放牧及AM真菌对垂穗披碱草生长和白粉病抗性的影响

于兰州大学玛曲高山草原站设3个不同放牧强度样地,采集样地的土壤和优势植物垂穗披碱草(Elymus nutans)种子,在温室建立盆栽试验,研究轻度、中度和重度放牧条件下,AM真菌对垂穗披碱草生长和白粉病(Blumeria graminis)发生的影响。结果表明:中度和重度放牧处理下接种AM真菌土(AM)侵染率显著高于轻度放牧土壤(P0.05),重度放牧条件下自然土(NS)和AM处理的侵染率比轻度和中度放牧分别高32.48%、2.39%和69.2%、21.17%;轻度、中度和重度放牧条件下AM处理的发病率比SS处理分别低22.1%,57.26%和20.46%,AM真菌有效抑制垂穗披碱草白粉病的发生,降低发病率,且对抗病相关酶活性产生显著影响,随放牧强度的增强AM真菌处理的SOD酶和PPO酶活性增高,POD酶活性在中度放牧强度下最高;中度放牧土壤的植物根系全磷含量最高;AM真菌不同程度提高植物根系全磷含量、总生物量、根冠比、叶绿素含量及光合速率。因此,在玛曲高山草原,适当增加放牧强度可提高AM真菌侵染率。AM真菌通过促进植物生长,调节抗病相关酶活性,有效降低了垂穗披碱草白粉病的发生。

Effects of grazing and AM fungi on growth and powdery mildew of Elymus nutans

This study was conducted by collecting soils under three grazing intensities and dominant plant seeds of Elymus nutans from Maqu alpine grassland experimental station of Lanzhou University.A pot experiment was carried out in a growth chamber to investigate the effects of soils under different grazing intensities (light grazing (LG),moderate grazing (MG) and heavy grazing (HG)) and AM fungi on growth of powdery mildew.The results showed that AM colonization in soils of MG and HG were significant higher than that of plants grew in LG soil (P＜0.05).Natural soil (NS) and AM treatments under HG were 32.48％、2.39％ and 69.2％ 、21.17％ higher than LG and MG,respectively.Disease incidence in AM treatment was 22.1％ 、57.26％ and 20.46％ lower than plants grew in sterilized soil under light、moderate and heavy grazing intensity.AM fungi effectively inhibited the occurrence of powdery mildew,reducing disease incidences and significantly affected defensive enzymatic activities.AMF treatments had higher SOD and PPO activities with the increasing of grazing intensity,while POD activities reached the highest under MG.Plants in moderate grazing soils had the highest contents of total phosphorus.AM fungi increased root total phosphorus content,total biomass,root/ shoot ratio,chlorophyll content and photosynthetic rate across the treatments.Therefore,in Maqu alpine steppe,proper increasing of grazing intensity could improve AM fungi colonization.AM fungi effectively reduced the occurrence of Elymus nutans powdery mildew by promoting plant growth and regulating the related defensive enzyme activities.