School of Environment, Key Laboratory of Environmental Pollution and Health of Guangdong Province, Jinan University, Guangzhou, 510632, China.
Department of Ecology, Jinan University, Guangzhou, 510632, China.
Environ Sci Pollut Res Int. 2018 Dec;25(36):36328-36340. doi: 10.1007/s11356-018-3566-x. Epub 2018 Oct 27.
Chinese flowering cabbage is a commonly consumed vegetable that accumulates Cd easily from Cd-contaminated soils. Cultivations of low-Cd cultivars are promising strategies for food safety, but low-Cd-accumulating mechanisms are not fully elucidated. To address this issue, 37 cultivars were screened to identify high- and low-Cd cultivars upon exposure to sewage-irrigated garden soil pretreated with different Cd concentrations (1.81, 2.90, and 3.70 mg kgdry soil). The results showed that shoot Cd concentrations differed among the cultivars by maximum degrees of 2.67-, 3.71-, and 3.00-fold under control and treatments, respectively. Soil-pot trial and hydroponic trial found no significant difference in Cd and Ca mobilization, uptake, and transport ability by root per weight between high- and low-Cd cultivars. Interestingly, a stable R/S ratio difference among cultivars (p < 0.01) was observed, and the cultivar variation of Cd accumulation in shoots was mainly dependent on their R/S ratios. R/S ratio was also statistically positively associated with Cd and Ca accumulation in high- and low-Cd cultivars (p < 0.05), both in soil and hydroponics culture. This was mainly due to the lower root biomass of low-Cd cultivars resulted in lower total release of root exudates, lower total Cd and Ca mobilization in rhizosphere soil, and lower total Cd and Ca uptake and transport. The higher shoot biomass of low-Cd cultivars also has dilution effects on Cd concentration in shoot. Overall, low R/S ratio may be regarded as a direct and efficient indicator of low Cd accumulation in the shoot of Chinese flowering cabbage. These findings provided the possibilities to screening low-Cd cultivars using their R/S ratio.
芥蓝是一种常见的食用蔬菜，容易从受镉污染的土壤中积累镉。种植低镉品种是保障食品安全的一种有前景的策略，但低镉积累的机制尚未完全阐明。为了解决这个问题，本研究在不同镉浓度（1.81、2.90 和 3.70 mg kg-1干土）预处理的污水灌溉菜园土中筛选了 37 个品种，以鉴定高镉和低镉品种。结果表明，在对照和处理条件下，各品种地上部镉浓度的差异最大分别达到 2.67、3.71 和 3.00 倍。土培和水培试验发现，高镉和低镉品种间根每单位重量对镉和钙的迁移、吸收和转运能力没有显著差异。有趣的是，各品种间的稳定 R/S 比值差异显著（p<0.01），而且地上部镉积累的品种变异主要取决于其 R/S 比值。R/S 比值与高镉和低镉品种在土壤和水培培养中的镉和钙积累均呈显著正相关（p<0.05）。这主要是由于低镉品种的根生物量较低，导致根系分泌物的总释放量较低，根际土壤中镉和钙的总迁移量较低，以及镉和钙的总吸收和转运量较低。低镉品种地上部生物量较高也对地上部镉浓度有稀释作用。总之，低 R/S 比值可作为直接有效的指标，用于筛选地上部镉积累量低的芥蓝品种。这些发现为利用 R/S 比值筛选低镉品种提供了可能。
