A study on nitrogen nutrition of apple trees
1990
Manru, G. | Huairui, S. | Hongwei, Z.
The research was carried out during 1978-1987. The results were followed: 1. The N nutrition variation of apple trees in a year was divided into three stages: the stage when large amount of N was required; the stage when N should be supplied constantly, the storage stage of N. 2. The direction of translocation and distribution of the reserved 15N in the plants was changed with transformation of the growth center. The reserved 15N played an important role in the growing of new organs in early Spring. 15N required for growing of roots and for thickening growth of perennial branches in Summer mainly depended on N absorbed from the soil that year. 3. The amount of 15NO3-N absorbed in the plants was always more than that of 15NH4-N, but the difference of new shoots and leaves absorbing different forms of N was less in Spring and more in Summer. 4. The determination of the content of N, P and K under different conditions of site in Shandong Province was carried out. The results revealed that the content of N was a main factor that decided the vigor and production of the apple trees. It especially was concerned with the total N content of the fine roots. The demand of apple trees for N was different among the varieties. There was greater demand for N in cv. Ralls than that in cv. Starking.
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