Relationship between production of ethylene and alpha-farnesene in apples,and how it is influenced by the timing of diphenylamine treatment

The relationship between ethylene and peel alpha -farnesene concentrations was examined by applying diphenylamine (DPA) and the ethylene analogue, pro pylene at varying times after harvest to superficial scald (scald) suscepti ble 'Granny Smith' apples (Malus domestica Borkh.) stored at 10 degreesC. D elaying DPA application after harvest had no large effect on ethylene or on peel alpha -farnesene production. Propylene advanced fruit ripening and pr omoted an increase in peel alpha -farnesene concentration before endogenous internal ethylene production, suggesting that ethylene has an important re gulatory role in alpha -farnesene production, but their biosynthetic pathwa ys are controlled independently. The effect of delayed DPA application (4 a nd 7 days after harvest) on the relationship between ethylene and peel alph a -farnesene was further examined at both a scald-inducing temperature (0 d egreesC) and a non-scald-inducing temperature (10 degreesC) with 'Granny Sm ith' and the scald resistant 'Crofton' cultivar. Similarly a delayed DPA ap plication had only minor effects on internal ethylene and peel alpha -farne sene concentrations. The relationship between internal ethylene and peel al pha -farnesene concentration was dependent on storage temperature, and the type of relationship was independent of cultivar. However, the magnitude of the relationship between cultivars was significantly different ('Granny Sm ith' produced significantly more alpha -farnesene than 'Crofton') and may b e related to scald development. (C) 2001 Elsevier Science B.V. All rights r eserved.