Maternal sex influences seed dormancy in a gynodioecious species

Maternal genotype and environment can influence seed characteristics, yet sex-specific maternal effects in gynodioecious systems remain poorly understood. We evaluated how maternal sex affects seed viability, mass, and dormancy in the gynodioecious plant, Sidalcea campestris. We compared seed viability and mass to determine whether differences in seed quality contribute to germination variability and female advantage. Seeds were scarified by manually nicking the seed coat with a razor blade and cold stratified at 5°C. Germination of seeds with and without scarification across 0, 6, and 12 weeks of cold stratification was evaluated in order to test how maternal sex affects dormancy. Seed viability and mass did not differ between sexes, suggesting that these traits do not contribute to female advantage in this system. Scarification and cold stratification increased germination, indicating germination may be influenced by physical and physiological dormancy. However, the effect of dormancy-breaking treatments on germination depended on maternal plant sex, with seeds from hermaphrodites being more easily released from dormancy than seeds from females. Seeds from hermaphrodites germinated significantly more than seeds from females when scarified, with probabilities 119% higher at 0 weeks and 18% higher at 12 weeks of stratification. Such differences may have consequences on the timing of germination and survival of seeds produced by females and hermaphrodites, with effects that may vary across time and space. Further work is needed to understand how sex-specific maternal influence on dormancy shape the ecology and evolution of gynodioecy.