Seed Dormancy Breaking and Germination Ecology of Bromus sterilis Under Different Temperature and Light Regimes

Abstract

Seed dormancy breaking and germination ecology of Bromus sterilis were investigated under varying temperature and light regimes to understand its adaptive germination strategies and persistence in agroecosystems. Freshly collected seeds were subjected to different pre-germination treatments and incubated under controlled laboratory conditions with combinations of constant and alternating temperatures under light and dark environments. Results indicated that B. sterilis seeds exhibited physiological dormancy that was partially alleviated by exposure to alternating temperature regimes, with significantly higher germination percentages observed under fluctuating day–night thermal conditions compared to constant temperatures. Light exposure enhanced germination response, indicating positive photoblastic behavior and a preference for surface or near-surface seed positioning. Cold stratification further improved germination rates, suggesting the role of low-temperature exposure in dormancy release mechanisms. Germination was strongly inhibited under complete darkness and extreme temperature conditions, highlighting narrow ecological constraints for successful seedling establishment. Interaction effects between temperature and light were significant, with optimal germination recorded under moderate alternating temperatures combined with light exposure. These findings indicate that B. sterilis employs a dormancy strategy closely aligned with seasonal environmental cues, enabling synchronization of germination with favorable field conditions. The species demonstrates strong ecological adaptation to disturbed agricultural systems, where soil disturbance and open canopy conditions enhance light penetration and temperature fluctuation. Understanding its germination ecology provides insights into its persistence and invasiveness in cereal-based cropping systems.