Tomato fruit of the fast-ripening cultivar Breton had higher rates of
ethylene production than the slow-ripening cultivar Daniela. The initi
al abscisic acid values were high in both cultivars, but fell during t
he first six weeks of development. After this time the levels increase
d, reaching a maximum before ethylene production began to increase. Th
is maximum was much more pronounced in the fast-ripening cultivar. The
polyamine/ethylene ratio also differed, with the slow-ripening cultiv
ar having higher levels of putrescine and lower levels of ethylene. In
this cultivar, putrescine was the major polyamine throughout, and it
increased sharply during the ripening stage. Spermidine levels, on the
other hand, decreased gradually, especially during the first two week
s of development.