Study On The Seleno-amino Acids Morphology Of The Tea Plant And The Effects Of Selenium Application On Seleno-smino Acids Contents And Morphology

In this paper, the seleno-amino acids were analyzed qualitatively and quantitatively by method of ion chromatography-integral pulse ampere assay (HPAEC-IPAD), and the Seleno-Amino Acids morphology of the tea plant and the effects of Selenium application on Seleno-Amino Acids contents and morphology were studied in order to provide a scientific basis for the yield of selenium-enriched tea and supplementation of selenium for people.Picking the fresh tea leaves, old leaves and root from natural selenium-rich tea plant, to detect the Seleno-Amino Acids contents and morphology in different parts of tea plant, then to compare them with the ones in the ordinary tea corresponding parts. It was concluded that the distribution trait of Seleno-Amin Acids in tea plant; At the same time, the distribution trait of total Selenium and Theanine, the other amino acids related to Seleno-Amino Acids (Methionine, Cystine/Cysteine) in the different parts of tea plant was got. A potted and field experiment were carried out, according to certain time gradient for picking and detecting the leave samples of tea plant, to study the effects of soil and spraying application of sodium selenite at different concentrations on the contents and morphology of Seleno-Amino Acids; to compare the content change of total Selenium and Theanine, Methionine and Cystine/Cysteine in the tea plant under condition of Selenium application. Finally, the Seleno-Amino Acids contents and morphology in the leaves of the selenium-rich tea plant by applying Selenium were compared with the natural selenium-rich tea plant, and the best condition to produce tea of high Seleno-Amino Acids contents was achieved.The main results showed as bellow:Using the ion chromatography-integral pulse ampere assay (HPAEC-IPAD), the extracts of tea plant samples don’t need derivatization reactions, the Seleno-Amino Acids can be very good analyzed qualitatively and quantitatively. Three kinds of selenium amino acids and other17kinds of amino acids can be baseline separated well. The standard deviation R2of the three selenoamino acids in the linear range were0.9994-0.9999, the relative standard deviation RSD (%) were2.47,3.17and3.77respectively, there exists a high correlation.In the leaves of the tea plant, Selenomethylcysteine(SeMeCys) was the main existence form of the seleno-amino acids. Selenomethionine (SeMet) and selenocysteine (SeCys) also exist in the tea plant, but they weren’t the main forms, the certain regularity for time and content of their existence were not found that may be influenced by Selenocysteine methyltransferase(SMT) in tea plant. The distribution trait of total seleno-amino acid content in the different parts of tea plant was consistent with total selenium content:the old leaves>roots>leaves; and the distributions of the three seleno-amino acids and total selenium content in the natural selenium-rich tea plant were same as the ordinary tea plant. The distribution trait of the Theanine content in the natural selenium-rich tea plant was also same as the ordinary tea plant:root>leaves> old leaves; Cystine/cysteine was present in the young leaves and roots where their contents were similar, and it was not detected in the old leaves; Methionine was not detected in three parts of the tea plants.Pot experiment showed that in the tea plants leaves of Selenium Application, Selenomethylcysteine(SeMeCys) was also the main existence form of the seleno-amino acids. Within a certain range,as the increasing of sodium selenite concentrations by the spray and soil application, the content of SeMeCys in the leaves tea plant increased at low concentrations and then decreased at high concentrations. The variation of total selenoamino acid content was consistent with that of SeMeCys.The total seleno-amino acid content was336.1μg/g, and was the most ideal for picking when spraying time was for12days or so at concentration for180μgSe·ml-1, but spraying concentration should not be higher than180μgSe·ml-1, otherwise the tea leaves will appear the brown coking spots which affected the appearance and quality of tea. It is better for picking when soil application of sodium selenite was at concentration of0.25-0.5mgSe/kg for6months. The total selenoamino acid content of the tea plant leaves was293.9-471.7μg/g. The results of the field test were matched with pot experiment. With increasing of sodium selenite content by the spray application, the content of total selenium was increasing; but as for soil application, when sodium selenite got certain concentration, the content of total selenium in the leaves non-significant increased. After foliar spraying different concentrations of sodium selenite on the tea plants leaves, the content of Theanine in tea leaves was increased, especially for spraying Se concentration at60μg·ml-1and120μg·ml-1and6-18days, the content of Theanine was2-3times as the control treatment. When spraying concentration of sodium selenite was high or spraying time was too long, the content of Theanine in tea leaves has decreased trend; after soil application different concentrations of sodium selenite on the tea plants leaves, the content of Theanine in tea leaves increased was not obvious for3-6months, especially soil application of low concentration Se, but began to improve after7months. Therefore, by spraying and soil application at different sodium selenite concentrations to product Selenium-rich tea, the most ideal time for picking was when there were a more content of Theanine. After foliar spraying and soil application different concentrations of sodium selenite on the tea plants leaves, there were no regularity about the content changes of Methionine and Cystine/cysteine, and some of them were even not detected, which were the same as Selenomethionine and selenocysteine.