硒元素在茶园土壤和茶树内的富集规律

Enrichment Patterns of Selenium in Tea Plantation Soils and Tea Plants

植物是人体从土壤中摄入硒的重要媒介,而茶树是富集硒能力较强的植物,能将土壤中的硒富集储存在茶树植株内,因此研究茶树对土壤中硒的吸收富集机制对人类健康具有重大意义。采集贵州省遵义市正安县两处茶园(茶园1、茶园2)的25份土壤样品和15株茶树样品,测定了土壤中总硒含量和茶树各部位硒含量,并对连续浸提法提取的土壤中各形态硒含量进行了检测,比较了两处茶园土壤的pH值和养分含量,分析了两处茶园生产富硒茶叶的潜力。结果表明:遵义市两处茶园土壤均为酸性土壤,pH值范围为3.7~5.5,适宜茶树种植;两处茶园均有土壤样品达到富硒土壤标准(硒含量>0.4 mg/kg);土壤中的硒以残渣态为主(百分比含量超75%),其生物利用度低;天然条件下硒主要富集在茶树的老叶中,根部基本无硒的积累;茶园1有55.6%的嫩叶样品硒含量(0.2~4.0 mg/kg)处于富硒茶叶标准,可认定为富硒茶叶,说明茶园1具有良好的生产富硒茶叶的潜力;茶园2土壤pH值更适宜、总硒含量更高,但因无人管理而无富硒茶叶产出,建议后续对茶园2进行合理开发利用。

Plants are the important medium for human body to absorb selenium from soil,and a tea plant is a plant with strong ability to accumulate selenium in soil,which can enrich and store selenium in soil.Therefore,it is of great significance for human health to study the mechanism of selenium absorption and enrichment in soil.25 soil samples and 15 tea plant samples were collected from two tea plantations(Tea Plantation 1 and Tea Plantation 2)in Zheng'an County,Zunyi City,Guizhou Province.The total selenium content in the soils and the selenium content of each part of the tea plants were determined,and the selenium content of each form in the soils extracted by sequential extraction method were examined.The pH value and nutrient content of the two tea plantations were compared,and the potential of the two tea plantations to produce selenium-rich tea were analyzed.The results show that the soils of both tea plantations in Zunyi city are acidic,with pH values ranging among 3.7~5.5,which are suitable for tea planting.Both tea plantations have soil samples that meet the standard for selenium-rich soil(selenium content>0.4 mg/kg);the selenium in the soil is predominantly in the residue form(>75%in percentage)and has low bioavailability.It is found that selenium is mainly enriched in the old leaves of tea plants under natural conditions,and the roots basically have no accumulation of selenium;the selenium content of 55.6%of the young leaf samples from Tea Plantation 1 is at the standard for selenium-rich tea(0.2~4.0 mg/kg),which can be identified as selenium-rich tea,indicating that Tea Plantation 1 has good potential for producing selenium-rich tea.Tea Plantation 2 has more suitable soil pH value and higher total selenium content,but no selenium-rich tea is produced due to unmanagement,so it is recommended that Tea Plantation 2 should be reasonably exploited subsequently.