Effects of alternate temperatures on seed germination of high Andean species from central Chile

Abstract

High-Andean ecosystems are among the most climatically extreme environments on Earth, characterized by low temperatures, short growing seasons, and frequent frost events. Seed germination, a critical life stage for plant recruitment, is particularly sensitive to temperature, making it a key process to understand under current climate change scenarios. Despite its importance, little is known about the thermal requirements for germination in high-Andean species from the Chilean Andes, where warming trends and reduced snow cover may profoundly alter recruitment dynamics. This study evaluated the effect of temperature on seed germination in 12 high-Andean species from the central Chilean Andes. Seeds collected were between 3200-3600 m a.s.l. and then cold-stratified for three months. Then seeds were exposed to four day/night temperature regimes (15/10°C, 20/10°C, 25/10°C, 30/10°C). Final germination percentage (%FG), germination speed (VG), and residual viability were assessed. Eight species germinated under experimental conditions, with responses varying among taxa. Erigeron andicola showed high %FG (~84%) across all treatments, indicating broad thermal tolerance. Montiopsis potentilloides displayed an optimum at 25/10°C (78%), while Chaetanthera linearis and Taraxacum officinale exhibited strong declines in germination and viability at 30/10°C, suggesting heat sensitivity. Cerastium arvense and Thlaspi magellanicum maintained low germination (<10%) regardless of temperature, with high residual viability (>80%), indicating persistent dormancy rather than loss of viability. Results highlight temperature as a key, but species-specific, driver of germination. Warming may benefit species with higher optima but hinder recruitment in heat-sensitive taxa. These findings provide a foundation for predicting species-specific vulnerabilities and for developing conservation strategies, that consider thermal requirements and projected climate shifts in high-Andean ecosystems.