Influence of cultivar and fertilization treatment on bioactive content of some apple (Malus domestica Borkh.) cultivars

The paper presents the chemical composition of the fruits of three apple cultivars (Jonagold Decosta, Red Idared and Gala Schnitzer Schniga) fertilized with three treatment: T1 (control-without fertilization); T2 (300 kg/ha NPK (6:18:36) + 150 kg/ha N (calcium ammonium nitrate-CAN)) and T3 (foliar nutrition-mixture organic-mineral fertilizer commercially named 'FitoFert Kristal' (0.6%) (10:40:10) + 'FitoFert Kristal' (0.6%) (20:20:20) + 'FoliFetril Ca' (0.5%) (N:Ca) in Bosnia and Herzegovina during two years (2020-2021). Significant differences of contents of soluble solids, total sugars, inverted sugars, sucrose, total phenolic content, content of flavonoids and antioxidant activity were found among cultivar/treatment combinations, cultivars, treatments and years. Differences in total acids content among treatments and years were not statistically significant, but significant differences among cultivars and cultivar/treatment combinations were found. The contents of soluble solids, total sugars and sucrose were the highest in fruits of cultivar Jonagold Decosta, while the highest contents of inverted sugars, total acids, total phenolics, flavonoids and antioxidant activity were found in fruits of Red Idared cultivar. The fertilization treatment T2 significantly influenced the content of soluble solids, total sugars, inverted sugars, total acids, total phenolic, flavonoids and antioxidant activity in the apple fruits. According to the results obtained, we can say that fertilization treatment T3 do not have much effect on bioactive ingredients, with the exception of the sucrose content. Among mineral elements, four were macroelements that were represented present in large amounts: potassium (K) (1266.15 mg kg-1 to 1652.89 mg kg-1), calcium (Ca) (122.76-474.90 mg kg-1), phosphor (P) (86.14-124.84 mg kg-1) and magnesium (Mg) (57.36-70.68 mg kg-1). On the other hand, four microelements were determined: boron (B) (1.06-14.25 mg kg-1); iron (Fe) (2.79-4.62 mg kg-1); manganese (Mn) (0.27-0.46 mg kg-1) and zinc (Zn) (0.15-0.48 mg kg-1). Results showed that contents of macroelements and microelements have been strongly affected by cultivar/treatment combinations, cultivars, treatments and years.