Fungi associated with legume root nodules and their effect on rhizobia.

Abstract

Fungi associated with the nodules of nine common legumes were isolated and identified. The nodules had a mycoflora consisting of Cephalosporium, Alternaria, Aspergillus, Penicillium, Rhizopus, Acrothecium, Fusarium, Rhizoctonia, Curvularia, Pythium, and Trichoderma. Mycoflora of nodules of Trifolium alexandrinum was also analyzed in relation to the age of the plant and the volume of nodules. The fungi were screened for antibiotic activity towards six species of rhizobia. The results showed that Rhizobium trifolii, Rhizobium phaseoli, Rhizobium leguminosarum, and Rhizobium japonicum were relatively more susceptible to fungal antibiotics than either Rhizobium meliloti or Rhizobium sp. (cowpea group). Mycocolonization in soil by an isolate of Cephalosporium sp. significantly reduced the fresh weight and nitrogen status of T. alexandrinum.