Abstract:NO- 3-N of the environment plays an important role in rhizobium-legume symbiotic nitrogen fixation of legume. A soil pot experiment was carried out to test the effects of NO- 3-N on nodule development and nitrogen fixing of pea nut. The results showed that number of nodule initials, nodule number and nodule dry weight of peanut decreased significantly along with increase of NO- 3-N application. When the supply of NO- 3-N was 50 or 100 mg·kg-1, the n it rogenase activity both per plant and per nodule...