Quality parameters and distribution of calcium in Idared apples under different fertilizer treatments
The main purpose of this study was to evaluate the effect of calcium fertilizer treatments on fruit quality and distribution of calcium in apple fruit (Malus domestica Borkh. cv. Idared). Four treatments were tested: application of calcium nitrate through the fertigation system, foliar application of calcium nitrate, application of calcium oxide through soil, and control treatment (without calcium fertilizer). In the experiment, freshly picked apples harvested in Gorazde region (eastern Bosnia) in September 2018 were analyzed. The highest impact to increase calcium content in apple had a treatment where calcium nitrate was added through the fertigation system. It was the result of the balance between calcium and nitrogen in the applied solution as well as the fertigation capacity to timely deliver nutrition to the main rooting zone. Calcium distribution was not uniform within the fruit: the highest content was found in the apple core, decreasing in the apple flesh, and rising again in the apple skin, regardless of fertilizer treatment. There was no difference among calcium fertilizer treatments in total soluble solids and titratable acidity of apple, indicating that these treatments were insufficient in order to improve the examined parameters of fruit quality.