Effect of Auxin Treatments on Calyx Senescence in the Degreening of Four Mandarin Cultivars

Abstract

The degreening process is crucial in citrus fruit for the marketing of extra-early mandarins. Nevertheless, the application of ethylene during this treatment can be associated with calyx senescence. Citrus marketing regulations do not allow either alteration to fruit quality or the presence of calyx browning, especially on product exported to the United States. In this research, four synthetic auxins were tested for control of calyx disorders caused by degreening in different Clementine cultivars: Oronules, Clemenules, Marisol, and Clemenpons. All the tested auxins reduced calyx senescence, but the best results for all cultivars were obtained by 3,5,6-trichloro-2-pyridyloxyacetic acid followed by 2,4-dichlorophenoxyacetic acid isopropyl ester. In general, the higher the doses, the smaller the calyx alterations. The most susceptible cultivar to calyx senescence was ‘Marisol’, whereas ‘Clemenules’ and ‘Clemenpons’ were the most tolerant. Treated fruit presented lower weight loss than untreated fruit. Every treatment achieved the commercial color index and no sensory alteration was observed.