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首页> 外文期刊>Hydrology and Earth System Sciences Discussions >Root growth, water uptake, and sap flow of winter wheat in response to different soil water conditions
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Root growth, water uptake, and sap flow of winter wheat in response to different soil water conditions

机译：不同土壤水分条件对冬小麦根系生长，水分吸收和液流的影响

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How much water can be taken up by roots and how this depends on the root and water distributions in the root zone are important questions that need to be answered to describe water fluxes in the soil–plant–atmosphere system. Physically based root water uptake (RWU) models that relate RWU to transpiration, root density, and water potential distributions have been developed but used or tested far less. This study aims at evaluating the simulated RWU of winter wheat using the empirical Feddes–Jarvis (FJ) model and the physically based Couvreur?(C) model for different soil water conditions and soil textures compared to sap flow measurements. Soil water content (SWC), water potential, and root development were monitored noninvasively at six soil depths in two rhizotron facilities that were constructed in two soil textures: stony vs. silty, with each of three water treatments: sheltered, rainfed, and irrigated. Soil and root parameters of the two models were derived from inverse modeling and simulated RWU was compared with sap flow measurements for validation. The different soil types and water treatments resulted in different crop biomass, root densities, and root distributions with depth. The two models simulated the lowest RWU in the sheltered plot of the stony soil where RWU was also lower than the potential RWU. In the silty soil, simulated RWU was equal to the potential uptake for all treatments. The variation of simulated RWU among the different plots agreed well with measured sap flow but the C?model predicted the ratios of the transpiration fluxes in the two soil types slightly better than the FJ?model. The root hydraulic parameters of the C?model could be constrained by the field data but not the water stress parameters of the FJ model. This was attributed to differences in root densities between the different soils and treatments which are accounted for by the C?model, whereas the FJ?model only considers normalized root densities. The impact of differences in root density on RWU could be accounted for directly by the physically based RWU model but not by empirical models that use normalized root density functions.
机译：根系可以吸收多少水，以及根系如何吸收根系和水分分布是描述土壤－植物－大气系统中水通量的重要问题。已经建立了将RWU与蒸腾作用，根系密度和水势分布相关联的基于物理的根系水分吸收（RWU）模型，但是使用或测试的模型要少得多。这项研究旨在使用经验性的Feddes–Jarvis（FJ）模型和基于物理的Couvreur？（C）模型，针对不同的土壤水分条件和土壤质地，与树汁流量测量相比，评估冬小麦的模拟RWU。在以两种土壤质地（石质和粉质）建造的两个根际设施中，在六个土壤深度对土壤水含量（SWC），水势和根系发育进行了无创监测，分别进行了三种水处理：遮蔽，雨养和灌溉。两种模型的土壤和根系参数均来自反演模型，并将模拟的RWU与液流测量值进行比较以进行验证。不同的土壤类型和水处理导致不同的作物生物量，根系密度和根系深度分布。这两个模型模拟了石质土壤避难所中最低的RWU，那里的RWU也低于潜在的RWU。在粉质土壤中，模拟RWU等于所有处理的潜在吸收量。不同田间模拟RWU的变化与测得的汁液流量非常吻合，但C？模型预测两种土壤类型的蒸腾通量比略好于FJ？模型。 C？模型的根部水力参数可能受现场数据的约束，而不受FJ模型的水应力参数的约束。这归因于C？模型解释的不同土壤和处理之间根系密度的差异，而FJ模型仅考虑归一化的根系密度。根密度差异对RWU的影响可以由基于物理的RWU模型直接解决，而不能由使用归一化根密度函数的经验模型来解决。

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