AMF对玉米生长、根系低分子有机酸分泌与Cd累积的影响

Effects of AMF on growth,low-molecular-weight organic acids secreted by roots,and Cd uptake in maize

为探讨铅锌矿区丛枝菌根真菌(Arbuscular Mycorrhizal Fungi,AMF)的生态功能,采用云南会泽铅锌矿区周边镉(Cd)污染的农田土壤,开展根袋盆栽试验,研究接种AMF对玉米生长、矿质营养、根系低分子有机酸分泌和Cd累积的影响。结果表明:接种AMF促进玉米生长,显著提高光合速率、株高和生物量;增加植株对氮、磷、钾的吸收,增幅达14.2~19.1倍;并促进根系分泌酒石酸、苹果酸、草酸和琥珀酸,分泌量增幅为1.1~3.8倍。此外,接种AMF使玉米根际铁锰氧化态Cd含量显著增加22.5%,有机结合态Cd含量显著降低12.8%,但交换态和有效态Cd含量无显著变化。接种AMF使玉米地上部和根系Cd含量显著降低,降幅分别为32.7%和77.9%,但地上部和根系Cd累积量显著增加,分别增加了12.5倍和25.8%。相关性分析发现,玉米地上部Cd累积量与草酸、酒石酸、苹果酸、琥珀酸分泌量和铁锰氧化态Cd含量呈极显著正相关。可见,AMF能促进玉米养分吸收,调节根系低分子有机酸分泌与根际Cd形态,降低植株Cd含量,从而促进植株生长。

The ecological functions of arbuscular mycorrhizal fungi(AMF)were explored by investigating its effects on maize growth,mineral nutrition,low-molecular-weight organic acid secretion,and Cd uptake via a root-bag experiment in soil polluted with Cd in the Huize lead-zinc mining area of Yunnan Province.The results showed that AMF promoted maize growth and significantly increased photosynthetic rate,plant height,and biomass.The absorption of N,P,and K increased by 14.2-19.1-fold,and tartaric acid,malic acid,oxalic acid,and succinic acid secretion by roots increased by 1.1-3.8-fold.In addition,AMF resulted in a significant increase of 22.5%in iron-and manganese-oxidized Cd content and a significant decrease of 12.8%in organic-bound Cd content in the maize rhizosphere,but no significant change in exchangeable and available Cd content was observed.AMF significantly reduced maize shoot and root Cd content by 32.7%and 77.9%,respectively,but significantly increased Cd accumulation in maize shoot and root by 12.5-fold and 25.8%,respectively.Correlation analysis showed that shoot Cd accumulation presented extremely significant positive correlations with oxalic acid,tartaric acid,malic acid,and succinic acid secretion,and iron-and manganese-oxidized Cd content.Thus,these results showed that AMF can promote the absorption of nutrients in maize,regulate the secretion of low-molecular-weight organic acid and Cd form in the rhizosphere,and reduce maize Cd content,thereby promoting plant growth.