investigating the performance of prechilling, and chemical and mechanical scarification treatments on the breaking seed dormancy in velvetleaf (abutilon theophrasti)

seed dormancy is one of the major problems in the study of the effects of different factors on the weed seed germination characteristics because healthy seeds without dormancy, having high vigor and germinability are needed in these studies. this experiment was carried out to find simple, applicable, cheap, quick and efficient methods to breaking seed dormancy in velvetleaf which is one of the most important weeds in iran. two seed populations gathered from two locations in golestan province were used in this study. experiments were conducted in a completely randomized design as a factorial with four replications. each seed population was divided to three parts; the first part (control) was stored in room conditions. the second and the third parts were placed in prechilling conditions (in a cool (4οc) and wet place) for two weeks and three months, respectively. then, nine mechanical and chemical scarification treatments were applied on each of these 3 seed parts. treated seeds transported to petri dishes 15 cm in diameter. germinated seeds were counted daily to calculate germination percentage, rate and uniformity. in addition, time trends of water absorption in different treatments were investigated. combined analysis of variance results indicated that the population (location) has no significant effect, and prechilling and scarification treatments and their interactions have significant effects on germination components. according to results, the most effective treatments in non-prechilling and 2 weeks prechilling were soaking in boiling water for 5 and 10 seconds followed by soaking in sulfuric acid for 20 minutes, respectively. based on obtained results, in prechilling for 3 months none of the chemical and mechanical treatments have acceptable germination. germination percentages were 52, 50.5 and 53 percentages (in non-prechilled seeds) and 58, 63.25 and 63.5% (in 2 weeks prechilled seeds) in soaking in acid for 20 minutes, and soaking in boiling water for 5 and 10 seconds treatments, respectively. in the prechilling for 3 months, germination percentages of these treatments decreased to 12, 19.25 and 19.2%.