铜胁迫和间作对玉米抗氧化酶活性及丙二醛含量的影响

Effects of Copper Stresses and Intercropping on Antioxidant Enzyme Activities and Malondialdehyde Contents in Maize

为探讨红壤地玉米-豌豆间作种植模式对铜污染的响应机制，通过盆栽试验，研究了不同铜浓度（0、100、200、400、600 mg· kg-1）对玉米单作和玉米间作豌豆条件下植株生物量、铜含量、玉米抗氧化酶活性[超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）]及丙二醛含量（MDA）的影响。结果表明：在高 Cu2＋浓度（600 mg·kg-1）胁迫下，间作玉米地上部和地下部干重较单作分别提高了20豫和36.6豫，与单作相比，随着 Cu2＋浓度升高（100、200、400、600 mg·kg-1），间作模式下玉米地上部铜含量分别降低了86.81豫、44.57豫、22.01豫、11.11豫，而地下部铜含量则分别提高了78.89豫、24.79豫、35.29豫、13.31豫，且差异均达到显著水平。在不同Cu2＋浓度胁迫下，玉米叶和根中的 SOD、POD、CAT 活性和 MDA 含量均随着 Cu2＋浓度的增加而提高，仅 Cu2＋浓度达到600 mg·kg-1时玉米体内的 CAT 活性有所下降。间作条件下玉米根的 SOD 活性较单作提高了48.07豫～117.27豫，间作玉米叶的 SOD 活性较单作提高了11.30豫～46.90豫。不同种植模式对 Cu2＋胁迫条件下的玉米 POD 活性均没有显著影响。在 Cu2＋（0～400 mg·kg-1）胁迫下，间作玉米叶的 CAT 活性较单作均显著提高，分别提高了71.37豫、140.40豫、229.80豫和161.75豫，间作玉米根的 CAT 活性与单作无显著差异。间作玉米根的 MDA 含量较单作降低了26.13豫～64.53豫；在100、200 mg·kg-1 Cu2＋胁迫下，间作玉米叶的 MDA 含量较单作降低了0.30豫和26.24豫，但在400、600 mg·kg-1 Cu2＋胁迫下，间作玉米叶的 MDA 含量较单作提高了32.62豫和93.51豫。综上所述，在一定范围的 Cu2＋胁迫条件下，玉米根和叶中的抗氧化酶活性及 MDA 含量均有所提高来维持正常生长，间作模式在 Cu2＋胁迫下对玉米根和叶的抗氧化酶系统能起到一定的保护作用。

With industrial development, the area of arable land contaminated by heavy metals is steadily increasing around the world, espe-cially in developing countries. Intercropping has shown the potential to phytoremediate heavy metal polluted soils. A pot experiment was conducted to explore the antioxidant responses of maize to copper（Cu）pollution in red soil under maize-pea intercropping. Five Cu concentrations（0, 100, 200, 400, 600 mg·kg -1）and two cropping patterns（maize monoculture and maize-pea intercropping）were de-signed. Plant biomass, Cu contents, antioxidant enzyme activities（SOD, CAT, POD）and MDA contents of maize were measured. Com-pared with those in the monoculture, the aboveground and underground dry biomass of maize in high Cu2＋ concentration（600 mg·kg-1）were increased by 20% and 36.6%, respectively, under the intercropping system. However, Cu contents in the aboveground were reduced by 86.81%, 44.57%, 22.01% and 86.81%, but root Cu increased by 78.89%, 24.79%, 35.29% and 24.79% in 100, 200, 400 mg·kg-1 and 600 mg·kg-1 treatments, respectively, under the intercropping system, compared with the maize monoculture. Significant difference in plant Cu was present between intercropping and monoculture. The SOD, POD, CAT activities and MDA content in leaves and roots of maize all in-creased with increasing Cu2＋ concentrations. But Cu2＋ addition at 600 mg·kg-1 caused CAT activity decrease. Compared to the monoculture, SOD activity under maize-pea intercropping increased by 48.07%～117.27% in roots and 11.30%～46.90% in leaves. Cropping patterns had no significant effect on POD activity under the same Cu2＋ stress. In 0～400 mg·kg-1 Cu stresses, CAT activities in maize leaves were signifi-cantly increased by 71.37%, 140.40%, 229.80% and 161.75% respectively under the intercropping over the monoculture, whereas no sig-nificant difference in the CAT activities in roots was observed between two cropping systems. The intercropping practice reduced MDA con-tents in maize roots by 26.13%～64.53%; while intercropping caused left MDA decline only at 100 mg Cu·kg-1 and 200 mg Cu·kg-1 but in-creased at 400 mg Cu·kg-1 and 600 mg Cu·kg-1, as compared with the monoculture. In summary, intercropping could improve antioxidant enzymatic system in maize roots and leaves and thus alleviate Cu toxicity under Cu2＋ stresses.