硒镉交互作用对西葫芦幼苗生长及抗氧化酶活性的影响

硒能够缓解镉胁迫对植物产生的毒害。为探明硒(Se)和镉(Cd)交互作用对植物的影响,本研究以西葫芦为材料,采用沙培的方式,研究了不同浓度Se(0.5、2.0和4.0 mg·L^-1)与Cd(0.2、0.4和0.6 mg·kg^-1)交互作用对西葫芦幼苗生长和抗氧化酶活性的影响。结果表明,单一Cd胁迫下,随着Cd浓度的增加,其对西葫芦幼苗的生长和抗氧化酶活性具有一定的促进作用。Se与Cd交互作用对西葫芦幼苗生长和抗氧化酶活性的影响与Se和Cd的浓度有关。不同浓度Se与低中浓度Cd(0.2和0.4 mg·kg^-1)交互作用可使Cd胁迫下西葫芦幼苗苗高、鲜重和干重显著增加,与高浓度Cd(0.6 mg·kg^-1)交互作用却抑制了西葫芦幼苗的生长。与单一Cd胁迫相比,不同浓度Se与0.2 mg·kg^-1Cd交互作用可显著提高西葫芦幼苗SOD和POD活性,不同浓度Se与0.4和0.6 mg·kg^-1Cd交互作用抑制了西葫芦幼苗SOD和POD活性,且Cd浓度越高,差异越明显。在高浓度(0.6 mg·kg^-1)Cd胁迫下,Se浓度越高,2种元素的交互作用对西葫芦幼苗生长和抗氧化酶活性产生的抑制作用越大。Cd胁迫下,外源Se可以降低西葫芦幼苗Cd含量,同时提高Se含量。较低浓度的Se能够有效缓解Cd对西葫芦幼苗造成的毒害作用,综合来看,2.0 mg·L^-1Se与Cd的交互作用对西葫芦幼苗的生长和抗氧化酶活性的促进作用最强。本研究表明施加外源Se缓解Cd胁迫对植物的毒害时,应同时考虑Cd的污染程度和施加Se的量,为Cd污染治理提供了一定的参考依据。

Interactive Effects of Selenium and Cadmium on the Growth and Antioxidative Enzymes in Zucchini Seedling

The selenium (Se) can alleviate the toxicity of cadmium (Cd) on plants. In order to investigate the effects of the interaction between Se and Cd on plants, a sand culture experiment was conducted to study the interactive effects of different concentration of selenium (0.5, 2.0 and 4.0mg·L^-1) and cadmium (0.2, 0.4 and 0.6mg·kg^-1) on the growth, antioxidative enzymes, Cd and Se content in pumpkin seedlings. The results indicated that exposure to increasing Cd concentrations promoted the growth and the activity of antioxidant enzymes of pumpkin seedlings. The interactive effect of Se and Cd on growth and the activity of antioxidative enzymes for pumpkin seedlings mainly depended on the concentration of Se and Cd. When Cd treatment level was 0.2 and 0.4 0.4mg·kg^-1, Se (0.5, 2.0 and 4.0mg·L^-1) could significantly increase seedling height, fresh weight and dry weight of pumpkin seedlings. However, with Cd level reaching 0.6 mg·kg^-1, the addition of Se resulted in decreasing biomass of pumpkin seedlings. Compared with single Cd stress, the combination treatment of Se (0.5, 2.0 and 4.0mg·L^-1) and Cd level at 0.2 mg·kg^-1 significantly enhanced, the activity of SOD and POD; Se (0.5, 2.0 and 4.0mg·L^-1) inhibited the activity of SOD and POD when Cd levels were 0.4 and 0.6 mg·kg^-1, furthermore, the higher the concentration of Cd was the more serious the inhibition was. There were the inhibitory effects of Se-Cd interaction on growth and activity of antioxidant enzyme in pumpkin seedlings under stress of Cd with 0.6 mg·kg^-1. The exogenous Se reduced Cd concentration and increased the Se concentration in zucchini seedlings under Cd stress. Se with lower levels could effectively alleviate Cd toxicity in zucchini seedlings.The optimum Se concentration is 2.0 mg·L^-1 for Se-Cd interactions to promote the growth and antioxidant enzyme activity under Cd stress with low concentration. This study suggested that the Cd pollution degree and concentration of exogenous Se should be considered when Se is used to alleviate Cd toxicity on plant, which provided a certain reference for Cd pollution control.