Rhythmicity in nitrate reductase activity in wheat embryos during germination

Abstract

Nitrate reductase (NR) activity, induced by germination in KNO₃ showed a strong rhythmicity during the early stages of germination of wheat embryos. Peaks of activity occurred approximately every 12 h. There was no relationship between the amounts of nitrate in the embryos and enzyme activity. The fluctuations in enzyme activity did not appear to be due to reversible inactivation of the enzyme. Some evidence suggests that the fluctuations in enzyme activity may result from a more rapid degradation of enzyme during the decreasing phase of the rhythm.