Small scaled and dynamic analysis of microstructural rhizo- and drilosphere properties: porosity,physicochemistry and their role for root growth, nutrient storage and transport/support

该项目的研究是基于前研究单位FOR 1320，其中研究了不同前茬作物和作物序列对底土中特征生物孔隙系统及其功能特性的发展的影响。使用X射线计算机断层扫描和图像分析非侵入性地量化孔隙网络结构。这些结果强调了生物孔通过支持更深的生根来提供水和空气的重要性。结果表明，在微尺度上，根系和根系产生的生物孔隙有明显的差异，尤其是在生物孔隙与土壤的界面（孔壁）。以前堵塞的毛孔e。G.恢复了连续性，而在其他孔隙中，次生根形成的孔隙或截断的侧通道被覆盖和/或堵塞。孔隙壁的性质在多大程度上影响空气和水以及养分通过根际土壤和孔隙之间的转移仍然是未知的。首次对微尺度气体扩散的测量表明，由于大量的侧向通道，根诱导的孔隙比蠕虫诱导的孔隙更适合于空气输送。另一方面，蠕虫诱导的孔可能会导致疏水孔壁，因为衬里有根和/或蠕虫分泌物，这将导致更水稳定的结构，但也减少了横向水运输。在该项目中，设想以组合方法（StrucDyn/卡塞尔和RhizPhy/基尔）对孔壁特性进行详细分析，包括生物孔网络的结构和微观形态（StrucDyn）以及孔壁的物理化学、物理和化学方面（RhizPhy）。StrucDyn将非侵入性地研究单个生物孔的结构，包括孔壁和根际孔隙空间的形态，这取决于孔的起源/定植（蠕虫或根）以及生物孔的老化。将利用形态学图像分析和数字图像相关性来检测孔改性。孔壁特性，如实际疏水性（排斥性），水的可转移性（吸附性，微渗透）和空气（氧扩散，氧化还原电位）以及微观机械特性（微渗透，流变学）将通过RhizPhy在完整的孔壁和根和蠕虫分泌物以及生物模型物质上进行测定。从StrucDyn和RhizPhy获得的数据将被用来参数化，并进一步开发一个根生长模型（RootMod），以研究根际微结构和水力/力学特性对根系发育和水分和养分吸收的影响。

The research of this project is based on the former research unit FOR 1320 where the effect of different preceding crops and crop sequences on the development of characteristic biopore systems and their functional properties in the subsoil was investigated. Pore network architectures were quantified non-invasively using X-ray computed microtomography and image analysis. The results underline the importance of biopores for water and air supply by supporting deeper rooting. It was found that earthworm and root generated biopores were distinctly different at the microscale, especially at the interface between biopore and bulk soil (pore wall). Previously blocked pores e. g. regained continuity, whereas in other pores earthworm cast lined and/or blocked the pores or truncated lateral channels previously formed by secondary roots. To what extent the pore wall properties influence the transfer of air and water as well as nutrients between bulk soil and the pore through the rhizodrilosphere is still unknown. First measurements on microscale gas diffusion revealed that root-induced pores are more suitable for air transport than worm-induced pores due the large amount of lateral channels. On the other hand, worm-induced pores might result in hydrophobic pore walls due to the lining with root and/or worm exudates that will lead to more water-stable structures but also reduce lateral water transport. In this project a detailed analysis of the pore wall properties is envisaged in a combined approach (StrucDyn/Kassel, and RhizPhy/Kiel) including both the structure and micromorphology of the biopore network (StrucDyn) and the physicochemical, physical and chemical aspects of the pore wall (RhizPhy). StrucDyn will investigate non-invasively the architecture of single biopores including the morphologies of the pore wall and rhizodrilosphere pore space depending on the pore origin/colonization (worm or root) as well as due to biopore aging. Morphological image analysis and digital image correlation will be utilized to detected pore modifications. Pore wall properties such as actual hydrophobicity (repellency), the transferability of water (sorptivity, microinfiltration) and air (oxygen diffusion, redox potential) as well as micromechanical properties (micropenetration, rheomtry) will be determined by RhizPhy on both intact pore walls and root and worm exudates as well as biological model substances. The obtained data from StrucDyn and RhizPhy will be used to parameterize and further develop a root growth model (RootMod) in order to investigate the effect of microstructural and hydraulic/mechanical properties of the rhizodrilosphere on root development and water and nutrient uptake.