Abstract

A short-term greenhouse experiment was carried out with two phosphorus (P) levels of purple soil to investigate P availability and associated processes in the rhizosphere of two different P-efficiency wheat genotypes using a thin slicing technique. Two genotypes with different P efficiencies were grown in a root-compartment experiment under low P (P 10: 10 P mg/kg) and high P (P 100: 100 P mg/kg) treatments. Results show that readily extracted forms of soil inorganic P were depleted by the two wheat genotypes, depletion zones extended further adjacent to 4 to 6 mm. Enhanced depletion of sodium hydroxide extractable organic P apparent in the rhizosphere of high P-efficient wheat cultivar 10098 compared with low P inefficient wheat cultivar10026 was related to the presence of greater concentrations of microbial biomass and higher soil acid phosphatase and phosphodiesterase enzyme activities. These results confirm that microorganisms and soil enzymic activities played important roles in the mineralization of soil organic P, particularly under high P-efficient wheat cultivar10098. These results suggest that improving P efficiency based on the character of P efficiency acquisition in P-efficient genotype would be a potential approach for maintaining wheat yield potential in soils with low P bioavailability.

Key words: Wheat, P efficiency, rhizosphere properties, P fractions, phosphates activity.