Autoinhibition of Ethylene Formation in Nonripening Stages of the Fruit of Sycomore Fig (Ficus sycomorus L.)

Abstract

Differences in the mechanism of ethylene emanation of Ficus sycomorus L. during various stages of the fruit development were investigated by enclosing the figs in jars. Two distinct patterns of ethylene emanation were found. Pattern a. in stages not capable of ripening, neither spontaneously nor as a result of physiological treatment (nonripening stages A and C), ethylene concentration in the jar increased linearly for a short time and then remained constant. Pattern b. in stages capable of ripening (ripening stages B, D, and E), the linear increase in ethylene concentration continued for the entire period of measurement. In nonripening stages, ethylene emanation stopped when ethylene concentration in the jar reached a constant value (0.6 mul/l at stage C). Aeration of the figs and the jar renewed ethylene emanation. CO(2) concentration in the jar never exceeded 0.5%. Treatment of stage C figs with 0.6 to 10 mul/l exogenous ethylene caused immediate and complete cessation of ethylene emanation whereas the same treatment did not cause any change in rate of ethylene emanation from figs at the ripening stages B and D. Gashing (wounding) of stage C figs temporarily changed the pattern of ethylene emanation from pattern a to pattern b.We concluded that in the nonripening stages ethylene acts as an autoinhibitor of its own production but this does not occur in the ripening stages.