ISHS Acta Horticulturae 511: XXV International Horticultural Congress, Part 1: Culture Techniques with Special Emphasis on Environmental Implications - Nutrient Management
EFFECT OF SEASONAL PHENOLOGICAL STAGE ON UPTAKE AND DISTRIBUTION OF 15N-LABELED AMMONIUM AND NITRATE IN YOUNG AVOCADO TREES |
| Authors: | S. Zilkah, Y. Yeselson, I. David, I. Klein |
| Keywords: | fertilization, nitrogen, Percea americana |
| Abstract:
Young avocado (Persea americana Mill, cv. Pinkerton, rootstock Schmidt), grown in a coarse sandy soil, were exposed to 15N-labeled potassium nitrate and ammonium sulfate for 10 days during 4 phenological periods of autumn, winter, spring and summer. Uptake efficiency (15N/15N applied, %), N-enrichment (15N/N,%), and distribution of the absorbed 15N in tree organs were determined for each period. The uptake efficiency of N-nitrate was significantly higher than N-ammonium in each of the plant organs and during each of the seasonal periods. Nitrogen absorption efficiency in the whole tree was higher in the summer. During the various seasonal periods, both of the nitrogen forms were distributed among roots, trunk+branches and leaves organs, at similar manner. During autumn and winter a major rate of the absorbed nitrogen concentrated at roots and trunk+branches. At springtime the absorbed nitrogen was readily translocated and enriched the N-content of the leaves in a highest rate among the other seasons. | |
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