干旱区生态环境知识资源中心

Plants have evolved diverse strategies to ensure their survival and regeneration in specific environments. Although temperature and soil moisture control seed dormancy, most studies have concentrated on temperature and little is known about the influence of moisture for species in the arid region. Responses of seed dormancy and germination of Agriophyllum squarrosun (Amaranthaceae), a pioneer and dominant species in Mu Us Sandland in northern China, to variations in soil moisture and temperature were examined. Our study showed that (1) freshly harvested seeds were in non-deep physiological (conditional) dormancy; (2) seeds in the soil exhibited dormancy cycling being non-dormant in spring and dormant from summer to autumn; (3) dry conditions at cold or warm temperatures alleviated dormancy; (4) germination was promoted by wetting-drying cycles; and (5) dormancy was induced by warm temperature (15/25 degrees) and particularly low soil moisture less than 14.0%. The seasonal pattern of seed dormancy/germination was regulated by seasonal rainfall and soil temperature. At the same time, a range of conditions enable dormancy break and germination regardless of soil moisture conditions allowing the species to persist in an unpredictable environment.