赣南地区水稻-根系土系统中硒含量影响因素分析

硒是人体必需微量元素之一,而水稻作为我国第一大主粮,其硒含量的高低与人体健康关系密切,因此研究水稻-根系土体系中硒含量的影响因素,可为富硒地区水稻种植及开发富硒农业提供科学理论依据。以赣南为研究区,采集138组水稻籽实及配套根系土样品进行了测试分析,探究赣南地区土壤理化条件对硒在水稻及其根系土中的实际影响效应,对富硒水稻及土壤进行质量综合评价,并构建富硒水稻地球化学适生模型。结果表明:赣南地区水稻根系土Se平均质量分数为0.29mg/kg,Se水平主要为足硒水平,富硒土壤仅占14.5%;有效硒(Sebio)质量分数平均为46.0μg/kg,占总硒质量分数的16.44%;水稻的Se平均质量分数为0.05mg/kg,无重金属元素超标的安全富硒水稻率达到45%,富硒水稻对Cd,Zn,Cu的生物富集能力较强。相关分析表明,根系土中Se质量分数与TFe2O3,MnO,MgO,有机碳(Corg)质量分数呈极显著正相关,与主要重金属元素存在一定程度的伴生关系。水稻Se质量分数与根系土Se,Sebio,SiO2质量分数和pH值呈极显著正相关,与Al2O3,有机碳(Corg)质量分数呈极显著负相关。单项污染指数表明研究区根系土中重金属元素基本属于清洁和尚清洁水平,Cd,Pb,As,Hg,Cu存在一些样品超标,其中Cd超标率最高;内梅罗综合污染指数表征77.0%的样品属于安全等级;富硒土壤综合评估显示研究区主要为良级富硒土壤,优级富硒土壤仅占8.7%。通过最佳子集回归分析最终选取了根系土总Se、有机质、pH值为自变量构建富硒水稻地球化学适生模型,拟合的模型可以解释水稻中Se30.6%的变异。

Analysis of Influencing Factors of Selenium Content in Rice-Root Soil System in Southern Jiangxi

Selenium is one of the essential trace elements for human body, and rice is the largest staple food in China. Its selenium content is closely related to human health. Therefore, the study of the influencing factors of selenium content in rice-root soil system can provide scientific basis for rice cultivation and development of selenium-rich agriculture in selenium-rich areas. Taking southern Jiangxi as the research area, this study collected 138 groups of rice and supporting root soil samples for testing and analysis, and explored the effect of soil physical and chemical conditions on selenium in rice and its root soil was explored. The study evaluated comprehensively the quality of selenium-rich rice and soil and constructed the geochemical fitness model of selenium-rich rice. The results show that the Se content of rice root soils in southern Jiangxi is of mainly sufficient Se level, with the Se content in the Se-enriched soil only 14.5%, and the Se content in the Se-enriched soil 0.29 mg/kg. The average effective selenium (Se bio ) is 46.03 μg/kg, accounting for 16.44% of the total selenium content, while the average Se content in rice seeds is 0.05 mg/kg. The safe Se-enriched rice without heavy metals exceeds the standard, up to 45%. Selenium-enriched rice has strong bioaccumulation ability for Cd, Zn and Cu.The correlation analysis shows that the content of Se in root soil is positively correlated with TFe 2O 3, MnO, MgO and C org , and is associated with major heavy metal elements to some extent. Se content in rice is positively correlated with Se, bio-Se, SiO 2 and pH in root soil, negatively correlated with Al 2O 3, C org .Single factor index of soils indicates that the heavy metals in root soils of the study area belong to the clean monk level, and Cd, Pb, As, Hg and Cu exceeds the standard to a certain extent, among which Cd is the main exceeding elements;Nemerow multi-factor indexes of soils indicate that 77% of the samples belong to the safety level. Selenium-rich soil comprehensive evaluation shows that the study area is mainly a good selenium-rich soil, with only 8.7% of the excellent selenium-rich soil. Through the best subset regression analysis, the total Se, organic matter and pH of root soil were selected as independent variables to construct the geochemical fitness model of Se-rich rice. The fitted model could explain 30.6% variation of Se in rice.