College of Environmental Science and Engineering, Guilin University of Technology, Guilin, China.
Innovation Center of Yangtze River Delta, Zhejiang University, Zhejiang 311400, China.
Ecotoxicol Environ Saf. 2023 Sep 15;263:115380. doi: 10.1016/j.ecoenv.2023.115380. Epub 2023 Aug 17.
The roots of hyperaccumulators can significantly alter soil pH and thus change the chromium (Cr) availability in the rhizosphere. The pH dynamics in the rhizosphere of Cr hyperaccumulator Leersia hexandra Swartz remains unknown. In this study, the spatial dynamics of pH in the rhizosphere of L. hexandra at different Cr exposure were examined using planar optode (PO). The effects of different Cr concentrations on the biomass, physiological parameters, and soil enzyme activity were investigated. The results showed that pH in the rhizosphere of L. hexandra was highly heterogeneous and followed the root shape. There were obvious soil acidification in all groups and the average pH values in the control, Cr50, and Cr100 groups decreased by 0.26, 0.27, and 0.35 pH unit, respectively. At a certain concentration (50 mg kg), Cr significantly increased the plant height and biomass of L. hexandra compared to the control (p < 0.05). The concentrations of chlorophyll a, chlorophyll b, and total chlorophyll in the leaves increased with increasing Cr concentrations. The acid phosphatase, urease, and catalase activities in the rhizosphere were higher than those in the bulk soil. These results provide new insights into elucidating the hyperaccumulating mechanism of Cr and improving the phytoremediation efficiency.
超积累植物的根系可以显著改变土壤 pH 值，从而改变根际铬（Cr）的有效性。铬超积累植物犁头尖（Leersia hexandra Swartz）根际 pH 值的动态变化尚不清楚。本研究采用平面光极（PO）技术研究了不同 Cr 暴露下犁头尖根际 pH 值的空间动态变化。研究了不同 Cr 浓度对生物量、生理参数和土壤酶活性的影响。结果表明，犁头尖根际 pH 值高度不均匀，且遵循根的形状。所有组均出现明显的土壤酸化，对照、Cr50 和 Cr100 组的平均 pH 值分别降低了 0.26、0.27 和 0.35 pH 单位。在一定浓度（50mgkg）下，Cr 显著增加了与对照相比犁头尖的株高和生物量（p<0.05）。叶片中叶绿素 a、叶绿素 b 和总叶绿素的浓度随着 Cr 浓度的增加而增加。根际的酸性磷酸酶、脲酶和过氧化氢酶活性高于体相土壤。这些结果为阐明 Cr 的超积累机制和提高植物修复效率提供了新的见解。
