The Effect of Calcium in the Fruit Puffiness Reduction of Satsuma Mandarin (Citrus unshiu 'Sugiyama')

In order to investigate the fruit puffiness status and the effect of calcium nitrate spray on quality and puffiness of Satsuma mandarin fruit, two separate experiments were conducted. In the first experiment, the puffing rate of Satsuma mandarin (Citrus unshiu 'Sugiyama') fruit in different orchards in the eastern region of Mazandaran was compared. In the second experiment, the effect of calcium nitrate application as foliar spray on reduction of fruit puffines was examined. The experiment was performed in a commercial orchard, with sour orange rootstock, based on a randomized complete block design, with six treatments and four replications. Treatments included: T1. Control (no Calcium nitrate spray); T2. Calcium nitrate spray in late May; T3. Calcium nitrate spray in mid- June; T4. Calcium nitrate spray in early July; T5. Calcium nitrate spray in late May and mid- June; T6. Calcium nitrate spray in late May, mid- June and early July. The results of the first experiment showed that the percentage of puffed fruits in the orchards of different regions varied from 27 to 46%, and the number of puffed fruits increased significantly from the early of November. The results obtained from the second experiment indicated that calcium nitrate spray in T5 (late May and mid- June) and T6 (late May, mid- June and early July) treatments had a significant effect on puffiness, so that the number of puffy fruits reduced by about 20% compared to the control, but this anomaly did not completely prevented. Also, calcium nitrate spray had a significant effect on Ca concentration in fruits. The highest concentration of Ca in whole fruit, fruit peel and inner skin (albedo) occurred in T5 and T6 treatments. Therefore, calcium nitrate spray is recommended at least 2 times (late May and mid- June) up to a maximum of 3 times (late May, mid- June and early July) in Satsuma mandarin Orchards.