摘要
采用盆栽方法模拟土壤Cd污染状况,研究接种丛枝菌根真菌对紫羊茅生长及对Cd吸收、分配的影响.结果表明,土壤加Cd15～50mg·kg-1对菌根侵染率无显著影响;在不加Cd的土壤中,接种菌根真菌有助于Cd的吸收和向地上部的运输;在Cd污染土壤中,接种菌根真菌并未明显改善紫羊茅的磷营养状况,并且也没有明显增加紫羊茅的生物量,但是地上部的Cd浓度和吸收量均显著低于不接种的处理,其原因是菌根真菌强化了Cd在紫羊茅根系的固持作用,减少Cd在地上部的分配比例,从而降低了紫羊茅地上部对Cd的积累.试验还观察到,不同菌根真菌对紫羊茅吸Cd量的影响具有一定差异,Glomusintraradices在Cd污染的土壤中对Cd吸收的抑制效应大于Glomousmosseae.这些结果一方面说明菌根真菌侵染是紫羊茅地上部Cd含量减少的直接原因,同时也反映出在自然生态系统中,作为污染物由土壤环境进入食物链系统的门户之一的丛枝菌根真菌在调节生态系统中重金属Cd的生物循环、减轻重金属Cd对食物链的污染风险方面发挥着重要作用.
Effect of arbuscular mycorrhizal fungi on cadmium uptake and translocation in Festuca rubra Linn. plant was investigated with a pot culturing method in greenhouse. Cadmium was added to a sandy loam soil as CdSO_4·8H_2O at 0,15, and 50?mg·kg^(-1). The soils had been precultured for three weeks before sowing the plant seeds. Two AM fungi, Glomus mosseae (BEG168) and Glomus intraradices (BEG141) were inoculated into plants, while a non-inoculating control was set up. The plants were harvested three times at 70?d, 105?d and 210?d respectively after sowing. At the first and second harvests, only shoots were cut, and at the third time , both shoots and roots were harvested. Three replications were set for each treatment. Mycorrhizal colonization, dry weight of plant, P concentration and Cd concentration were measured. The results showed that the addition of 15 and 50?mg·kg^(-1) Cd in soil did not reduce mycorrhizal colonization. P concentration in shoot of Festuca rubra plant was not significantly affected by inoculating with the both AM fungal species, while the dry weights of Festuca rubra plant with mycorrhizal fungi were lower than that of non-mycorrhizal plant. Under Cd contaminated soil condition, arbuscular mycorrhizal fungi strengthened the bio-fixity of Cd in root and reduced Cd translocation from root to shoot, which induced decreasing of Cd concentration in shoot in all three harvests and root at the final harvest furthermore. The total accumulation of Cd in both shoot and root in mycorrhizal plants was also lower than that of non-mycorrhizal plants. For example, at 50?mg·kg^(-1) Cd level, Cd concentration and Cd uptake in mycorrhizal plants were decreased 50% and 60% respectively comparing with non-mycorrhizal plant. The two fungal species showed different effectiveness in reducing Cd concentration in plant shoot. The relative reducing rate of G. mosseae was 25%, while G. intraradices was 52%～55% at the same two Cd addition levels. The results implied that mycorrhizal fungi colonization might be the direct cause for the reduction of Cd uptake in Festuca rubra. It was concluded that arbuscular mycorrhizal fungi, one of the entrances for contaminants from soil environment to food chain, played a crucial important role in regulating Cd bio- recycling in ecosystem and in alleviating the stress of Cd contamination on food chain.
出处
《环境科学学报》
CAS
CSCD
北大核心
2004年第6期1122-1127,共6页
Acta Scientiae Circumstantiae
基金
国家自然科学基金(30370818)
科技部"863"(2001AA645010 4)资助项目
