Maternal temperature effects on seed dormancy mitigate the negative impact of global warming on germination and population fitness.

Abstract

A negative relationship is typically observed between maternal temperature and seed dormancy at dispersal. This could affect germination timing in current and future environments given the context of global warming. We conducted field and laboratory experiments to investigate the effects of maternal temperature on the dormancy level of Polygonum aviculare seeds. Data were used to simulate the germination timing and subsequent population reproductive performance under different thermal scenarios. Increasing maternal temperature reduced the dormancy level of seeds, altered the induction of secondary dormancy, and generally increased seedling emergence in the field. Simulations for current thermal scenarios demonstrated that the effect of maternal temperature on seed dormancy could lead to changes in germination timing from year to year. For future warming scenarios, our simulations indicated that rising maternal temperatures, along with those experienced by the seed bank, could decrease the proportion of seeds capable of germinating and delay germination timing, resulting in cascading negative effects on population reproductive fitness. However, changes in the germination timing and the reproductive fitness were more pronounced when the simulations excluded the effects of the maternal temperature on dormancy level, suggesting that this modulation could play a significant role in mitigating the consequences of global warming.