Research on Glutamate Dehydrogenase Activity in Sugar Beet（Beta vulgais L）under Different Nitrogen Levels

The experiment of Glutamate Dehydrogenase(GDH) activity in various plant parts under dif-ferent nitrogen levels in frame culture during the whole period of growth was carried out on campus of Northeast Agricltural University in 1993.The result showed that GDH activity in leafblades un-der four nitrogen applied levels rose rapidly to the acme from the seedling to foliage rapid growth stage,then diminished rapidly to the lower level at the latter stage of foliage rapid growth.This level was kept to harvest.GDH activity in roots at each growth stage under all nitrogen levels exhibited little disparity and did not show ostensible regularity of changes.GDH activity in leat blades was stimulated with nitrogen,however,it reduced with nitrogen fertilizer applying further.GDH activity in leaf blades was the biggest compared with crowns,petioles and roots ,which suggested that it could represent the highest enzyme activityof the whole plant.