DENITRIFICATION IN INTACT LUCERNE PLANTS

Denitrification activity upon nitrate supply by intact, attached nodul es of lucerne has been measured. This activity clearly shows that nitr ate is metabolised in nodules. However, the extent of such an activity was extremely low and only represented 2% of the potential activity o f the isolated bacteroids. Also, this activity represented only 0.05% of the nitrogen fixation rate of these nodules. It is concluded that t his process is of a very limited impact in normal circumstances and it s physiological significance in nodules remains to be understood.