Morphological And Physiological Study On Germination And Emergence Of Polygonatum Cyrtonema Hua.seed And Seed Stem

Polygonatum cyrtonema Hua.is a medicinal plant in the liliaceae family.In Polygonatum cyrtonema Hua.of seeds and stems as the experimental material,since the seed harvesting to the early stage of the emergence and harvest stem to bud emergence,head of seeds and stems of morphology,nutrient content,and associated with the emergence of enzymes and hormones for dynamic monitoring,in order to explore Polygonatum cyrtonema Hua.seed and stem morp hological and physiological changes during the process of emergence.The main research results are as follows:1.The germination and emergence process of Polygonatum cyrtonema Hua.seeds can be divided into postmature dormant stage,germination stage,corm formation stage,germ formation stage,primary rhizome formation stage and seedling emergence stage.The newly harvested Polygonatum cyrtonema Hua.seeds had morphological and physiological characteristics of dormancy,and their embryos did not differentiate into cotyledon,germ and radicle.The germination and emergence of Polygonatum cyrtonema Hua.seeds was accompanied by the degradation of endosperm.The germination and emergence process of the stem of Polygonatum cyrtonema Hua.can be divided into overwintering dormant period,growing period and seedling emergence period.2.In the germination and emergence process of the seeds,ABA content of the seeds decreased from 8.69ng/g to 0.46ng/g.At this time,the content of GA3 increased rapidly and the inhibition of ABA was weak.GA₃induced seed germination.The content of IAA reached the maximum value of 191.87ng/g at4?for 3 months.At this time,IAA and ABA jointly maintained dormancy of seeds.Then,the content decreased rapidly.In the process of seed storage at4?,the content of TZR generally increased,contrary to the overall decreasing trend of ABA,indicating that TZR and ABA may have antagonistic effects.The ratio of GA₃/ABA to TZR/ABA reached its peak at seed germination,which was 10.54,6.59,respectively.The ratio of GA₃/ABA to TZR/ABA was one of the key factors to regulate dormancy release and germination of Polygonatum cyrtonema Hua.seeds.In the process of germination and emergence,the contents of TZR in the conversion section,extension section and sprouting section reached the maximum value at the beginning of the growth of the seed stem,which were 3.23ng/g,3.08ng/g and 6.78ng/g,respectively.At the end of overwintering dormancy,the content of IAA in the transition section and bud head reached the maximum value of 181.63ng/g and 139.21ng/g,respectively.At this time,IAA maintained dormancy in the transition section and bud head.At the time of seedling emergence,the junction between the extension section and the aboveground section expanded to form a new transformation section,and the content of IAA in the extension section increased.At this time,IAA promoted the formation of new rhizome.The contents of GA₃in the transition section,extension section and buds reached the maximum value at the end of dormancy,which were 23.71ng/g,5.43ng/g and 81.56ng/g respectively,indicating that GA₃could break dormancy of rhizome of Polygonatum cyrtonema Hua.and induce rhizome growth.At the time of seedling emergence,the content of GA3 decreased to the minimum,and the inhibition of GA₃on the formation of new rhizome decreased significantly.The ABA content in the transition stage at 1 month after planting was significantly higher than that before planting,indicating that ABA could promote the healing of the transition stage.As the ABA content in buds continued to decrease,the inhibition of ABA on bud growth also continued to decrease.ABA content in the transition and extension segments was significantly higher than that in other stages?17.20ng/g and 26.43ng/g,respectively?,and ABA promoted the formation of new roots.Conversion period,stretch and buds of GA₃/ABA values in the late winter dormancy are maximum,4.02,0.83 and 0.81,respecti vely,conversion and stretching of GA₃/ABA to minimize when emergence,are0.07,shows that the high ratio of GA₃/ABA is regulating the Polygonatum cyrtonema Hua.stem dormancy breaking one of the key factors,low GA₃/ABA ratio is one of the key reasons for the formation of new roots.3.During the germination and emergence of Polygonatum cyrtonema Hua.seeds,the activity of beta-amylase was activated at 3.70U/g?FW?,and the starch was decomposed into soluble sugar to provide raw materials for the respiration of seeds.With the increase of the storage time at 4?,the activity of beta-amylase increased from 0.32U/g?FW?to 0.70U/g?FW?.The activity of CAT,POD and SOD increased continuously in the process of seed storage at 4?,decreased after seed germination,and increased again before seed emergence,indicating that CAT,POD and SOD played a certain role in the removal of reactive oxygen species and H₂0₂during seed germination and emergence,creating a good condition for seed germination and emergence.After seeds were deposited at4?,the activity of malate dehydrogenase?MDH?decreased,and the activity of glucose-6-phosphate dehydrogenase?g-6-pdh?increased after seeds were deposited at 4?for 3 months,indicating that the respiration and metabolic pathway of seeds changed from TCA to PPP pathway and dormancy was relieved.During the winter dormant period,the activities of CAT,POD and SOD in the transition and extension stages increased,and decreased after the beginning of the growth period,indicating that POD and SOD maintained high activity to remove the accumulated peroxides during the dormancy of the rhizome of Polygonatum cyrtonema Hua.to create good conditions for the seedling emergence of the seed stem.4.In the seedling emergence process of Polygonatum cyrtonema Hua.seeds,the stored starch is hydrolyzed into soluble sugar and soluble protein,which are used by the seeds to provide carbon source and energy for the growth and development of the seeds.When the primary rhizome of Polygonatum cyrtonema Hua.seeds is formed,the unused soluble sugar is stored in the primary rhizome.Nutrient flow during seed emergence provides material support for seedling formation.During the dormancy stage,the starch content in the transition stage,extension stage and buds of the seed stem increased significantly,and the soluble substance was transformed into insoluble starch to ensure the smooth dormancy stage of the seed stem.After the beginning of the growth of the seed stem,the starch content in the extension section and the transformation section decreased significantly,which was decomposed into soluble substances,and provided energy and carbon source for the growth of the seed stem.After seedling emergence,the soluble sugar content in the extension and transformation sections showed a decreasing trend,while the soluble sugar in the buds showed an increasing trend.At this time,the soluble sugar in the transition and extension sections flowed to the buds,which provided material guarantee for the formation of seedlings.