Differential patterns of germination and desiccation tolerance of mesic and xeric wild barley (Hordeum spontaneum) in Israel

Differential patterns of germination were identified in mesic (Maalot) versus xeric (Wadi Qilt) ecotypes of wild barley, Hordeum spontaneum C. Koch, in the following traits: afterripening (dormancy), seedling desiccation tolerance, and the effect of glumellae and ethanol on afterripening and seedling growth. The following results were indicated: (i) Dispersal unit afterripening average (75%) was identical, but its coefficient of variation was larger in the xeric than in the mesic ecotype (29.9% and 9.9%, respectively). (ii) Survival ratio of seedlings after 1-month dehydration was higher in the xeric ecotypes indicating that seedling desiccation tolerance was higher in the xeric ecotype. (iii) Inhibition of germination and seedling growth by glumellae were higher in the mesic ecotypes. Ethanol sterilization of naked caryopsis promoted root growth of mesic seedlings but not xeric seedlings. Seedlings originating from xeric ecotypes had longer roots than mesic seedlings. It appears that, in the germination stage, natural selection adapted wild barley to a xeric environment by increasing the diversity of afterripening, enhancing desiccation tolerance, and improving root length growth. (C) 2003 Elsevier Science Ltd. All rights reserved.