Dynamics of soil water content in the rhizosphere
Dynamics of soil water content in the rhizosphere
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DOI：
10.1007/s11104-010-0283-8
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发表时间：
2010-07-01
期刊：
影响因子：
4.9
通讯作者：
Oswald, Sascha E.
中科院分区：
文献类型：
--
作者：
Carminati, Andrea;Moradi, Ahmad B.;Oswald, Sascha E.
从土壤到植物的水流取决于根部附近土壤的性质，即根际。尽管一些研究表明根际土壤具有与非根际土壤不同的性质，但根际土壤对根系吸水的影响通常被忽视。为了调查根际的属性，我们使用中子射线照相成像的水分含量分布在土壤样品种植羽扇豆在干燥和随后的再润湿。干燥过程中，根际土壤含水量比本体土壤含水量大0.05。再润湿后，立即扭转和根际仍然显着干燥的图片。在随后的几天中，根际的含水量增加，60小时后，它超过了散装土壤。根际的厚度约为1.5毫米。根据所观察到的动态，我们推导出明显的，滞后和时间依赖性的根际持水曲线。我们的假设是，根际水分保持曲线是由根系分泌的粘液决定的。根际特性减少了根周围的水分消耗，减弱了向根的水势下降，因此有利于在干燥条件下的水分吸收，如通过分析计算到单个根的水流量所证明的。
Water flow from soil to plants depends on the properties of the soil next to roots, the rhizosphere. Although several studies showed that the rhizosphere has different properties than the bulk soil, effects of the rhizosphere on root water uptake are commonly neglected. To investigate the rhizosphere's properties we used neutron radiography to image water content distributions in soil samples planted with lupins during drying and subsequent rewetting. During drying, the water content in the rhizosphere was 0.05 larger than in the bulk soil. Immediately after rewetting, the picture reversed and the rhizosphere remained markedly dry. During the following days the water content of the rhizosphere increased and after 60 h it exceeded that of the bulk soil. The rhizosphere's thickness was approximately 1.5 mm. Based on the observed dynamics, we derived the distinct, hysteretic and time-dependent water retention curve of the rhizosphere. Our hypothesis is that the rhizosphere's water retention curve was determined by mucilage exuded by roots. The rhizosphere properties reduce water depletion around roots and weaken the drop of water potential towards roots, therefore favoring water uptake under dry conditions, as demonstrated by means of analytical calculation of water flow to a single root.