Influence of local adaptations, transgenerational effects and changes in offspring's saline environment on Baccharis halimifolia L. under different salinity and light levels

Abstract Evolutionary and transgenerational processes affect offspring trait expression. We examined the influence of local adaptations, maternal environment, maternal traits, and changes in seedling environment on progeny performance of Baccharis halimifolia under different salinity and light levels. Over 34,500 seeds from 72 mother plants from 6 native, expansive, and introduced populations were sown and grown in a common garden. We monitored seed germination and seedling emergence, survival and early growth. Our results show that native saline populations had higher germination under high salinity than inland expansive populations, whereas the latter performed better in non-saline conditions. For populations within saline wetlands, offspring from maternal plants growing in saline sites generally had higher and faster germination and slower growth than seeds from subsaline areas, regardless of level of germination salinity. Progeny from high maternal light conditions performed better in the light treatment and the opposite was found in shade conditions. Maternal traits had a stronger effect on seed germination and seedling early growth when the offspring were subjected to saline environments; however, under non-saline conditions, maternal traits had greater influence on seedling survival. Generally, offspring from larger plants had increased germination and survival rates, whereas those from shrubs with larger inflorescences and/or higher flower number exhibited greater seedling survival. Lastly, seedlings constantly exposed to salinity had higher survival and growth than those transferred to saline environments 2–3 weeks after emergence. Our results suggest that local adaptations, transgenerational effects, and changes in seedling environment have profound impacts on progeny performance.