Effect of calcium and boron spray application on fruit's quantitative and qualitative characteristics of  Golab-e Kohanz apple

In order to study the foliar application effect of calcium and boron on fruit quantitative and qualitative characteristics of ‘Golab-e kohanz’ apple, an experiment was carried out for two years. Experiment was conducted as a randomized complete block design with 10 treatments and 4 replications (totally include 40 trees). The treatments included calcium chloride (CaCl2) with 3 concentrations of 0.5%, 0.75% and 1%, calcium chloride with 3 mentioned concentrations 0.05% Boric Acid, and three commercial calcium fertilizer, Calsiogreen (34% Ca), Calboron (34% Ca 1% B) and Set (8% Ca 0.5% B), and control. Pre-harvest fruit drop, some of fruit quantitative and qualitative traits, potassium (K), calcium (Ca) and boron (B) content, as well as some antioxidant enzymes activities including Catalase (CAT), Ascorbic peroxidase (APX), and Super oxide dismutase (SOD) were measured. Results showed that almost all of Ca treatments (single, in combination with B and even commercial Ca fertilizers) comparing to the control, decreased pre-harvest fruit drop, bruising and russetting incidence as well as fruit color but increased firmness, pH, ascorbic acid, Ca and B as well as antioxidant enzymes activities. Combined treatments of Ca and B performed better results or had no significant difference with single Ca treatments in many of evaluated fruit characteristics. However, there were no significant differences among different concentrations of Calcium chloride as well as between calcium chloride and commercial Ca fertilizers in most of the measured fruit characteristics but generally calcium chloride of 0.75% combined with 0.05% boric acid was the best treatment.