Experimental seed germination for ex situ conservation of Mexican Podostemaceae

Abstract

Background: Podostemaceae are extremely susceptible to local extinction by habitat loss. Since ∼70 % of the river systems in Mexico show some degree of water contamination, it is relevant to generate information about seed storage and germination behavior to design germplasm conservation strategies (e.g., ex situ seed banks) of Mexican podostemads. Hypotheses: Seed germination decreases as seed storage time increases. Further, light quality, temperature and collection site influence similarly the germination response of both species. Studied species: Marathrum foeniculaceum Humb. & Bonpl., Noveloa coulteriana (Tul.) C. Philbrick Study site and years of study: 13 different seeds collections (1996-2013), at four locations in the rivers Horcones and Arroyo del Rincon Jalisco, México. Methods: A germination chamber experiment was performed to evaluate the effect of temperature, light quality and storage time on the germination of both species. Results: Seeds lose viability after nine years of storage. In both species, the time to reach the highest Accumulated Germination Percentage (AGP) was faster in seeds of one-two yr compared to seeds of six-seven yr. N. coulteriana have significant differences in Final Germination Percentage (FGP) between collection rivers. Storage time affects AGP of N. coulteriana more than in M. foeniculaceum. Conclusions: Both species can form ex situ seed banks up to 8 yr age in paper bags storage. N. coulteriana is more susceptible to variation in storage conditions compared to M. foeniculaceum. Collection site affect seed germination after storing. Long-term conventional ex situ seed germination storage is not a viable strategy to conserve germplasm of Podostemaceae.