Chapter 4 The rhizosphere
The rhizosphere Chapter 4
Aims of this lecture Summarize properties of the rhizosphere, especially Gradients in Nutrient concentration Redox potential Exudates Microbial activi Non-infecting rhizosphere mIcroorganIsms necting rhizosphere mIcroorganisms that are relevant to plant mineral nutrition T/d from H Marschner: Fig 15.1
Aims of this lecture Summarize properties of the rhizosphere, especially: Modified from H. Marschner: Fig. 15.1 …that are relevant to plant mineral nutrition
The rhizosphere(根际) Width not to scale Layer of soil surrounding the -Root- growing root that is affected by the root(concept) pidermal and cortical cells Usually a few mm wide, up to lysed and invaded say 1 cm(no sharp boundary) by bacteria Extent depends on plant properties; e.g 20 CIm Root hair length density Micro-organisms Rhizodeposition(exudates etc) with microbial and plant mucilages spreading into the sd Nutrient uptake versus supply Sloughed root cap celis Root cap Mycorrhizospheres'(菌根际)can extend many cm Rovira
The rhizosphere(根际) Rovira 1960? • Layer of soil surrounding the growing root that is affected by the root (concept) • Usually a few mm wide, up to say 1 cm (no sharp boundary)* • Extent depends on plant properties; e.g. - Root hair length & density - Rhizodeposition (exudates etc) - Nutrient uptake versus supply Width not to scale * ‘Mycorrhizospheres’ (菌根际)can extend many cm c
The rhizosphere: soil factors Width not to scale Layer of soil surrounding the Root→·tSol growing root that is affected B the root Epidermal and cortical cells lysed and invaded Usually a few mm, up to say 1 bacteria cm (no sharp boundary EXtent depends on soil properties, e. g 鬆- Micro-organisms with microbial an d pH buffering plant mucilages spreading into the soi-Sorption capacity Nutrient supply rate Sloughed root cap cells Microbial populations Root cap Decomposition of exudates Rovira
The rhizosphere: soil factors Rovira 1960? • Layer of soil surrounding the growing root that is affected by the root • Usually a few mm, up to say 1 cm (no sharp boundary) • Extent depends on soil properties; e.g. - pH & buffering - Sorption capacity - Nutrient supply rate - Microbial populations - Decomposition of exudates Width not to scale
The rhizosphere: some conventions Root Rhizoplane Inner rhizosphere Outer 0-10um 10-500pm rhizosphere 根土界面 内根际 500-5000pm
The rhizosphere: some conventions Outer rhizosphere 500-5000 µm 外根际 Inner rhizosphere 10-500 µm 内根际 Rhizoplane 0-10 µm 根土界面 Root