Effects Of Soil Factors On The Selenium Absorption Characteristics Of Tea Plants

Selenium (Se) is widespread in the environment, and has been recognized as an essential trace element for humans by FAO/IAEA/WHO. For humans, the most of selenium intake from the diet, a small amount from taking selenium supplements. Plants absorb selenium from the environment will be affected by multiple factors. This experiment used tea plant as the research object. The research including a sampling of tea plant in Ankang of shaanxi province and a pot experiment and a hydroponic experiment in Tea Research Institute of Chinese Academy of Agricultural Sciences. In order to establish the effects of different soil selenium content, soil moisture content and pH value on the selenium accumulate in tea plant.1 The influence of soil selenium content to tea plant selenium accumulationThe experiment is set with 4 different kinds soils(S1、S2、S3、S4), selenium content of the 4 kinds of soils are 3.67 mg/kg、0.897 mg/kg、0.769 mg/kg、0.592 mg/kg. Zhongcha 108 was used as materials. Tea plants were detected by HG-AFS. The result showed that the selenium content in tea plant and the soil selenium content were positively correlated. S1 was significantly higher than other treatments, the selenium content in roots were 1.836mg/kg, selenium in leaves were 1.123mg/kg. Different parts of tea presents gradient distribution as root>leaf>stem>cutting.S3 was higher selenium content than S4 in soil, but lower in root. This suggests that the selenium content in soil is not the only factors affecting tea tree accumulation of selenium.2 The influence of soil moisture content to tea plant selenium accumulationThe experiment is set with 1 kind soil, selenium content is 0.592mg/kg, physical-chemical properties of the tested soil as follows, organic matter 23.4g/kg, total nitrogen 1.04g/kg, available nitrogen 938.0mg/kg, total phosphorus 0.27g/kg, available phosphorus 1.98mg/kg, total potassiums 9.9g/kg, available potassium 31.7mg/kg, pH 3.8. Zhongcha 108 was used as materials. The experiment is set as different soil moisture content gradient,50%～55%、70%～75%、80%～85%及 90%～95%. Tea plants were detected by HG-AFS. The result showed that with therise of soil moisture content, selenium content of root showed the increasing trend. When the soil moisture content is 90%～95%, the selenium content of roots, cuttings, stems and leaves are significant higher than other 3 treatments, and very significant among roots. When the soil moisture content is 70%～95%, tea plant is in a suitable growth environment of water. When the soil moisture content is 90%～95%, is the suitable soil moisture content for tea to absorb selenium from the environment.3 Effects of drought stress on the selenium content in tea plantThe experiment is set with 1 kind soil, selenium content is 0.592mg/kg, physical-chemical properties of the tested soil as follows, organic matter 23.4g/kg, total nitrogen 1.04g/kg, available nitrogen 938.0mg/kg, total phosphorus 0.27g/kg, available phosphorus 1.98mg/kg, total potassiums 9.9g/kg, available potassium 31.7mg/kg, pH 3.8. Zhongcha 108 was used as materials. After 28 days drought stress, the result showed that drought stress affected the absorption of selenium in tea plant. The analysis of the underground part showed that highly significant different in roots, after 7 days’ and 28 days’ drought stress. There is significant different in roots, after 14 days’ and 21 days’ drought stress. It indicated that water shortage reduced the absorption of selenium in roots. As the stress of drought was intensified and last, the accumulation of selenium in roots presented a increasing trend both in treatment group and control group. Within 28 days, the average absorption rate was 错误！未找到引用源. (CKroot0～28)=0.013 mg/(kg-d) in control group, much higher than that 错误!未找到引用 源. (DSroot0～28)=0.009mg/(kg·d) in treatment group. The highest absorption rate were k(CKAXroot0～7)=0.050 mg/(kg·d) and k(DSMAXroot0～7)=0038 mg/(kg·d) in the previous 7 days.The analysis of the overground part showed that treatment group and control group were both presented significant different in selenium absorption. The average absorption rate of control group4 Effects of different pH on the selenium content in tea plantThe experiment is set with nutrient solution, Zhongcha 108 was used as materials. The Se6+ concentration was 0.5mg/L. This experiment set 4 kinds of pH, as follows 3.5,4.5,5.5 and 6.5. The result showed that different treatments lead to different selenium absorption rate and different selenium accumulation concentration. In the short term culture stage (0-72h), within 72 h, selenium absorption rate presented reducing trend expect pH 6.5. After 24 hours, pH 3.5,selenium absorption rate was highest,k(24h 3.5)=0.010mg/(kg·h). In terms of total selenium accumulation concentration, the earlier stage (0～48h), pH 3.5 and 4.5, leaf>root, pH 5.5 and 6.5, leaf<root; the later stage (48-72h), cause of selenium absorption rate reducing in leaves, selenium absorption rate raising in roots, total selenium accumulation concentration in roots higher than that in leaves. pH 5.5 and 6.5, total selenium accumulation concentration in roots was negative growth,the selenium in stems and cuttings was transported to the top of the tea plants, caused total selenium accumulation concentration in leaves higher than that in roots.In the long term culture stage (72h-28d), within 28d, pH 3.5, selenium absorption rate was around the rate of 2.5×10-3 mg/(kg-h), other treatments has Substantially fluctuations. In the selenium accumulation concentration, all the treatments showed leaf>root>stem>cutting; reached the highest selenium accumulation in 21 days, except pH 3.5. After 21 days, all the selenium content reduced.5 The distribution regularity of selenium accumulation in in Ankang of Shaanxi provinceThis experiment determinate the selenium content in tea plant and soil of 5 tea gardens in Ankang of Shaanxi province by microwave digestion-hydride generation atomic fluorescence spectrometry. The result showed that the selenium content in tea plant and the soil selenium content were positively correlated. The Longjing 43 mature leaf content highest selenium(0.544 mg·kg-1) grown in haoping of ziyang than other areas. It is 8.77 times than the Fudingdabai grown in xiangyang of ziyang. Selenium content between each part of the tea tree is also different, such as, fibrous root is highest,new shoots is lowest. Phloem contents more selenium than xylem. The trends of selenium content is,mature leaf>the fourth leaf>the third leaf>the second leaf>the first leaf.