Quantification of hydraulic redistribution in maize roots using neutron radiography
Quantification of hydraulic redistribution in maize roots using neutron radiography
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DOI：
10.1002/vzj2.20084
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发表时间：
2020-01-01
影响因子：
2.8
通讯作者：
Carminati, Andrea
中科院分区：
文献类型：
--
作者：
Hayat, Faisal;Zarebanadkouki, Mohsen;Carminati, Andrea
植物通过根系将水分从湿土层重新分配到干土层，这一过程被称为水力再分配。虽然这一过程的相关性和发生被广泛接受，但解决水力再分布的空间分布仍然具有挑战性。在这里，我们展示了如何使用中子射线照相来量化从根到土壤的水流出率。玉米（Zea mays L.）植株生长在40 cm深的沙质基质中。在底部湿室注入氘化水（D2O），利用中子射线照相技术对其通过根部向顶部干燥土壤的输送过程进行成像。采用扩散-对流模式模拟了土壤和根系中D2O的运移，并反演了对流通量。一夜之间，D2O出现在顶部室的节根和侧根。通过逆向建模，我们估计侧根进入干燥土壤的外排量等于j(r) = 2.35 x 10(-7) cm（-1）。重新分配的水的很大一部分流向节根的尖端(每根3.85 x 10(-8) cm（3) s(-1)）以维持其生长。节根的外排量与根的长度和生长速率有关。总之，中子成像成功地用于量化水力再分配。需要一个数值模型来区分扩散和对流的影响。高分辨率图像显示了水力再分布的空间异质性。
Plants redistribute water from wet to dry soil layers through their roots, in the process called hydraulic redistribution. Although the relevance and occurrence of this process are well accepted, resolving the spatial distribution of hydraulic redistribution remains challenging. Here, we show how to use neutron radiography to quantify the rate of water efflux from the roots to the soil. Maize (Zea mays L.) plants were grown in a sandy substrate 40 cm deep. Deuterated water (D2O) was injected in the bottom wet compartment, and its transport through the roots to the top dry soil was imaged using neutron radiography. A diffusion-convection model was used to simulate the transport of D2O in soil and root and inversely estimate the convective fluxes. Overnight, D2O appeared in nodal and lateral roots in the top compartment. By inverse modeling, we estimated an efflux from lateral roots into the dry soil equal to j(r) = 2.35 x 10(-7) cm(-1). A significant fraction of the redistributed water flew toward the tips of nodal roots (3.85 x 10(-8) cm(3) s(-1) per root) to sustain their growth. The efflux from nodal roots depended on the roots' length and growth rate. In summary, neutron imaging was successfully used to quantify hydraulic redistribution. A numerical model was needed to differentiate the effects of diffusion and convection. The highly resolved images showed the spatial heterogeneity of hydraulic redistribution.