# Seed Wings Optimize the Regulation of Temperature and Light on Smith Fir Seed Germination Timing

## TL;DR

Seed wings in Smith fir inhibit germination through chemical signals, delaying it until favorable spring conditions, which is an adaptive strategy in subalpine ecosystems.

## Contribution

This study reveals that seed wings in gymnosperms chemically inhibit germination, optimizing timing in response to seasonal cues.

## Key findings

- De-winged seeds had significantly higher germination rates than intact or mixed seeds.
- Optimal germination occurred at 15/2 °C–25/5 °C, with light enhancing germination under cold conditions.
- Seed wings impose chemical inhibition, delaying germination until favorable spring conditions.

## Abstract

Seed wings are widely recognized for facilitating dispersal and influencing germination in angiosperms, but their functional role in gymnosperm germination is poorly understood. To assess the effect of seed wings on the germination ecology of Smith fir (Abies georgei var. smithii), we evaluated the germination of three seed treatments—intact seeds, mixed seeds (de-winged seeds mixed with detached wings), and de-winged seeds—under varying light and temperature conditions. Results showed that de-winged seeds achieved a final germination percentage of 48.5 ± 5.0%, which was significantly higher than that of intact seeds (26.0 ± 2.4%) and mixed seeds (32.5 ± 3.5%) (p < 0.001), confirming that seed wings significantly inhibit germination. There was no significant difference between intact and mixed seeds, and both were significantly lower than de-winged seeds (p < 0.001), suggesting that germination inhibition is likely mediated by chemical inhibitors in the wings rather than mechanical restriction. Optimal germination occurred at 15/2 °C–25/5 °C, while light significantly enhanced germination under cold conditions (5/1 °C), indicating conditional dormancy. These findings suggest that seed wings optimize the regulation of germination timing by imposing chemical inhibition that, combined with conditional dormancy, delays germination until favorable spring conditions, reflecting an adaptive strategy to seasonal environmental cues in subalpine ecosystems.