M.G. ZAROUG and D.N. MUNNS

Abstract

Several strains of Rhizobium were greenhouse-tested on clitoria (Clitoria ternatea) and phillipesara (Vigna trilobata) to determine effectiveness in a soil of pH 6.3 that was N-deficient but otherwise fertile. Selected strains were further tested on phillipesara in an acid soil, unlimed or limed to pH 6.6.
Yield of N and visual ratings of shoot growth and color gave similar ratings of effectiveness. Variations of effectiveness did not relate to variation in nodule number, nodule weight, or rates of acetylene reduction when the acid soil was used.
In soil at pH 6.3 four strains that were highly effective on clitoria outyielded the NH₄NO₃ control treatment. With phillipesara the best strains yielded 75% as much as the NH₄NO₃ control. In the acid soil, symbiotic performance of strains ranked differently than in the neutral soil. Liming the acid soil depressed plant growth.