Seed germination characteristics of Xanthium spinosum populations from different climatic regions of Türkiye: Implications for weed management

Xanthium spinosum is a troublesome invasive weed widely distributed through many agroecological zones in Türkiye, adversely affecting crop production and local biodiversity. Understanding its seed germination biology is essential for formulating efficient, region-specific management measurements. This study assessed the influence of photoperiod, temperature, pH, salinity, osmotic potential, and seed burial depth on the germination characteristics of X. spinosum populations collected from four geographical regions (Southeastern Anatolia, Mediterranean, Black Sea, and Central Anatolia) in Türkiye. Peak germination was observed under a 12-hour light/dark photoperiod, with Southeastern Anatolia and the Mediterranean populations exhibiting higher responsiveness to light. The highest germination occurred at ~30 °C for Southeastern Anatolia and Mediterranean populations, whereas Black Sea and Central Anatolia populations preferred relatively lower temperatures (25–27 °C) for peak germination. Similarly, neutral pH (~7.0–7.6) resulted in the highest germination of all populations, whereas Southeastern Anatolia had better pH tolerance. Salinity and osmotic stress tests revealed significant demographic differences, with the Southeastern Anatolia population exhibiting higher tolerance to salinity and drought stresses. Seedling emergence peaked at lower burial depths (~2–4 cm) and had a sharp decline at increased depths. These results highlight significant population-specific adaptation patterns associated with local climatic and edaphic conditions. Deep tillage and management strategies based on environmental tolerance determined in the current study may restrict the further spread of X. spinosum.