接种AM真菌对黑麦草吸收和分配Cd的影响

Effect of Arbuscular Mycorrhizal Fungi on Uptake and Distribution of Cadmium in Lolium L.

采用盆栽实验方法模拟不同程度的Cd污染状况,研究接种丛枝菌根(AM)真菌对黑麦草生长和耐Cd毒性的影响。结果表明,土壤中Cd水平提高,明显增加了黑麦草的菌根侵染率,但对其生长无显著影响,表明黑麦草在磷营养和生长上对丛枝菌根真菌依赖性较小。Glomusmosseae和Glomusintaradices对Cd毒害均具有一定耐性,它们的存在明显促进了黑麦草对重金属Cd的吸收,强化了Cd在根系中的固持作用,进而减少了Cd向地上部的分配比例,减轻了Cd对地上部的毒害。这一特性对于Cd污染土壤的改良和牧草品质的保持具有重要意义。

For understanding the leading mechanism of arbuscular mycorrhizae (AM) mediated alleviation of cadmium phytotoxicity, and investigating on the possible application of mycorrhizal symbiosis in bioremediation of contaminated soils, the role of arbuscular mycorrhizae in metal translocation from soil to plant was studied under simulated contaminations on a sandy loam soil. Mycorrhizal effects on plant growth and Cd uptake by Lolium L. inoculated with AM fungi Glomus mosseae, Glomus intraradices were determined in pot experiments under three Cd addition levels (0,15,50 mg·kg-1). Plants were harvested three times at 70 d, 105 d and 210 d respectively after sowing. Only shoots were reaped at the first and second harvests, but both shoot and root were harvested at the third time. These two AM fungi showed some endurance to Cd contamination in soil, since the addition 50 mg·kg-1 Cd in soil didn't decrease mycorrhizal colonization. P concentration in shoot of ryegrass plant was not significantly affected by inoculation with AM fungi, so did the dry weights of ryegrass plant, implying low mycorrhizal dependency of ryegrass on AM fungi. In Cd contaminated soils, AM fungi didn't increase Cd concentration in shoot, but strengthened the bio-fixing of Cd in root and reduced Cd translocation from root to shoot. The distribution proportion of Cd in mycorrhizal plants shoot was lower than that of non-mycorrhizal plants. AM fungus could adjust the distribution proportion of Cd in host plant and protect host plants against heavy metal contamination. These functional characters of AM fungi could play a great role in the melioration and the quality keeping of Cd contaminated pasture soil.