Modelling integrative behaviour of soil plant systems: plant uptake of strongly sorbed solutes

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Developing integrated models of plant and soil processes to understand the behaviour of the system as a whole challenges both the modeller concerned with capturing the complexities at the different scales in a consistent way, and the experimentalist concerned with corroborating the overall model and its component parts. Recent advances in modelling techniques and computing power, and in experimental materials and methods, greatly enhance possibilities for developing and corroborating plant-soil models across scales. We here propose to bring together new modelling techniques, novel plant material, and innovative experimental techniques to develop and experimentally test a model of solubilisation and uptake of strongly-sorbed solutes by branching root systems, integrated at the whole plant scale. The general problems to be tackled are: 1. Processes governing solubilisation and uptake of strongly-sorbed solutes at the scale of the individual root, and competitive or complementary interactions with the root¿s immediate neighbours. 2. Integration of single-root models in models of the whole root system and whole plant. 3. Experimental testing of these individual components and of the whole-plant model. We will use as a test case newly-available near isogenic lines of upland rice with exceptional ability to extract P from P-deficient soil. We will compare solubilisation and uptake by these with their P-inefficient parent, with is greater than 90 per cent genetically identical and has similar growth and P uptake under P-sufficient conditions. We will also use novel techniques for measuring concentrations of P and root-released solutes in the rhizosphere soil solution with 0.1mm spatial resolution and sub micrometre sensitivities. The outputs will include generic methodologies for developing and testing such models, as well as understanding of the mechanisms of efficient P acquisition in the test plants.