The influence of light and nitrate on the induction of nitrate reductase in dark grown seedlings of Raphanus sativus

In cotyledons of 4 day old etiolated, dark-induced radish seedlings a high level of nitrate reductase was found after an induction period of 24 hours. The activity declined after a prolonged induction time. It was shown that the decrease in activity was not due to a decrease in uptake of nitrate. In the dark other factors must become limiting after induction periods exceeding 24 hours.