Mycorrhizal fungi: Highways for water and nutrients in arid soils
Mycorrhizal fungi: Highways for water and nutrients in arid soils
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DOI：
10.2136/vzj2006.0068
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发表时间：
2007-05-01
影响因子：
2.8
通讯作者：
Allen, Michael F.
中科院分区：
文献类型：
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作者：
Allen, Michael F.
菌根真菌是众所周知的增加养分吸收，但其对土壤物理结构和水分流动的影响还不太清楚。在这里，我探索我们所知道的菌根外部菌丝体的物理结构，并研究物理结构如何影响植物水分吸收和非饱和土壤中的反向水力提升。菌根真菌的结构是这样的，有线性细胞质单位，可以延伸一米或更长。细胞膜可能仅位于植物内的菌丝顶端，并且在距离植物根几厘米至几米的外部。单个菌丝形成穿过土壤孔隙的线性表面，增加了水流路径的曲折因子（伽马），从而增加了电导率。但是菌丝的直径很小，只提供了一个很小的表面积用于运输。关于反向流动（从植物到真菌的水力再分配）的了解很少，除了它们的发生和在干旱中维持菌丝的关键作用。真菌在植物-水分关系中的最终重要性取决于干燥模式、土壤孔隙结构和从根延伸到土壤中的菌丝连接的数量。需要新的技术来充分参数化水的水平流动模式的模型：（一）观察和监测的根和菌根真菌的生长在原地;和（二）在高的时间和空间分辨率描述局部环境。
Mycorrhizal fungi are well known for increasing nutrient uptake but their effects on soil physical structure and water fl ow are less well understood. Here I explore what we know about the physical structure of mycorrhizal external mycelia and examine how that physical structure affects plant water uptake and reverse hydraulic lift in unsaturated soils. Mycorrhizal fungi are structured such that there are linear cytoplasmic units that can extend for a meter or more. Cell membranes may be only located in hyphal tips within the plant and externally several centimeters to meters distant from the plant root. Individual hyphae form a linear surface that goes across soil pores increasing the tortuosity factor (Gamma) of the pathway for water fl ow, thereby increasing conductivity. But hyphae are small in diameter, providing only a small surface area for that transport. Little about the reverse flows ( hydraulic redistribution from plant to fungus) is known other than that they occur and could play a critical role in sustaining hyphae through drought. The ultimate importance of mycorrhizae in plant - water relations depends on the drying patterns, the soil pore structure, and the number of hyphal connections extending from the root into the soil. New technologies are needed to adequately parameterize models of water horizontal fl ow patterns to: (i) observe and monitor the growth of roots and mycorrhizal fungi in situ; and (ii) describe the localized environment at high temporal and spatial resolution.