外源施硒对小白菜硒富集与土壤生物活性的影响

Effects of selenium fertilization on selenium uptake of pakchoi and soil biological activities

硒是人和动物生长发育必需的微量营养元素,具有增强免疫、抗癌及抗衰老等功效,但同时也是一种环境毒素。外源施硒是提高作物硒浓度的常见措施,然而目前其对土壤生物活性方面的影响关注较少。本研究采用盆栽试验,探讨了不同形态(亚硒酸钠、氨基酸螯合态硒)与水平(土壤硒含量3 mg/kg和6 mg/kg)硒肥施用对小白菜硒富集、土壤微生物群落及酶活性的影响。结果表明:1)外源硒添加水平越高,小白菜硒富集效果越明显。同等硒添加水平下,亚硒酸钠处理小白菜硒富集的效果显著优于氨基酸螯合态硒处理。2)外源硒低量施用时对土壤微生物生物量没有显著影响,高量施用时显著降低土壤微生物生物量。3)高低量亚硒酸钠施用对土壤β-乙酰葡糖胺糖苷酶(NAG)与碱性磷酸酶(ALP)活性影响均不明显;氨基酸螯合态硒则是在低量施用时无影响而高量施用时显著提升土壤NAG、ALP酶活性。总体而言,外源施硒对小白菜硒富集的影响与硒形态和硒施用水平均密切相关,而对土壤生物活性的影响则取决于硒施用水平而非硒形态。

Selenium(Se),an essential trace element for human and animals,plays important roles in enhancing immunity,fighting cancer and aging,but it is also an environmental toxicant.Application of Se-containing fertilizers is a common practice to increase Se concentration of crops.So far,however,little attention has been paid to the impact of Se application on soil biological activities.A pot experiment was conducted to investigate the effects of Se application on Se accumulation in pakchoi,soil microbial community and enzyme activities.Se was applied with different forms(i.e.selenite and amino acid-chelated Se)and levels(0,3 and 6 mg/kg soil).The results showed that 1)Se accumulation in pakchoi increased with the application rates of exogenous Se.At the same level of Se addition,more Se accumulation in pakchoi was observed under selenite than under amino acid-chelated Se treatments.2)No significant responses of soil microbial biomass were observed to lower rate of Se fertilization,while higher rate of Se fertilization significantly reduced soil microbial biomass.3)Applications of selenite with both 3 and 6 mg/kg soil had no significant effects on theactivies of soil β-N-acetylglucosaminidase(NAG)and alkaline phosphatase(ALP).For amino acid-chelated Se application,lower rate did not alter but higher rate significantly stimulated the activities of soil NAG and ALP.Overall,the effect of Se fertilization on Se accumulation of pakchoi is highly dependent on both Se form and its application rate,while the impact of Se fertilization on soil biological activities largely depends on Se application rate,rather than Se form.