Interrelation between mineral nutrients and calcium disorders in apple Red Delicious and Golden Delicious cultivars

To investigate the causes of the spot disorders on fruits, random sampling was performed on trees of Red Delicious and Golden Delicious in two regions of Semirom and Padena, Iran. Concentration of minerals (calcium, potassium, magnesium and nitrogen) were determined in a compound sample for each garden and analyzed in an unbalanced complete randomized design. Results showed that fruits with symptoms for Red Delicious have only calcium deficiency, while for Golden Delicious both deficiency and excess calcium had found. Regarding erratic changes in the samplings, three orthogonal contrasts (including treatment groups: cultivars, regions and symptoms presence) were evaluated. The results showed that Red Delicious cultivar is more susceptible than Golden Delicious and Padena region is more favorable for occurrence of calcium disorders than Semirom region. Orthogonal contrasts between treatments with and without symptoms, showed significant differences for ratios of Kﰦ, (K)/Ca2 and (N⯯貃)/Ca2. Therefore, the disorder has negative relation with potassium content and Kﰦ ratio and positive relation with calcium content in the fruit. The research showed that occurance of calcium disorders in apple orchards of Semirom region were related to wheather changes and overuse of some minerals.