Study on Discipline of NK and N/K Ratio of Flue-cured Tobacco

Field trials were carried out to study the changes of nitrogen and potassium levels in soils and contents and balance of nitrogen and potassium in leaves in middle position of flue cured tobacco in central Yunnan Province. Results showed as follows: (1) Contents of nitrogen in soils and leaves decreased gradually in the whole period of growth. Contents of nitrogen in leaves had a peak between 64-78 days, and the more the fertilizing rates of N, K fertilizer the earlier this peak got to. (2) Contents of potassium in soils and leaves decreased gradually in whole period of growth, but the contents of potassium in leaves had a higher point in the 78?th day. (3) The ratio of nitrogen to potassium (N/K) in leaves had the tendency of increasing in the whole period of growth. The peak came in the 108?th day. But there were not any changing regulation of the N/K ratio in soils.