Abstract:

This study aimed to investigate the effects and mechanism of UV-C treatments on control of botrytis inpostharvest apples. Red Fuji apple fruits were treated by UV-C at different doses (3.5, 7.0, and 10.5 kJ/m2) and, two dayslater at normal temperature (20 ± 1) ℃, inoculated with conidial suspension of Botrytis cinerea, and inoculated sampleswithout UV-C treatment were used as control. The results showed that UV-C treatments at 3.5 and 7.0 kJ/m2 significantlydecreased the incidence of gray mold rot, and effectively suppressed the expansion of lesions caused by B. cinerea, andthe suppression effect of UV-C treatment at 7.0 kJ/m2 UV-C on gray mold was better than at 3.5 kJ/m2. However, UV-Ctreatment at 10.5 kJ/m2 had an adverse effect on gray mold of apple fruits only after inoculation for the earlier days while atthe later stage after inoculation, and even increased morbidity of fruits and promoted the expansion of lesions. In addition,the activities of chitinase (CHT), β-1,3-glucanase (GLU), peroxidase (POD), polyphenol oxidase (PPO) and phenylalanineammonia-lyase (PAL) of apple fruits were promoted remarkably by UV-C treatments at 3.5 and 7.0 kJ/m2, and phenolicscontent was also increased significantly. The promoting effects of UVC-treatment at 10.5 kJ/m2 on those defense enzymesactivities and phenolics content was found only in the first several days after inoculation.

Key words: apple, gray mold, UV-C, disease control, mechanisms, defense enzyme activity