Ozone (O3) is a potential fumigant to control pests in stored grain since it can safely and rapidly auto-decompose without leaving residues. In this study, the efficacy of O3 on all life stages of Rhyzopertha dominica (Fabricius) and Tribolium castaneum (Herbst) in barley and the physiological effects on barley and its quality were investigated. Complete control of all life stages of pests was obtained at 700 ppm for 1440 min of ozone exposure without negatively impacting the contents of soluble protein, moisture content, seed colour, hardness, and the weight of thousand barley seeds. The eggs and pupae of these two insects were the more tolerant stages than their larvae and adults. Prolonged exposure times (40 to 1440 min) and mortality assessment intervals (1, 2, and 7 days) increased O3 efficacy due to the reaction characteristics and delayed toxicity. Aging barley seeds appeared to be more sensitive to prolonged ozone duration than new seeds. A total of 20 and 40 min could promote germination rate, and longer O3 exposure (1440 min) was unfavourable for germination and seedling growth. Thus, it is imperative to select an optimal O3 exposure time to transfer ozone into quality contributors of final products and achieve the desired functional outcomes.
Keywords: barley (Hordeum vulgare L.); fumigant; germination; insect control; ozone (O3); quality.