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^-1 Pb、25 mg·L^-1 Cd、500 mg·L^-1Pb-25 mg·L^-1 Cd)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^-1 Pb 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^-1 Cd 单一胁迫和500 mg·L^-1 Pb-25 mg·L^-1 Cd 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^-1 Pb 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^-1 Cd 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^-1 Pb-25 mg·L^-1 Cd 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-1 Pb 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 (P>0. 05), while those decrease significantly compared with the control (P<0. 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^-1 Cd single stress condition, contents of Chla and Chlb in leaf are significantly 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.