Enhancing germination of eastern gamagrass seed with stratification and gibberellic acid

Eastern gamagrass (Tripsacum dactyloides, L.), a warm season, perennial grass with great potential for forage and conservation uses, has a high level of seed dormancy, making establishment difficult. Stratification at 4 degreesC for 6 wk is a standard method for providing germinable gamagrass seed. Earlier research showed that gibberellic acid (GA(3)) increased germinability of gamagrass caryopses removed from the cupule, but was less effective when the caryopses remained in the cupule. We hypothesized that gibberellic acid together with stratification may increase germination of seed above levels obtained by stratification or gibberellic acid alone. This study assessed the germination of three seed lots of eastern gamagrass to 1 mM GA(3) and exposure to 4 degreesC for 0 to 7 wk. Seed soaked in GA(3) solution averaged 43% germination during the first 3 wk of stratification and was significantly higher than the germination of water soaked seed averaging 35% germination. Seed reached peak germinability after 4 wk of stratification and remained at this level during the final weeks. After 4 wk of stratification, germination levels of GA3 and water treated seed were similar at 64 to 70%. The most pronounced effect of GA(3) was more rapid germination of seed in all of the stratification durations tested.