STUDIES ON PHOSPHATASE ACTIVITY AND CLUSTERBEAN PRODUCTION AS INFLUENCED BY THE P MOBILIZING ORGANISM EMERICELLA RUGULOSA

Abstract

Phosphorus is one of the major plant growth limiting nutrients although it is abundant in soils in both inorganic and organic forms. In soils the hydrolysis of organic P is predominantly mediated by the activity of phosphatases, such as acid and alkaline phosphatases and phytase released by plant roots and microorganisms. In order to evaluate the effect of Emericella rugulosa on soil enzyme activities and crop yield, an experiment was conducted under green house conditions and field (clusterbean as a test crop). A significantly higher enzyme activities and improvement in plant biomass, root length and P content was observed in sterilized soil mainly due to increased population of Emericella rugulosa. The test plants influenced acid phosphatase and phytase activity but resulted in no significant increase in alkaline phosphatase activity in the inoculated soil. The depletion of organic P was much higher than mineral and phytin P. The microbial contribution was significantly (p=0.05) higher than the plant contribution to the hydrolysis of the different P fractions. A significant (p=0.05) improvement in seed and straw yield and P concentration of seed and straw resulted from inoculation. The results suggested that Emericella rugulosa produces phosphatases and phytase, which mobilize P from native P sources and enhance the production of clusterbean in an arid soil.