Image-based modelling of nutrient movement in and around the rhizosphere.
Image-based modelling of nutrient movement in and around the rhizosphere.
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DOI：
10.1093/jxb/erv544
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发表时间：
2016-02
影响因子：
6.9
通讯作者：
Roose T
中科院分区：
文献类型：
--
作者：
Daly KR;Keyes SD;Masum S;Roose T
使用严格的数学技术和基于图像的建模来量化根毛对养分吸收的影响，并研究生长的根毛是如何影响吸收的。在这项研究中，我们开发了一个基于根际土壤结构的X射线计算机断层图像的根毛养分吸收的空间显式模型。这项工作将我们以前的工作扩展到更大的领域，因此在更长的时间内有效。与以前使用的只考虑根部周围一小块土壤的模型不同，我们考虑了根际周围实际上无限大的土壤体积。我们提出的问题是：在离根表面多远的地方，根毛的特定结构特征和土壤团聚体形态并不重要，因为平均特性开始主导养分的运输？通过分别考虑远离根部和靠近根部的代表性土壤体积，所得到的模型被用来捕捉土壤的总体和根际性质。通过增加我们考虑的体积的大小，散体土壤的扩散阻抗和根系吸收被认为是收敛的。我们对两种不同的含水率值进行了测试。我们发现，养分吸收特性收敛到固定值的区域的大小取决于含水饱和度。在完全饱和的情况下，对于土壤流动性较差的物种，如磷酸盐，我们需要考虑的土壤区域仅为1.1 mm半径。然而，在部分饱和介质(相对饱和度为0.3)的情况下，我们发现半径1.4 mm是必要的。这表明，除了根际的几何特性外，土壤水分特性还有一个额外的影响，这种影响从根部延伸到更远的地方，可能与根际的其他化学变化有关。后者没有明确地包含在我们的模型中。
Rigorous mathematical techniques and image-based modelling were used to quantify the effect of root hairs on nutrient uptake and to investigate how uptake is influenced by growing root hairs. In this study, we developed a spatially explicit model for nutrient uptake by root hairs based on X-ray computed tomography images of the rhizosphere soil structure. This work extends our previous work to larger domains and hence is valid for longer times. Unlike the model used previously, which considered only a small region of soil about the root, we considered an effectively infinite volume of bulk soil about the rhizosphere. We asked the question: At what distance away from root surfaces do the specific structural features of root-hair and soil aggregate morphology not matter because average properties start dominating the nutrient transport? The resulting model was used to capture bulk and rhizosphere soil properties by considering representative volumes of soil far from the root and adjacent to the root, respectively. By increasing the size of the volumes that we considered, the diffusive impedance of the bulk soil and root uptake were seen to converge. We did this for two different values of water content. We found that the size of region for which the nutrient uptake properties converged to a fixed value was dependent on the water saturation. In the fully saturated case, the region of soil we needed to consider was only of radius 1.1mm for poorly soil-mobile species such as phosphate. However, in the case of a partially saturated medium (relative saturation 0.3), we found that a radius of 1.4mm was necessary. This suggests that, in addition to the geometrical properties of the rhizosphere, there is an additional effect of soil moisture properties, which extends further from the root and may relate to other chemical changes in the rhizosphere. The latter were not explicitly included in our model.