Associative nitrogenase activity by some Hawaiian grass roots

Abstract

Nitrogenase activity by the roots of some tropical grasses was detected by the acetylene reduction technique. In some cases particular plant species, evaluated at different times from different sites, displayed marked variations in nitrogenase activity. Acetylene reduction by root samples which had undergone preincubation under low O2 displayed an increase of approximately 5-fold when compared to plant-containing soil cores. These increases in nitrogenase activity correspond to an increase in the number of nitrogen-fixing bacteria associated with the roots.