水分胁迫和接种丛枝菌根对香樟幼苗根系形态特征的影响

Effects of Water Stress and AM Inoculation on Root Morphological Characteristics in Cinnamomum camphora Seedlings

为了探索喀斯特地区植物接种丛枝菌根真菌后幼苗的耐旱适应性,我们对香樟Cinnamomum camphora进行了幼套球囊霉Glomus etunicatum、层状球囊霉Glomus lamellosum和摩西球囊霉Glomus mosseae的单独接种和混合接种处理.香樟苗接种80d后再进行60d的强度(维持田间持水量的35%～45%)、中度(维持田间持水量的50%～60%)、轻度(维持田间持水量的65%～75%)和正常浇水(维持田间持水量的80%～90%)的水分胁迫处理.用WinRhizo分析系统测定苗木根系形态指标.结果表明:水分和菌根真菌的交互作用使香樟幼苗根系形态发生改变,以适应土壤环境.中度水分胁迫能提高根系总长和根尖数量,但是水分胁迫降低了根系生物量的积累和根体积.根系生物量、根系总长,根系表面积、根体积和根尖数表现为接种处理高于非接种处理.非接种处理的根平均直径在重度和中度水分胁迫下显著增强.菌根真菌接种处理的根系,平均直径随水分胁迫增加而有所降低.相同胁迫下的不同菌种处理之间,幼套球囊霉和混合接种处理较摩西球囊霉和层状球囊霉有较高的菌根依赖性.而在同一接种处理条件下,中度水分胁迫的香樟幼苗具有较强的菌根依赖性,重度水分胁迫却降低了菌根依赖性.同一水分条件下混合接种和幼套球囊霉有较高的菌根依赖性.

Seeds of Cinnamornurn carnphora were inoculated by three arbuscular mycorrhizas （Glomus etu- nicatum, G. larnellosurn and G. mosseae） via single and combined species in limestone soil. Eighty days after the inoculation, the seedlings were subjected to 60-day stress treatments： serious drought （35%- 45% of field capacity）, moderate drought （50%-60% of field capacity）, mild drought （65%-75% of field capacity） and normal water supply （80%-90%of field capacity）. Then, some morphological indexes were measured by scanner （STD1600 Epsom USA） with WinRhizo （Version 410B） roots analysis system. The results showed that seedlings of C. caznphora responded to water status and arbuscular mycorrhizas at their root morphology to adapt to the soil environment. Moderate water stress treatments increased to- tal root length and root-tip number of the host but decreased root biomass and volume. AM inoculation in- creased the biomass, total length and surface area and volume of the root and the number of root-tips, as compared with the control. Average root diameter of the non-inoculated seedlings was significantly greater in serious and moderate water-stress treatments. Average root diameter of the AM inoculation treatments decreased with increasing water stress. Among different species treatments under the same water stress, higher mycorrhizal dependency was observed of C. camphora seedlings inoculated with G. etunicatum or with G. mosseae and G. lamellosum in combination, whereas in the same fungus, greater mycorrhizal de- pendency was noticed in moderate water stressed treatments.