Roots in the surroundings of biopores

迄今为止，由于土壤中养分吸收的先决条件普遍不利，土壤中根长密度普遍较低，因此对土壤中养分的作用存在争议，而另一方面，至少在一定的环境条件下，作物可以从土壤中吸收很大比例的养分。生物孔的周围环境可能是地下土壤中根系生长的热点。然而，通过比自身直径大得多的孔腔生长的根至少部分暴露在空气中，并且获得孔壁资源的机会有限，而通过生物孔环境生长的根可以更容易地建立根与土壤的接触，并从高浓度的营养物质、微生物活性和容易获得水和氧气中获益。本项目将利用先进的采样技术对生物孔周围的根系生长进行研究。该项目的总体假设是，在生物孔的环境中，土壤的化学和物理性质受到蚯蚓（沉积富氮粪便）和植物根（侧根形成细孔）的活动的影响。-根长密度大于散装土。根的结构在直径和分枝方面不同于生长在大块土壤中的根。根的代谢活性通过根际pH梯度图结合同位素标记得到提高。试验将在土壤柱和田间的受控条件下进行。该项目将考虑到生物孔的个体属性取决于它们的形成历史，即蚯蚓和根的前活动。建立不同根系和蚯蚓对孔隙影响的微观实验。根长密度将通过图像分析来量化。利用99原子% 13c -尿素和叶片标记技术，用同位素示踪剂定量测定根代谢活性。培养后用质谱法测定13C释放量。此外，pH敏感平面光电器件将用于绘制通过生物孔和块状土壤生长的根周围的pH梯度。用气相色谱法分析生物孔鞘中木栓素的含量，作为老根的标志。

To date, the role of the subsoil for nutrition of arable crops is in dispute because on the one hand the prerequisites for nutrient uptake in the subsoil are generally adverse and root-length densities in the subsoil are generally low, whereas on the other hand, at least under certain environmental conditions, crops can take up large proportions of nutrients from the subsoil. The surroundings of biopores have probably a key function as hot spots for root growth in the subsoil. Whereas the roots growing through the lumen of pores much larger than their own diameter are at least partly exposed to air and have limited access to the resources of the pore wall, roots growing through the surroundings of biopores can establish root-soil contact more easily and draw benefit from high concentration of nutrients, microbiological activity and facile access to water and oxygen. This project will focus on investigation of root growth in the surroundings of biopores with advanced sampling techniques. The overall hypotheses of this project are that in the surroundings of biopores - chemical and physical soil properties are influenced by the activities of anecic earthworms (deposition of feces rich in N) and plant roots (creation of fine pores by lateral roots).- root length density is greater than in the bulk soil.- root architecture in terms of diameter and branching is different from roots growing in the bulk soil.- metabolic activity of roots as indicated by mapping of pH gradients in the rhizosphere in combination with isotopic labeling is increased.Experiments will be carried out under controlled conditions in soil columns and in the field. The project will take into account that individual properties of biopores depend on their formation history, i.e. the former activity of earthworms and roots. Microcosm experiments with pores differently influenced by roots and earthworms will be established. Root-length densities will be quantified by image analyses. Metabolic activity of roots will be quantified with isotope tracers using 99 atom% 13C-urea applied with the leaf labelling technique. After cultivation, 13C release will be quantified with mass spectroscopy. Moreover, pH sensitive planar optodes will be used for mapping of pH gradients around roots growing through surroundings of biopores and the bulk soil. Suberin contents, in the biopore sheath as markers of old roots will be analyzed with gas chromatography.