不同施氮水平对茶鲜叶中氟的调控效应研究

为探明茶园施肥降氟途径，试验研究了不同氮素施用量下，宣城（机采茶园）、休宁（手采茶园）2地黄红壤茶园茶鲜叶中含氟量的动态变化。结果表明：（1）机采茶园（宣城）和手采茶园（休宁），均随施氮量增加，1芽3叶茶鲜叶中氟含量呈逐级逐年下降趋势。宣城和休宁回归方程分别为：y=2.7072x²- 36.641x+305.73(R²=0.9827)和y=-0.4235x²-6.7592x+118.48(R²=0.9815)；（2）1芽3叶茶鲜叶中氟含量均随采摘时间的推移而迅速增加，至8月开始下降，茶园施氮对春、夏、秋茶鲜叶都能起到一定的调控作用，降氟效果为：夏茶＞秋茶＞春茶，与对照相比分别下降了27.75%、15.41%和12.37%；（3）每千克氮素施用效益结果表明，2地茶园均以N180降氟效果最好，与对照相比，每千克氮素施入量可使茶鲜叶中氟下降1.73%和0.45%。因此，茶园长期合理施用氮素，可有效降低茶鲜叶中氟含量。

Regulation Effect of Different Nitrogen Levels on the Content of Fluoride in Fresh Tea Leaves

3-year field experiments were conducted on two yellowish red earth tea plantations in Xuancheng and Xiuning, which were mechanical plucking tea garden and artificial plucking tea garden respectively, to study the dynamic of fluoride content in the fresh tea leaves under different nitrogen levels in tea gardens located on the yellowish red earth. The results showed that, the content of fluoride in fresh tea leaves decreased year by year, and decreased with the increase of nitrogen rates in both mechanical plucking tea garden and artificial plucking tea garden. The regulation equations of Xuancheng tea garden and Xiuning tea garden were y=2.7072x2-36.641x＋305.73（R2=0.9827） and y=-0.4235x2-6.7592x＋118.48（R2=0.9815）, respectively. The fluorine content in one bud with three leaves shoot increased rapidly with the delay of plucking time, but it began to decline in August. Applying nitrogen in tea garden had some regulatory effects on the fluoride content in fresh leaves of spring tea, summer tea and autumn tea. The fluoride contents decreased in the followingorder： summer tea autumn tea spring tea, and decreased by 27.75%, 15.41% and 12.37%, respectively,comparing to that under the control treatment. The nitrogen application benefit results showed that N180 was the best nitrogen level to reduce fluoride content in tea leaves in Xiuning and Xuancheng. The fluorine content in fresh tea leaves decreased by 1.73% and 0.45% with per kilogram N application, comparing to the control treatment. Therefore, long-term rational application of nitrogen fertilizer in tea garden can effectively reduce the fluoride content in fresh tea leaves.