大田县茶园土壤和茶叶中硒含量及影响因素分析

Factors Affecting Selenium Contents in Soil and Tea Leaves at Plantations in Datian City

采集大田县25个典型茶园0~20 cm和20~40 m两个土层土壤样品,同时采集了相应的茶叶样品(一芽二叶),分析茶园土壤和茶叶中硒含量及其影响因素。结果表明:0~20 cm土层,土壤全硒含量为0.99~4.19mg·kg^(-1)(均值为1.95 mg·kg^(-1)),远高于全国土壤硒含量平均值(0.29 mg·kg^(-1))和福建省土壤硒含量背景值(0.55 mg·kg^(-1)),属于富硒土壤;土壤有效硒含量为0.015~0.78 mg·kg^(-1)(均值为0.18 mg·kg^(-1)),土壤硒活化率为1.1%~41.3%(均值为10.3%),土壤中硒活化率较低。两个土层之间土壤硒及有效硒含量变化不明显。大田县茶园土壤属于富硒土壤,土壤供硒潜力巨大,但是硒活化率较低,生产富硒茶必须提高土壤中硒的可利用度。供试茶叶硒含量为0.023~0.087 mg·kg^(-1)(均值为0.057 mg·kg^(-1)),均未达到天然富硒茶标准(>0.25 mg·kg^(-1))。茶叶硒含量与土壤有效硒含量呈显著正相关,土壤有效硒及活化率与土壤有机质和全氮之间呈显著或极显著正相关性。

Factors affecting the selenium （Se） contents in tea plantation soil and tea leaves of the bushes grown on it were investigated with a field study in Datian city. Soil samples from the depths of 0-20 cm and 20-40 cm at 25 typical tea plantations and one-bud-2-leaves tea leaf samples from the bushes at the same site were collected for Se analysis. It was found that in the 0-20 cm soil layer the Se content ranged from 0.99 to 4.19 mg·kg^-1 with a mean of 1.95 mg·kg^-1 , which was higher than the national average of 0.29 mg·kg^-1 or that of Fujian province at 0.55 mg·kg^-1 . The available Se in soil were 0.015-0.78 mg·kg^-1 averaging 0.18 mg·kg^-1 . The Se activating rate ranged from 1.1% to 41.1% with a mean of 10.3%. The total and available Se in the 0-20 cm and 20-40 cm layers did not differ significantly. The soil in Datian was rich in Se but low on activating rate, therefore, it was no surprise to find that the Se content in the tea leaves was only 0.023-0.087 mg·kg^-1 with a mean of 0.057 mg·kg^-1 which did not reach the standard for a natural Se-enriched tea of 0.25 mg·kg^-1 . There was a significant correlation between the available Se in soil and Se in tea leaves, as well as one between the available Se or Se activating rate and the organic matters and total nitrogen contents in the soil.