Possibility of reducing Satsuma mandarin (Citrus unshiu) fruit puffing in East of Mazandaran

Puffing is a physiological disorder in some citrus cultivars which splits pulp from peel and reduces marketing, increases rind damage and reduces shelf life of fruit. To investigate possibility of decreasing puffing, an experiment was performed in randomized complete block design with 11 treatments: 1. control, 2. mono ammonium phosphate, 3. calcium chloride, 4. potassium nitrate, 5. mono ammonium phosphate potassium nitrate, 6. mono ammonium phosphate GA3, 7. 2,4-D, 8. Potassium nitrate 2,4-D, 9. Potassium nitrate GA3, 10. Potassium nitrate 2,4-D and 11. 2,4-D GA3 and 4 replications with mature trees of Satsuma mandarin on sour orange rootstock. Results showed that all treatments caused to increase fruit peel density compared to control. The best treatments in increasing peel density were compound treatments: 8, 10 and 11 and nutritional treatment: mono ammonium phosphate (treatment 2). Also, treatment 2 produced the highest fruit size. The heavier and larger fruits were more puffy. Leaf copper and phosphorus concentration had a respectively positive and negative correlation with puffy fruits number. According to this experiment, it is recommended that at fruit colour break time, phosphorus foliar application should be done, while, the use of copper compound should be reduced as much as possible.