水稻籼粳品种对铊(I/III)吸收能力比较及根系草酸分泌特征

Comparison of Thallium (I/III) Absorption Capacity and Oxalic Acid Secretion Characteristics in Roots of Indica and Japonica Rice Varieties

摘要: 铊是一种高毒性的重金属元素，具有Tl(I)和Tl(III)两种价态，Tl(III)比Tl(I)毒性更强，通过植物富集进入食物链的方式严重威胁人类健康。本文通过水培方法培育4个籼粳水稻品种，利用两种价态铊进行处理，研究铊吸收量及水稻根系草酸分泌量的关系。结果表明：籼稻的黄广金占与中嘉早17、粳稻的日本晴与秀水123，在Tl(I)处理中的铊吸收量分别为0.21 mg•g⁻¹ FW与0.16 mg•g⁻¹ FW、0.19 mg•g⁻¹ FW与0.14 mg•g⁻¹ FW，水稻对Tl的吸收量与所属亚种并无明显关系；在Tl(III)处理中，这四种水稻的铊吸收量分别下降至0.18 mg•g⁻¹ FW与0.13 mg•g⁻¹ FW、0.17 mg•g⁻¹ FW与0.11 mg•g⁻¹ FW，均显著低于各品种在Tl(I)处理的铊吸收；对铊吸收量与草酸分泌量进行二次函数回归分析，相关系数r = 0.474，相关性低。表明两种价态铊处理下根系草酸分泌量对铊吸收的影响较小，水稻根系铊吸收受其他机制作用。

Abstract: Thallium is a highly toxic heavy metal element with two valence states of Tl(I) and Tl (III). Tl(III) is more toxic than Tl(I). It seriously threatens human health by entering the food chain through plant enrichment. In this paper, four indica and japonica rice varieties were cultivated by hydroponic method and treated with two kinds of valence thallium to study the relationship between thallium absorption and oxalic acid secretion of rice roots. The results showed that the thallium absorption of Indica Rice Huangguangjinzhan and Zhongjiazao 17, japonica rice Nipponbare and Xiushui 123 in Tl(I) treatment are 0.21 mg•g⁻¹ FW and 0.16 mg•g⁻¹ FW, 0.19 mg•g⁻¹ FW and 0.14 mg•g⁻¹ FW respectively. There is no significant relationship between the Tl absorption of rice and its subspecies; In Tl(III) treatment, the thallium absorption of the four kinds of rice decreased to 0.18 mg•g⁻¹ FW and 0.13 mg•g⁻¹ FW, 0.17 mg•g⁻¹ FW and 0.11 mg•g⁻¹ FW respectively, which are significantly lower than that of all varieties in Tl(I) treatment; the quadratic regression analysis of thallium absorption and oxalic acid secretion showed that the correlation coefficient is r = 0.474, and the correlation is low. The results showed that the secretion of oxalic acid in roots had little effect on thallium absorption under the treatment of two valence thallium, and thallium absorption in rice roots was affected by other mechanisms.