Abscisic acid and the development of storage breakdown in apples

(±)-ABA injected into the calyx of mature fruit increased the incidence of storage breakdown in Jonathan apples. The increase in disorder was greater when ABA was added early in the storage period and was proportional to the amount of ABA added. Most of the added ABA was converted into ‘bound’ ADA which remained at high concentrations throughout storage; however, the amount of ‘free’ ABA was also always higher than that in a control fruit. GA₃ decreased and geraniol increased the amount of ‘free’ ABA in the fruit on injection into the calyx. This could explain the ability of these compounds to respectively decrease and increase the incidence of breakdown.