Study On The Adsorption And Accumulacation Of Fluoride In Tea Plant And Primary Control

Tea plant(Camellia sinensis L.) is a typical plant of accumulating and tolerating fluoride,the fluoride mainly exsited in the old leaves of tea plant,and its content was high to 6400 mg/kg.Hence,the content in some brick teas which were prepared by the old leaves was high than of the standard of China(≤300mg/kg). Some paths such as tea cultivate,tea processing and drinking for reducing the fluoride content in brick tea were carried out,and these methods must reduce the fluoride content in the materials that means tea plant leaves,therefore,the characters and factors needed to be studied,and,this article would study the regularity of tea plant accumulating fluoride content and the control technology.The knowledges and methods of Cultivation of Tea Plant,Plant Physiology and Plant Nutrition were utilized to analyse the characters of uptaking and accumulation of flluoride in tea plant and would discuss the conditions and factors of accumulation fluoride in tea leaves.Moreover,this article would study the preliminary methods for control the tea plant accumulating fluoride.The results of this article would supply theoretical basis of reducing the fluoride content in the materials of brick tea,meanwhile,it would enrich the content of Tea Plant Physiology.The methods of field research and nutrient liquid culture were utilized in this article,and analyzed:(1) Fluoride distribution character and environmental factors in tea plant;(2) The fluoride absorption and accumulation characteristics in tea plant leaves;(3) Absorption,accumulation and metastasis characteristics of fluoride in nutrient liquid cultured tea plant;(4) The influences of Ca and Al to the absorption and accumulation characteristics of fluoride in nutrient liquid cultured tea plant;(5) The methods of control fluoride content in tea leaves from the plant crown,soil and tea picking were preliminary studied,and the results as follows:(1) Tea leaves were the main organ of accumulating fluoride,about 96.22%fluoride was in it. Fluoride content in different organs were not coincident,its order was:Leaves＞buds＞rinds＞productive branches＞chief branches＞fine roots＞spindle of stems＞tap-root＞lateral roots.The fluoride content increased following the phyllotaxis adding notably,and the content of fluoride acuumulated in tea leaves was linearly increased by the leaves aging(y=12.87x-155.49,R²=0.9752).Morevore,the fluoride content was significant difference in 26 plant varieties(F=31.310^**＞F_0.01(25,55)=2.1508).It was significantly positive correlation between the fluoride content in old leaves and the water soluble fluoride content in tea garden soils(F=6.6370^*＞F_0.05(1,29)=4.18),and it was significantly positive correlation between the fluoride content in old leaves and the fluoride content in irrigation water(F=7.03^*＞F_0.05(1,14)=4.6001),Morevoer,the pH of 0～20cm soil was significantly lower than that in 20～40cm soil (F=11.6672^**＞F_0.01(1,34)=7.4441).The pH and water soluble fluoride content of tea plant soil were both lower than those in non-tea plant soil,it means that the tea garden soil acidification was benefit for the tea plant adsorbing and accumulating fluoride in soil.(2) Fluoride content in tea old leaves and new tips were significant linear relationship between corase fiber content(y_{New tips}=33.7687x-172.569,R²=0.9091;y_Leaves=63.585x-595.81,R²=0.7662),it means that the fluoride content increased following the maturity of the tea leaves.About 85%fluoride was water soluble in tea leaves,it's the main form existed in tea plant,and it's linearly correlation between the total fluoride content in tea plant.Meanwhile,fluoride content in new tips and old leaves was linearly correlation,it's accumulated fluoride more than that in new tips,and it's strongly water soluble,it could transfered into the new tips,as well. (3) The fluoride content was increased following the cutured time in the organs of nutrient liquid cultured tea plant under the same fluoride background,and the uptaking and accumulating fluoride degree was:old leaves＞new tips＞roots＞stems(F=31.1004＞F_0.01(3,24)=4.7181).The fluoride content in old leaves was high to 6809.39mg/kg,it means that there existed particular "fluoride storage mechanism" in tea leaves,it promoted tea roots to adsorb low content fluoride in enviroment and stored in leaves.Under the conditions of F^- 250mg/L in the nutrient liquid,the tea plant showed the symptom of fluorosis when cutured 14 days,and the fluoride content was high to 4958.6±16.3 mg/kg,it showed that the tolerance of tea plant to fluoride was extremely strong.In the non-fluoride culured condition,the fluoride in new tips and roots was deeply increased following tea plant upgrowth,it testified that highly content of fluoride in old leaves aould transferred to new tips and roots,and it testified that it existed stronge transfer and repartion character of fluoride in tea plant.(4) Al³⁺ in liquid could increase the uptaking and accumulating speed of fluoride in tea leaves from the environment,but Calcium compounds could decrease the uptaking and accumulating speed of fluoride in tea leaves deeply,the effect of Ca₃(PO₄)₂ was mostly sighficant,especially.(5) During the new tips' upgowth,0.90%N nutrition was sprayed on tea levaves,the results showed that the fluoride content was 63.6%of the control tea leaves,and it could decreased the corase fiber content and phenol/amino acids,it could increase the quality of tea materials,as well.In the acided(pH=4.62) tea garden soils,0.5%CaCO₃ or marble powder was added,it could decrease the water fluoride content 38.10%～46.03%in the soil.Moerover,it was lineraly incresed of fluoride content in tea plant during its upgrowth,but the weigh of new tips increased as Logistic,thorefore,it could control the materials' fluoride content effectively when the tea new tips weight increasing slower and picking tea new tips in time.The results of this article would supply theoretical basis of reducing the fluoride content in the materials of brick tea,meanwhile,it would enrich the range of Tea Plant Physiology.