DORMANCY OF HORDEUM-SPONTANEUM CARYOPSES FROM A POPULATION ON THE NEGEV DESERT HIGHLANDS

Freshly harvested caryopses of Hordeum spontaneum do not germinate, ev en after a long period of imbibition at 10, 20 and 30 degrees C, in da rkness or in continuous white light. Their dormancy results from an in hibitory effect of the covering structures, since isolated embryos are able to germinate. Breaking of dormancy, termed 'after-ripening', occ urs during storage in dry conditions at 35 degrees C or in the natural habitat during summer. Dormancy remains when caryopses in dispersal u nits are stored at -35 degrees C. The ecological importance of dormanc y and after-ripening at high temperatures affecting the 'readiness for germination' is discussed. (C) 1996 Academic Press Limited