Quality Changes in On-Tree Stored 2,4D Treated Washington n. Oranges and Cold Stored Untreated Ones.

Quality changes during 5 months of on-tree storage of 2,4-dichlorophenoxyacetic acid (2,4D) treated Washinghton navel oranges [Citrus sinensis (L.) Osbeck] were monitored monthly from January to June. Fruit from the on-tree treatment were also harvested in Februaray, April and May and cold stored at 8°C for 1 month. THe same observations were performed on untreated fruit harvest at January and cold-stored until June. On-tree stored fruit evidenced a rapid reduction of ascorbic acid content during the first three months (from 56 to 38 mg/100 mL juice), and aslower loss in the last two months (from 38 to 33 mg/100 mL juice). Cold stored, untreated fruit showed significantly lower loss of vit.C (from 56 to 45 mg/100 mL juice) during the same period. Cold storage of 2,4 D- treated fruit harvested at February, April and May reduced ascorbic acid loss, compared to the on-tree stored fruit. The appearence of the on-tree stored fruit wasbetter until March,but after this time cold storage resulted in improved preservation of fruit appearence and reduced onset of granulation disorders. Fruit harvested in May were xharacterized by having a very low juice content (22%), mainly due t higher granulation. When fruit were harvested in April and cold stored for 1 month, juice content was found unchanged (42%). During storage, untreated fruit was mainly affected by Penicillium italicum, while 2,4-D -treated fruit showed a significantly higher infection due to P. digitatum. The later the treated fruit were harvested the higher wasthe decay during subsequent storage and simulated shelf-life.