤-植被-大气模型在模拟气体交换和作物生长方面的改进应强调水分胁迫下叶面积的动态减少以及气孔调节。