Rhodanese activity of flooded and nonflooded soils

Abstract

Rhodanese activity (RA) was studied in 4 soils, incubated under flooded and nonflooded (60% water-holding capacity) conditions. RA in 3 soils including an acid sulphate soil pokkali increased 2.5-6.0-fold (over respective nonflooded soils), while activity of the enzyme decreased markedly in flooded alluvial soil. Similarly, anaerobic incubation of nonflooded soils under N₂ decreased RA in an alluvial soil, but increased it in pokkali soil. RA was negligible in soils, that had been reduced by flooding for 30 days and then sterilized by autoclaving. Rice rhizosphere soil exhibited significantly higher RA than the nonrhizosphere soil samples under flooded or nonflooded conditions. RA in aerobic soils was related to the microbial oxidation of S° to SO^2-₄. But, no relationship could be established between RA and S-oxidation in flooded soils and in rhizosphere soil suspensions of flooded rice plants.