A ripened apple placed in a bowl with green apples will, by its release of ethylene, hasten the ripening of its neighbors, which, in turn, increase their own ethylene production. Ethylene plays various roles in plant behavior. It releases potato tuber buds from dormancy, stimulates leaf abscission, influences the flowering of pineapple plants, induces the formation of adventitious roots in stem cuttings, helps germinating seeds push up through the soil, and helps bring about senescence. Ethylene is produced not only by ripening fruit but also by flowers, seeds, leaves, and roots. If fruits are bruised or cut, ethylene seems to be produced in a surge. Application of IAA stimulates ethylene production sometimes as much as tenfold. When pea seeds germinate, an increase of ethylene causes the cells of the stem tip to produce a tighter bend, thus aiding the seedling in pushing through to the surface.
