Pb、Cd单一及复合胁迫对花菖蒲幼苗生长及部分生理指标的影响

Effects of single and combined stresses of Pb,Cd on growth and some physiological indexes of Iris ensata var. hortensis seedling

采用液体培养法研究了Pb、Cd单一胁迫及Pb-Cd复合胁迫(500 mg.L-1Pb、25 mg.L-1Cd、500 mg.L-1Pb-25 mg.L-1Cd)对花菖蒲(Iris ensata Thunb.var.hortensis Makino et Nemoto)幼苗生长和部分生理指标的影响。结果显示,在500 mg.L-1Pb单一胁迫条件下,花菖蒲幼苗地上部分(叶片)和地下部分(包括根茎和根系)的干质量及耐性指数与对照差异不显著(P>0.05);而在25 mg.L-1Cd单一胁迫和500 mg.L-1Pb-25 mg.L-1Cd复合胁迫条件下,幼苗地上部分和地下部分的干质量及耐性指数显著下降(P<0.05),其中耐性指数分别仅为0.86和0.79。在500 mg.L-1Pb单一胁迫条件下,叶片中的光合色素(包括叶绿素a、叶绿素b和类胡萝卜素)含量和地下部分的丙二醛(MDA)含量显著高于对照,地上部分的MDA含量显著低于对照,而过氧化物酶(POD)活性则与对照差异不显著;在25 mg.L-1Cd单一胁迫条件下,叶片中的叶绿素a和叶绿素b含量显著低于对照,类胡萝卜素含量和地上部分的MDA含量以及地上部分和地下部分的POD活性均显著高于对照,而地下部分的MDA含量与对照差异不显著;在500 mg.L-1Pb-25 mg.L-1Cd复合胁迫条件下,叶片中的光合色素含量均显著低于对照,地上部分和地下部分的MDA含量和POD活性均显著高于对照,其中MDA含量分别是对照的1.7和2.7倍、POD活性分别是对照的2.5和3.4倍。研究结果表明,花菖蒲幼苗对500 mg.L-1Pb单一胁迫具有一定的耐受性;在复合胁迫条件下Pb和Cd具有协同作用,对花菖蒲幼苗的生长和代谢有显著的抑制作用。

Effects of single and combined stresses of Pb and Cd（500 mg·L-1 Pb,25 mg·L-1 Cd,500 mg·L-1 Pb-25 mg·L-1 Cd） on growth and some physiological indexes of Iris ensata Thunb.var.hortensis Makino et Nemoto seedling were studied by liquid culture method.The results show that under 500 mg·L-1 Pb single stress condition,dry weight of above-ground part（leaf） and under-ground part（including rhizome and root） and tolerance index of I.ensata var.hortensis seedling have no significant difference with the control（P0.05）,while those decrease significantly compared with the control（P0.05） under 25 mg·L-1 Cd single stress or 500 mg·L-1 Pb-25 mg·L-1 Cd combined stress conditions,in which,the tolerance index is 0.86 and 0.79,respectively.Under 500 mg·L-1 Pb single stress condition,the content of photosynthetic pigment（including Chla,Chlb and carotenoid） in leaf and MDA content in under-ground part are significantly higher than those of the control,but MDA content in above-ground part is significantly lower than that of the control,and POD activity has no significant difference with the control.Under 25 mg·L-1Cd singlestress condition,contents of Chla and Chlb in leaf aresignificantly lower than those of the control,but carotenoid content in leaf,MDA content in above-ground part and POD activity in seedling are significantly higher than those of the control,and MDA content in under-ground part has no significant difference with the control.Under 500 mg·L-1 Pb-25 mg·L-1 Cd combined stress condition,photosynthetic pigment content in leaf is significantly lower and MDA content and POD activity in above-ground and under-ground parts are significantly higher than those of the control,in which,MDA content is 1.7 and 2.7 times and POD activity is 2.5 and 3.4 times of the control,respectively.It is suggested that I.ensata var.hortensis seedling appears a certain tolerance to 500 mg·L-1 Pb single stress.And under Pb-Cd combined stress condition,there is a synergistic effect of Pb and Cd,which causes obvious inhibition to growth and physiological metabolism of I.ensata var.hortensis seedling.