锰胁迫对美洲商陆种子发芽及幼苗生长的影响

Manganese Stress on Seed Germination and Seeding Growth of Pokeweed(Phytolacca Americana L.)

以美洲商陆(Phytolacca Americana L.)种子为材料,采用培养皿滤纸水培培养法,研究不同ρ(Mn2+)(0、50、100、200、300、400和500 mg/L)对美洲商陆种子发芽参数(发芽率、发芽势、发芽指数和活力指数)及幼苗生长指标(鲜重、芽长和根长)、超氧化物歧化酶(SOD)和丙二醛(MDA)含量的影响。结果表明,Mn2+处理对美洲商陆种子发芽产生负效应,降低了发芽率、发芽指数和种子活力,提前了种子集中萌发时间;低浓度Mn2+(≤200 mg/L)处理促进幼苗生长,但随着ρ(Mn2+)增加,幼苗生长受到抑制,且对芽的抑制大于对根的抑制;随着ρ(Mn2+)升高,美洲商陆幼苗SOD活性先升后降,ρ(Mn2+)为200 mg/L时达最大,在SOD活性升高时,MDA含量缓慢增加,在SOD活性降低时,MDA含量骤然增加,表明美洲商陆幼苗SOD活性与丙二醛含量存在某种关系,此外,美洲商陆幼苗对Mn2+胁迫具有一定耐性,其耐性机制可能与超氧化物歧化酶活性有关;高ρ(Mn2+)对美洲商陆幼苗产生毒性,其毒性机制可能与膜质过氧化有关。

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 Mn^2 ＋（≤200 mg/L） promoted pokeweed seedling growth, while with the concentration of Mn^2 ＋further increasing, seedling growth was suppressed, and the suppression on bud was greater than on root. With the increase of Mn^2 ＋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.