Rhizobium sp.W33对不同植物吸收铜和根际分泌物的影响

通过盆栽试验,采用1株植物促生细菌Rhizobium sp.W33接种黑麦草、狼尾草、高羊茅、紫花苜蓿、猪屎豆、油菜和印度芥菜等7种不同植物,考察了Cu胁迫下菌株对植物生物量、Cu含量和根际土壤中分泌物的影响,并筛选根瘤菌-植物联合修复重金属污染土壤的组合体系,以期初步探明细菌-植物联合修复重金属污染土壤的机制.结果表明,接种Rhizobium sp.W33后,有5种植物的干重增加了11%~56%,增加幅度为印度芥菜黑麦草高羊茅狼尾草油菜,紫花苜蓿和猪屎豆的干重下降.黑麦草、狼尾草、高羊茅和猪屎豆根内Cu含量接近或超过1000mg·kg-1,Cu大量积累在植物根部.Rhizobium sp.W33能够显著促进黑麦草吸收Cu(p0.05),并提高其对Cu的富集系数和转移系数,增加根部和地上部的Cu总量.苹果酸是供试植物-细菌联合修复Cu污染土壤的主要有机酸种类,接种根瘤菌W33后黑麦草、狼尾草根际的苹果酸和水溶性糖含量降低,过氧化氢酶活性增加,其中,苹果酸、水溶性糖含量与黑麦草中Cu含量呈显著相关性(p0.05).因此,根瘤菌W33-黑麦草联合体系修复重金属Cu污染土壤的效果最好,具有应用于重金属Cu污染土壤稳定修复的潜力.

Effect of Rhizobium sp.W33 on copper accumulation and organic exudations of different plants grown on copper-contaminated soil

The plant-microbe partnerships and the interactions between plants and microorganisms play the important roles in exploiting and improving the PGPB-assisted phytoremediation technology in the contaminated soils. In a pot experiment, the effects of a Cu resistant Rhizobium sp. W33 on the growth and Cu uptake of seven plants (Lolium perenne L., Medicogo sativa L., Pennisetum americanum × P. purpureum CV.23A × N51, Festuca elata Keng ex E. Alexeev, Crotalaria mucronats Desv., Brassica campestris L. and Brassica juncea) were evaluated. Furthermore, the organic exudations in the plant rhizospheres soils were analyzed. The tested plants inoculated with Rhizobium sp. W33 exhibited an increase in plant dry weight with 11% to 56% compared with the controls (p<0.05) in the presence of Cu. The promotion of the tested plants growth by Rhizobium sp. W33 was in the order Lolium perenne>Festuca elata>Pennisetum americanum×P. purpureum>Brassica campestris. It was found that higher Cu accumulation was in the roots than in the shoots of Lolium perenne, Medicogo sativa, Pennisetum americanum× P. purpureum, Festuca elata, Crotalaria mucronats. The Cu-resistant Rhizobium sp. W33 could also significantly increase the Cu uptake and bioconcentration factors of ryegrass grown in metal contaminated soils (p<0.05). Malic acid was the predominant components of organic acids in the rhizosphere exudates. Malic acid and water-soluble sugar contents in the rhizosphere soils of inoculated-ryegrass were decreased in the Cu contaminated soil, but the catalase activity increased. The results revealed that the best partnership of Rhizobium sp. W33 and ryegrass could be used to enhance phyto-stabilization of Cu contaminated soils.