Evaluation of messenger plant activator as a preharvest and postharvest treatment of sweet cherry fruit under a controlled atmosphere.

The preservation methods as an alternative to chemical control to prevent postharvest quality losses of sweet cherry were examined. The efficacy of preharvest and postharvest messenger (M) treatments on sweet cherry cv. '0900 Ziraat' was tested under a controlled atmosphere in 2004 and 2005. The factors investigated included the separate or combined effect of low oxygen, high carbon dioxide and M on the quality and fungal pathogens of sweet cherries in a normal atmosphere (NA) and in a controlled atmosphere (CA). Cherries were placed at six different atmosphere combinations (0.03%:21% [NA, control], 5%:5%, 10%:5%, 15%:5%, 20%:5% and 25%:5% CO(2):O(2)) at 0°C and 90% relative humidity for up to 8 weeks. Mass values were higher in cherries stored under NA compared with CA. Initial firmness was 1.45 kg and 1.41 kg in fruits without messenger (WM) and in M fruits, respectively; and was measured as 0.30-0.59 kg in WM and 0.57-0.95 kg in M at the end of the trials. The highest acidity and ascorbic acid values were recorded at the end of storage from the fruit stored under CA + M. The CA + M treatment proved the most effective with regard to delaying the maturity and preserving the fruit quality in sweet cherries during storage. Moreover, the CA + M treatments reduced the rotten fruit from 24.06% to 3.80% in cv. '0900 Ziraat'. Better fruit quality was obtained under CA + M compared with NA and CA. The fungi most frequently isolated from sweet cherries were Botrytis cinerea, Penicillium expansum, Monilinia fructicola, Alternaria alternata and Rhizopus stolonifer. It was concluded that sweet cherry cv. '0900 Ziraat' could be stored successfully under CA (20%:5%) + M, and partially under CA (25%:5%) + M, conditions for more than 60 days. Thus, it is recommended that CO(2) levels for sweet cherry storage can be increased above 15% with M.