College of Resources and Environment, Yunnan Agricultural University, Kunming, 650201, China.
College of Horticulture and Landscape, Yunnan Agricultural University, Kunming, 650201, China.
Bull Environ Contam Toxicol. 2021 Dec;107(6):1059-1064. doi: 10.1007/s00128-021-03361-x. Epub 2021 Aug 30.
This study assessed how the Sonchus asper L.-Zea mays intercropping influenced the plant Cd level, as well as the organic acid (low molecular mass) types and concentrations in root secretions, which was accomplished by conducting pot experiments with soil that was collected from a farmland surrounding a mining area. The results showed that the oxalic and citric acids were the prevailing organic acids in the plant root secretions, and that the intercropping led to prominently elevated root exudate concentrations of the two acids for S. asper by 43.8 and 75.4%, respectively, while decreased such concentrations by 18.5 and 18.7% for Z. mays, compared to monoculture. According to observations, the root exudate concentrations of citric and oxalic acids were significantly positively related to the available rhizosphere soil Cd and plant Cd. The results indicate that changes in root exudation of oxalic acid and citric acid result in different available Cd contents of the rhizosphere soil, thereby affecting the bioavailability of soil Cd, which increases Cd uptake and accumulation in S. asper but inhibits Cd accumulation in Z. mays.
本研究通过在矿区周边农田采集土壤进行盆栽实验，评估了苦苣菜-玉米间作对植物 Cd 含量以及根系分泌物中有机酸（低分子量）类型和浓度的影响。结果表明，草酸和柠檬酸是植物根系分泌物中主要的有机酸，与单作相比，间作分别使苦苣菜的根分泌物中草酸和柠檬酸浓度显著增加了 43.8%和 75.4%，而玉米的这两种有机酸浓度则分别降低了 18.5%和 18.7%。根据观察，柠檬酸和草酸的根分泌物浓度与可利用根际土壤 Cd 和植物 Cd 呈显著正相关。结果表明，草酸和柠檬酸的根分泌物的变化导致根际土壤中 Cd 的有效性不同，从而影响土壤 Cd 的生物有效性，这增加了苦苣菜对 Cd 的吸收和积累，但抑制了玉米对 Cd 的积累。
