Abstract: In order to study the effect of ozone on controlling the postharvest black spot disease of apricot fruit, freshly harvested ‘Saimaiti’ apricot fruit grown in Xinjiang, China were artificially wounded, inoculated with Alternaria alternate, fumigated with 200 mg/m3 of ozone for 30 minutes, and stored at 1–2 ℃ and 90%–95% relative humidity for 49 days. During this period, fumigation was repeated once every seven days for 42 days. The lesion diameter and disease incidence of apricot fruit inoculated with A. alternata, the activities of phenylalanine ammonia-lyase (PAL), cinnamic acid-4-hydroxylase (C4H), 4-coumaric acid CoA ligase (4CL), β-1,3-glucanase (GLU) and chitinase (CHT), and the total phenolic and flavonoid contents were measured regularly. The results showed that ozone treatment increased the activities of PAL, C4H, 4CL, GLU and CHT and the contents of total flavonoids and total phenolics in apricot fruit. Besides, ozone treatment significantly inhibited lesion expansion and the increase in the incidence of black spot disease (P < 0.05), and improved the disease resistance of apricot fruit by a mechanism closely related to the regulation of phenylpropane metabolism.

Key words: apricot fruit; ozone; postharvest diseases; phenylpropane metabolism