| Ginkgo,also known as Ginkgo tree,is a relict plant after Quaternary glacial movement and has many application values.The fruit of Ginkgo is called seed,Its growth and development are not only regulated by genetic gene expression,but also affected by many factors,such as origin,tree age,photosynthesis,hormones and so on.In this study,the female trees bearing Ginkgo biloba in Dong'an ginkgo demonstration base in Hunan Province were taken as the research objects.By studying the growth and development of Ginkgo biloba under different conditions,the photosynthetic characteristics,photosynthetic pigment content and the yield and quality of the seeds of natural open-hearted and trunk-stratified ginkgo female trees were determined,and the content of endogenous hormones and secondary metabolites in Ginkgo biloba seeds and the expression of genes related to ethylene and flavonoid metabolism were also measured after exogenous hormones ethephon and abscisic acid,and explored the efficient and effective hormone harvesting technology of Ginkgo seeds.The main results are as follows:(1)By measuring the changes in photosynthetic characteristics and photosynthetic pigment content of Ginkgo biloba under different conditions,it was found that the natural photosynthesis parameters and photosynthetic pigments of Ginkgo biloba and trunk stratified ginkgo have the same trend,and the content of natural open heart photosynthesis and photosynthetic pigments are higher than the main stem Layer shape.The diurnal and seasonal changes of net photosynthetic rate and transpiration rate are bimodal curves,and the diurnal changes are obviously different around 10:00 and 16:00,and the seasonal changes are obviously different in the middle of June.The diurnal variation of stomatal conductance is bimodal curve,the seasonal variation is unimodal curve,and the diurnal variation is obviously different at about 10:00 and 16:00,and the seasonal variation is obviously different in the middle of June.The diurnal variation of intercellular CO2 concentration is "V" type,the seasonal variation shows a single peak curve,and the diurnal variation is obvious in the morning and evening,and the seasonal variation is obvious in the middle of August.The content of photosynthetic pigment increased first and then decreased,and there was significant difference between July and mid August.(2)Through the measurement of Ginkgo seed seed traits and physiological indicators under different conditions,it was found that the Ginkgo seed seed volume increased rapidly from April to June,and the seed fresh weight was synchronized with the growth of the seed volume.Continue to grow to maturity.The coefficients of fruit type,kernel type and kernel type of the two tree species are basically the same.The content of soluble sugar,fat,starch and soluble protein in the natural open center tree kernel of Ginkgo biloba was higher than that in the trunk stratified kernel,and the difference was significant from July to mid August.The seed yield per plant of Ginkgo biloba with stratified trunk is 9.62 kg higher than that of natural open center.According to the comprehensive analysis,the natural happy shape is the high quality tree shape of ginkgo seed production.(3)Exogenous hormone treatment caused the change of endogenous hormone content in seed.The study found that the content of endogenous hormones IAA and GA3 showed a general downward trend during the ripening process of Ginkgo biloba seeds,the content of ZR and ABA generally increased,and the ratio of(IAA+ZR+GA3)/ABA generally showed a downward trend.Compared with the control treatment,the content of IAA,ZR,GA3 decreased and the ABA content increased after the application of exogenous hormones,and the(IAA+ZR+GA3)/ABA ratio decreased significantly.After exogenous hormone treatment,the content of endogenous hormone ABA in Ethephon treated species increased more than that in ABA treatment,and the content of IAA and GA3 decreased more than that in ABA treatment.(IAA+ZR+GA3)/ABA ratio decreased compared with ABA treatment The amplitude is larger,and the two exogenous hormones in the ZR content are basically the same.(4)Exogenous hormone treatment has a significant effect on the content of secondary metabolites in seeds.The study found that during the maturation of Ginkgo biloba seeds,the content of anthocyanins and flavonoids in the secondary metabolites of the exogenous hormones and control treatments showed an overall upward trend,while the control treatment of the ginkgo acid content showed an overall upward trend,and there was no significant change in the ABA treatment.Ethylene treatment generally shows a downward trend.Compared with the control treatment,the content of anthocyanins and flavones increased and the level of ginkgoic acid decreased after the application of exogenous hormones.After exogenous hormone treatment,the content of anthocyanins and flavonoids in ethephon treated species increased more than that in ABA treatment,and the content of ginkgoic acid decreased more than that in ABA treatment.(5)qPCR was used to analyze the expression of key enzymes and key enzymes of ethylene synthesis in flavonoid metabolism in hormones after hormone treatment.Compared with the control treatment,the expression of GbACS,GbACO,GbPAL,and GbANS genes was up-regulated after the application of exogenous hormones.After exogenous hormone treatment,the expressions of GbACS,GbACO,GbPAL,and GbANS genes in Ethephon-treated seeds were more significant than those induced by ABA.(6)By spraying different concentrations of ethephon and abscisic acid solution to collect ginkgo seeds,it was found that the best concentration of ethephon was 500 mg/L,the best concentration of abscisic acid was 300 mg/L,and the fruit dropping rate could reach 90%.In addition,the closer to the natural harvest period,the higher the fruit falling rate,and there was no effect on the growth and development of ginkgo tree and the next year's yield after the application of hormone. |
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