| Wuyi Rock tea(Camellia sinensis),as one of the oolong tea series,is a famous tea product at home and abroad as the special reputation for its rock-charm.However,the annotation,chemical basis of the rock-charm and the relationship of the tea rock-charm and the tea plantations were unknown yet.In this paper,three conservation zones of tea germplasms with the governmental qualification in Wuyishan county,i.e.a genuine-rock-zone of Yu tea plantation,a semi-genuine-rock-zone of Guiyan tea plantation,and a non-genuine-rock-zone of Qishan tea plantation,were chosen as research sites,and three most famous and popular tea cultivars(Camellia sinensis),i.e.Dahongpao,Shuixian,and Rougui,were used as representative tea materials.The chemical indexes,soil enzymes,and trace elements of rhizosphere soils from the 3 cultivars in three plantations were measured.The growth indexes,photosynthesis indexes of tea leaves,and the chemical components and volatiles,as well as the trace elements in tea leaves were determined.And the relationships between the soil characteristics of tea plantations and the quality of fresh tea leaves were further analyzed and compared for valuations.The results were summarized as follows:(1)The pH values,contents of nitrogen,phosphorus and potassium,and organic matter in rhizosphere soils of the 3 cultivars in three plantations were almost get to the first level of fertilizer for tea culture.By cluster analysis,the soil indexes of Yu tea plantation and Guiyan tea plantation were similar,while they were significant different to Qishan tea plantation.The soil indexes of Qishan tea plantation were the lowest,showing the available potassium and organic matter in rhizosphere soils were the second level and the three level of fertilizer,respectively for tea culture.(2)The number of leaves,bud density,leaf area,one-hundred-bud weight,and product were significant different in the same cultivars between the 3 tea plantations.The net photosynthetic rate,stomatal conductance,intercellular CO2 concentration,transpiration rate,and chlorophyll content in tea leaves were Yu plantation>Guiyan plantation>Qishan plantation.(3)The contents of aqueous extracts,tea polyphenol,and soluble sugar in the 3 tea leaves were Yu plantation>Guiyan plantation>Qishan plantation and were significant different between tea plantations.The contents of free amino acid in the 3 tea leaves were Guiyan plantation>Yu plantation>Qishan plantation and were significant different between tea plantations.And the contents of caffeine in the 3 tea leaves were Qishan plantation>Yu plantation>Guiyan plantation and were significant different between tea plantations.(4)The composition of 8 catechins in tea leaves were almost significant different and were Yu plantation>Guiyan plantation>Qishan plantation.The contents of epigallocatechin gallate(EGCG)were significant different both in the 3 tea plantations and in the 3 tea cultivars.The contents of EGCG was significant high in the genuine-rock-zone than that in the non-genuine-rock-zone.The astringency index(4 ester catechins/8 catechins)were little differences between plantations and cultivars.(5)The composition of 18 free amino acids in tea leaves were almost significant different and were Guiyan plantation>Yu plantation>Qishan plantation.The 11 out of the 17 hydrolytic amino acids,accounting for 64.83·74.84%,were significant different,and it was>74%in Yu plantation,>70%in Guiyan plantation,and ?65%in Qishan plantation.The fresh and brisk index(theanine/18 free amino acids)were Yu plantation>Guiyan plantation>Qishan plantation.The fresh and brisk index of the 3 cultivars was similar grown in Yu plantation,however,it were significant lower when grown in Guiyan plantation and Qishan plantation.(6)The numbers and contents of tea volatiles in leaves were Yu plantation>Guiyan plantation>Qishan plantation.There was a great difference in contents of hotrienol compound between plantations and cultivars.The hotrienol index(hotrienol/terpenoids in total)were Yu plantation>Guiyan plantation>Qishan plantation.It was suggested that hotrienol index might be a represent compound which incarnate the special rock-charm of Wuyi rock tea,and it could better distinguish tea leaves from the different rock-zone.(7)The results of trace elements indicated that Cu,Mn and Mg have high correlations among the rock,soils and tea leaves,and have positive-significant correlations with the quality of tea leaves.The three elements,Cu,Mn and Mg,were recommended as the most potential candidate for geographical indications of tea products from the genuine-rock-zone.In summary,based on the results above,we confirmed the cultivars of Wuyi rock tea grown in different rock-zones could have different qualities,and the tea qualities have significant correlations with the soil characteristics.We proposed that the fresh and brisk index,on account of the ratio of theanine:18 free amino acids,and the hotrienol index,on account of the ratio of hotrienol:terpenoids in total,could be as qualities indexes for evaluating tea leaves grown in the different rock-zone.We also recommended Cu,Mn and Mg as the potential candidate for geographical indications in Wuyi rock tea.These results will supply the research foundation and scientific basis for the culture,management,and quality identification of Wuyi rock tea,as well as the geographical indication. |
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