四种牧草植物替代控制对黄顶菊入侵土壤细菌多样性的影响

Effects of replacement control with four forage species on bacterial diversity of soil invaded by Flaveria bidentis

土壤微生物群落与植物的生长发育密切相关,入侵植物可以改变入侵地土壤微生物类群,使土壤理化性质发生变化,从而促进其入侵过程。该文通过比较高丹草(Sorghum bicolor×S.sudanense)、向日葵(Helianthus annuus)、紫花苜蓿(Medi-cago sativa)和多年生黑麦草(Lolium perenne)4种替代植物与黄顶菊(Flaveria bidentis)混合种植(以下简称混种)后不同时期的土壤细菌多样性的变化,揭示土壤细菌群落对黄顶菊入侵及替代管理措施的响应规律。结果表明,单独种植(以下简称单种)黄顶菊的土壤细菌多样性下降,并且在整个生长期多样性指数多数情况下低于高丹草、向日葵、紫花苜蓿和多年生黑麦草单种或与黄顶菊混种的土壤。当4种替代植物与黄顶菊混种后,土壤细菌16S rRNA的变性梯度凝胶电泳(DGGE)图谱与它们分别种植时存在明显差异,且不同生长期各个混种土壤都有特征细菌群落。4种替代植物单种或与黄顶菊混种的土壤细菌Shannon多样性指数变化规律与植物生长发育趋势相同,7月份达到高峰,8月份开始降低。总之,黄顶菊入侵降低了土壤细菌群落多样性,4种替代植物与黄顶菊混种后,又可提高土壤细菌群落多样性,这种变化对黄顶菊成功入侵和替代防控具有重要作用。

Aims Invasive plants can alter soil physicochemical properties by changing the soil microbial community （which is closely related to plant growth and development） and thus further promote the invasion process. Our objectives were to （a） compare changes in soil bacterial diversity with cultivation of four replacement plants （Sorghum bicolor x S. sudanense, Helianthus annuus, Medieago sativa and Lolium perenne） mixed with Flaveria bidentis in different growth period and （b） determine invasion and replacement. the responses of the soil bacterial community to F. bidentis Methods Total soil bacterial DNA was extracted by PowerSoil~ DNA Isolation Kit, 16S rRNA V3 fragments were amplified with bacterial universal primers, and purified fragments were cloned into pGEM-T-Easy vector. Sequence results were aligned on NCB1. Important findings Soil bacterial diversity was decreased in E bidentis monoculture and was lower than in the soils of the monocultures of the four replacement plants and in the soils of the replacement plants and E bidentis. There were significant differences in soil bacterial 16S rRNA denaturing gradient gel electrophoresis （DGGE） fingerprinting patterns between the mixed- and monoculture soils. Also, there were characteristic bacterial communities with each mixed culture soil on different dates. The Shannon diversity index of soil bacteria peaked in July and decreased starting in August, and this change was synchronous with plant growth. Soil bacterial diversity was reduced following the invasion of E bidentis, and that the diversity level was increased by cultivating replacement plants with E bidentis. Therefore, we proposed that soil bacteria play an important role in E bidentis invasion and control.