Below-ground physiological processes enhancing phosphorus acquisition in plants

Phosphorus (P) is an essential element for crop growth and development. In acid soils, inorganic P (Pi) is immobilised with Fe3+ and Al3+, whereas in calcareous soils, it is fixed with Ca2+. Therefore, P nutrition is not constrained by soil P content per se but by its bioavailability to plants. The large amounts of P fertiliser applied to agricultural land to increase crop P availability can cause eutrophication of non-flowing water bodies. Being a non-renewable resource, P reserves are becoming depleted. Soil P mobilisation is governed by multiple adaptations at the physiological and molecular levels. Below-ground physiological processes including favourable root architecture and morphology, and release of carboxylates, protons and root secretory phosphohydrolases result in significant modification of the rhizosphere microenvironment thereby enhancing P acquisition. Beneficial soil microorganisms work in tandem with plants to mobilise bioavailable soil P. Phosphorus acquisition through rhizosphere modifications is an exciting area of research for plant nutritionists.