Physical Interactions in the Rhizosphere.

The dynamic interaction between roots and soils affects both the growth rate of the roots themselves and the environment into which they are growing. The physical, chemical and biological modification of the soil surrounding roots, the rhizosphere, and the ways in which this can be managed represent a considerable challenge for future research efforts with far-reaching consequences for crop production, plant and microbial biodiversity, and land conservation and reclamation.

Advances in genetics and phenotyping have facilitated studies of physical and chemical changes in the rhizosphere. Root traits such as the presence or absence of root hairs influence rhizosheath formation, aggregation and other soil physical properties, while phytase expression contributes to genotypic variation in phosphatase activity. Screening of cereal and potato genotypes for root architectural properties and high water-use and P-use efficient phenotypes is underway to deliver new crop phenotypes that can enhance production while using resources more efficiently.

Soil deformation to allow root elongation is facilitated by the release of root cap cells and mucilage which reduce the frictional resistance of the soil while, longer term, the mucilage also affects water and nutrient availability in the rhizosphere and contributes to the development of aggregates and soil structure. Consequences of these localised changes for whole plant growth will be explored together with the role of gene expression in affecting the ability of roots to capture resources in contrasting environments.