Truly Predicting Root Uptake of Water: Case Study with Wheat

真正预测根部对水分的吸收：小麦案例研究

基本信息

批准号：
BB/J000388/1
负责人：
Sacha Mooney
金额：
$ 39.18万
依托单位：
University of Nottingham
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2012
资助国家：
英国
起止时间：
2012 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FJ000388%2F1
关键词：
Truly Predicting Root Uptake Water

项目摘要

We heavily rely on soil to support the crops on which we depend. Less obviously we also rely on soil for a host of 'free services' from which we benefit. For example, soil buffers the hydrological system greatly reducing the risk of flooding after heavy rain; soil contains very large quantities of carbon which would otherwise be released into the atmosphere where it would contribute to climate change. Given its importance it is not surprising that soil, especially its interaction with plant roots, has been extensively researched. However the complex and opaque nature of soil has always made it a difficult medium to study. Soil is complex in that it is composed of different materials (mineral particles, organic matter, water, microrganisms) of all shapes and sizes (from centimetres to microns) which aggregate together to form a complex porous material. While the function of soil is determined by the processes taking place at the micro-scale (often called pore scale), within this complex material we have traditionally only been able to measure and observe soil function at the larger, macro-scale (usually referred to as the field scale). We can manipulate soil systems at the macro-scale and empirically observe what occurs, and this empirical description is useful, but it offers no scope to truly predict how the system would respond to modification. This is important because we have the potential and most likely the future need to manipulate the underlying processes at the microscale (in both plants and soil). For example we will need to know: should our crops root deeper? Would a change in root architecture be useful? To what extent can roots adapt to stresses in the soil physical environment? What management induced changes to soil structure are desirable for future environments? Evaluating such possibilities at the field scale currently requires case by case empirical investigation with little direction offered by any underlying theory; this is a huge gap in current knowledge. Even if good theories existed to explain soil-root interactions at the micro-scale, it is not clear how this could be applied to the field scale. Understanding and manipulating the system at the scale of <1mm is all very well, but we want to make a difference at the scale of >10 kms! We need to be able to 'scale up' our micro-knowledge to a scale that is useful. Progress can be made to address the microscale understanding of soil-root interactions, however this progress will only be of real importance if we also find ways to scale up to the field situation. This is also a huge gap in knowledge. These knowledge gaps can now be addressed as a result of two recent methodological developments. Firstly new experimental techniques based on X-ray Computed Tomography (CT) are making it easier to visualise and quantify soil and root micro-structure in a non-invasive manner. Secondly, mathematical homogenisation theory offers new ways to correctly scale up micro-scale processes to macro-scale models thereby addressing the scale problem. Integrating these two new methods for the first time we will consider the specific question of water movement in soils and its uptake by wheat, an important crop for UK agriculture. We will undertake experiments to measure the micro-structure of soils and investigate how water passes through these soils to the roots of plants. Our aim will be to use this information to develop and test theoretical models of water movement and uptake and use these to evaluate the performance of different wheat root architectures. We will do this in a way that is specifically designed to enable us to 'scale up' the results so we can make predictions at the field scale, based on the observable micro-scopic characteristics of soil. Thus, because of the generic methodology produced within this project the results are not only applicable for wheat, but for wide range of agricultural crops.

我们在很大程度上依靠土壤来支持我们依赖的农作物。不太明显，我们还依靠土壤来获得许多我们受益的“免费服务”。例如，土壤缓冲水文系统大大降低了大雨后洪水的风险。土壤中含有大量的碳，否则这些碳将释放到大气中，在那里它会导致气候变化。鉴于它的重要性，已经对土壤，尤其是其与植物根部的相互作用进行了广泛研究并不奇怪。但是，土壤的复杂和不透明的性质一直使其很难研究。土壤很复杂，因为它由各种形状和尺寸（从厘米到微米）组成的不同材料（矿物颗粒，有机物，水，微生物）组成，它们共同形成复杂的多孔材料。虽然土壤的功能取决于在微尺度上发生的过程（通常称为孔尺度），但在这种复杂的材料中，我们传统上只能在较大的宏观尺度（通常称为田间尺度）测量和观察土壤功能。我们可以在宏观尺度上操纵土壤系统，并从经验上观察发生的事情，并且这种经验描述很有用，但是它没有真正预测系统将如何响应修改的范围。这很重要，因为我们有潜力，而且很可能未来需要操纵微观的基础过程（在植物和土壤中）。例如，我们需要知道：我们的农作物应该更深入吗？根体系结构的更改会有用吗？根部可以在多大程度上适应土壤物理环境中的压力？对于未来的环境，需要哪些管理对土壤结构的变化？目前，在现场量表上评估这种可能性需要案例实证研究，而任何基本理论几乎没有方向；这是当前知识的巨大差距。即使存在良好的理论来解释在微尺度上的土壤根相互作用，也不清楚如何将其应用于田间尺度。以<1mm的比例了解和操纵系统的情况非常好，但是我们希望以> 10公里的比例有所作为！我们需要能够将我们的微知识“扩展”到有用的规模上。可以取得进展来解决对土壤与根部相互作用的微观理解，但是，只有当我们找到可以扩展到现场状况的方法时，这种进度才真正重要。这也是知识的巨大差距。这些知识差距现在可以通过最近的两个方法论发展来解决。首先，基于X射线计算机断层扫描（CT）的新实验技术使以非侵入性方式更容易地可视化和量化土壤和根微结构。其次，数学同质化理论提供了新的方法来正确扩展微型流程到宏观尺度模型，从而解决了规模问题。首次将这两种新方法整合在一起，我们将考虑土壤中水流动的具体问题及其对英国农业的重要作物的小麦吸收。我们将进行实验，以测量土壤的微观结构，并研究水如何通过这些土壤进入植物的根。我们的目的是使用这些信息来开发和测试水运动和吸收的理论模型，并使用这些信息来评估不同小麦根体系结构的性能。我们将以专门设计的方式执行此操作，以使我们能够“扩展”结果，以便我们可以根据可观察到的土壤的微观特征在现场尺度上进行预测。因此，由于该项目中产生的通用方法，结果不仅适用于小麦，而且适用于各种农作物。