鸭梨秋施^15N尿素的吸收与分配

Studies on the Absorption and the Distribution of ~(15)N-Labelled Urea to 'Yali' Pear Trees Following Autumn Application

Three-year-old pear trees growing in field microplots were treated with ~(15)N -labelled urea via soil in autumn. The results were as follows: The ~(15)N was absorbed by tree in annual cycle, 3. 1% of NDFF was recovered in tree in the current year, 17. 8% of NDFF was recovered in the tree in the first ten-day period of August the following year, the ~(15)N was absorbed the fastest in the first ten-day period of May; loss percentage of NDFF was the highest from the winter to the spring and 50. 7% of NDFF was lost. The absorbed ~(15)N was largely stored in the trunk and roots during dormant period, the concentration of NDFF was higher in spurs and the fine roots, it was the lowest in the long shoot; the ~(15)N in the perennial branch was rapidly transferred to the new growth in spring, During shoot rapid-growing period 53. 3% of the total ~(15)N in the whole tree was recovered in the long shoot. During fruit rapid-growing period, the ~(15)N in the new shoot, especially in the long shoot were returned to other organs.