EFFECT OF NITROGEN-FERTILIZATION ON THE AMYLASE ACTIVITIES IN POTATO-TUBERS

The activities of alpha and beta -amylases were studied in potato tube rs cv. Uran grown in the fields under two different nitrogen fertiliza tion (200 kg/ha and 0 kg/ha). Activities of amylolytic enzymes fluctua ted in potato tubers during storage and were related to their physiolo gical state. At the beginning of storage, when the tubers were dormant , low activities of alpha and beta -amylase were observed. Thereafter amylolytic activity increased. Maximum of alpha -amylase activity was observed at the time prior to the sprouting. Maximum of beta-amylase w as observed about two weeks later, at sprouting time and during the in tensive growth of the sprouts. The activity of alpha-amylase was alway s higher than beta-amylase. Nitrogen fertilization reduced amylolytic activity in potato tubers cv. Uran and shortened their dormancy by abo ut two weeks.