| Fritillaria tortifolia X.Z.Duan et X.J.Zheng is a perennial herb of Fritillaria of Liliaceae,which is an important medicinal plant with fresh and elegant fragrance and peculiar flower shape.The study uses Fritillaria tortifolia seeds as test materials,Because the embryo is immature and the development cycle is long,the morphological post-ripening of the embryo needs 60 days at 5-10℃,and the physiological post-ripening needs 100 days at 0-5℃,so the time is long.Systematically studies the basic characteristics of Fritillaria tortifolia seeds,causes of dormancy,methods of releasing dormancy,and analysis physiological and biochemical changes of the seeds during the process of releasing dormancy in morphological post-ripening and physiological post-ripening periods,find out the inhibitory or promoting factors in the dormant germination stage,and analyze the inhibitory-promoting changes of each factor.The research results are as follows:The seed of Fritillaria tortifolia belongs to morphological and physiological dormancy type.The development of seed embryo is not complete.The point embryo needs to develop into linear embryo to complete morphological after-ripening;Under the control condition,the morphological dormancy of Fritillaria tortifolia seeds was completed in 80 days,and the morphological dormancy could be released 20 days earlier when the seeds were treated with exogenous GA3 50 mg · L-1,and the physiological dormancy period of seeds was 40 days.The soluble sugar content increased,starch content decreased,crude fat content and soluble protein content increased at first and then decreased,and were degraded and consumed in large quantities.The content of amino acid increased at first and then decreased.In conclusion,the contents of starch,crude fat,soluble protein and amino acid all have vary ing degrees of decline at morphological after-ripening stage,and they were continuously decomposed and transformed into small molecular substances for embryos to provide energy.The relative water content and free water content increased,and the bound water content decreased.The seeds were saturated with water,and the metabolism was more vigorous.The normal growth and development of seeds were guaranteed by water.The activities of SOD,POD and CAT increased;The trend was different,SOD activity was the first to play a role,CAT activity reached the maximum on the 40th day,POD activity increased sharply on the 60th day.The content of GA3 increased gradually,the content of ABA decreased slowly,the content of IAA increased at first and then decreased.In the physiological ripening stage:soluble sugar content continued to increase,starch continued to degrade,but the degree of reduction was about 2 times lower than that in the morphological ripening stage.The content of crude fat and soluble protein increased at first and then decreased,and were degraded and consumed in large quantities.Amino acid content continued to rise.The change of nutrients is more obvious,the internal metabolism is strong,the release of physiological dormancy is accelerated,and the seed germination is promoted.Relative water content and free water content continued to increase,while bound water content increased first and then decreased.The activity of SOD increased continuously,the activity of POD decreased gradually,and the activity of CAT decreased first and then increased.The activity of SOD in the treatment of GA3 50 mg · L-1 was always higher than that in the treatment of CK.With the completion of morphological ripening of seeds,in the physiological ripening stage,the three enzymes cooperate with each other to further eliminate reactive oxygen species and toxic substances in the body,jointly protect the normal development of seeds and promote seed germination.The content of GA3 decreased at first and then increased,the content of ABA decreased continuously,and the content of IAA decreased slowly.The content of GA3 and IAA in the treatment of 50 mg·L-1 GA3 was always higher than that in the treatment of CK,which indicated that the content of GA3 and IAA increased with the extension of low temperature culture time,and the inhibition of ABA was reduced,thus accelerating the release of seed dormancy and promoting seed germination. |
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