Rhizodeposition under drought is controlled by root growth rate and rhizosphere water content
Rhizodeposition under drought is controlled by root growth rate and rhizosphere water content
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DOI：
10.1007/s11104-017-3522-4
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发表时间：
2018-02-01
期刊：
影响因子：
4.9
通讯作者：
Carminati, Andrea
中科院分区：
文献类型：
--
作者：
Holz, Maire;Zarebanadkouki, Mohsen;Carminati, Andrea
根际沉积是土壤微生物的重要能量来源。因此，估计根源碳(C)在土壤中的分布及其随土壤水分含量的变化是至关重要的。我们通过耦合植物(CO2)-C-14标记和磷成像来估计C在根际的分配，测试了干旱对根际渗出物分布的影响。利用中子照相技术对根际水分进行可视化研究。通过一个数值模型来预测渗出物的释放及其沿生长根和周围的时空分布，干植物和湿植物分配到根中的C-14量相似，但在干燥土壤中，根的伸长减少了48%，从而减少了根际的纵向伸长。根际水分含量与干旱无关(31%)，这可能是因为粘液具有很高的保水能力。该模型预测，根际水分含量的增加将促进分泌物的扩散，特别是在干旱土壤中，并增加其微生物分解。根系生长和根际水分含量对根系释放碳以及根际分泌物在根际的分布起着重要作用。粘液的释放可能是一种植物策略，以保持分泌物的快速扩散和高微生物活性，即使在水分限制的情况下也是如此。
Rhizodeposition is an important energy source for soil microorganisms. It is therefore crucial to estimate the distribution of root derived carbon (C) in soil and how it changes with soil water content.We tested how drought affects exudate distribution in the rhizosphere by coupling (CO2)-C-14 labelling of plants and phosphor imaging to estimate C allocation in roots. Rhizosphere water content was visualized by neutron radiography. A numerical model was employed to predict the exudate release and its spatiotemporal distribution along and around growing roots.Dry and wet plants allocated similar amounts of C-14 into roots but root elongation decreased by 48% in dry soil leading to reduced longitudinal rhizosphere extension. Rhizosphere water content was identical (31%) independent of drought, presumably because of the high water retention by mucilage. The model predicted that the increase in rhizosphere water content will enhance diffusion of exudates especially in dry soil and increase their microbial decomposition.Root growth and rhizosphere water content play an important role in C release by roots and in shaping the profiles of root exudates in the rhizosphere. The release of mucilage may be a plant strategy to maintain fast diffusion of exudates and high microbial activity even under water limitation.