茶树根际与非根际土壤硒特性及其影响因素分析

Characteristic differences of selenium in the rhizospheric and non-rhizospheric soils of tea plantations, and its influencing factors

茶树根际效应影响茶园土壤的化学组成及特性。通过对江苏宜兴南部丘陵山区富硒茶园根际与非根际土壤采样调查,比较茶树根际与非根际土壤硒特性,并探讨其与土壤化学性质的相关性,为富硒土壤地区开发生产富硒茶叶提供依据。结果表明:大部分茶园茶树根际土壤全硒、有效硒含量及硒的活化率均高于非根际,茶树根际对土壤硒具有一定程度的富集与活化效应;根际土壤全硒含量与非根际土壤全硒含量有关,而茶树非根际土壤有机质对土壤硒有一定的固持作用,所固持的硒可作为根际土壤硒的来源,有利于根际硒的积累。根际土壤有效硒含量与全硒含量呈极显著正相关(P<0.01),相关系数达0.938;土壤p H、全磷、速效磷含量未对根际硒的活化效应起主导作用,但根际p H的降低具有降低有效硒含量的趋势。茶树根际特殊的聚铝特性对土壤硒形态具有一定影响,其中以交换态铝(Ex-Al)对硒特性的影响最为显著,Ex-Al决定着土壤潜在酸度,影响土壤硒的有效性,根际土壤Ex-Al的增加使这一影响更显著,与根际土壤全硒、有效硒含量呈显著负相关(P<0.05),相关系数分别为-0.646、-0.659。为提高茶树根际土壤对硒素的利用,应重视茶园土壤酸化、铝毒问题,增加土壤有机质含量,同时调控土壤p H,降低Ex-Al含量,以利于增加根际土壤全硒、有效硒含量。

The"rhizosphere effect"of plants has been widely understood.However,there are few studies on the characteristics of selenium in the rhizosphere and the bulk soil of tea gardens,where the soils are acidic,selenium-enriched,and aluminum-enriched.In this study,the content and availability of selenium in the rhizosphere and the bulk soil from tea plantations,together with the chemical properties of the soil,were investigated.The contents of total selenium,available selenium,and the activation rate of selenium were higher in the rhizospheric soil,than in the bulk soil.The enrichment and activation of selenium occurred in the rhizospheric soil.The total selenium in the rhizospheric soil was related to that of the non-rhizospheric soil.The organic matter of non-rhizospheric soils could fix soil selenium,the primary source of rhizospheric selenium.The available selenium in rhizospheric soils had a significant positive correlation with the total selenium(P<0.01),with a correlation coefficient of 0.938.The pH,total phosphorus,and available phosphorus had little effects on the activation of rhizospheric selenium.The decrease in soil pH could reduce the available selenium in the rhizospheric soil.In addition,the exchangeable aluminum(Ex-Al)was negatively correlated to the total and available selenium in rhizospheric soils,with correlation coefficients of-0.646 and-0.659,respectively.Our results can provide strategies for the production of selenium-enriched tea.