The effect of cold stratification and perigynia removal on the germination of three prairie carex species

Sedges (Carex spp. Linneaus. [Cyperaceae]) are a major component of Midwestern U.S. tallgrass prairie and prairie wetland plant communities, yet they are often lacking in restoration projects because they can be difficult to germinate. Cold-wet stratification and perigynia removal have been shown to increase germination in some Carex species. The germination response of 3 native species, plains oval or shortbeak sedge (C. brevior (Dewey) Mack.), field oval or troublesome sedge (C. molesta Mack.), and prairie or Bicknell’s sedge (C. bicknellii Britton.), was tested to cold-wet stratification (28d) and perigynia removal in stored seed (10 months). Seed treatments included nonstratified with perigynia intact (control), nonstratified with perigynia removed, stratified with perigynia intact, and stratified with perigynia removed. Four replicates of 100 seeds treatment were held under a diurnal temperature regime 30/15 °C (86/59 °F) with 12 hours of light for 84 days. Fresh seed was also tested for C. brevior and C. molesta. Stratification increased total germination in fresh C. molesta and stored C. brevior seeds and marginal increased total germination in stored C. molesta and fresh C. bicknellii seeds. Stratification also increased germination rate in all species and seed states. Perigynia removal increased total germination in fresh C. bicknellii and stored C. brevior seeds and marginally in stored C. molesta seeds. Perigynia removal also increased germination rate in C. brevior. Combining stratification with perigynia removal did not provide any additional advantage and actually resulted in a decrease in total germination in fresh C. brevior seeds. C. molesta germinated well, to at least 91.3%, without treatment. Generally speaking, stratification overall increased germination in all species most effectively, but perigynia removal may provide some benefits if stratification is not available