2.2 Preparing of extracts
Two kinds of plant extracts were prepared. The whole plant extracts were prepared by soaking whole fresh aboveground parts in distilled water (w/v, 1:4). The aqueous pieces extracts were prepared by cutting plants into 1-2 cm pieces and soaking them in distilled water (w/v, 1:4). The containers of soaked plant materials were shaken at 500 rpm for 5 minutes per 12 hours in 72 hours at room temperature. Soil extracts were prepared by soaking fresh root zone soil in distilled water (w/v, 1:2) and shaken at 200 rpm for 24 h in gyratory shaker at room temperature.
The resulting mixtures were passed through qualitative filter paper and 0.45 μm aqueous membrane, respectively. And thus 0.25 g·mL-1 plant extracts and 0.5 g·mL-1root zone soil extracts were obtained. The solutions were stored at 4°C until use.