Effect of oxygen availability on nitrogen fixation by two Lotus species under flooded conditions

the low pO 2 treatment in both species. Immunogold labelling showed that the MAC265 antigen was localThe pasture legumes Lotus uliginosus (Schk.) and ized primarily within intercellular spaces within nodule Lotus corniculatus (L.), known to differ in their tolercortices from both Lotus species. A marked decrease ance to flooding, were inoculated with Rhizobium loti in deposition of the MAC265 antigen within the cortiand flooded for 60 d while subjected to two levels of ces of L. uliginosus nodules grown in the lower pO 2 . dissolved pO 2 : 0.241 and 0.094 mmol ml−-1. L. uligis discussed in terms of the relative abilities of the inosus showed significantly greater growth (shoot and two Lotus spp. to maintain an O 2 supply to the N 2 root) and N 2 fixation under both pO 2 s, compared tofixing bacteroids within submerged nodules. L. corniculatus, although growth and N 2 fixation by L. corniculatus was not affected by the low pO 2 .