Effects Of Physiological And Biochemical And Secondary Metabolites In Dendrobium Nobile Lindl.Under Exogenous Zn Treatment

Zinc is an essential micronutrient to plants and animals for growing,due to its wide important physiological and biochemical functions in the body,zinc is known as"life element".At the same time,zinc is also a kind of common toxic heavy metals to the environment,and it can be used as an inducer to promote the generation of secondary metabolites.Dendrobium nobile Lindl.is a valuable botanical plant and full of ornamental value.However,the wild resources of Dendrobium nobile Lindl.are limited because of its own biological characteristics and environmental degradation.Therefore,it is of practical significance to study the related changes of Dendrobium nobile Lindl.'s physiological and biochemical and secondary metabolites under exogenous zinc stress,and to select the best zinc concentrations that promote the growth of the plant and produce effective substances.In this article,a pot experiment was conducted to explore the effects of the photosynthesis,antioxidant system,secondary metabolism and absorption of zinc,while spraying different concentrations of exogenous zinc on Dendrobium nobile Lindl..And this experiment can provide some references for the further development and utilization of Dendrobium nobile Lindl..This study shows that different concentrations of Zn[0,50,100,200,400,800,1000,2000,?mol/L]have a significant influence on the physiological and biochemical and secondary metabolism of Dendrobium nobile Lindl..1.Low concentration Zn promoted the photosynthesis of Dendrobium nobile Lindl..Low concentration of zinc processing??400?mol/L?promoted the Dendrobium nobile Lindl.photosynthesis.It increased the net photosynthetic rate,transpiration rate,stomatal conductance and chlorophyll a and chlorophyll b contents,reduced the intercellular CO₂ concentration and water use efficiency.However,when the concentration of Zn was>400?mol/L,the photosynthesis of Dendrobium nobile Lindl.was significantly inhibited.2.Low concentration Zn enhances the anti-oxidation ability of Dendrobium nobile Lindl..Exogenous zinc treatment improved the Dendrobium nobile Lindl..leaves'H₂O₂ and MDA,soluble sugar,soluble protein content and O₂·-generating rate,Dendrobium nobile Lindl.were under some stress,but low concentrations of zinc processing??400?mol/L?reduced the free proline content of leaves,increased the SOD,POD,CAT,APX,GR activity,increased the content of GSH and AsA,high concentration of zinc showed opposite change,suggests that the right amount of zinc can promote the peroxide resistance of Dendrobium nobile Lindl.,and enhance its resistance.3.Zn increased the content of secondary metabolites of Dendrobium nobile Lindl..The polysaccharide content of the stem of Dendrobium nobile Lindl.was increased when the concentration of zinc was less than 1000?mol/L,and the maximum content was found at the concentration of T4?400?mol/L?.Each zinc treatment concentration increased the content of polyphenols and flavonoids in the stem of Dendrobium nobile Lindl.,and had the greatest promote effect at the concentration of T4?400?mol/L?.4.Zn promoted the accumulation of zinc in the roots and stems of Dendrobium nobile Lindl..The zinc content in the roots and stems of Dendrobium nobile Lindl.was enhanced by external zinc,which promoted the absorption of zinc in Dendrobium nobile Lindl.,and the zinc content increased with the increase of zinc treatment concentration.The Zinc content in the roots is higher than stems.5.Zinc polysaccharide was found in Dendrobium nobile Lindl.and affected by Zn concentration.The study found that there was zinc polysaccharide in the stem of Dendrobium nobile Lindl.,and the zinc content of polysaccharide was promoted by the exogenous zinc,and the highest concentration of zinc was in 800?mol/L.All in all,the results of this study indicate that low concentration zinc can promote the photosynthesis of Dendrobium nobile Lindl.and improve its anti-oxidation ability.Zinc can promote the production of secondary metabolites and increase the zinc content in the roots,stems and polysaccharides.Therefore,considering both secondary metabolism and physiological and biochemical process,400?mol/L exogenous zinc can promote Dendrobium nobile Lindl.'s content of secondary metabolites best,and does not persecute the normal physiological metabolism.