Germination of seeds of five annual species of barley grass.
In the laboratory, seeds of Hordeum geniculatum, H. glaucum, H. leporinum, H. marinum and H. murinum showed some innate dormancy which was most evident in H. glaucum and least evident in H. murinum. The most rapid germination of fresh seed of all the species occurred at 10 deg or 15 deg C. Following dry storage, the speed of germination, the final % germination and the range of constant temps. at which germination occurred all increased. Dormancy was lost more rapidly in H. murinum than in the other species. Even after prolonged storage H. glaucum seeds showed relatively low germination at constant temps. but germination could be increased by physically damaging the seeds, by treating them with GA or by varying the temp. to which the imbibed seeds were exposed. None of the species germinated at 35 deg C but subsequent transfer to a lower temp. resulted in a high % germination. In the field, most seeds of all species germinated readily in response to autumn rains and, at most sites, relatively few seeds survived to germinate in the winter and spring. Thus, if annual Hordeum spp. are effectively controlled in one year so that no seeds are produced, there should be little problem from these spp. in the following year.