<p><em>Magnolia pugana</em> es una especie endémica y en peligro de extinción localizada en el occidente de México, que se distribuye en bosques de galería en las barrancas del sur de Zacatecas y centro-norte de Jalisco. El objetivo de este trabajo fue conocer la viabilidad de las semillas e identificar los tratamientos para romper la latencia de semillas de esta especie. Se colectaron semillas de cuatro localidades, tres en Jalisco (Centro Universitario de Ciencias Biológicas y Agropecuarias, San Lorenzo y San Nicolás) y una en Zacatecas (Palo Verde). Se aplicaron los siguientes tratamientos germinativos: (1) remoción manual del arilo, (2) remoción de arilo por lixiviación, (3) inmersión en ácido giberélico con 100 mg L^-1, (4) inmersión en ácido giberélico con 200 mg L^-1, (5) inmersión en ácido giberélico con 300 mg L^-1y (6) control. Se utilizaron 100 semillas por tratamiento con cinco repeticiones cada una. El tratamiento que presentó el mayor porcentaje de germinación para las cuatro localidades fue la remoción manual del arilo con 52 %, mientras que el tratamiento con menor germinación fue el control con 3.5 %. Por localidad, San Lorenzo obtuvo el mayor porcentaje de germinación con 16.5% en promedio, mientras que San Nicolás registró el menor con 5.33 %. Los tratamientos germinativos no lograron romper la latencia (porcentajes de germinación &lt; 70 %). Las semillas de las cuatro localidades se embebieron de agua por lo que no se presenta la latencia física. Las semillas con mayor biomasa absorbieron menos agua.</p>

Numerous Neotropical Magnolia species are endangered and red-listed by the IUCN. Here we highlight major results from over a decade of research on endangered magnolias in western Mexico. Particularly, we compare three species of Magnolia (M. pugana, M. pacifica and M. vallartensis) along a large-scale continentality and moisture gradients, in terms of a) their morphological adaptations, b) genetic structure, diversity, and differentiation, c) reproductive phenology, and d) floral scents and their floral visitors. Fieldwork along this gradient unveiled two new species of Magnolia sect. Magnolia; M. granbarrancae and M. talpana. We found that most continental populations have a higher extinction risk than those with greater maritime influence, due to their lower genetic diversity, and greater fragmentation, isolation, and water stress. Also, these populations are more vulnerable to the environmental conditions predicted with the global warming climate scenarios. We share fieldwork experience and advise on pre-germination treatments and seed dormancy. We propose an ex-situ and in-situ conservation strategy, identify new challenges, and suggest future directions of collaborative work as a global Magnolia conservation consortium.

Background: Populus luziarum and P. primaveralepensis are endemic species of western Mexico; growing in riparian forests they are critically endangered. The best way to conserve their seeds is unknown, which could be limiting for their conservation. Hypothesis: The germinability of both subtropical species is like that of boreal and template Salicaceae species that disperse seeds in spring and early summer, as they germinate quickly with high percentages, and rapidly lose their viability when stored at ambient temperature. Studied species: Populus luziarum and P. primaveralepensis. Study site and dates: Western Trans-Mexican Volcanic Belt. Jalisco, Mexico. October 2019. Methods: The physical integrity of the seeds was assessed by X-ray imaging and compared with germinability. In addition, the effect of storage time (nine weeks) under two temperatures (4 and 21 °C) on the percentage and mean germination rate was evaluated. Results: No significant differences were found between physical integrity and germination in freshly collected seeds for both species. Germination in the first 24 hrs was 91 and 95 % for Populus luziarum and P. primaveralepensis, respectively (week 0). Germination percentages were lower when stored at 21 °C, but P. primaveralepensis was decreased more slowly. Conclusions:  Seeds of subtropical Populus respond similarly to those of species from temperate and boreal climates with early seed dispersal, a crucial condition for establishing ex situ reforestation and conservation programs.

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