镉对柠条种子萌发及幼苗生长的影响

为探讨重金属镉(Cd)对柠条种子萌发的毒物刺激效应,采用培养皿滤纸萌发法,研究了不同Cd2+浓度(0,2,5,10,15,50mg/L)对柠条种子萌发、幼苗生长和酶活性的影响。结果表明:在5mg/L的Cd2+浓度下柠条种子的发芽率、胚芽和胚根的长度达最大,分别比对照提高3.8%,13.4%和11.2%,根和芽的POD活性分别比对照增加19.2%、1.8%,CAT活性比对照增加6.3%、10.4%;Cd2+浓度为50mg/L时,柠条种子的发芽势、发芽指数、活力指数分别比对照显著降低46.9%,26.1%和27.8%;高浓度Cd2+(10,15和50mg/L)对柠条种子萌发及酶活性表现为抑制作用,低浓度Cd2+(2、5mg/L)表现为促进作用。镉对柠条种子萌发具有"低促高抑"的毒物刺激效应,5mg/L的Cd2+浓度为柠条种子萌发刺激效应的临界浓度。

Effects of cadmium stress on seed germination and seedling growth of Caragana korshinskii

In order to study the hormesis effect of heavy metal cadmium on Caragana korshinskii ,the seed germination,seedling growth,enzyme activity was measured in petri dishes with different concentration of Cd2 +stress (0,2,5,10,15,50 mg/L).The results showed that the seed germination,bud and root length reached to the maxium when the concentration of Cd2 + was 5 mg/L.Compared with the controls,the seed germination,bud and root length improved 3.8%,13.4% and 1 1.2%,respectively,the POD activity in root and bud increased 1 9.2% and 1.8%,respectively,CAT activity increased 6.3 % and 10.4%.When the concentration of Cd2 + was 50 mg/L,the seed germination potential,germination index,vigor index were decreased 46.9%,26.1% and 27.8% respectively compared with the controls.In the range of Cd2 + concentration between 2 to 50 mg/L,the high concentration of Cd2 + solution (10 mg/L,15 mg/L,50 mg/L)had the stress on germination and enzyme activity inhibitory,however,the low concentration of Cd2 + solution (2 mg/L,5 mg/L)promoting them.The Cd2 + concentration with 5 mg/L was the upper limit to hormesis effect on seed germination.