THE EFFECT OF NITRATE ON THE TIME COURSE OF NITROGEN-FIXATION AND GROWTH IN PISUM-SATIVUM AND VICIA-FABA

In pots nitrate depressed growth and nitrogen accumulation of both peas and faba beans. Nitrogen fixation reached a maximum in -N peas during pod filling. Acetylene reduction rates were highly correlated with nitrogen fixation rates in beans, but poorly correlated in peas. The conversion ratio C2H2:N2 was near 3 for early samples, but fell to 1 or lower in both peas and beans. Acetylene reduction rate fell during assay, more quickly in peas than in beans. RE was 0.6-0.7 for peas in early samples but rose to near 1.0 by the end of the experiment. © 1990 Kluwer Academic Publishers.