Effects Of Zinc And Selenium On Physiology And Secondary Metabolites Of Dendrobium Nobile

With the development of urbanization,the environment and residents’ health problems are also coming one after another in modern times.At the same time,as the important carrier of human activities,ecological environment can also impact the health of residents.The ecological environment is inseparable from plants,and some health-care garden plants not only have ornamental value,but also bring great economic value.As a high-quality garden plant,the Dendrobium nobile Lindl.have beautiful flowers and good health efficacy.Therefore,how to increase the biomass and health-care elements of Dendrobium nobile Lindl.has become a new hot spot.In this study,the effects of zinc,selenium and zinc combined selenium on the Dendrobium nobile Lindl were studied by adjusting the different concentrations of zinc and selenium.And results are as follows:Significant effects on the physiology and secondary metabolism of Dendrobium nobile Lindl.were appeared under different concentrations of zinc and selenium treatments.Firstly,the photosynthesis and biomass of Dendrobium nobile Lindl.were promoted under the medium concentration of zinc treatment(≤20.0 mg/L)and low and medium-concentration of selenium treatment(≤2.5 mg/L).Among them,the 10.0mg/L concentration of zinc combined 2.5mg/L concentration of selenium had the best effect.While the concentration of zinc ≥40.0mg/L and concentration of selenium ≥5.0mg/L,the photosynthesis of Dendrobium nobile showed significant inhibiting effects.Secondly,the contents of MDA,soluble sugar and soluble protein of leaves of Dendrobium nobile Lindl.were increased under zinc treatments and zinc combined selenium treatments,and the MDA content of the leaves of Dendrobium nobile Lindl.was increased under selenium treatments.The SOD and POD activities of leaves were increased under medium concentration of zinc treatment(≤20.0 mg/L)and medium concentration of selenium treatment(≤2.5 mg/L),while opposite changes were showed under high concentration of zinc or selenium,which indicate that the proper amount of zinc or selenium can promote the stress resistance of Dendrobium nobile Lindl.Thirdly,the contents of polysaccharides,flavonoids and polyphenols in the stalk of the Dendrobium nobile Lindl.were significantly increased under the medium concentration of zinc and the maximum value was reached under the zinc concentration(20.0 mg/L);The contents of polysaccharides and flavonoids in the stalk of the plants were significantly increased under the medium concentration of selenium and the maximum value of polyphenols was reached under the selenium concentration(5.0 mg/L).When zinc and selenium were combined,there had the synergistic effects on the accumulation of secondary metabolic products of Dendrobium nobile Lindl.In conclusion,considered from processes of physiology and secondary metabolism in plants,the content of secondary metabolic products of Dendrobium nobile Lindl.was maximally promoted at the concentration of selenium(2.5 mg/L)combined zinc(10.0-20.0mg/L)without persecuting its normal physiological metabolism.