INFLUENCE OF NITROGEN, POTASSIUM AND MAGNESIUM FERTILIZATION ON FRUIT QUALITY AND STORABILITY OF GOLDEN DELICIOUS APPLES
A 5-year fertilization trial was carried out by crossing 3 doses of N (0, 50, 150 kg/ha) with 4 doses of K2O+MgO (0+30, 0+0, 50+0, 150+0 kg/ha) in an apple orchard at Ora (Bolzano - Italy). Apple-tree yields, fruit sizes, levels of macronutrients and micronutrients in leaf and fruit were recorded and the main fruit quality features were determined at harvest and after storage (4 and 8 months). Nitrogen fertilization increased N leaf and fruit levels, tree yields, fruit acidity at harvest and after storage and soluble solids at harvest; it affected flesh firmness only after storage. N50 always resulted in higher soluble solids, pH, flesh firmness and, only at fruit harvest, increased acidity. The effects of K fertilization were less remarkable. Potassium fertilization affected flesh firmness, soluble solids and acidity; pH at harvest, only. K150 depressed soluble solids after storage and flesh firmness at harvest; K50 resulted in lower soluble solids and acidity at harvest and in higher soluble solids and flesh firmness after storage. Magnesium fertilization made the fruit firmer and with less soluble solids at harvest; after storage, the fruits also contained more soluble solids and were more acid than N and K treatments.
Noè, N., Eccher, T., Stainer, R. and Porro, D. (1995). INFLUENCE OF NITROGEN, POTASSIUM AND MAGNESIUM FERTILIZATION ON FRUIT QUALITY AND STORABILITY OF GOLDEN DELICIOUS APPLES. Acta Hortic. 383, 439-448
apple, fruit mineral content, fruit quality, Golden Delicious, leaf analysis, magnesium, nitrogen, potassium