The Effect of Temperature on Nitrogenase Activity

Acetylene reduction by detached nodules of four non-legumes (Alnus, Hippophaē, Myrica, Casuarina), five legumes (Glycine, Lupinus, Pisum, Vicia, Medicago), and two blue-green algae (Anabaena, Plectonema) was tested with respect to the effect of temperature on nitrogenase activity. In all cases the activity was sensitive to temperature change, and with the exception of the legumes there was a simple exponential response to temperature up to the optimum. The temperature sensitivity of nitrogenase activity in the two blue-green algae was reduced in low light intensities. Temperature data for several other species are compared, and a simple method of correcting for temperature differences suggested. It is emphasized that allowance for the sensitivity of acetylene reduction to temperature differences must be made if field data are to be used for purposes of comparison.