Dr León A. Bravo
Laboratory of Plant Physiology and Molecular Biology
Department Agronomical Sciences and Natural Resources
Universidad de La Frontera, Temuco Chile.
‘Unraveling the impact of regional warming on Antarctic vascular plants: Learning from an in situ warming experiment.’
Antarctic vascular plants are freezing tolerant, with LT50 of -22.8°C for D. antarctica (Da) and -15.3°C for C. quitensis (Cq). The accelerated warming (3.5°C in the last century) and heat waves experienced by Maritime Antarctica, especially during summer, could cause plant cold de-acclimation making them vulnerable to stochastic frosts during the growing season. This work describes the effect of experimental in situ and laboratory warming on freezing resistance in Da and Cq. The results of in situ warming experiments using open top chambers (OTC) installed near Arctowski Station showed that after two seasons of OTC exposure, LT50 increased slightly, 2°C in Cq, at two studied sites and 2.8°C at one of the 3 studied sites for Da. A contrasting situation was observed after four growing seasons in OTCs, while Cq showed a 2°C lower LT50 in plants grown in the OTC than untreated plants, Da showed no significant differences between treatments. Therefore, this suggest that warming 3 to 4°C above average temperature would not make these plants significantly more vulnerable to freezing. This was consistent with similar antifreeze activity observed in leaf apoplastic extracts of Da grown in OTC and in open areas. These results could be associated with the fact that OTC being a passive heating system does not exert night warming. Laboratory studies in which these two species were subjected to simulated day and night warming confirm this hypothesis. Preliminary results from nocturnal in situ warming systems are presented and discussed.
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