大气对流层臭氧浓度升高下AM真菌对小麦生长的影响

利用中国唯一的开放式空气组分增高(free-air component enrichment,FACE)稻麦轮作试验平台,研究大气对流层O3浓度升高条件下接种外源AM真菌对小麦生长及土壤微生物生物量的影响.结果发现,O3浓度升高处理小麦苗期AM真菌侵染率有升高趋势,而从孕穗期起逐渐显示出对小麦生长的不利影响,收获时植株地上部生物量、株产与千粒重均显著下降(p0.05),分别降低22%、29%和9%,土壤微生物生物量N也下降了37%,但籽粒全N含量从2.2%显著提高到2.6%(p0.05).O3浓度升高条件下接种外源AM菌剂对小麦根系AM真菌侵染具有促进作用,孕穗期AM真菌侵染率与植株地上部生物量均显著高于不接种对照(p0.05),收获时植株受灾程度降低了50%,土壤微生物生物量N也显著升高(p0.05),虽然小麦产量没有提高,但籽粒全N含量下降到与当前O3浓度处理没有显著差异的水平上.结果表明,O3胁迫下小麦通过提高苗期AM真菌侵染来增强其抗胁迫能力,接种外源AM真菌可以促进小麦营养生长,并可通过改善根系分泌物等来提高土壤微生物生物量.

Arbuscular Mycorrhizal Fungal Effects on Wheat Growth in Response to Elevated Tropospheric O3 Concentration

A FACE (Free-air component enrichment) system in a rice/wheat rotation field was used to investigate the effects of arbuscular mycorrhizal fungal (AMF) inoculation on wheat growth and soil microbial biomass under elevated tropospheric O₃ concentration. The elevated O₃ concentration tended to increase AM colonization of wheat seedling and bate plant growth during the booting period, then significantly (p<0.05) reduced aerial biomass, individual yield and kernel weight by 22%, 29% and 9%, respectively, and decreased soil microbial biomass N by 37% after wheat harvesting. However, the total N content in wheat grain significantly (p<0.05) increased from 2.2% to 2.6%. Under elevated O₃ concentration, AMF inoculation accelerated AM colonization successfully, and improved colonization rate and aerial biomass significantly (p<0.05) during the booting period, thus reduced the damage of aerial biomass by 50% when harvesting, and increased soil microbial biomass N significantly (p<0.05) related to the noninoculated treatment. Although wheat yield didn't increase, the total N content in grain decreased to the same level of that of the control wheat. It suggested that higher AM colonization is the resistance behavior of wheat in response to O₃ intimidation, and AMF inoculation can accelerate wheat growth, increase root exudates and soil microbial biomass subsequencely.