SEED DORMANCY DIFFERENCES AMONG COMMON RAGWEED (AMBROSIA ARTEMISIIFOLIA L.) POPULATIONS DISTRIBUTED IN DIFFERENT CLIMATIC REGIONS OF TURKEY

Common ragweed (Ambrosia artemisiifolia L.) is an allergenic invasive weed rapidly expanding its distribution range throughout Europe. Seed dormancy is among the most important seed adaptation traits, helping colonizing plants to avoid adverse environmental conditions. Furthermore, knowledge of seed dormancy enables to predict the seed germination timing of species and enforce specific management practices at suitable times. This study was aimed at determining the seed dormancy differences among different common ragweed populations distributed in two distinct regions of Turkey (i.e., eastern and western parts of the country). The seeds of all populations were extremely dormant (80.50-96.71% dormancy). The populations distributed in western part of the country were more dormant than eastern populations.Mechanical scarification and cold-wet stratification at 4°C for 2, 3 and 4 weeks were tested to infer their potential in releasing seed dormancy. Cold-wet stratification proved effective in releasing seed dormancy; however, populations differed in the stratification time required for seed dormancy release. Overall, eastern populations became non-dormant with lesser stratification time (i.e., 2 weeks), while western populations took longer stratification time to become completely non-dormant. Mechanical scarification with sandpaper also released seed dormancy and all populations behaved similar for this technique. This knowledge can be used to predict the germination timing of different populations distributed in two distinct regions of the country. Furthermore, the results can also be utilized in implementing effective management strategies at the proper time.