Comparative study of seed germinations and phenology of population of the invasive weed Solanum rostratum Dunal in Israel

Phenotypic variation in germination and phenological traits can enhance the invasive potential of alien weeds by promoting establishment across heterogeneous environments. Solanum rostratum Dunal (buffalobur), a prickly annual species native to Mexico, has become invasive in several regions worldwide, yet little is known about the mechanisms underlying its spread in the Mediterranean Basin. We evaluated variation among seven Israeli populations in seed morphology, germination under different temperature regimes, emergence from burial depths, and subsequent plant growth and flowering phenology. Seed traits varied significantly among populations, with heavier seeds (e.g. SL, MM) or lighter seeds (KL, KM), reflecting trade-offs between establishment potential and dispersal. Germination was generally highest at 32/38°C, but populations differed in optimal conditions; KSH and SL reached 100% germination at 22/28°C, whereas others required higher temperatures. Emergence declined with burial depth, yet the KL population maintained up to 30% emergence from 15 cm, suggesting local adaptation to soil disturbance. Phenological comparisons revealed modest variation in flowering onset, but pronounced differences in flowering duration (4.35–7.81 days), with extended flowering windows potentially enhancing pollination opportunities in this buzz-pollinated species. Collectively, these results highlight substantial intra-specific variation in key life-history traits of S. rostratum. Such variation likely facilitates persistence across diverse Israeli habitats and contributes to invasion success by combining broad environmental tolerance with population-specific adaptive strategies. Our findings emphasize the need for regionally tailored weed management approaches and advance understanding of how phenotypic differentiation supports weed invasions.