Fertilization effect on trees and fruits characteristics and leaf nutrient status of apricots which are grown at Cacak region (Serbia)

The influence of cattle manure, complex NPK (15:15:15) and calcium ammonium nitrate (CAN) mineral fertilisers and natural zeolite commercially named “Agrozel” on tree growth, productivity, fruit physico-chemical features and leaf nutritional status of four apricot cultivars was studied under acidic soil conditions in Western Serbia. Tree growth and yield performances were increased by CAN and NPK applications in general, whereas manure promoted the highest fruit weight. All fertilisers, except NPK promoted flesh firmness. Application of NPK improved primary fruit metabolites (soluble solids and total sugars content and titratable acidity), whereas Agrozel induced the highest levels of secondary metabolites [total phenolic content (TPC), total flavonoid content (TFC) and total antioxidant capacity (TAC)]. The highest tree vigor and the lowest productivity were observed in ‘Biljana’, while ‘Harcot’ had low tree vigor and high productivity. The largest fruits and highest flesh firmness were observed in ‘Vera’ and ‘Biljana’, respectively. Fruits of ‘Aleksandar’ are rich source in soluble solids content and TFC, ‘Biljana’ in total sugars, ‘Vera’ also in total sugars and TAC, while ‘Harcot’ had the highest levels of titratable acidity and TPC. Fertiliser treatments positively affected leaf macro- and micronutrients content, except leaf N and K at 120 days after full bloom (DAFB). All fertilisers induced excessive leaf P content, and deficiency of other nutrients in most cases. Leaf K and Mn contents, partially N and Cu, were not consistent. The highest imbalances and better balances among macronutrients were found when trees of ‘Vera’ and ‘Harcot’ fertilized with manure, respectively, whereas these characteristics among micronutrients were observed when trees of ‘Aleksandar’ and ‘Biljana’ fertilized with CAN, respectively. Leaf of ‘Harcot’ showed better balance values among macronutrients, and ‘Biljana’ among micronutrients.