Comparison of rhizosphere processes of Vicia sativa and Vicia villosa in response to phosphorus deficiency

China is rich in leguminous green manure resources, but the rhizosphere processes-based mechanisms of efficient nutrient acquisition and use were not fully understood. A pot experiment with hydroponics was conducted under a controlled condition in a growth chamber by adopting two popular green manure species, Vicia sativa L. and Vicia villosa Roth, in the North China to compare the difference in rhizosphere processes of these two legume species in association with their adaptation mechanisms to the phosphorus (P)-deficient stresses. In the present study, the biomass of shoots and roots, H+-release rate from the roots, carboxylate (organic acid) exudation and acid phosphatase activity on the root surface were measured at interval of 6 d after the P-deficient treatment. There was an evident difference in adaptation mechanisms of both legume green manure species to P deficiency. The adaptation of Vicia sativa L. to P-deficient stress was dominantly dependent on enhanced H+-release rate and acid phosphatase activity on the root surface in comparison to adequate P supply treatments. In contrast, H+-release rate of Vicia villosa Roth did not change, but the plant significantly increased the root-shoot ratio and the biomass of the roots under the P-deficient conditions. A greater acid phosphatase activity on the root surface was also found in P-deficient Vicia villosa Roth. The results suggest that Vicia sativa L. and Vicia villosa Roth have different strategies to adapt the low P stress environment by coordinating root morphological and physiological plasticity.