Assessing AMF abundance in the soil.

To determine the abundance of AMF hyphae in the soil (extra-radical hyphae), I thoroughly充分 mixed all the air-dried soil saved from each pot. I extracted the 提取hyphae from a 5 g subsample二次抽样样品 of each sample by stirring 搅拌it into 90 mL of 20 g/L sodium hexametaphosphate六偏磷酸钠 on a stir plate,

sonicating声处理,

filtering a subsample二次抽样样品 through 20 µm mesh网丝,

resuspending the hyphae trapped收集到的 on the mesh in trypan blue stain锥虫蓝染色, staining overnight,

filtering through 1.2 µm pore size nitrocellulose filters孔隙硝化纤维过滤器,

mounting安装 the filters滤光片 with immersion oil on microscope slides载玻片, and quantifying定量 AMF hyphal abundance using the gridline intercept method 网格线截距法at 400x magnification (modified from Miller et al. 1995).

To increase accuracy精度 of quantifying测定 extra-radical hyphae, I counted each slide twice and used the averaged value. 数两次，取平均值

硕士学位论文 中国农大

丛枝菌根真菌对茨蔡状首蓓抗砷酸

能力的影响及其机制

称5g左右混匀的土样或菌剂,倒入IL的大烧杯中,加水后充分搅拌使抱子脱落,静置至

无明显旋涡时,将悬浊液倒入上筛为20目,下筛为400目的双层筛中过滤"再加水,重复两次"

用250而水将下筛中的物质冲入搅拌机中"搅10秒,停5秒,再搅20秒"

将搅好的悬浊液转移至300而的三角瓶中,剧烈摇晃后,静置1分钟,然后在液面下同一

深度处吸取5而悬浊液,进行抽滤"将滤膜取下,置于载玻片上,滴l一2滴.05%的锥虫蓝溶液"

再重复两次从/剧烈摇晃0至/抽滤0步骤"

将所得的滤膜置于200倍显微镜下观察25个样点(图3一3)"记下菌丝与网格的交叉点数"

菌丝密度计算公式:

菌丝密度(mg/)=菌丝长度(m)/所称土样质量(g)

菌丝长度(m)二11/14X交叉点数x网格单元格长度x滤膜上样块面积/网格面积

菌丝密度(m菌丝g/士)二lPl/714X总交叉点数/所称土样质量

菌丝密度测定