长江中下游两种典型水稻土微生物对砷污染的响应

Response of microbial community to arsenic contamination in two major type of paddy soils in the middle and lowerreaches of the Yangtse River

基于温室盆栽实验,利用磷脂脂肪酸分析(PLFA)方法研究了As污染、土壤类型和水稻品种对水稻抽穗期土壤微生物群落的影响.结果表明,水稻土土壤中微生物生物总量(总PLFAs)以及微生物组成均不同程度的受到了As污染、土壤类型及水稻品种的影响;As污染增加了土壤总PLFAs,黄泥田的土壤总PLFAs、真菌/细菌(F/B)、革兰氏阳性细菌/阴性细菌(G+/G-)、腐生真菌/丛枝菌根真菌(SF/AMF)显著高于红泥田;在黄泥田中,种植籼稻品种的土壤总PLFAs较杂交稻和粳稻品种平均减少30.0%,而在红泥田中平均增加24.8%.偏Mantel检验和冗余分析(RDA)表明土壤p H值、DOC、NH4+和As浓度是驱动水稻土微生物群落演变的主控因子,其中受As影响较大的特征PLFAs包括20:0、i17:1ω9c、18:1ω9c、cy17:0和18:3ω6c;ABT预测模型显示水稻品种和土壤类型对总PLFAs、F/B、G+/G-和SF/AMF指标的贡献相对较大,而As处理的影响较小.

In a pot experiment, the effects of As contamination, soil type and rice cultivar on the composition of soil microbial communities in rice heading stage were unalyzal using phospholipid fatty acid（PLFA） technique. The results unveiled that the amount of total PLFAs and microbial compositions were to some extent affected by arsenic contamination, soil types and rice cultivars. The As contaminated soils had a higher amount of total PLFAs than the uncontaminated soils. Yellow Paddy soils（YP） had higher total PLFAs, fungi to bacteria ratio（F/B）, Gram-negative bacteria to Gram-positive bacteria ratio（G^＋/G^-） and saprotrophic fungi to arbuscular mycorrhizal fungi ratio（SF/AMF） than in Red Paddy soils（RP）. Total PLFAs associated with indica plants vs. those associated with japonica and hybridplants decreased by an average of 30.0% in YP, but increased by 24.8% in RP. Partial Mantel tests and redundancy analysis（RDA） showed that soil p H, DOC, NH4^＋ and As concentration were the dominant factors in shaping soil microbial communities. The individual PLFAs including 20：0, i17：1ω9c, 18：1ω9c, cy17：0 and 18：3ω6c were easily affected by As contamination. Aggregated boosted tree（ABT） analysis suggested that soil types and rice cultivars exerted more influence than As concentration on the variation of parameters of total PLFAs, F/B, G^＋/G^- and SF/AMF.