ACTUAL AND POTENTIAL NITROGEN-FIXATION OF ALBIZIA-RHIZOBIUM SYMBIOSESAS AFFECTED BY NITRATE

Actual nitrogen fixation of root nodules of different Albiza-rhizobium symbioses was compared with the potential nitrogen fixation of isolat ed bacteroids. The potential nitrogen fixation exceeded actual nitroge n fixation in all symbionts. After addition of nitrate the actual nitr ogen fixation decreased more than did potential nitrogen fixation in e ffective symbiosis, whereas in a less effective symbiosis, the actual and potential nitrogen fixation increased as a result of better photos ynthate supply to the roots and nodules. As confirmed by correlation a nalysis, the nitrogen fixation and photosynthetic yield of suboptimum symbioses were relatively enhanced by dressing with inorganic nitrogen fertilizer.