Colonization by Rhizobia of the seed and roots of legumes in relation to exudation of phenolics

Abstract

A study of the colonization pattern of Rhizobium inoculated either in the soil or on to the seeds of green gram ( Phaseolus aureus Roxb.), black gram ( P. mungo L.) and sun hemp ( Crotalaria juncea L.) revealed a significant reduction of Rhizobium in the spermosphere of sun hemp which was attributed to excretion of phenolic compounds by the seed. As the plants aged, the quantity of phenolics exuded by the roots was reduced and there was a parallel increase in the Rhizobium population in the rhizospheres of the three plant species.