Studies on the Inhibition of Ripening in Attached Avocado (Persea americana Mill.) Fruits1

The inability of ‘Fuerte’ and ‘Hass’ avocado fruits to ripen on the tree has been attributed to a ripening inhibitor which has been presumed to be transported from the tree to the fruits. These studies, undertaken to explain this phenomenon, indicate that leaves, usually considered to be the source of this substance, did not delay ripening. Fruit on detached branches abscissed before ripening and softened later than detached fruit. Leaves on the detached branches accelerated abscission and subsequent ripening. Fruit detached from the branch with the peduncle attached ripened later than when it was removed. The peduncle and stem may supply a ripening inhibitor to the fruit or the stem may act as a sink for a ripening hormone produced in the fruit.