Abstract
In the laboratory, silver sagebrush (Artemisia cana Pursh ssp. cana [Asteraceae]) seeds germinated with increasing temperatures similar to those of spring and early summer or with cooling temperatures that occur in late summer or autumn. However, exposing seeds to similar temperatures under field environments reduced germination, with greater reductions occurring when seeds were put in the field in autumn (−36% to −81%) compared to spring (−18% to −24%). Germination of seeds placed in the field in autumn declined abruptly as daily temperatures rose in early spring, however, a gradual decline in germination was noted for seeds put in the field in spring. Nearly all non-germinating seeds were infected with fungi and were non-viable, indicating that recruitment of seedlings may be limited by loss of viability of seeds in the soil. Despite the fact that viability of seeds declined with exposure to field environments, 19% to 82% of the seeds remained viable, with greater viability in spring- than autumn-placed seeds. Seeding silver sagebrush in spring is recommended to maintain viability and high germination of seeds.
