Seed Traits and Germination of Invasive Plant Solanum rostratum (Solanaceae) in the Arid Zone of Northern China Indicate Invasion Patterns

The ability of seeds to germinate under a wide range of environmental conditions is an important characteristic of invasive alien plant species. Solanum rostratum Dunal, has been widely distributed in the Northeast and Northwest of China and is causing huge damage to the local agricultural production. Studies on seed germination and response among populations to environmental stress may assist in revealing the adaptability of invasive plants and how they cope with climate change. In this study, we collected seeds from five invasive plant populations of S. rostratum, with intervals of over 3000 km between them, distributed in different habitats and climate zones. We measured the differences in seed traits between populations and studied the trends in germination responses of S. rostratum seeds under diverse abiotic stress conditions. The weight and size of S. rostratum seeds distributed in Northeast China were significantly greater than those distributed in Northwest China; for the response of S. rostratum seed germination to environmental factors, seeds from arid and extremely arid areas of Northwest China had greater tolerance to high temperatures and osmotic stress, while seeds from semi-arid areas of Northeast China were more sensitive to low temperatures and high salt stress. Overall, the germination of S. rostratum seeds responded differently to various environmental stress factors, reflecting the ability of S. rostratum to occupy germination sites under low resource competition. Given the rapid changes in the global climate, our findings provide new insights into the seed adaptation strategies of alien plants during the invasion process and the mechanisms involved.