Hydrogen peroxide and color sorting improves germination and vigor of eastern gamagrass (Tripsacum dactyloides) seeds

Eastern gamagrass (Tripsacum dactyloides) is a warm-season perennial grass used for forage, as an ornamental grass in landscapes, and for conservation plantings. The seed is encased in a cupule and requires cold moist stratification for germination, which rarely exceeds 60%. The objective of this study was to investigate cupule color as a marker for germination in seeds treated by stratification or hydrogen peroxide (H₂O₂). Cupules of 'Pete' and 'Highlander' varieties were visually separated into green, medium, and dark categories. Seed and cupules for each category were measured for chlorophyll content, size and weight. Seed-containing cupules were stratified for 6 weeks at 4°C or were soaked in 0 to 30% H₂O ₂ for up to 48h and then germinated at 20°C/30°C (12h: 12h) in the dark. "Dark" cupules and seeds were heavier, larger, and had less chlorophyll than "medium" or "green". "Green" seeds had the lowest germination percentage and shortest shoots regardless of treatment. Soaking in 15% H₂O₂ for 18h broke dormancy most effectively. Seed-containing cupules treated with H₂O₂ germinated within two weeks, while isolated seeds began germinating within 4 days, indicating that the cupule is at least partially responsible for dormancy. Rigorous sorting of gamagrass cupules by color or weight will improve the germination and vigor of the resulting seedlot. Treatment with 15% H ₂O₂ for 18h can substitute for six weeks of stratification at 4°C in satisfying dormancy of eastern gamagrass.