The Possible Role of Low Temperature in Breaking the Dormancy of Seeds ofFraxinus excelsiorL.

It has been shown that the growth-inhibiting substances present in the embryo and endosperm of F. excelsior are not removed during pretreatment or during the actual germination process. On the other hand, evidence is presented that the inhibitor may be physiologically effective in preventing germination. A biological assay technique using embryos of the same species from which the growth substances were extracted was used to demonstrate the production of a germination and growth-promoting substance during the process of low temperature after-ripening and its apparent counteraction of the effect of the endogenous inhibitor.