喷施稀土对茶叶中不同状态的稀土元素组成及含量的影响
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汪东风 曹心德 赵贵文 叶盛 摘 要：茶树叶面喷施稀土是一项增产提质的栽培措施。但人们关心外源稀土对茶叶中稀土元素(REE)含量、组成及存在状态所产生的影响。试验表明，喷施至采摘间隔期愈长，喷施稀土对茶叶中稀土含量及组成等的影响愈小。茶叶中REE约有80%左右以水不溶态残存于茶渣中，不进入茶汤。进入茶汤中的REE约有10%是以稀土多糖状态存在，其中尤以La、Ce、Nd为主。间隔期愈短，稀土进入茶汤的量及参与稀土多糖配合物的量愈高。 Effects of Spraying Rare Earth on Compositions and Contents of WANG Dong-feng CAO Xin-de ZHAO Gui-wen Abstract：Tea plants sprayed rare earth can increase tea yield and quality,but the effects of spraying rare earth on the contents and compositions of rare earth elements(REE) in tea are unknown.The contents and compositions of REE in teas from tea garden sprayed "Cheng Lu" rare earth,cont.300mg/kg and 750kg/ha,and from natural tea garden have been determined.The results show that the longer the interval between spraying and picking was,the less the effects of sprayed rare earth on contents and compositions of REE in the teas were.About 80% ΣREE in tea whether it came from spraying or no spraying the rare earth were insoluble in its infusion.There were about 10% the soluble REE in infusion,in particular La,Ce and Nd,participating in coordinating polysaccharide,the amount of REE which participated in forming polysaccharide 15 days after spraying the rare earth was larger than those of 25 days and 35 days. 茶叶是我国传统的出口商品，内销也随人们生活水平的提高而日益增多。为满足市场需要，广大茶叶工作者不断探讨增产提质新技术。叶面喷施稀土具有增产提质、提早发芽、改善茶鲜叶机械组成等作用〔1〕。但茶树喷施稀土后，新生幼嫩芽叶中稀土含量明显上升〔2〕，这些幼嫩芽叶正是茶叶加工的原料，茶叶又是直接冲泡饮用。最近的研究结果表明〔3〕，人日摄入稀土仅为4.2mg。因此，稀土在茶叶生产中应用时，人们十分关注喷施稀土对茶叶中稀土存在状态、在茶汤中浸出率等的影响及采摘间隔期问题。目前虽有茶叶中稀土总量〔2，4〕、矿区茶叶REE组成〔5〕以及发现茶叶中存在有稀土茶多糖〔6〕等报道，但对上述人们普遍关心的问题还缺乏研究。本工作利用ICP-MS测试技术，选择在我国绿茶之乡——安徽省郎溪县以前未曾施用稀土的茶园，进行了不同时间喷施稀土对茶叶中不同状态的REE组成及含量影响的试验。 1 材料与方法 1.1 试验设计 |
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