Seed germination traits and seed storage techniques for the threatened plant species Chikusichloa aquatica Koidz

Seed germination traits and seed storage techniques for the threatened plant species Chikusichloa aquatica Koidz. (Poaceae) were assessed to facilitate the planning of conservation strategies for this species. Germination tests based on a gradually increasing and decreasing temperature method indicated the following seed dormancy and germination characteristics: (1) a 2-3 week moist-chilling treatment was necessary to break dormancy; (2) higher temperatures induced secondary dormancy; and (3) the lower temperature limit for seed germination was approximately 20℃. These thermal-germination characteristics suggest that the seeds of this species are dispersed in autumn, their dormancy is broken during winter, and germination occurs the following spring. Tests performed using seeds stored under different moisture conditions indicated that a submerged-chilling treatment implemented for several months did not adversely affect the viability and germination of the seeds. The results of germination tests performed under different water-depth conditions showed that submerging the seeds a few centimeters under water did not restrict seed germination. These traits related to moisture and water-depth conditions are likely to be advantageous for establishment success in frequently inundated wetlands. Tests performed using seeds maintained under different storage conditions indicated that when a vacuum-packaging treatment was used, most seeds retained their viability for at least 3 years, suggesting that seed storage using vacuum packaging is helpful for the conservation of this species.