【摘要】 为探讨菌根真菌对宿主植物在酸雨逆境中的调节作用,以华北地区森林群落常见树种栾树(Koelreuteria paniculata)幼苗为研究对象,采用双因素完全随机试验设计开展盆栽试验,设置了3个酸雨梯度(pH分别为3.5、4.5、5.6)及2种土壤微生物接种方式(接种、不接种),对各处理下幼苗生长情况、叶片氮磷含量、根内泡囊-丛枝菌根真菌(Vescile-Arbuscular Mycorrhizal fungi)定殖情况进行测定及分析。结果表明:(1)栾树幼苗根系泡囊-丛枝菌根真菌表现出趋酸性的特征,其侵染率在pH 3.5中定殖率最高(76.3%),在pH 5.6中定殖率最低(34.4%);(2)在pH 3.5和pH 4.5酸雨处理中,接种土壤微生物显著促进了栾树幼苗的生长(P<0.05),但在p H 5.6处理则无显著促进作用(P>0.05),接种土壤微生物显著降低了3种酸雨胁迫下栾树幼苗叶片氮及氮磷比值,栾树幼苗在强酸胁迫下有更高的菌根依赖性(pH3.5:MD=54.2%,p H4.5:MD=38.7%,pH5.6:MD=0);(3)相关性分析表明,在pH3.5和pH4.5处理中,菌根真菌侵染率与苗木生物量、株高、基径、叶片氮及叶片氮磷比等显著相关(P<0.05),而在pH 5.6处理中则均无显著相关关系。栾树幼苗泡囊-丛枝菌根真菌在强酸胁迫下表现出提高定殖率的适应策略;强酸胁迫下(pH 3.5、pH 4.5),泡囊-丛枝菌根真菌对栾树幼苗生长的调节作用较弱酸胁迫(pH5.6)明显;接种土壤微生物通过提高泡囊-丛枝菌根真菌的侵染率促进强酸雨下栾树幼苗基径、株高、地上及地下生物量。研究结果在一定程度上反映了接种土壤微生物对酸胁迫下栾树幼苗的促生长作用模式及调节作用。更多还原

【Abstract】 Acid rain affecting plant growth and development has been becoming a worse problem all over the world.Vescile-arbuscular mycorrhizal fungi has been shown to enhance plant tolerance for many biotic and abiotic stresses. However, the influences of Vescile-arbuscular mycorrhizal fungi on plant tolerance to acid stress of forest tree species are incompletely understood.To test our hypothesis that the symbiont would improve Koelreuteria paniculate tolerance for acid rain, a greenhouse pot experiment with a two-factor factorial design was conducted. Seedlings were cultivated in inoculated or sterilized soils and exposed to one of 3 different acid stress intensity(pH 3.5, pH 4.5, pH 5.6) during one growing season. Plant growth, nutrient uptake rate,nitrogen-phosphorus ratio as well as mycorrhizal fungi colonization of each and every harvested seedling were investigated to assess the microbiota-plant interaction under stressful conditions of strong acidity. The results showed that acid stress increased vescile-arbuscular mycorrhizal fungi colonization of seedling root, with the highest colonization rate of 76.3% under the greatest simulated rain acidity. Soil microbial inoculation improved plant growth to get a higher biomass, stem diameter, and plant height accumulation for seedlings exposed to both pH 3.5 and pH 4.5 acid rain treatments(P<0.05), simultaneously, higher mycorrhizae dependence(MD) of Koelreuteria paniculate seedlings was objected in pH 3.5 and pH 4.5 acid rain treatments(pH 3.5: MD=54.2%,pH 4.5: MD=38.7%, pH5.6: MD=0). On the other hand, it decreased the leaf nitrogen concentration and nitrogen to phosphorus ratio of seedlings under all the three stressful conditions(P<0.05). Correlation analysis showed that the plant performance indices have a strong relationship with the vescile-arbuscular mycorrhizal fungi colonization under pH 3.5 and pH 4.5(P<0.05) but not in pH 5.6 situation. As a conclusion, vescile-arbuscular mycorrhizal fungi could play a very important role in plant resistance to acid stress and facilitate nutrient uptake and growth performance of Koelreuteria paniculate seedlings. While being exposed to strong stress of acid deposition, Koelreuteria paniculate seedlings would adopt a typical adaptive strategy by increasing mycorrhizal fungi colonization to take advantages of root-fungi associations in regulating nutrient absorption and promoting seedling growth.更多还原