The main method of producing selenium-enriched tea in low selenium soil is to supplement exogenous selenium artificially. The effective way is to spray a certain concentration of inorganic selenium aqueous solution on the leaves to improve the organic selenium content of tea by biotransformation of tea trees. The bioaccumulation effect of selenium in tea is not only affected by spraying selenium concentration, but also changes with time. Climatic conditions will have a corresponding impact on this process, and it is necessary to control the inorganic selenium residue on the leaves of selenium-enriched tea. The purpose of this experiment is to understand the influence of the above factors on the production of selenium-enriched tea in low selenium soil, and to provide methods for the production of hygienic and safe selenium-enriched tea.
Keywords: selenium-enriched tea spraying selenium-enriched soil selenium-enriched application
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Selenium is an important trace element in human and animal life activities and an indispensable component of glutathione peroxidase in higher animals. Selenium deficiency in human body will lead to Keshan disease, Kaschin-Beck disease and so on. Selenium supplementation can improve the immunity of exercise body [1]. Eating inorganic selenium such as sodium selenite is easy to cause selenium poisoning in the process of selenium supplementation, so finding suitable natural food rich in organic selenium has become the focus of attention. Tea tree is a kind of crop that can collect selenium, and can convert the absorbed inorganic selenium into organic selenium [2]. However, because the production of selenium-enriched tea is limited by natural conditions such as regional soil, its output is far from meeting the huge market demand, so it is of great practical significance to study and develop low-selenium soil to produce selenium-enriched tea. The main method of producing selenium-enriched tea in low selenium soil is to supplement exogenous selenium artificially, and to improve the organic selenium content of tea by biotransformation of tea tree itself.
1 Se-enriched soil to produce Se-enriched tea
Spray selenium with 1. 1
The purpose of selenium enrichment is achieved through the absorption of tea leaves. Tao Shuaiping and Jiang's research show that spraying a certain concentration of sodium selenite aqueous solution on tea can significantly increase the selenium content in tea. Artificial production of selenium-enriched tea in low selenium soil will not affect the growth and yield of tea trees, but also make the inorganic selenium residue on the leaves as little as possible. Selenium spraying concentration and picking time should be selected according to different seasons. The climatic conditions in spring are suitable for the growth of tea trees. The concentration of spraying selenium should be controlled within the range of 100~300ppm, the picking period should be controlled within 7 ~ 10 days after spraying, and the picking should be completed within 15 days after spraying. There are many high temperatures and droughts in summer and autumn, the evaporation of tea gardens is large, and the growth of tea trees is slow. The concentration of spraying selenium should be low rather than high. Generally, it should be within the range of 50~ 100ppm, and the picking time should be within the range of 15 ~ 20 days after spraying, which should not be too early and can be delayed for several days.
1.2 The soil fertilizer is rich in selenium.
Roots are the main part of selenium accumulation in plants. By applying selenium-enriched fertilizer, tea can achieve the purpose of selenium enrichment. Selenite is absorbed into the roots of plants through sulfate carriers and transported from xylem to leaves without changing its chemical form [6-7]. Once in the chloroplast of leaves, selenate is assimilated by sulfate assimilating enzyme. Liu Yin's study on the selenium content and distribution of tea in Anhui Province found that the selenium content in the soil of tea with selenium content of 35~ 102μg/kg ranged from159 ~1715μ g/kg, while the selenium content was1kg.
Application of Se-enriched tea in Se-deficient soil
Selenium-enriched tea beverage has a huge market demand in contemporary society because of its unique health care value. Lu Xinquan, Gao Xiang, An Xinxin and other surveys show that selenium-enriched tea drinks are generally made of middle and low-grade selenium-enriched black tea and oolong tea [8]. However, due to the low yield and high price of natural selenium-enriched tea raw materials, its development is greatly limited. Producing selenium-enriched tea in low selenium soil can solve this problem well.
3 Conclusion and prospect
In recent 20 years, some achievements have been made in the research of selenium-enriched tea, which laid a solid foundation for further research and development of selenium-enriched tea. However, in the past, it was only limited to spraying sodium selenite and applying selenium fertilizer in the soil, and there was no study on the best soil environment and climate conditions for tea trees to absorb selenium, nor on the effects of selenium on the physiology and biochemistry of tea trees, and there was no study on the breeding of selenium-enriched tea trees.
Source: 360 paper net.