Assessing the relevance of an enhanced root growth due to the activity of rhizobacteria for plant phosporus uptake under low P supply

促进植物生长的根际细菌以不同的方式帮助植物在次适磷供应下生长。它们增加了根际磷的有效性，并能促进根的生长，从而使植物能够利用更大的土壤容量。目的是评估肠杆菌属菌株(根癌肠杆菌)在这些过程中哪一种更重要。玉米的根生长动态将在根箱中确定，这样可以每天观察到玉米的根。此外，还将在田间试验中量化不同磷和接种水平下的根生长。在不同主要磷源土壤的培养研究中，将研究根癌埃希氏菌提高土壤中磷浓度的能力。此外，培养和未培养植物根际土壤的P分级结果表明，根际土壤中的P形态主要是由根际假单胞菌来解决的。最后，田间、盆栽和培养实验的所有数据将用于模拟吸附过程、土壤迁移和吸收。这提供了关于在次优磷供应下促进根生长和/或磷溶解对更好的植物生长的相关性的信息。

Plant growth promoting rhizobacteria help plants to grow at sub-optimal P supply in different ways. They increase P availability in the rhizosphere and they can induce an enhanced root growth which enables plants to exploit larger soil volumes. The objective is to assess for an Enterobacter strain (E. radicincitans) which of these processes is of more importance. Root growth dynamics of maize will be determined in rhizoboxes which allow a daily view on the roots. Furthermore, root growth will also be quantified in field experiments at different P and inoculation levels. The ability of E. radicincitans to increase P soil solution concentration will be investigated in incubation studies with soils differing in their main P source. Additionally, a P fractionation of rhizosphere soil of incubated and non-incubated plants in comparison to bulk soil reveals which P form is mainly solved by E. radicincitans. Finally, all the data of the field, pot, and incubation experiments will be used for modelling sorption processes, soil transport, and uptake. This gives information about the relevance of enhanced root growth and/or P solubilization for a better plant growth at sub-optimal P supply.