Abstract:

Citrus fruits (citrus sinensis L. Osbeck cv‘. Jincheng 447#’) were immersed in 1.5% (g/g) oligochitosan solution for 1 min, induced for 1, 2, 3, 4, 5 d, respectively, and then inoculated with Colletotrichum gloeosporioides Penz. Then the fruits were stored at 20 ℃ with relative humidity at 85% － 95%, and the formation of infection hyphae was recorded. Results indicated that the infection ratio in oligochitosan-treated fruits was significantly lower than that in control fruits on the 9th day of the storage, and the infection ratio in one day-oligochitosan-induced fruits was the lowest. Compared with control, 1.5% oligochitosan treatment accelerated biosynesis of hydrogen peroxide (H2O2) and delayed the reduction of ascorbate (ASA) and glutathione (GSH) content. Furthermore, 1.5% oligochitosan effectively enhanced activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), polyphenoloxidase (PPO), ascorbate peroxidase (APX) and glutathione reductase (GR).

Key words: oligochitosan, citrus fruit, active oxygen, postharvest, induced disease resistance