Bromus tectorum seed germination: Between-population and between-year variation

被引:74
作者
Beckstead, J
Meyer, SE
Allen, PS
机构
[1] BRIGHAM YOUNG UNIV, DEPT BOT & RANGE SCI, PROVO, UT 84602 USA
[2] US FOREST SERV, INTERMT RES STN, SHRUB SCI LAB, PROVO, UT 84606 USA
来源
CANADIAN JOURNAL OF BOTANY-REVUE CANADIENNE DE BOTANIQUE | 1996年 / 74卷 / 06期
关键词
after-ripening; invading species; dormancy; mean germination time; cheatgrass; downy brome;
D O I
10.1139/b96-109
中图分类号
Q94 [植物学];
学科分类号
071001 ;
摘要
Cheatgrass (Bromus tectorum L., Poaceae), an introduced winter annual, has invaded a variety of habitats in western North America. This study examines variation in cheatgrass germination response and after-ripening patterns that are related to differences in habitat and to yearly differences in weather conditions during seed maturation. Seeds collected from five contrasting populations in 1992 and 1993 were subjected to controlled dry storage and then incubated across a range of temperatures. Recently harvested seeds were dormant and germinated slowly, while fully after-ripened seeds were nondormant and germinated rapidly. The optimal incubation temperature for mean germination time shifted from 5:15 to 20:30 degrees C as a result of after-ripening. Between-population differences in germination response appear to be related to the potential risk of precocious summer germination. The results from this 2-year study suggest that the more extreme yet predictable environments select for seed germination and after-ripening patterns that are genetically fixed, while populations from more favorable environments tended to show more between-year variations, suggesting more phenotypic plasticity. Germination percentage showed greater between-year variation than mean germination time. Between-year differences could not be explained simply by differences in maximum temperature or total precipitation during maturation. Adaptive germination responses in cheatgrass populations from contrasting habitats may have both genetic and environmental components, thus explaining why this species can become established in such a variety of habitats.
引用
收藏
页码:875 / 882
页数:8
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