2004 Volume 29 Issue 4 Pages 495-502
Astragalus adsurgens is a rare species in Hokkaido, Japan. However, there are many large populations of A. adsurgens in Oshima-oshima Island in Hokkaido, and this advanced to bare ground. This suggests that this species is a promising vegetation recovery material around their habitat area, though it is a rare species in Hokkaido. In this study, to conserve and use this as a material for revegetation, germination and initial growth were investigated. Seeds had physical dormancy and the germination rate was 10% or less in seeds without any treatment. The physical dormancy was not broken by freezing and thawing treatments, but by soaking with concentrated sulfuric acid for 20-90 min, near to 100% of germination was brought within six days after sowing. Observation by electron microscopy revealed that the concentrated sulfuric acid causes cracks or cavities in the seed coat. The seeds whose dormancy was broken showed a germination rate of 90% or more within ten days after sowing within a wide temperature range of 10-30°C. Germination of about 90% in the seeds released from dormancy was retained for at least 14 months of storage. Eighty-six percent of the seeds sown in May in the outdoors emerged 25 days after sowing, and six out of ten seedlings, which were transplanted at experimental field, flowered and set seeds in October of the subsequent year.