Insecticidal Effect of Carbon Dioxide Treatment on Onion Thrips (Thrips tabaci: Thripidae: Thysanoptera)

Abstract

This study was carried out to investigate the effects of hot solution soaking and chilling treatment on sprouting and enlargement of bulblets obtained through in vitro culture in Korean native lilies with ornamental values. In vitro bulblets of Lilium cernuum, L. hansonii, L. hansonii for. mutatum, L. leichtlinii, and L. tsingtauense were soaked in distilled water or 100 and solution maintained at for two hours (hot water treatment) and/or exposed at for 0, 4, or 8 weeks (chilling treatment) and then planted in plastic trays filled with media and grown in a greenhouse at and under 16 h photoperiod. In all species, no bulblet propagated by tissue culture sprouted without chilling or hot water treatment due to dormancy. For dormancy breaking, hot solution treatment increasing sprouting by 55-96%, whereas distilled water or GA was not effective in sprouting. Chilling treatment for 4 weeks induced sprouting by 50-70% in L. cernuum and L. leichtlinii, whereas 8 weeks was needed for sprouting of L. hansonii and L. hansonii for. mutatum. Combined treatment of hot water and chilling treatments synergistically promoted sprouting. Especially, in L. cernuum and L. hansonii, hot solution soaking prior to chilling for 4 weeks promoted sprouting by 35-45% compared with the reverse order. Enlargement of bulblets resulted from increase in fresh weight and diameter was promoted by the treatments that increased the sprouting percentage of bulblets. Only in L. cernuum, shoots emerged from bulblets soaked in hot solution or chilled at and shoot emergence rate was highest in bulblets soaked in hot solution and then chilled for 8 weeks. From these results, the most effective method for bulblet sprouting and enlargement was to soak in hot solution and then chill for 4 weeks in L. hansonii, hansonii for. mutatum, and leichtlinii, and to soak in hot solution and then chill for 4 weeks in L. cernuum and tsingtauense.