RELATIONSHIP BETWEEN ABSCISIC ACID CONTENT AND RIPENING OF APPLES

The evolution of endogenous ABA content in the apple fruit (Malus domestica. Borkh. c.v. Red winesap) during development shows an increase from rather constant low levels to higher concentrations about two months before normal ripening and remains high until harvest.

Fruit collected at two different stages of development (92 and 147 days after full bloom) were treated by injection with 1 mM ABA. This treatment induces an increase in respiration and ethylene production compared to controls treated with water or not treated, and ripening is advanced. This effect is specially pronounced in the younger fruits in which the controls do not show any change related to ripening during three weeks. It is suggested that the capacity of fruit to ripen is related to the ABA content. The effect on ethylene production seems to be indirect.