Abstract: Sweet pepper (Cap sicum annuum L. ) grown in water culture was used to study the distribution dynamics of nitrogen absorbed at early flowering stage with ¹⁵N tracer technique. The results obtained are as follows: The nitrogen concentration in root and fruit was kept steady from the early picking stage. In the leaves it decreased rapidly with growth and development and was not much different from the root and fruit at the profuse fruiting stage but it was two times higher than that in the stem and branch. The nitrogen accumulat ion dynamics was similar to the accumulation dynamics of the dry matter. Most of the labeled nitrogen, which was absorbed at early flowering stage by root, have been remained in leaves and its translocation ratio was 50. 6% from the leaves to the new organs after two weeks, and 57. 1% and 58. 0% after 4 weeks and 6 weeks respectively, indicating the new absorbed nitrogen is easier to be translocated. The labeled nitrogen in fruit harvested 2 weeks after early flowering stage make up 3. 24% of the total labeled nitrogen absorbed at early flowering stage and 11. 12% , 4. 49%, 4. 75% for the fruits harvested 3, 4 and 6 weeks after early flowering stage respectively. It is indicated that fruit is the strong nitrogen sink in the plant of sweet pepper. It is the fruit that have the most competit ive ability of
nitrogen.

Key words: Nitrogen, Distribution dynamics, Sweet pepper