Study On Seed Dormancy Mechanism And Dormancy Breaking Methods Of Datura Stramonium L.

Datura stramonium L. is a annual plant of Solanaceae. Its flowers, leaves and seeds can be used for herbal medicine with the function of smooth wheezing, cough, spasmolysis, analgesic and anesthesia and so on. Its main active substances are scopolamine, scopolamine and atropine, they are used for various diseases treatment in clinic. In addition, it has agricultural biological activities such as kill the rats, insecticidal, sterilizing, weeding and so on. So that it has broad development utilization foreground in the plant protection field. Datural stramonium L. breeds by its seeds but there is significant dormancy in its seeds. The research of dormancy mechanism and dormancy breaking methods of Datura stramonium L. seeds has not been reported both at home and abroad. Present study investigated it for the first time in order to provide scientific basis for resource protection and artificial planting for Datura stramonium L.Present study investigated the seed dormancy mechanism of Datura stramonium L. by seed viability test, seed germination test, imbibition test, enzyme activity determination, embryos morphology observation and germination inhibitor assay. Physical and chemical treatments were carried out to find the best dormancy breaking method of Datura stramonium L. seeds. The results showed that:The new harvest seeds of Datura stramonium L. have significant dormancy and their dormancy belongs to comprehensive dormancy. The reason of seed dormancy incluses seed coat barrier (poor permeability of water and oxygen, seed coat mechanical constraint), shortage of hormone rated to germination such as GA and germination inhibitors existing in both seed kernel and seed coat (the water-soluble inhibitory activity of seed kernal is stronger than seed coat, but the fat-soluble inhibitory activity of seed kernal is weaker than seed coat). The seed coat barrier is the primary limit factor of germination for Datura stramonium L. seeds.The seed kernel dormancy of Datura stramonium L. can be relieved after storing at room temperature for 6 months or low temperature (4℃) and variable temperature (4℃/25℃) stratification for 1 month. Mechanical friction, NaOH and concentrated H2SO4 treatments were used to overcome seed coat barrier and improve the germination rate of Datura stramonium L. seeds. All of them can reach the goal, but the best method was treating with 10% NaOH for 90 minutes, germination rate was increased to 82.5%. 50mg/L-300mg/L gibberellin, 0.001mg/L-1mg/L brassinolide, laxonin or laxogenin, all of them can promote germination of Datura stramonium L. seeds. Treating with 10% NaOH for 90 minutes and then soaking with 300 mg/L GA3 for 24 hours was the best method to break the seed dormancy of Datura stramonium L.Germination potential and germination rate of Datura stramonium L. seeds and seed kernels both reached the highest in full-ripe stage (S3), and yellow-ripe stage (S2) was slightly lower. Thus we suggest that the best harvest time of Datura stramonium L. seeds is from yellow-ripe stage (S2) to full-ripe stage (S3).