Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China; SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou, 510006, China.
Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
Chemosphere. 2020 Sep;254:126800. doi: 10.1016/j.chemosphere.2020.126800. Epub 2020 Apr 16.
The root soil interaction affects metal bioavailability in the rhizosphere, thus impacting the uptake and accumulation of metals by plants. In this study, a greenhouse experiment using a root-bag technique for castor bean plants was conducted to determine the i) rhizosphere effect on the fractions of Cu, and ii) the characteristics of dissolved organic matter (DOM) in the rhizosphere soil. Results showed that the Cu concentration in the leaves, stems, and roots was 15.41, 6.71, and 47.85 mg kg, respectively, in the control and reached up to 96.5, 254.9, and 3204 mg kg in Cu400 treatment, respectively. After cultivating castor bean plants, the concentration of acid exchangeable Cu in rhizosphere soil was higher than that in the bulk soil for the same Cu addition, whereas the concentrations of reducible Cu, oxidizable Cu, and residual Cu in the rhizosphere soil were all lower than those in the bulk soil, respectively. In comparison to the bulk soil, the pH decreased while the total nitrogen and total carbon concentrations both increased in the rhizosphere soil. Moreover, the concentrations of total low molecular weight organic acids (LMWOAs) and total amino acids in the rhizosphere soil of the Cu treatments increased by between 15.18% to 47.17% and 36.35%-200%, respectively with respect to the control. The less complex DOM with a high LMWOAs concentration in the rhizosphere soil shifted the soil Cu from a relative stable fraction to available fractions.
根际土壤相互作用会影响根际中金属的生物有效性，从而影响植物对金属的吸收和积累。本研究采用根袋技术在温室条件下种植蓖麻，以确定（i）根际效应对 Cu 形态的影响，以及（ii）根际土壤中溶解有机物质（DOM）的特征。结果表明，在对照处理中，叶片、茎和根中的 Cu 浓度分别为 15.41、6.71 和 47.85mgkg-1，而在 Cu400 处理中，Cu 浓度分别达到 96.5、254.9 和 3204mgkg-1。在种植蓖麻后，与对照相比，对于相同的 Cu 施加量，根际土壤中酸可交换态 Cu 的浓度高于非根际土壤，而根际土壤中可还原态 Cu、可氧化态 Cu 和残渣态 Cu 的浓度均低于非根际土壤。与非根际土壤相比，根际土壤的 pH 值降低，而总氮和总碳浓度均增加。此外，Cu 处理的根际土壤中总低分子量有机酸（LMWOAs）和总氨基酸的浓度分别比对照增加了 15.18%至 47.17%和 36.35%至 200%。根际土壤中 DOM 浓度降低，低分子量有机物浓度升高，导致土壤 Cu 从相对稳定的形态向有效形态转化。
