Maternal and Cold-Stratification Warming Outweigh Germination-phase Warming in Regulating Seed Germination of Alpine Plants.

BACKGROUND AND AIMS: Global warming impacts on key plant life-history stages represent a central focus in ecology. Seed germination, the critical starting point in the plant life cycle, lacks a systematic understanding of its response mechanisms to climate warming. METHODS: Here, we examined how warming at the maternal, cold stratification, and germination stages affects seed germination in ten alpine plant species. KEY RESULTS: Cold stratification (absence vs. presence) is decisive in regulating seed dormancy, but its effect is modulated by temperatures experienced during both the maternal and germination stages. Importantly, "historical" warming during the maternal and cold stratification stages had a stronger influence on seed germination than "current" warming. We further found complex interactions among temperature signals across stages, in that thermal experience at one stage can alter how germination responds to temperature at other stages. These interactions also were species-specific. CONCLUSIONS: This study reveals integrated effects of multi-stage temperature memory in seed germination, highlighting the essential role of past environmental experiences in mediating plant responses to climate warming. Our findings offer a new theoretical basis for predicting future changes in plant population dynamics and community composition.