| Tea plant is a typical plant of accumulating fluoride, and soil F is an important source of the F in tea plants. Moreover, one of the important dietary sources of F for humans is drinking tea. The drinking tea fluorosis caused by long-term consumption tea of high F content. In recent yeas, the drinking tea fluorosis attracted close attention, therefore, how to reduce the F content in tea also become hot topics. The relationship between F in tea plants and in soils was researched by pot experiments and field tests in order to clarify the bio-availability of F in soils and its impact factor. At the same time, we can have preliminarily realized the measures of reducing F and provided theory clues to know the measues of reducing F through this study, as well seek a breakthrough of prevention and treatment methods of drinking tea fluorosis. Through this research, the summary of the results as follows:(1) The F content in tea plant was different with different parts, the distribution of F in tea plants was that lesves>the absorption roots>stems>main roots, and the absorption of F in leaves was more larger than in other parts. The difference of F absorption of the tea plants in different soils mainly was leave F, and the differences of the F concentration in stems, mian roots and absorption roots in different soils were small.(2) The F absorption in tea plants was influenced by the effectiveness of soil F. The water soluble fluorine and 0.01 mol/L CaCl2 soluble fluode could be good indicators to characterize the bio-availability of soil F.(3) There were great differencs with soil total F, soil water soluble F and salt soluble F in different investigation points. There were significant differences between soil F in 0-20 cm and 20-40 cm. On the whole, the distribution of soil total F was that 0-20 cm<20-40 cm. and the distribution of soil water soluble F and salt soluble F was that 0-20 cm>20-40 cm.(4) The distribution of tea F was that mature leaves>4th leave>3th leave>2th leave>1th leave>bud, the F concentration in mature leaves was 6. 59 times that of bud, the F concentration in stems was between 90 mg/kg and 120 mg/kg.(5) The soil water soluble F was influenced by soil pH. The salt soluble F was correlated significantly with soil pH, and the salt soluble F in 0-20 cm was significantly negative correlation with soil organic matter.(6) Soil F extracted with water and diluted CaCl2 solutions was correlated significantly with the concentrations of F in leaves and stems. But there was no significant correlation between soil total F and the concentrations of F in leaves and stems.(7) The field of fresh tea leaves was not significantly influenced by the measures for decreasing fluorine of fertilization and soil improvement.(8) There were significantly negative correlation between the measures for decreasing fluorine of fertilization and soil improvement with F concentration of fresh tea leaves. The F contentration of brick tea leaves could be reduced to 377-438 mg/kg form 536mg/kg, and the defluoridation rates reached 18.2%-29.7%. Defluoridation efficiency in two leaves and a bud was better than four leaves and a bud, the F contentration of two leaves and a bud could be reduced to 78.5%-88.9 mg/kg form 118mg/kg, the defluoridation rates reached 24. 8%-33.6%. The F contentration of four leaves and a bud could be reduced to 148-183 mg/kg form 203 mg/kg, the defluoridation rates reached 9. 7%-27.1%.(9) It has been preliminarily verified that the defluoridation efficiency was best after 30 d and no fluctuation, the F contentration of old leaves could be reduced to1276-1586 mg/kg form 1889 mg/kg, the defluoridation rates reach 16. 0%-32. 4%。...
|
PDF Full Text Request