温度和CO_2浓度升高下转Bt水稻种植对土壤活性碳氮和线虫群落的短期影响

Short-term effects of CO_2 concentration elevation,warming and transgenic Bt rice cropping on soil labile organic carbon and nitrogen,and nematode communities

全球气候变化下转Bt水稻种植对土壤生态系统的影响仍是未知领域。利用野外开顶式气室(OTC)模拟气候变化,探讨了温度和CO2浓度([CO2])升高后种植转Bt(华恢1号)水稻对土壤活性碳氮和线虫群落的影响。结果表明:(1)温度和[CO2]升高条件下种植转Bt水稻显著影响土壤可溶性碳(DOC)、可溶性氮(DON)和硝态氮(NO-3-N)含量,同时DOC和DON受到升温和[CO2]升高与转Bt水稻的交互影响;在正常温度和[CO2]下,转Bt水稻显著降低了土壤微生物量碳氮含量(MBC、MBN),但在温度和[CO2]升高后转Bt水稻种植使土壤MBC和MBN含量显著高于亲本水稻。(2)在温度和[CO2]升高条件下,转Bt水稻土壤线虫总数呈高于亲本水稻的趋势,植食性线虫的比例随[CO2]和温度升高呈增大的趋势。此外,升温和转Bt水稻种植提高了土壤线虫群落的能流通道指数,而[CO2]升高和转Bt水稻种植则提高了土壤线虫群落的富集指数。总之,在模拟全球气候变化下,种植转Bt水稻在短期内对土壤活性碳氮和线虫群落均产生影响,但短期研究并未发现转Bt水稻种植对土壤生态系统的不利影响。

Interactions of global change and transgenic Bt rice （Huahui-1, HH1） cropping on soil ecosystem remain largely unexplored. Here we conducted an OTC （Open Top Chamber） experiment to evaluate the effects of transgenic Bt rice cropping on soil labile organic carbon and nitrogen, and nematode communities under elevation of temperature and [CO2] with two rice varieties including non-Bt rice （MH63） and its transgenic Bt line （HH1）. Results showed that （1） Under the condition of elevated [CO2] and warming, transgenic Bt rice cropping significantly affected the content of soil dissolved organic carbon, dissolved organic nitrogen and NO-3-N. Significantly interactions of transgenic Bt rice, warming and elevated [CO2] were observed for the content of soil dissolved organic carbon and dissolved organic nitrogen. Further, the transgenic Bt rice reduced microbial biomass carbon and nitrogen significantly under ambient temperature and [CO2]; whereas warming and [CO2] elevation reversed that trend. （2） At ambient temperatures and [CO2], the total number of nematodes in soil grown with transgenic Bt rice cropping were significantly more than those in soil grown with the parental line. Herbivorous nematodes tended to increase under the condition of warming and elevated [CO2], though not reaching to a significant level. Transgenic Bt rice and warming significantly increased the Nematode Channel Ratio, demonstrating the shift from bacteria-dominated to fungi-dominated energy channel. But [CO2] elevation and transgenic Bt rice significantly increased the nematode Enrichment Index. In conclusion, climate change modified the responses of soil labile organic matter and nematode community to transgenic Bt rice cropping, though it does not lead to negative effects on soil based on the results of short-term experimental duration.