This research was carried out to assess the effects of fruit maturity at harvest and its treatment with 1-methylcyclopropene (1-MCP) on flesh browning (chilling injury) and ripening during cold storage of 'Laetitia' plums. Fruits were harvested at two maturity stages in commercial orchards located in Lages (in 2006 and 2008) and São Joaquim (in 2008): with 20-45% (maturity 1) and 46-80% (maturity 2) of surface with red coloration. Fruit were cold stored in air, at 0.5ºC ± 0.5ºC and 90-95% RH, within 36 h after harvest, treated four days latter with zero (control) or 0.5 µL.L-1 of 1-MCP, and then kept under refrigeration for up to 73 days. Fruit were assessed at harvest, periodically during cold storage and after three days of shelf life (at 22±4ºC) in terms of flesh firmness, titratable acidity (TA), soluble solids content (SSC) and incidence of shrinkage, flesh browning and decay. In Lages, fruit harvested at the maturity stage 1 had flesh firmness values of 2.5 to 2.3 lb higher than fruit harvested at the maturity stage 2, in 2006 and 2008, respectively. In São Joaquim, fruit harvested at the maturity stage 1 had flesh firmness value 1.3 lb higher than fruit harvested at the maturity stage 2. The fruit harvested at an advanced maturity (maturity 2) and the treatment with 1-MCP delayed the expression of flesh browning during cold storage, regardless of orchard location and year. In general, for fruit harvested at maturity stage 2 and treated with 1-MCP, the increase of cold storage period without the occurrence of flesh browning, assessed after three days of shelf life, was >20 days, in comparison to fruit harvested at maturity stage 1 and non-treated with 1-MCP. Additionally, 1-MCP delayed the loss of flesh firmness, but it did not substantially improve the preservation of TA and SSC of the fruit during cold storage.
Prunus salicina; chilling injury; ripening; 1-methylcyclopropene
