Abstract: Study on the mechanism of high efficiently utilizing nitrogen of potatoes in different seasons could direct the application of nitrogen fertilizer and promote the utilization efficiency of nitrogen fertilizer. Through pot culture experiment in spring and autumn, the differences of nitrogen accumulation and physiological property of function potato leaves in six nitrogen levels were studied. The results could be summarized as follows: (1) With the increasing rate of nitrogen applied, the nitrate nitrogen content of spring potatoes increased, but that of autumn potatoes decreased after first increase. And the nitrate reductase (NR) activity of potatoes both in spring and autumn increased first and then decreased. Under the same nitrogen level, the peak value of NR activity of spring potatoes in tuber formation and maturity stages were 35.3% and 74.0% higher than those in autumn. (2) The nitrogen content and nitrogen accumulation of potato plants both in spring and autumn increased with the inceasing nitrogen fertilizer. But these two indicators of potatoes in spring were both higher than those in autumn under the same growth period and nitrogen levels. (3) There was a higher correlation coefficient between the nitrate nitrogen content and the total nitrogen content in potato plants, which could induct the effective utilization of nitrogen.

Key words: potatoe, nitrogen fertilizer level, nitrate nitrogen, nitrate reductase, nitrogen accumulation