Nut traits and nutritional composition of hazelnut (Corylus avellana L.) as influenced by zinc fertilization

Abstract

BACKGROUND: Zinc is an essential element for plants and its deficiency is a widespread problem throughout the world, causing decreased yields and nutritional quality. In this study the effect of zinc fertilization on some nut traits and the nutritional composition of 'Tombul' hazelnut (Corylus avellana L.) variety cultivated in the Black Sea region of Turkey was investigated and the contribution of this nut to human nutrition determined. Trials were carried out at 'Tombul' hazelnut orchards, and zinc fertilizers were applied at 0, 0.2, 0.4, 0.8 and 1.6kg Zn ha-1 in three consecutive years. RESULTS: Significant differences in some nut traits and mineral composition (protein, total oil, ash, kernel percentage, empty and wrinkled nuts, copper, boron, manganese and molybdenum) were observed with zinc fertilizer applications. In terms of daily nutritional element requirements, 100g of hazelnut provided about 44.74% phosphorus, 13.39% potassium, 19.32% calcium, 37.49% magnesium, 0.19% sodium, 51.63% iron, 25.73% zinc and 14.05% boron of the recommended daily amounts (RDAs), while copper, manganese and molybdenum contents exceeded their RDAs. CONCLUSION: In order to improve some nut traits and the mineral composition of hazelnut, 0.8 and 1.6 kg Zn ha-1 fertilizations could be recommended in practice.