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 the temperature experienced by the seeds during their development and maturation on the mother plant (maternal temperature) and seed dormancy at dispersal, and this could affect the timing of germination 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, and the results were used to simulate the timing of germination 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, the 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.