SUPERFICIAL SCALD OF GRANNY-SMITH APPLES IS EXPRESSED AS A TYPICAL CHILLING INJURY

To examine the hypothesis that superficial scald of apple (Malus domestica Borkh.) is a chilling injury, ''Granny Smith'' apples were stored at temperatures ranging from 0 to 20C, temperature-conditioned before storage, and warmed during storage. Fruit stored at 0 or 4C developed superficial scald. At 10C, surface defects occurred but they were not typical symptoms of scald, and at 15 or 20C no symptoms developed. Accumulation of alpha-farnesene and conjugated trienes in fruit peel correlated with increasing ethylene production, which was greater at higher temperatures. However, concentrations of conjugated trienes were highest at 0 and 4C. When fruit were kept at 10C for 5 or 10 days before storage, scald development after storage was not reduced. An interruption of OC storage,vith a single warming period at 10 or 20C reduced scald development after 25 weeks of storage, maximum reduction occurring when fruit were warmed for 3 to 5 days at 20C after 1 to 4 weeks at OC. Amelioration of scald declined as time at OC before warming increased. Diphenylamine application after the same intervals at 0C, instead of warming, also was less beneficial as time;before treatment increased, alpha-Farnesene and conjugated trienes increased during warming, but at the end of storage (when scald was developing) the conjugated triene concentrations in peel were reduced in fruit that had been warmed. Warming slightly increased yellowing, softening, and greasiness of fruit after storage. We conclude that chilling induced superficial scald on ''Granny Smith'' apples.