Nutrient Content with Different Fertilizer Management and Influence on Yield and Fruit Quality in Apple cv. Gala

Assessing a plant's nutritional status and fertilizer rates and types that can optimize fruit quality and yield are critical in intensive apple orchards. The aim of this work was to identify correlations between nutrients in the different organs that allow the early diagnosis of the nutritional status and to assess the impact on the optimal nutrient content in apple leaves, as well as in the yield and quality of chemical and organic fertilization. Five orchards of 'Gala' were fertilized with different levels of NPK over a period of four years. Macro and micronutrients of buds, flowers, 45 and 90-110 days after full bloom (DAFB) leaves and 60 DAFB and 15 days before harvest (DBH) fruits were determined. Boron was the only element for which strong correlations, 0.7 < r < 0.9, were observed between all organ pairs. The fertilization treatments did not affect the nutrient concentrations in the leaves of 90-110 DAFB other than P, Ca and Mg and did not affect the macronutrients in the fruit. In one of the five orchards, the yield increased by 26% with double fertilization compared to standard fertilization and, for the other four orchards, the impact depended on the year. Fruit size was more related to crop load than to fertilization and TSS and firmness were not affected by the type or amount of fertilizers. Replacing part of the chemical fertilizer with organic materials did not affect productivity or fruit quality.