Water for Carbon, Carbon for Water
Water for Carbon, Carbon for Water
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DOI：
10.2136/vzj2015.04.0060
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发表时间：
2016-02-01
影响因子：
2.8
通讯作者：
Ghezzehei, Teamrat
中科院分区：
文献类型：
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作者：
Carminati, Andrea;Kroener, Eva;Ghezzehei, Teamrat
植物根系通过光合作用将约10%的碳同化到土壤中，这一过程称为根沉积。在这里，我们表明，根沉积物的粘液部分，被称为粘液，土壤植物水分关系起着至关重要的作用，它有可能提高植物耐旱性。粘液是一种凝胶，可以吸收大量的水，改变根际的物理性质，并在土壤干燥时保持根际湿润和导电。据推测，粘液作为根和土壤之间的水力桥梁，促进根系吸水和维持蒸腾在干燥的土壤。通过采用根系吸水与粘液动力学相结合的简化模型，我们发现，在桑迪土壤中，当土壤基质势降至约-0.8 MPa以下时，粘液在维持根系吸水方面的益处开始显现。这一临界基质势随蒸腾速率、根长和渗出速率而变化。在临界势以下，粘液维持光合作用并导致碳的净增加。总之，根系沉积改变了土壤物理环境，并对蒸腾作用和光合作用产生影响。换句话说：水换碳，碳换水。
Plant roots exude approximately 10% of the carbon assimilated through photosynthesis into the soil, a process referred to as rhizodeposition. Here, we show that the mucilaginous fraction of the rhizodeposits, referred to as mucilage, plays a crucial role on soil-plant water relation and it has the potential to increase plant drought tolerance. Mucilage is a gel that can absorb large volumes of water, altering the physical properties of the rhizosphere and maintaining the rhizosphere wet and conductive when the soil dries. It is hypothesized that mucilage acts as a hydraulic bridge between roots and the soil, facilitating root water uptake and maintaining transpiration in dry soils. By employing a simplified model of root water uptake coupled with mucilage dynamics, we found that in a sandy soil the benefit of mucilage in maintaining root water uptake commenced to manifest when the soil matric potential dropped below approximately -0.8 MPa. This critical matric potential varied with transpiration rate, root length, and exudation rate. Below the critical potential, mucilage maintained photosynthesis and resulted in a net gain of carbon. In summary, rhizodeposition modifies the physical soil environment and has an impact on transpiration and photosynthesis. In other words: water for carbon, but also carbon for water.