镉、铅对沙打旺种子萌发及早期生长发育的毒性效应

Toxicological effects of Cd^(2+) and Pb^(2+) on the seed germination and seedling growth of Astragalus adsurgens

采用溶液培养和盆栽实验研究了镉(Cd2+)和铅(Pb2+)对沙打旺种子萌发、幼苗生长、幼苗叶绿体色素含量、脯氨酸含量、抗氧化系统中的2种抗氧化酶(SOD、CAT)活性的影响。Cd2+、Pb2+实验梯度分别为:0,1,2,3,10,20和0,500,1 000,1 500 mg/kg。结果表明,随着Cd2+浓度的增大,种子发芽率、发芽势、发芽指数总体上呈先下降后上升的趋势;随着Pb2+浓度的增大,种子发芽率、发芽势、发芽指数均呈下降趋势,种子发芽进程受到严重抑制。Cd2+和Pb2+对沙打旺幼苗的株高、根长、根重和地上重产生明显的抑制作用。浓度越高,植物生长受到的影响越大。在同一浓度下,Cd2+、Pb2+对沙打旺胚根伸长抑制率大于对芽伸长的抑制率。随着Cd2+、Pb2+浓度的增大,叶绿素含量总体呈下降趋势,但Pb2+对叶绿素的影响大于Cd2+。脯氨酸含量、SOD和CAT的活性均出现低浓度(Cd2+浓度1 mg/kg,Pb2+浓度500 mg/kg)上升,高浓度(Cd2+浓度≥10 mg/kg,Pb2+浓度≥1 000 mg/kg)下降的趋势。

The effects of individual Cd^2＋ and Pb^2＋ pollution on seed germination, seedling growth, chlorophyll and proline content, and of two antioxidant enzymatic activities （SOD, CAT） in the antioxidant system of A. adsurgens were tested with concentration gradients of Cd^2＋ and Pb^2＋ added to water and soil respectively. The concentrations of Cd^2＋ and Pb^2＋ were 0, 1, 2, 3, 10, 20 and 0, 500, 1 000, 1 500 mg/kg respectively. The germination percentage, germination rate and germination indexes all decreased at low Cd^2＋ concentrations and increased at higher concentrations. They also decreased with a concentration increase of Pb^2＋. With the same content of Cd^2＋ and Pb^2＋ , the radicle length was more strongly inhibited than seed elongation. The seedling length, root length, root biomass as well as aboveground biomass were progressively inhibited as concentrations of Cd^2＋ and Pb^2＋ increased, but the chlorophyll content decreased. The effect of Pb^2＋ on the formation of chlorophyll was greater than that of Cd^2＋. The proline contents and the activities of SOD and CAT tended to increase at lower concentrations（Cd^2＋ 1 mg/kg,Pb^2＋ 500 mg/kg） and decrease at higher concentrations（Cd^2＋≥10 mg/kg,Pb^2＋≥1 000 mg/kg）.