Abstract
Background: Magnolia pugana populations are declining, in addition, it is estimated that precipitation will decrease by up to 10 % and temperatures will increase (2-4 °C) under the most severe climate change scenario, which may affect germination.
Hypotheses: The interaction of increased temperature and decreased water potential reduces and delays the germination of Magnolia pugana seeds.
Studied species: Magnolia pugana, an endangered species endemic to western Mexico.
Study site and dates: Southern Zacatecas and central Jalisco, Mexico. April 2019.
Materials and methods: Seed viability was evaluated with tetrazolium test. In addition, the effects of temperature (24, 28, and 37 °C), water potential with PEG 8000 (0, -0.3, -0.6, -0.9, -1.2 MPa) and its interaction on the percentage and mean germination time were analyzed with factorial ANOVA tests.
Results: Viability was 80 %. The interactions between temperature and water potential on germination percentage and mean germination time were significant. There was no germination at 37 °C. The highest germination (78 %) was at 24 °C and -0.3 MPa, while the lowest (3 %) was at 28 °C and -0.6 MPa. The control treatment (24 °C and 0 MPa) facilitated germination in a shorter time (23.9 ± 1.5 days). At 28 °C and -0.9 MPa, the mean germination time was slowed by 1.5 times.
Conclusions: Magnolia pugana germinability was reduced by the interaction between low water potentials and increased temperature, conditions predicted by future climate change scenarios, therefore its vulnerability to extinction couldincrease.
Publisher
Botanical Sciences, Sociedad Botanica de Mexico, AC
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