INHIBITION OF RIPENING AND INDOLE‐3‐ACETIC ACID OXIDASE OF BANANA FRUIT BY p‐2,4‐CHLOROPHENOXY‐ISOBUTYRIC ACID

Abstract

p‐2,4‐dichloro‐phenoxy‐isobutyric acid (p‐CPIB) was observed to repress the ripening of green banana fruit after injection into the peel‐pulp juncture at concentrations ranging from 10−5 to 10−3M. Application of 10−2M p‐CPIB resulted in rapid necrosis at the site of injection and accelerated ripening at distal areas of the banana. Repression of ripening occurred regardless of whether fruit were gassed with exogenous ethylene. Indole‐3‐acetic acid oxidase isolated from the pulp of banana fruit was inhibited by concentrations of p‐CPIB which repressed ripening. In addition, injection of indole 3‐acetic acid and 2,4‐dichlorophenoxy acetic acid into the peel‐pulp juncture delayed ripening for up to 15 days at 10−3M. It is suggested the p‐CPIB affected ripening in banana fruit by blocking the oxidative metabolism of endogenous auxins