| Blueberry scientific name lingonberry(Vaccinium spp.),belongs to the Rhododendron family(Ericaceae)lingonberry genus plants.Blueberry fruit has high nutritional value,and rich in antioxidant substances,the market demand for the fruit is enormous,blueberry planting industry has a broad development prospect.Blueberry buds have dormant characteristics,under natural conditions,the dormant blueberry flower buds and leaf buds need a certain amount of time to accumulate low temperature to end dormancy,and start new branch growth and flowering and fruiting.If the amount of cold is not enough,the flowering is delayed,the flowering period is extended,resulting in delayed fruit maturity,low fruiting rate,and even extinction in serious cases;if the blueberry dormancy is not released in time,it will make the blueberry fruit market delay.How to use dormancy buster scientifically and effectively to precisely regulate blueberry dormancy,promote the release of dormancy,and make the fruit market as early as possible,has important theoretical significance and practical value in blueberry facilities cultivation.This paper focuses on the role of dormancy breaker hydrogen cyanamide in releasing blueberry bud dormancy and the regulatory mechanism of dormancy breaking by hydrogen cyanamide,the main findings are as follows.Firstly,blueberry variety‘ M7 ’ plants were treated with different concentrations of hydrogen cyanamide and 0.67% hydrogen cyanamide in combination with gibberellin,ethephon,potassium nitrate and mineral oil,and then treated with various dormancy breakers and subjected to phenological investigations and yield measurements.The results showed that compared with the distilled water sprayed control,the dormancy breaker treatment could advance bud initiation by 15-19 d,flower initiation by 1-3 d,and fruit ripening by 6-8 d.However,there was no significant difference in the phenological stage of the plants between the different dormancy breaker treatments.The appropriate concentration of hydrogen cyanamide significantly increased the soluble solids content of fruits and significantly increased the pre-harvest yield and total yield of blueberries of different ages.In addition,the results of two consecutive years showed that 0.67% hydrogen cyanamide significantly increased the preharvest yield and total yield of ’M7’ and ’Brigitta’.It shows that suitable concentration of hydrogen cyanamide can make blueberry buds release from dormancy earlier,make high fruit market earlier and increase fruit yield,and thus improve the benefit of blueberry cultivation.Hydrogen cyanamide can be used as a dormancy buster for anti-seasonal cultivation of blueberry.Secondly,the effects of hydrogen cyanamide on the physiological indexes of ’M7’ and’Brigitta’ flower buds and fruit quality were studied.To investigate the physiological mechanism of hydrogen cyanamide-induced dormancy release in blueberry flower buds.The results showed that compared with the distilled water-treated control buds,the hydrogen peroxide(P <0.05)content,peroxidase(P <0.001),phenylalanine aminolase(P <0.05)activity and reduced glutathione(P <0.01)content were significantly increased and catalase(P <0.05)and superoxide dismutase(P <0.001)activities were significantly decreased in the hydrogen cyanamide-treated buds;the ratio of unsaturated fatty acids to saturated was increased;the content of abscisic acid(P <0.05)was significantly decreased,and the content of indoleacetic acid(P <0.001)and zeatin riboside(P <0.01)was significantly increased.In our analysis,hydrogen cyanamide may regulate physiological metabolism by activating hydrogen peroxide signaling,increasing the content of auxin and cytokinin,promoting cell growth and division,and thus inducing flower bud germination;at the same time,hydrogen cyanamide may also regulate the balance of reactive oxygen species and stabilize the membrane system by activating the antioxidant system and increasing the content of unsaturated fatty acids,thus activating the metabolic activities related to flower bud germination and promoting flower bud.Then,to investigate the metabolic mechanism of hydrogen cyanamide induced flower bud germination in blueberry,metabolomic analysis using GC-TOF-MS technique on hydrogen cyanamide-treated and distilled water-treated endodormancy flower buds.Sixteen differential metabolites(VIP > 1,P < 0.05)were screened.Analysis of differential metabolic pathways showed that hydrogen cyanamide treatment of blueberry buds mainly regulated amino acid metabolism and the tricarboxylic acid cycle.The analysis of the contents of different metabolites revealed that the contents of soluble sugars(fructose,glucose,maltose)and organic acids(citric acid,α-ketoglutaric acid,succinic acid)in flower buds of the hydrogen cyanamide-treated group were significantly higher,the contents of aspartic acid,glutamic acid and phenylalanine were significantly higher,while the contents of tyrosine,tryptophan and asparagine were significantly lower.The content of secondary metabolites such as salicin,4-vinyl phenol and neohesperidin was significantly increased.Hydrogen cyanamide may provide energy for flower bud germination on one hand and material basis for flower bud germination on the other hand by promoting polysaccharide degradation,tricarboxylic acid cycle and nitrogen assimilation.Finally,We performed metabolomic analysis using GC-TOF-MS on flower buds released from dormancy by hydrogen cyanamide-treated and those released from dormancy under natural conditions.To investigate the mechanism of efficient dormancy-breaking action of hydrogen cyanamide and to develop novel dormancy regulation.A total of 10 differential metabolites were screened,and changes in differential metabolite pathways were mainly focused on carbon and nitrogen balance and energy metabolism.The content of fructose,citric acid,amino acids(serine,isoleucine,alanine),and phenolpropane metabolites(salicin,epicatechin,and neohesperidin)in flower buds of the hydrogen cyanamide-treated group was significantly higher and the content of maltotriose,putrescine,asparagine,and erucic acid was significantly lower compared with the naturally dormant group.The content of the three glycogenic amino acids was increased in the hydrogen cyanamide-treated group compared with the natural dormancy-release group to supplement the carbon and nitrogen supply for flower bud germination;the content of asparagine was decreased to play a regulatory and stabilizing role in the carbon and nitrogen balance in flower buds.Starting from the perspective of regulating amino acid metabolic pathways in dormant flower buds,it can provide ideas for the development of dormancy breakers.In conclusion,this thesis analyzed the physiological mechanism of hydrogen cyanamide induced dormancy release of blueberry flower buds with the object of facility blueberry cultivation,and analyzed the regulatory mechanism of hydrogen cyanamide induced germination of blueberry flower buds and the mechanism of efficient dormancy breaking effect using metabolomics technology,which has theoretical and practical significance to the development of blueberry industry. |
PDF Full Text Request