Interactions between root exudates, mineral nutrition and plant growth

Exudates represent a significant flow of carbon from roots into soil. However there is a dearth of information concerning slow-growing perennial plants. The functional role of these flows is also very uncertain except for a few specific exudates. The potential interactions between exudation and mineral nutrition, particularly phosphorus uptake, and their effect on plant growth are explored in this paper. A mechanistic mathematical model linking plant growth to P uptake is first developed and validated using published data-sets. This model is then coupled to a model describing microbial dynamics in the rhizosphere. The prediction from the simulations was that the rhizosphere microbial biomass could have a significant detrimental effect on plant growth (20% dry-matter depression). The model revealed complex dynamics on both spatial and temporal scales which represent a considerable challenge for experimental investigations.