Low oxygen pre-storage treatment is effective in reducing chilling injuries of deciduous fruit

Apple and pear fruits stored at low temperatures may suffer from chilling injury symptoms, caused by oxidative stress. Application of a low-oxygen (LO2) atmosphere (0.5%) for 10 d at 20°C or 500 ppb 1-methylcyclopropene (1-MCP) at 20°C for 24 h, prior to cold storage at 0°C, were equally effective in reducing superficial scald on ‘Granny Smith’ apples, after six months of cold storage at 0°C plus seven days at 20°C. Compared to untreated control fruit, the LO2 and 1-MCP-treated fruit produced less ethylene, a-farnesene and its oxidation product, 6-methyl-5-hepten-2-one (MHO), as determined by SPME/GC-MS technique. In addition, LO2 pretreatment applied to Californian ‘Bartlett’ or Israeli ‘Spadona’ pears, was effective in reducing superficial scald, senescent scald and internal breakdown, after 4–4.5 months of cold storage at –1°C or 0°C, respectively, plus five to seven days at 20°C. We assume that LO2 and 1-MCP pretreated fruit remained free of physiological disorders, due to the reduced production of ethylene and the oxidation product MHO during cold storage.