Background and Aims: In wetland plant communities, species-specific responses to pulses of white light and to red: far-red light ratios can vary widely and influence plant emergence from the seed bank. Carex species are the characteristic plants of sedge meadows of natural prairie wetlands in mid-continental USA but are not returning to restored wetlands. Little is known about how light affects seed germination in these species - information which is necessary to predict seed bank emergence and to develop optimal revegetation practices. The effects of light on germination in eight Carex species from prairie wetlands were investigated. Methods: Non-dormant seeds of eight Carex species were used to determine the influence of light on germination by examining: (a) the ability of Carex seeds to germinate in the dark; (b) the effect of different lengths of exposures to white light on germination; (c) whether the effect of white light can be replaced by red light; and (d) whether the germination response of Carex seeds to white or red light is photoreversible by far-red light. Key Results: Seeds of C. brevior and C. stipata germinated >25 % in continuous darkness. Germination responses after exposure to different lengths of white light varied widely across the eight species. Carex brevior required <15 min of white light for ≥50 % germination, while C. hystericina, C. comosa, C. granularis and C. vulpinoidea required ≥8 h. The effect of white light was replaced by red light in all species. The induction of germination after exposure to white or red light was reversed by far-red light in all species, except C. stipata. Conclusions: The species-specific responses to simulated field light conditions suggest that (a) the light requirements for germination contribute to the formation of persistent seed banks in these species and (b) in revegetation efforts, timing seed sowing to plant community development and avoiding cover crops will improve Carex seed germination.
Bibliographical noteFunding Information:
This study would not have been possible without field and laboratory assistance from Stacey Olszewski; growth chamber support from Mike Emerick; seed collection by Myrna Rieck, Brenda Tholen, Karen Nemchik and Andy Place; access to wetlands for seed collection at the Minnesota Landscape Arboretum, the Cedar Creek Natural History Area and Minnesota Valley State Park; and funding from a graduate student grant from Applied Ecological Services, a Brand Fellowship from the University of Minnesota Graduate School, a Delta Waterfowl graduate student fellowship, a Dayton Fellowship from the Bell Museum of Natural History and the University of Minnesota Agricultural Experiment Station.
- Far-red light
- Prairie wetland
- Red light
- Seed germination ecology
- White light