Effects of Foliar Application of Nano-selenium on Selenium Content and Quality of Summer Tea
In this experiment,the tea variety Baiye 1 was used as test material to study the effects of foli-ar spraying different concentrations of nano-selenium on the total and organic selenium contents in summer tea leaves and the quality of its green tea.The results were as follows.(1)The contents of total selenium and or-ganic selenium in tea leaves increased gradually with the increase of nano-selenium concentration,and the se-lenium content in tea leaves decreased with the prolongation of picking time.The contents of total and organic selenium in tea leaves were the highest at 7 days after 10.0 g/L nano-selenium treatment,which were 0.763 and 0.609 mg/kg,respectively.(2)The main selenium form in tea leaves treated with different concentrations of nano-selenium was organic selenium,accounting for 69.0％～80.8％of the total selenium content.(3)Spraying a certain concentration of nano-selenium could increase the sensory quality,significantly reduce the content of anthocyanins and tea polyphenols,increase the content of free amino acids,and reduce the ratio of total polyphenols to total amino acids.The ratio of total polyphenols to total amino acids was the lowest under 10.0 g/L nano-selenium treatment as 4.47.In summary,foliar application of a certain concentration of nano-selenium could significantly increase the selenium content in tea leaves and improve the quality of processed green tea.Among them,foliar application of 5.0～10.0 g/L nano-selenium and picking leaves at 7～14 days af-ter spraying had the significant selenium-rich effect,which could be used to produce green tea that meets the national selenium-rich level.
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