Intermittent warning effects on superficial scald development of 'Cortland', 'Delicious' and 'Law Rome' apple fruit

'Cortland', 'Delicious' and 'Law Rome' apples were intermittently warmed to 20 degrees C for 24 h every 1, 2, or 4 weeks during cold storage for 16 we eks, not warmed, or treated with diphenylamine (DPA) at harvest. The effect s of these treatments on fruit ripening and on the accumulation of alpha-fa rnesene and its oxidation products in hexane extracts of the peel, were ass essed throughout storage. Incidence and severity of superficial scald were assessed after 22 weeks. Warming treatments, especially the weekly regime, advanced fruit ripening. Without warming, scald incidence in 'Cortland', 'D elicious' and 'Law Rome' was 70, 14 and 85%, respectively. Intermittent war ming treatments reduced scald but the magnitude of effects varied among cul tivars. In 'Cortland', scald was reduced only by the weekly warming treatme nt, which was less effective than DPA treatment. In 'Delicious', all warmin g treatments were equally effective but less so than DPA. In 'Law Rome', we ekly warming controlled scald better than DPA, but less frequent warming wa s proportionately less effective in controlling the disorder. Concentration s of conjugated trienes measured at 281 nm were not related consistently to scald incidence after storage, but ratios of measurements at 258 and 281 n m in crude hexane extracts were. The results are discussed in relation to t he a-farnesene hypothesis of scald development and chilling injury. (C) 199 9 Elsevier Science B.V. All rights reserved.