Investigation of Puffing Reasons in Satsuma Mandarin and Possibility of Its Reduction in East of Mazandaran.

Puffing is a physiological disorder in citrus fruit especially in some mandarin cultivars which is characterized by splitting of pulp from peel of fruit which cause reduction in marketing, increase rind damage and reduces shelf life of this variety. To investigate reasons of puffing in mandarin fruits of east Mazandaran, a 30 years old of Satsuma mandarin garden that had puffing in the last years, was chosen in Baharestan garden in Sari. 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 44 trees. Result showed that all treatments (nutritional, hormonal, and compound) caused to increase peel density compare to control. The best treatments in increasing peel density were compound treatments: 8 (mono ammonium phosphate+GA3, 10 (nitrate potassium+GA3) and 11 (2,4-D+GA3) and nutritional treatment: mono ammonium phosphate (treatment 2). The late, produced the highest fruit size, too. What the fruits was heavier and larger, number of healthy fruits was lower and number of puffy fruits was higher. The lowest percent of mean and severe puffy fruit (degree 3 and 4) was observed in the first harvest time (24%) and the highest in the last harvest time (34%). Cupper and phosphorus amount in leaf had a respectively negative and positive correlation with number of degree 3 fruits. Therefore, it is recommended that larger fruits be harvested after physiological maturation and also, be used from phosphorus application at fruit colour break time; in contrast, using from cupper compound be done with caution and if necessary. Keywords: Citrus fruit, physiological disorders, nutrition, plant growth regulators