土壤微生物对紫茎泽兰生长与竞争的反馈:不同灭菌方法的比较

Feedback of soil biota on Ageratina adenophora growth and competitiveness with native plant: A comparison of different sterilization methods

土壤微生物去除是验证土壤微生物反馈调节入侵植物竞争排斥本地植物群落的重要手段。为了确定土壤微生物反馈效应的最佳土壤微生物去除方法,以及土壤微生物对紫茎泽兰与本地植物竞争中的反馈作用,本试验比较了添加蛭石和未添加蛭石下,3种常见土壤微生物灭菌方式(干热灭菌、湿热灭菌、辐照灭菌)处理的紫茎泽兰单优群落根际土壤对紫茎泽兰与本地植物香茶菜生长的影响。结果表明:与未灭菌处理土壤相比,3种灭菌处理土壤均显著抑制了紫茎泽兰和香茶菜的生长;添加蛭石灭菌的土壤相对于未添加蛭石的灭菌土壤显著促进了2种植物的生长;灭菌土壤添加蛭石的情况下辐照灭菌土壤的两种植物的生物量显著地高于干热灭菌和湿热灭菌土壤两种植物的生物量,其中辐照灭菌下紫茎泽兰的生物量分别比干热灭菌和湿热灭菌条件下增加30.8%和66.5%,香茶菜生物量分别显著增加109.5%和63.4%。辐照灭菌土壤添加蛭石的处理方式最接近真实地反映土壤微生物对植物生长的反馈效应。进一步进行辐照灭菌土壤添加蛭石处理与未灭菌土壤添加蛭石处理的紫茎泽兰与香茶菜混种的盆栽试验,结果显示,土壤微生物显著增强了紫茎泽兰对香茶菜的竞争优势,相对竞争优势度增加16.0%。

Soil sterilization is often used to explore feedback effects of soil microbes in community successions of competitive exclusion of native plants by invasive plants. In order to choose the most suitable soil sterilization method and to further analyze feedback effects of soil microbes on invasive plant Ageratina adenophora competition with native plants, we compared the differences in biomass between A. adenophora and native plant Rabdosia amethystoides cultured in sterilized soils. The tested soil sterilization methods in the study included dry-heating sterilization, autoclaving sterilization and irradiation sterilization. Non-sterilized soil was the control. In order to mitigate effects of sterilization on soil physico- chemical properties, vermiculite was added to soils sterilized with different methods. The results showed that sterilization by the three methods significantly decreased A. adenophora and R. amethystoides biomass, regardless of vermiculite addition. For the three different sterilization methods, adding vermiculite to soil promoted the growth of A. adenophora and R. amethystoides whereas plant biomass in non-sterilized soils was not affected by vermiculite addition. A. adenophora and R. amethystoides biomass under irradiation sterilization soils plus vermiculite was 30.8% and 66.5% higher than that under dry-heating and autoclaving sterilization soils with vermiculite, respectively. Then R. amethystoides biomass under irradiation sterilization soils plus vermiculite increased by 109.5% and 63.4% compared with that in dry-heating sterilization or autoclaving sterilization soils plus vermiculite, respectively. Plants in gamma irradiated soils had the highest plant biomass among the soils subjected to the three sterilization treatments. Through mixed pot experiment of A. adenophora and R. amethystoides under irradiation sterilization soils plus vermiculite and non-sterilized soils plus vermiculite, we found that soil microbes enhanced the competitive ability of A. adenophora over the native plant R. amethystoides and relative competitive advantage increased by 16%. These results indicated that irradiation sterilization soil plus vermiculite treatment was efficient in pot experiment studies on feedback effects of soil microbes on plants. Soil microbes exerted positive feedback during invading process of invasive plant A. adenophora.