克隆整合对异质性光照环境下紫竹根际土壤氮素有效性的影响

以根状茎克隆植物紫竹为对象,研究克隆整合对遭受异质性光照胁迫分株根际土壤有机碳(SOC)、总氮(TN)、溶解性有机碳(DOC)、溶解性有机氮(DON)、氨氮(NH_4~+-N)、硝态氮(NO_3~--N)以及微生物群落组成的影响。所取紫竹克隆片段由一个母本分株和一个子代分株组成,母本分株置于全光照下,而子代分株置于80%遮阴环境中,同时母本分株与子代分株间的根茎保持连接或割断处理。结果表明:与切断处理相比,紫竹遮荫子代分株根际土壤的SOC、TN、DOC、NH_4~+-N在保持根状茎连接时显著更高,这表明异质性光照环境下克隆整合可能改善紫竹连接遮荫子代分株根际土壤的氮素有效性。克隆整合提高了连接遮阴状态下紫竹子代分株根际土壤中的放线菌、真菌和革阴细菌的PLFAs浓度。通过对遮阴子代分株根际土壤微生物群落PLFAs主成分分析得出克隆整合导致遮阴子代分株根际土壤微生物群落结构发生显著变化。该研究结果暗示了紫竹可能通过克隆整合作用降低土壤中某些对氮利用有效性影响较低的细菌数量,而增加对土壤氮利用起重要作用的放线菌和真菌的数量,进而改善紫竹对土壤中氮利用的有效性,这有利于增强克隆植物对时空异质性生境的适应能力。

Effects of clonal integration on the nitrogen availability of rhizosphere soil in Phyllostachys nigra suffering from heterogeneous light

To study the effects of clonal integration on SOC, TN, DOC, DON, NH₄⁺-N, NO₃^--N and microbial community composition, a pot experiment was conducted by rhizome clonal plant Phyllostachys nigra fragments consisting of two successive ramets subjected to heterogeneous light. Mother ramets suffering from full sun versus offspring ones suffering from 80% shade, meanwhile, the rhizome was kept connected or severed. The results showed that SOC, TN, DOC and NH₄⁺-N concentrations of shaded P. nigra offspring ramets showed a significant difference between connected and severed treatments, which means clonal integration improves soil nitrogen utilization effectiveness for connected shaded offspring ramets; Principal component analysis of PLFAs concentration of rhizosphere soil microbial for P. nigra showed a significant difference between the two treatments of shading connected and severed conditions. The results indicated that P. nigra could reduce the percent of bacteria in soil which nitrogen utilization effectiveness was low, and could increase the percent of actinomycetes and fungi by clonal integration, so as to improve the soil nitrogen utilization efficiency of whole P. nigra, which endued them with the adaptive advantages to heterogeneous habitats.