Effect of high temperature stress on ethylene biosynthesis, respiration and ripening of 'Hayward' kiwifruit

Temperatures up to 35 degreesC have been shown to increase ethylene production and ripening of propylene-treated kiwifruit (Stavroulakis, G., Sfakiotakis, E.M., 1993. We attempted to study the regulation by high stress temperature of the propylene induced ethylene biosynthesis and ripening in 'Hayward' kiwifruit. 'Hayward' kiwifruit were treated with 130 mul/l propylene at temperatures from 30 to 45 degreesC up to 120 h. Ethylene biosynthesis pathway and fruit ripening were investigated. Propylene induced normal ripening of kiwifruit at 30-34 degreesC. Fruit failed to ripe normally at 38 degreesC and above 40 degreesC ripening was inhibited. Propylene induced autocatalytic ethylene production after a lag period of 24 h at 30-34 degreesC. Ethylene production was drastically reduced at 38 degreesC and almost nil at 40 degreesC. The 1-aminocyclopropane-1-carboxylic acid (ACC) content was similar at 30-38 degreesC and was very low at 40 degreesC. The 1-aminocyclopropane-1-carboxylate synthase (ACC synthase) and 1-aminocyclopropane-1-carboxylate oxidase (ACC oxidase) activities decreased with a temperature increase above 30 degreesC, but ACC oxidase decreased at a faster rate than ACC synthase. Fruit not treated with propylene showed no ripening response or ethylene production. However, kiwifruit respiration rate increased with temperature up to 45 degreesC, reaching the respiration peak in 10 h. At temperatures up to 38 degreesC, propylene treatment enhanced the respiration rate. After 48 h at 45 degreesC, fruit showed injury symptoms and a larger decrease in CO2. The results suggest that high temperature stress inhibits ripening by inhibiting ethylene production and sensitivity while respiration proceeds until the breakdown of tissues. (C) 2000 Elsevier Science B.V. All rights reserved.