Identification of tolerance to soil acidity in inoculant strains of Rhizobium leguminosarum bv. trifolii

The acid-soil tolerance of six strains (WU95, NA3001, WSM409, TA1, NA3025 and NA3039) of Rhizobium leguminosarum bv. trifolii was assessed in a three-year cross-row field experiment in an acid sandy soil of pH 4.2. Strains WSM409, NA3039 and WU95 were more acid-soil tolerant than strains NA3025, TA1 and NA3001. Strains WSM409 and NA3039 colonised and persisted in acid-soil to a greater degree than strains TA1 and NA3001. The data from this study clearly identified strain WSM409 as a strain with outstanding potential for improving the production of clovers on acid soils.