Ozone Effect to Control Lemon Postharvest Diseases in Storage Chamber

Abstract

Ozone was extensively evaluated to control postharvest pathogens and its use presents commercial interest since it is considered an innocuous substance free of residues. In Tucuman (Argentina), research carried out on this technology in citrus is scarce. In this paper the ozone effectiveness to control citrus green mold (Penicillium digitatum) (Pd) was evaluated. In vitro and in vivo tests were conducted in storage room. Petri dishes with potato dextrose agar (PDA) with and without Pd disks, were exposed to ozone (0.05 ppm) at 5 and 12 °C, at two different height of 0.10 and 1.5 m, for 8, 24 and 48 hs. Wounded and artificially inoculated lemons were kept in the same storage room. In other tests, artificially inoculated lemons were stored in three open boxes and six export boxes, separately. Fruit were evaluated on the 7th, 14th, and 21st days after treatments. These same treatments were conducted in another room without ozone as control. The average diameter and the number of Penicillium digitatum colonies grown in vitro were inversely proportional to the ozone exposure time, showing that this gas reduced the environmental contamination after 24 hs of exposure. The incidence of the disease in inoculated lemons was similar in both storage rooms, whereas in wounded fruit the infection was inversely proportional to the exposure time to ozone. Results showed that disease severity was low when ozone was used, even though the incidence was high. The ozone static effect was higher when fruit was in direct contact with the gas.