Physiological Studies on Dormancy in Cape Tulip

Abstract

A high proportion of cormils of the two· leaved species of the weed, Cape tulip, showed long-term dormancy, and e.xperiments showed that this dormancy is not due to a high level of endogenous growth inhibitors but is due to physical factors associated with the presence of intact cormil coats. Dormancy is broken if the thin and papery inner cormil coat is ruptured, and observations suggest that this coat is impermeable to water and probably oxygen and carbon dioxide as well. The outer cormil coat is not impermeable to these substances but is thick and heavily lignified and thus protects the fragile inner coat.