Filters: Tags: after-ripening (X)
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After-ripening, the loss of dormancy under dry conditions, is associated with a decrease in mean base water potential for germination of Bromus tectorum L. seeds. After-ripening rate is a linear function of temperature above a base temperature, so that dormancy loss can be quantified using a thermal after-ripening time (TAR) model. To incorporate storage water potential into TAR, we created a hydrothermal after-ripening time (HTAR) model. Seeds from two B. tectorum populations were stored under controlled temperatures (20 or 30 �C) and water potentials (?400 to ?40 MPa). Subsamples were periodically removed from each storage treatment and incubated at 15 or 25 �C to determine germination time courses. Dormancy status...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Bromus tectorum,
Seed Science Research,
after-ripening,
dormancy loss,
hydrothermal after-ripening time,
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 °C...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Canadian Journal of Botany,
after-ripening,
cheatgrass,
dormancy,
downy brome,
Bromus tectorum L. is an invasive winter annual grass with seeds that lose dormancy through the process of dry after-ripening. This paper proposes a model for after-ripening of B. tectorum seeds based on the concept of hydrothermal time. Seed germination time course curves are modelled using five parameters: a hydrothermal time constant, the fraction of viable seeds in the population, base temperature, mean base water potential and the standard deviation of base water potentials in the population. It is considered that only mean base water potential varies as a function of storage duration and incubation temperature following after-ripening. All other parameters are held constant throughout after-ripening and at...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Bromus tectorum,
Seed Science Research,
after-ripening,
dormancy loss,
hydrothermal time,
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