ISHS Acta Horticulturae 640: XXVI International Horticultural Congress: Viticulture - Living with Limitations
THE INFLUENCE OF NPK, PHOSPHORUS SOURCE AND POTASSIUM FOLIAR APPLICATION ON GROWTH AND FRUIT QUALITY OF THOMPSON SEEDLESS GRAPEVINES |
| Authors: | A.T. Salem, A.E. Kilany, G.S. Shaker |
| Keywords: | yield, fertility, root density, leaf number, fertilizer ratio |
| Abstract:
A study was conducted in a drip irrigated vineyard to investigate the response of 11-year-old Thompson Seedless grapevines to various NPK fertilizer treatments, consisting of two nitrogen rates (60 and 80 kg/feddan), two sources of phosphorus (monoammonium phosphate and phosphoric acid) and foliar potassium (potassium thiosulfate, 2 ml/L) applied during the veraison to harvest period. Within each N-rate, six NPK ratios were achieved. Nitrogen at 80 kg/feddan improved vine growth and fruit composition more than did 60 kg/feddan. However, improvements in vine productivity and cluster quality were related to NPK ratio, with an optimum achieved in response to 1: 1: 3 NPK. Monoammonium phosphate resulted in higher yields with better fruit composition than did phosphoric acid. Spraying K at weekly intervals during the veraison to harvest stage improved the fruit composition, and so additional foliar K is recommended to sustain the advantages achieved by high NPK soil applications. | |
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