Vergara Cid Carolina, Oburger Eva, Preiner Julian, Pignata María L, Rodriguez Judith H
Instituto Multidisciplinario de Biología Vegetal, Área Contaminación y Bioindicadores, Universidad Nacional de Córdoba, CONICET, FCEFyN, Av. Vélez Sársfield 1611, X5016CGA, Córdoba, Argentina.
BOKU, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences, Konrad-Lorenz Strasse 24, A-3430, Tulln, Austria.
Chemosphere. 2020 Oct 13:128602. doi: 10.1016/j.chemosphere.2020.128602.
In the present study we assessed how modified rhizosphere pH and root exudation (total carbon (C) and soluble proteins released) affected lead (Pb) solubility as well as plant growth and Pb accumulation. A pot experiment with Pb polluted agricultural soils was performed, which involved growing two species, Capsicum annum (pepper) and Tagetes minuta, with the latter being a native herb indicated as potential phytoextractor of Pb, in monocrop and co-cropping conditions. Changes in plant growth, metal uptake as well as rhizosphere soil parameters (pH, EC) and total C and protein exudation were determined. In addition, the metal extraction efficiency of exudates released under mono- and co-cropped conditions were investigated. Results showed that in contrast to the control soil (with low Pb concentration), total C exudation was higher in co-cropping systems in Pb contaminated soils which lead to increases in Pb uptake in both species. Exudates originating from T. minuta were more efficient in solubilizing Pb than exudates from pepper when grown under mono-cropping conditions. Exudates derived from co-cropping both species were either equally or less efficient in mobilizing Pb than exudates from T. minuta. The capacity of exudates to mobilize metals was dependent not only on the species specific quality of root exudates released, but also on its quantity, with the metal extraction efficiency increasing with C concentration in exudates. However, the role of exuded proteins in Pb solubilization was found to be negligible. Biochemical interactions in the rhizosphere under co-cropping conditions favored metal solubilization, and consequently Pb accumulation. The co-cropping conditions could allow accumulation of Pb to levels in pepper that pose risks when the plants are used as a food source.
在本研究中，我们评估了改良的根际pH值和根系分泌物（释放的总碳（C）和可溶性蛋白质）如何影响铅（Pb）的溶解度以及植物生长和铅积累。我们进行了一项针对铅污染农业土壤的盆栽试验，该试验涉及在单作和间作条件下种植两种植物，即辣椒（Capsicum annum）和小花万寿菊（Tagetes minuta），后者是一种本地草本植物，被认为是铅的潜在植物提取剂。测定了植物生长、金属吸收以及根际土壤参数（pH值、电导率）和总碳及蛋白质分泌的变化。此外，还研究了单作和间作条件下释放的分泌物的金属提取效率。结果表明，与对照土壤（铅浓度低）相比，铅污染土壤中间作系统中的总碳分泌量更高，这导致两种植物对铅的吸收增加。在单作条件下生长时，小花万寿菊分泌的分泌物比辣椒分泌的分泌物在溶解铅方面更有效。两种植物间作产生的分泌物在调动铅方面的效率与小花万寿菊分泌的分泌物相同或更低。分泌物调动金属的能力不仅取决于释放的根系分泌物的物种特异性质量，还取决于其数量，金属提取效率随着分泌物中碳浓度的增加而提高。然而，发现分泌的蛋白质在铅溶解中的作用可以忽略不计。间作条件下根际的生化相互作用有利于金属溶解，从而有利于铅的积累。间作条件可能会使辣椒中的铅积累到一定水平，当这些植物用作食物来源时会带来风险。
