接种4种丛枝菌根真菌对榆树幼苗抗旱性的影响

Effects of four arbuscular mycorrhizal fungi inoculation on the drought resistance of Ulmus pumila seedlings

干旱造成植物根系吸水困难,导致植物生长倒退。丛枝菌根(arbusular mycorrhiza,AM)真菌能够与寄主植物根系形成互惠共同体,改善寄主植物的生长发育状况。选用摩西斗管囊霉、幼套近明球囊霉、根内根孢囊霉及其三者混合菌种为试验菌剂,以盆栽榆树幼苗为供试材料,通过人工控水的方法设置3种水分梯度:正常供水、中度干旱、重度干旱。研究在干旱胁迫下4种AM真菌对榆树幼苗抗旱性的影响,结果表明:1)在不同水分条件下,与未接种对照植株相比,接种AM真菌均不同程度的增加了榆树幼苗的株高、根冠比和菌根依赖性,降低菌根侵染率;2)在3种水分条件下,与对照植株相比,接种AM真菌均不同程度的降低榆树幼苗丙二醛含量,提高了榆树幼苗过氧化氢酶、过氧化物酶、过氧化物歧化酶活性;3)随着水分供应量的减少,榆树幼苗的净光合速率、蒸腾速率、叶片气孔导度逐渐降低,胞间CO 2浓度逐渐升高;4)菌根榆树幼苗耐旱能力均强于非菌根幼苗,其耐旱能力从强到弱依次为混合菌剂>幼套近明球囊霉>根内球囊霉>摩西球囊霉>CK。

[Background]Elm(Ulmus pumila)is a masculine tree species with well-developed root system,rapid growth and drought tolerance,and it is an ideal tree species for afforestation in arid and semi-arid sandy areas.However,in recent decades,frequent droughts due to global climate change have led to serious degradation of elm forest ecosystems.The ability of arbuscular mycorrhizal(AM)fungi to form a reciprocal community with host plant roots and improve the growth and development of host plants is of great significance to the improvement of terrestrial ecosystem functions.In this experiment,we investigated the physiological mechanism of AM fungi increasing the drought resistance of U.pumila by artificially simulating the drought environment,and screened the drought-tolerant strains,so as to provide preliminary theoretical preparation and technical support for mycorrhizal technology to restore vegetation and improve ecological environment in arid and semi-arid areas.[Methods]Funneliformis mosseae,Claroideoglomus etunicatum,Rhizophagus intraradices and their mixtures of above three were selected as experimental agents,and potted elm seedlings used as experimental materials.Three water gradients were set by manual water control:normal water supply,moderate drought,and severe drought.The root shoot ratio,mycorrhizal infestation rate,mycorrhizal dependence,photosynthetic parameters,malondialdehyde content,peroxidase,catalase and peroxide dismutase activities of elm seedlings under different treatments were measured,and the data were statistically analyzed by Microsoft Excel 2012,and the data were analyzed by two-factor ANOVA with SPSS23 software,and the fuzzy integrated evaluation method of affiliation function was used to comprehensively evaluate the drought resistance of different strains.[Results]1)Under different moisture conditions,inoculation with AM fungi increased the plant height,root shoot ratio and mycorrhizal dependence of U.pumila seedlings to different degrees and decreased the mycorrhizal infestation rate compared with the uninoculated control plants.2)Under three moisture conditions,inoculation with AM fungi decreased the malondialdehyde content of U.pumila seedlings to different degrees and increased the catalase,peroxidase and peroxidase activities of U.pumila seedlings compared with the control plants.3)The net photosynthetic rate,transpiration rate and leaf stomatal conductance of U.pumila seedlings gradually decreased and the intercellular CO 2 concentration gradually increased as the water supply decreased.4)Mycorrhizal elm seedlings were all more drought tolerant than non-mycorrhizal seedlings,and their drought tolerance was from the strongest to the weakest in the order of mixed bacterial agent>C.etunicatum>R.intraradices>F.mosseae>CK.[Conclusions]Under water stress,AM fungi could make U.pumila seedlings more adaptable to soil moisture changes,and the mixed mycorrhizal agent had the best drought tolerance.