IMPORTANCE OF USING THE CORRECT TEST HOST IN ASSESSING THE EFFECTIVENESS OF INDIGENOUS POPULATIONS OF RHIZOBIUM TRIFOLII

Abstract

Nodule isolates from indigenous white clovers {Trifolium repens L.) growing in wet, acid, infertile soil were much more effective with the indigenous clover from which they were isolated than with com mercial white clover (SI00). Commercial clover sown in such a soil became nodulated initially with a relatively ineffective population of rhizobia, but the effectiveness of nodule isolates improved with time. The results have led to the concept that alteration of the fertility status of a pasture may result in the emergence of a different white clover ecotype rather than cause changes in the rhizobial popula tion per se. It is also concluded that nodulation of white clover under field conditions in Ireland probably always tends towards effectiveness.