Preparation of POD solution: cutting stem and lid of 108 different concentrated folacin acid into pieces and mixed from 9 cans of each group with 12 groups in total.

• 对12组每组9瓶共108瓶经不同浓度叶酸处理银针菇的菌盖、菌柄剪碎混匀后，从每份样品中称取0。