OXYGEN LIMITATION OF N-2 FIXATION IN VARIOUS LEGUME SYMBIOSES

Two O-2 ramping techniques (linear versus exponential) were used to in vestigate the response of H-2 evolution from intact nodules of soybean (Glycine max (L.) Merr. 'Maple Arrow'), stem-girdled soybean, pea (Pi sum sativum L. 'Juneau'), and common bean (Phaseolus vulgaris L. 'Ex R ico 23') to increasing O-2 concentrations from 20 to 100% over a 30-mi n period. The data indicate symbiosis-specific responses to the two ra mps, and possible implications for determination of O-2 limitation of N-2 fixation.