RESIDUAL EFFECTS OF ALAR ON THE CARBON DIOXIDE AND ETHYLENE PRODUCTION OF McINTOSH APPLES AT HARVEST AND AFTER LONG STORAGE

Abstract

Applications of 750 and 1500 ppm Alar to mature McIntosh apple trees in late July delayed the preclimacteric minimum 9 to 15 days and first detection of ethylene 8 to 12 days, respectively. Both carbon dioxide and ethylene evolution from the treated fruit were lower at harvest with the largest differences occurring before the treated fruit reached the preclimacteric minimum. As the season progressed the differences became smaller. Fruit stored at 2 C until May produced carbon dioxide and ethylene at a greater rate after treatment with Alar. Fruit harvested one year after Alar was applied produced more carbon dioxide and ethylene. The residual effects of Alar on respiration and ethylene production are discussed in relation to commercial practice.