Effects Of Selenium On Strawberry Fruit Quality And Its Physiological Mechanism Of Regulating Fruit Ascorbic Acid Accumulation

In order to study the effect of selenium on strawberry fruit quality,at the same time clear selenium regulation of strawberry fruit development of ascorbic acid in the process of accumulation of physiological mechanism,this study adopts the pot experiment,simultaneously exogenous spraying on the leaf 10,30,60 mg·L^-1 three concentrations of sodium selenite（Na₂SeO₃）solution treatment,the strawberry mature fruit weight,fruit hardness,selenium content,fruit shape index,sugar acid ratio and soluble solids,ascorbic acid（ASA）,protein,anthocyanins,total phenol content was determined.While selenium concentration of different treatment on strawberry in young fruit stage,fruiting stage,big fruit,ginkgo,turn color fruit period and mature period of six dehydrogenation ascorbic acid（DHA）,ASA content and ascorbic acid in fruit related metabolic enzymes L-galactose-1,4-lactone dehydrogenase（GalLDH）,ascorbic acid peroxidase（APX）,ascorbic acid oxidase（AAO）,single dehydrogenation ascorbic acid reductase（MDHAR）,the dehydrogenation ascorbic acid reductase（DHAR）,glutathione reductase（GR）activity of regulation and control function.Through the above studies,the aim is to provide a theoretical basis for improving the quality of strawberry fruits by selenium,so as to provide a scientific basis for the application of selenium in strawberry production.1.Effects of different concentrations of exogenous Na₂SeO₃ on the fruit quality of strawberry（1）Exogenous Na₂SeO₃ can significantly improve the fruit shape index and average single fruit weight of strawberry.At the same time,to some extent,Na₂SeO₃ increased the soluble sugar content in the fruit,significantly reduced the organic acid content,and increased the sugar-acid ratio of the fruit.Among all the treatments,the effects of medium concentration of Na₂SeO₃ on above indicators were the best.（2）Exogenous Na₂SeO₃ can significantly increase the content of total phenol and soluble solids in strawberry fruits at mature stage.Among all the treatments,the effects of medium concentration of Na₂SeO₃ on above indicators were the best.（3）Low concentration of Na₂SeO₃ significantly increased the contents of protein and anthocyanin in strawberry fruits,compared with other concentrations.（4）Exogenous Na₂SeO₃had no significant effect on the hardness of strawberry fruit.2.Physiological mechanism of Na₂SeO₃in regulating ASA accumulation in strawberry fruit（1）Selenium had better effect on AsA accumulation in strawberry fruit in the middle and late stages of strawberry fruit.At the beginning of white fruit stage,the ASA content showed obvious differentiation between selenium and selenium-free treatments.During mature stage,there was significant difference in ASA content between different concentrations of Na₂SeO₃.（2）Although different concentrations of Na₂SeO₃ can increase ASA accumulation in strawberry fruits,the mechanism of their action was not the same.The action of low concentration of Na₂SeO₃depended on the increase in DHAR activity.The action of medium concentration of Na₂SeO₃mainly depended on the increase in the activities of GalLDH and MDHAR.The action ofhigh concentration of Na₂SeO₃mainly depended on the reduction in AAO activity.（3）Among different concentrations,medium concentration of Na₂SeO₃significantly increased the accumulation of ASA in strawberry fruits.While selenium concentration is too high,the effect will be reduced.In summary,medium concentration of Na₂SeO₃ can be applied in the production of strawberry to improve the fruit quality and ascorbic acid content in fruit.