Effect of Post Harvest Putrescine and Methyl Jasmonate Treatment on Chilling Injury and Some of Orange (Citrus sinensis) " Valencia" Fruit Characteristics

Valencia is one of the major orange cultivars which is grown in south of Iran. A great portion of annual fruits is usually cold stored for several months. This experiment was carried out to determine the effects of putrescine and methyl jasmonate on some of orange (Citrus sinensis) “Valencia” fruit characteristics. Fruits were treated with 0 (control), 2.5 and 5 millimoles of putrescine and 0 (control), 10 and 20 micromoles of methyl jasmonate and then stored at 5±1°C, 85-90% relative humidity for 4 months. Oranges treated with 5 millimoles of putrescine and10 micromoles of methyl jasmonate indicated significantly reduced chilling injuries and fruit weight loss compared to the control treatment. During storage, ascorbic acid, organic acids, total soluble solids of the treated and control fruits reduced, and pH increased though, putrescine and methyl jasmonate treatments led to decreases in the latter changes, relative to the control. In conclusion, fruits treated with 5 millimoles of putrescine showed the best appearance with the most controlling effect on chilling injury.