The effect of varying oxygen tension, temperature and sample size on acetylene reduction by nodules of Alnus and Hippopha�

Abstract

The rate of acetylene reduction by detached nodules of Alnus and Hippophae was found to be correlated with temperature between 4 and 20°C, and with oxygen tension between 1 and 15 per cent O2. No further increase in rate occurred in nodules of either species when the oxygen tension was increased to 20 percent. Alnus continued to reduce acetylene for at least 20 hours after detachment provided that the ratio of the volume of gas phase to sample size was large: if the ratio was small reduction stopped earlier, and would only restart if the gas phase was completely reflushed.