Increasing Phosphorus Efficiency: An Investigation of Phosphorus Uptake Mechanisms In the Rhizosphere of Various Wheat Culivars.

Phosphorus (P) is the second most limiting plant nutrient, with 5.7 billion hectares being P deficient worldwide. As the price of P continues to increase, there is a need for more P efficient crops to increase yields on P deficient soils and conserve limited P resources. Most soils have a large amount of total P (100-1500 mg kg^-1), yet only a small portion is plant available, as currently estimated by an agronomic P test such as Mehlich-3 (M3).  However, certain varieties of plants have been noted as being “P efficient” with the ability to extract and uptake this relatively “non-labile” pool through a variety of mechanisms. 

The objective of this project was to identify cultivars that are P-uptake efficient and subsequently analyze their rhizosphere soil to determine what chemical mechanisms are being used to increase P uptake. Twenty-two winter wheat cultivars were screened for P-uptake efficiency in low P acid and calcareous soils. The three most efficient and three least efficient for each soil were then grown in rhizo-cells. Rhizosphere soil was analyzed for pH, organic acids, phosphatase enzymes, and changes in soil P-pools. Traits from the efficient cultivars can be used to increase phosphorus efficiency of breeding programs.