Regulation by Temperature of the Propylene Induced Ethylene Biosynthesis and Ripening in “Hayward” Kiwifruit

The present study was undertaken to determine the critical temperature and the step in the ethylene biosynthetic pathway at which low temperature exerts its inhibitory effect in ethylene production. Hayward kiwifruit treated with propylene (150 ppm) at temperatures from 0° to 35°C showed (with Arrhenoius plot) a critical range (11°–14.8°C) above of which autocatalytic ethylene production was proceeded with an accumulation of ACC and an increase in EFE activity. Below the critical temperature range propylene was unable to trigger autocatalytic ethylene production and the inhibition was rather attributed to limited ACC production than to the low EFE activity. By reducing the storage temperature in the propylene treated fruit the rate of ripening (softening, changes in SSC) was retarded and the number of days to ripen was prolonged.