Germination Ecology of Danthonia Sericea Populations

Seed were collected from nine populations of Danthonia sericea on either wet or well‐drained, sandy sites ranging from Georgia to New Jersey. Germination tests were conducted in the laboratory and in field plots established on contrasting habitat types. Factors considered were temperature, light, prechilling, scarification, and after‐ripening. The majority of freshly harvested seed from all nine populations exhibited innate dormancy the intensity of which decreased with age. Dormancy was removed by scarification and prechilling treatments of 60 days. Seed from wet habitats showed significantly greater germination in light (alternating night‐day) than in dark, while seed from well‐drained habitats had a higher germination percentage in dark than in light. Both responses are considered to be physiological adaptations of the populations to their respective habitats. Alternating night‐day temperatures of 15–25 C produced the greatest overall germination for the nine populations; 15–20 and 10–25 C produced the next highest responses. Field observations confirmed that peak germination occurred in the spring, at the time soil temperatures were in the same range found to be optimum in the laboratory. A comparison of the germination responses obtained from six New Jersey populations in field plots on contrasting habitat types further revealed distinctive physiological adaptations for populations from differing habitats.