Light Requirement for Seed Germination of Payson Sedge

Abstract

Payson sedge (Carex paysonis Clokey) is a dominant component of many alpine floras in the western United States. This species appears to be a highly adapted colonizer (early invader) on disturbances such as acidic mine spoils at high elevations, and its rhizomatous growth habit offers promise for revegetation of these sites. The few natural seedlings observed in the field suggest that seed germination of Payson sedge is low compared with that of other alpine colonizers, and seeding trials with this species have met with poor success. Therefore, studies were designed to determine the germination requirements of this species. The effects of 2 levels each of light (visible vs. complete darkness), temperature (constant 25 degrees C vs. variable 25/3 degrees C day/night), and seed position in soil (surface vs. buried) on germination were investigated under controlled conditions in the laboratory. The highest germination percentage (mean = 28.8%) was attained under conditions of complete darkness followed by exposure to light at variable temperatures. There were no significant differences (p<0.05) in germination levels under conditions of light coupled with variable temperature (mean = 21.3%), and complete darkness followed by light at constant temperature (mean = 22.8%). Germination levels were low (mean = 10.0%) under light at constant temperature and seeds subjected to complete darkness alone germinated poorly (mean is lesser than or equal to 1.2%). We recorded low levels of germination (mean is lesser than or equal to 2.8%) from treatments of buried seeds exposed to both light conditions and both temperature levels. A requirement for light coupled with low germination levels of buried seeds suggests that standard revegetation techniques, where seeds are buried beneath the soil surface, may be inappropriate for Payson sedge. We recommend surface seeding in the fall so that extended periods of natural snow cover will promote germination the following spring.