Manganese Stress on Seed Germination and Seeding Growth of Pokeweed(Phytolacca Americana L.)
Impact of different concentrations of Mn2+(0, 50, 100, 200, 300, 400 and 500 mg/L) treated on pokeweed(Phytolacca Americana L.) seeds by using the petri dish germination method was investigated. The germination rate(GR),germination energy(GE), germination index(GI), vigor index(VI), bud length(BL), root length(RL), fresh weight(FW) of pokeweed seedlings, superoxide dismutase(SOD) activity and malondialdehyde(MDA) content in seedling were studied.Results showed that Mn2+had negative effects on pokeweed seed germination. The treatments with Mn2+significantly reduced seed germination rate, germination index and vigor index, but it advanced the seeds focus germination time. The treatment with low concentrations of Mn2 +(≤200 mg/L) promoted pokeweed seedling growth, while with the concentration of Mn2 +further increasing, seedling growth was suppressed, and the suppression on bud was greater than on root. With the increase of Mn2 +treatment concentration, SOD activity increased at lower concentrations(≤200 mg/L), then decreased at higher concentrations(300, 400 and 500 mg/L). MDA contents in the seedlings gradually accumulated in a dose-response manner.When SOD activity increased, MDA contents increased slowly. However, when SOD activity decreased, MDA contents increased rapidly, which indicated that there was a relationship between SOD activity and MDA contents. In addition, the tolerance mechanism of manganese on pokeweed seedlings may be associated with SOD activity. The damage mechanism of manganese on pokeweed seedlings may be related to the lipid peroxidation of the biomembrane.