1958 Volume 27 Issue 4 Pages 256-264
1. Experiments were carried out to clarify the mechanism of after-ripening and germination of apple seeds from the viewpoint of natural growth substances. The apple veriety “Jonathan” was used for both germination and Avena tests. 2. Germination tests of intact seeds and excised embryos showed that embryos and intact seeds required about 35-day and 77-day stratifications, respectively, for maximum germination.
3. The embryo contained an unidentified acidic growth-promoter at the outset which increased rapidly as a result of stratification. The breaking of embryo dormancy apparently coincided with the increase in activity of this acidic growth-promoter.
4. A growth-promoter was found to occur in both stratified and non-stratified endosperm, but the production of the growth-promoter was much higher in stratified endosperm. The relationships between the production of growth-promoter in the endosperm, afer-ripening, and embryo germination is not clear.
5. Seedcoats were found to contain both a strong growth-inhibiting substance and a growth-promoting substance. During stratification the growth-inhibiting substance decreased and the growth-promoter increased. After 77-day stratification, ether extracts showed a striking promotion of the elongation of Avena coleoptile. Germ-inhibition was apparently dependent on the inhibitor, but the possible associations between after-ripening of the embryos and fluctuations in natural growth-substances in seedcoats is not clear.