Neutron radiography and tomography of water distribution in the root zone
Neutron radiography and tomography of water distribution in the root zone
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DOI：
10.1002/jpln.200900188
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发表时间：
2010-10-01
影响因子：
2.5
通讯作者：
Oswald, Sascha E.
中科院分区：
文献类型：
--
作者：
Esser, Hanna G.;Carminati, Andrea;Oswald, Sascha E.
根系吸水和由此产生的水分沿沿着土壤剖面的再分布取决于土壤水力特性和根系分布，以及根区发生的物理、化学和生物土壤植物相互作用。根区土壤的水力特性难以在所需的高空间分辨率下进行原位研究，并且它们仍然是重要的未决问题。例如，根土界面处的水与土壤相比是多了还是少了？中子射线照相术（2-D）和层析成像（3-D）是有效的方法来回答这些问题，提供了可能性，同时图像的水分布和根结构在原位在高空间分辨率。我们在装满桑迪的长方形盒子里种了一种羽扇豆和一种玉米。植物在受控条件下生长3周，渗透水和随后的水分再分布通过中子射线照相术和断层摄影术定期成像5 d。土壤含水量分布进行了定量的射线照片后，校正中子散射。射线照片显示，在渗透过程中和渗透后，根区中的含水量高于散装土壤中的含水量。类似地，断层图像显示，在根系的某些位置周围，特别是在羽扇豆的尖端附近，局部区域的含水量高。局部地区的水枯竭，这是预期的水吸收的结果，是明显的沿着主根的地方分枝。这些结果反映了土壤-植物水分关系的复杂性，显示了土壤和根区的不同性质，以及沿根系沿着变化的水分梯度。
Water uptake by roots and resulting water redistribution along the soil profile depend on soil hydraulic properties and root distribution, as well as on the physical, chemical, and biological soil plant interactions that occur in the root zone. The hydraulic properties of the soil in the root zone are difficult to investigate in situ at the needed high spatial resolution, and they still present important open questions. For instance, is there more or less water at the root soil interface compared to the bulk soil? Neutron radiography (2-D) and tomography (3-D) are efficient methods to answer such questions, providing the possibility to image simultaneously water distributions and root structure in situ at high spatial resolution. We planted a lupin and a maize in rectangular boxes filled with sandy soils. The plants were grown for 3 weeks at controlled conditions.Infiltrated water and subsequent water redistribution were imaged for 5 d at regular intervals by means of neutron radiography and tomography. Soil water-content distributions were quantified from the radiographs after correcting for neutron scattering. The radiographs showed that the water content in the root zone was higher than in the bulk soil both during and after infiltration Similarly, the tomograms showed localized regions of high water content around some locations of the roots, in particular near the tips of the lupin. Local regions of water depletion, which are expected as a consequence of water uptake, were visible along the main root where laterals branched. These results reflect the complexity of soil plant water relations, showing the different properties of bulk soil and root zone, as well as the varying moisture gradients along the root system.