Study On Seed Dormancy Mechanism And Elimination Methods Of Agropyron Mongolicum Keng

Agropyron mongolicum Keng is also known as Mongolian Wheatgrass.It is one of the main vegetation of desert steppe and typical steppe in sandy land with excellent characteristics of drought resistance,cold resistance,disease resistance,salt and alkali resistance.However,the seeds of A.mongolicum had wild characteristics such as low germination rate and long germination duration,which affected the artificial seed reproduction,production and utilization of A.mongolicum to a certain extent.This study explored the dormancy mechanism of A.mongolicum seeds and found a way to increase the germination rate of A.mongolicum seeds,laying a foundation for the rational development and utilization of the germplasm resources of A.mongolicum.By measuring the water absorption of the A.mongolicum seeds,the germination inhibitory part of the A.mongolicum seeds,and the biological activity of the shells extracts of the A.mongolicum seeds,and using gas chromatography-mass spectrometry(GC-MS)to determine the types of organic compounds At the same time,liquid chromatography tandem mass spectrometry(LC-MS/MS)was used to determine the endogenous hormone content of different levels of dormancy of A.mongolicum.The physical and chemical methods of breaking the dormancy of A.mongolicum seeds are carried out,and methods to improve the germination rate of A.mongolicum seeds are found by measuring the germination potential,germination rate,radicle and embryo of the A.mongolicum seeds.The main results are as follows:(1)The organic solvent extract of A.mongolicum shells can significantly inhibit the germination rate,radicle and embryo growth of cabbage seeds,and A.mongolicum shells are the main reason for inhibiting seed dormancy.The GC-MS detection of the substances on the shells of the grasses showed that there are alkanes,alcohols,esters,ketones,benzenes,amides,acetals,acids and phenols in the husks of the grasses.There are 9 types of 32 kinds of organic compounds,including alcohols,ketones and alkanes,and most of them are water-soluble substances.The content of phytohormones in two different dormancy levels of A.mongolicum seeds were detected by liquid chromatography-tandem mass spectrometry(LC-MS/MS).The results showed that the cytokinins in the seeds of A.mongolicum with low germination rate the content of 43 kinds of hormones in six categories,including ABA,abscisic acid,gibberellin,jasmonic acid,auxin and salicylic acid,were significantly higher than those of A.mongolicum seeds with high germination rate.(2)The physical and chemical treatments of A.mongolicum seeds showed that the water soaking treatments,KNO3,and NaCl soaking treatments could not increase the germination rate of A.mongolicum seeds,but would inhibit the growth of A.mongolicum seeds.Among them,the effect of water flushing treatments on the seeds is better,and it can be verified again that most of the inhibitory substances are water-soluble.The results of running water flushing on the seeds of A.mongolicum for 36 hours are the best,which can significantly improve the germination potential of the seeds,germination rate.Its germination potential and germination rate were 53.20%and 58.40%respectively,which were increased by 291.18%and 78.05%respectively compared with the control group.To sum up,the shell is the main reason for inhibiting the germination of A.mongolicum seeds.There are 9 types of alkanes,alcohols,esters,ketones,benzene,amides,acetals,acids and phenols and other 32 organic compounds on the shell,most of which are water-soluble.The effect of water flushing for 36 hours on A.mongolicum seeds is the best,which can significantly increase the germination rate of A.mongolicum seeds.