Reciprocal Common Garden Studies of the Germination of Seeds of Big Sagebrush (Artemisia tridentata)

Abstract

Experiments were conducted to compare the influence of production site and seed source on the germination of big sagebrush seeds in relation to incubation temperatures. Seeds of big sagebrush were collected from five plant communities located on the margin of the Carson Desert in western Nevada. Seedlings were grown from the seeds and transplanted back to the sites of collection in reciprocal gardens. Seeds from 1-yr-old gardens were tested for germination at a constant 15 C for three consecutive years. The greater quantity of seeds produced by 2- and 3-yr-old gardens were tested at 55 constant or alternating temperature regimes. Seeds of big sagebrush produced in reciprocal gardens had lower germination than seeds collected from native stands at the same locations. The reduced germination disappeared as the reciprocally transplanted plants grew older and larger, but seeds from these plants did not reach the same levels of germination as those collected from native stands at the same location. Moisture stress and/or freezing temperature conditions during flowering may have directly influenced the quality of seeds produced or interacted with the inherent genotypes of big sagebrush to trigger seed production of variable quality in relation to germination characteristics.