Dormancy ofHordeum spontaneumcaryopses from a population on the Negev Desert Highlands

Freshly harvested caryopses ofHordeum spontaneumdo not germinate, even after a long period of imbibition at 10, 20 and 30 °C, in darkness or in continuous white light. Their dormancy results from an inhibitory effect of the covering structures, since isolated embryos are able to germinate. Breaking of dormancy, termed ‘after-ripening’, occurs during storage in dry conditions at 35 °C or in the natural habitat during summer. Dormancy remains when caryopses in dispersal units are stored at −35 °C. The ecological importance of dormancy and after-ripening at high temperatures affecting the ‘readiness for germination’ is discussed.