Effect Of Selenium-Zinc Interaction On Mineral Nutrition And Chemical Quality Of Mengshan Tea

Three years old Mengshan tea 9 was chosed as the research subject, under potted plant experiment, foliar spraying of different concentration levels of Na₂SeO₃ and ZnSO₄·7H₂O was carried out to determine the effect of Se, Zn and Se-Zn interaction on the content and component of Se and the content of Zn, meanwhile, the chemical quality variety of other mineral nutrition(P, K, Ca, Mg, S etc.) , tea-polyphenol and amino acid were discussed.(1) Se-Zn interaction has significant effect on Se content and its organic ratio in spring, summer, and autumn. Under the treatment of selenium(50～200 mg·kg^-1) and zinc(0.25%～1.00%) interaction, the contents of Se are 0.35～3.66 mg·kg^-1 in spring, 0.56～3.36 mg·kg^-1 in summer and 0.41～2.90 mg·kg^-1 in autumn, which are 1.37～21.32 times, 2.08～11.79 times and 2.13～14.13 times of the control(CK). Compared with single-Se treatment with the same concentration, the content of Se is lower on the whole. It is indicated that there is antagonistic effect of selenium and zinc interaction on the accumulation of Se in tea. The organic ratio of Se rises along with the increase of the concentration of selenium, and it is higher under selenium and zinc interaction treatment than under single-Se treatment, but selenium and zinc interaction with high concentration has adverse effect on increasing the organic ratio of Se.In the same season but different picking time, the contents of total Se and organic Se in each treatment decrease with the prolonging of time. The decrease gets to maximum in the mid period, but trends to be stable in later period. However, the organic ratio of Se gradually rises with the prolonging of time after the treatments.When under the treatment of selenium(50～200 mg·kg^-1) and zinc(0.25%～1.00%) interaction, the content of Zn in tea is in the range of 87.30～235.35 mg·kg^-1 . The content of Zn is impacted mainly by the spraying concentration of ZnSO₄·7H₂O. Under the treatment of the interaction of zinc with certain concentration and selenium with different concentrations, the content of Zn reduces along with the increase of the concentration of selenium on the whole. It is very obvious in the treatment of Se₃Zn₁(Se₂₀₀+Zn_0.25) of summer tea, and in the treatment of Se₃Zn₃(Se₂₀₀+Zn_1.00) of autumn tea, which are decreased by 25.2% and 39.3% compared with the treatments of Se₁Zn₁(Se₅₀+Zn_0.25) and Se₁Zn₃(Se₅₀+Zn_1.00) respectively during the same periods.In summary, when aiming to increase the content of Se in tea, it is best to apply 100 mg. kg^-1Na₂SeO₃ only, and pick tea after 16 days. When aiming to increase the content of Zn in tea, it is best to apply 0.50%ZnSO₄·7H₂O only, and pick tea after 16 days. When aiming to increase the content of both Se and Zn in tea, it is best to apply 100 mg·kg^-1Na₂SeO₃ and 0.50%ZnSO₄·7H₂O, also pick tea after 16 days, and summer is the best season to increase Se and Zn effectively.(2) The effect of Se-Zn interaction on the content of the mineral elements such as N, P, K, Ca, Mg and S is significant. As far as spring tea, compared with the control, the contents of P, K and Ca are reduced and the contents of N and Mg are increased by interaction treatment, but there is no obvious effect to the content of S. Se-Zn interaction has positive effect on the absorption of N, P, K, Ca and S of summer tea. Thereinto, the effect difference of S is nor remarkable, and there is no notable impact on the content of Mg. Se-Zn interaction has positive effect on increasing the content of P and K, but has antagonistic effect on the absorption of Ca.As far as microelement, compared with the control, the content of Fe in spring tea is increased by the effect of selenium, zinc and their interaction significantly, and the contents of Mn and Cu are reduced. Single-Se or single-Zn treatment has very remarkable effect on increasing the content of Fe, Mn and Cu in summer tea. The content of Fe is increased very significantly by Se-Zn interaction treatment, but the content of Mn is reduced, and there is no obvious effect on the content of Cu. Se-Zn interaction treatment has promotional effect on the absorption of Fe in autumn tea, but it has antagonistic effect on the absorption of Cu and Mn, and the decrease of Cu is very obvious. It is reduced by 30% under the treatment of Se₁Zn₃(Se₅₀+Zn_1.00), compared with the control.Generally speaking, the improving effect of Se-Zn interaction on mineral nutrients of Mengshan tea mainly presents in summer, but there is no remarkable effect in spring or autumn. However, it even has antagonistic effect on the absorption of P, K, Ca, Mn and Cu. When applying foliar spraying selenium and zinc to increase the contents of Se and Zn in tea, it is best to apply foliar spraying 50mg·kg^-1Na₂SeO₃ and 0.25%ZNSO₄·7H₂O in summer, if improvement of other mineral nutrients is considered at the same time. (3) As far as the effect on Se-Zn interaction on tea chemical quality, low concentration of Se(50 mg·kg^-1) and Zn(0.25%) significantly decreases the content of tea-polyphenol and increases the content of theine. The interaction treatment of high concentration of Zn(1.00%) and different concentrations of Se(50,100,200 mg·kg^-1) has very significant effect on reducing the content of amino acid when compared with the single-Zn treatment, and other treatments have no obvious effect on spring tea. When it comes to summer tea, compared with single-Se or single-Zn treatment, after Se-Zn interaction treatment, the content of tea-polyphenol is reduced on the whole, while the of theine is increased remarkably, and the increase of the content of amino acid is most obvious under the treatment of low concentration Se-Zn interaction. Other treatment has no significant effect on the chemical quality of summer tea. And Se-Zn interaction has less effect on the content of tea-polyphenol and theine.When it comes to the ratio of tea-polyphenol to amino acid, it is in the range of 7 to 11 under the treatment of Se-Zn interaction. It indicates that Se-Zn interaction has significant effect on improving the chemical quality of spring tea. Compared with the control(13.07), the ratio of tea-polyphenol to amino acid in summer tea under the treatment of Se-Zn interaction decreases, but it is still higher than under the treatment of single-Se. This indicates that Se-Zn interaction has certain effect on improving the chemical quality of summer tea, but the effect is not as remarkable as it is under the treatment of single-Se. There is no significant effect of Se-Zn interaction on the ratio of tea-polyphenol to amino acid in sutumn tea.When applying Se-Zn interaction to improve the content of Se and Zn in tea, it is best to apply foliar spraying 100 mg·kg^-1Na₂SeO₃ and 0.25%ZNSO₄·7H₂O in spring, if improvement of chemical quality is considered at the same time.