The influence of nitrate, water potential and oxygen tension on nitrogen fixation in detached pea roots

Abstract

Nodulated pea roots were detached from the plant shoots and exposed to different nitrate concentrations, water potentials, and oxygen tensions. The rates of nitrogen fixation in the detached pea roots following these treatments were determined by the acetylene reduction assay. It was found that increasing the nitrate concentration up to 5 mM brought about reduced nitrogen fixing activity, and this occurred independently of the depressing effects of low water potential and low oxygen tension.