小麦幼苗生长及其抗氧化酶活性对模拟酸雨与金属离子复合胁迫的响应

Growth and Activities of Antioxidant Enzymes in Wheat Seedlings under Combination Stress of Simulated Acid Rain,Aluminum,Cadmium and Lead

通过水培试验,研究了模拟酸雨（pH 3.5）与Al（3、30 mg/L）、Pb（25、250 mg/L）、Cd（0.11、mg/L）单独或复合胁迫对小麦幼苗生长及抗氧化酶活性的影响。结果表明,模拟酸雨与Al、Pb、Cd单独或复合处理12 d后,小麦幼苗根长降低54.01%～94.81%,苗高降低18.88%～77.95%,单粒萌根数降低21.87%～80.37%,其生长发育受到显著抑制,抑制效应随处理浓度增大和作用时间延长而增强,且复合处理组抑制效应更强;幼苗根部超氧化物歧化酶（SOD）活性在模拟酸雨与单一金属离子处理下显著升高,而在3种金属离子复合处理下显著降低,但酸性条件下无论金属离子单独及复合处理后,过氧化物酶（POD）活性均显著升高,过氧化氢酶（CAT）活性均明显下降。研究发现,酸性条件下3种金属离子对植物细胞均产生氧化胁迫作用,且它们复合胁迫的毒性效应大于其单独胁迫。

Effect of single and combined stress of aluminum（3,30 mg·L^-1）,cadmium（0.1,1 mg·L^-1） and lead（25,250 mg·L^-1） under acidic rain on growth and activities of antioxidant enzyme were studied in wheat seedlings.The experimental results showed that Al,Pb and Cd can inhibit root length,shoot height and root number per seedling significantly after exposure to single or combined metal ions for 6 days or 12 days.The decrement of root length and shoot height were 54.01%～94.81% and 18.88%～77.95% respectively,while root number per seedling decreased by 21.87%～80.37% after exposure for 12 days.The inhibition effects increased with increasing treatment concentrations and prolonged exposure duration,meanwhile stronger inhibition effects were found in the combination treatments of three metal ions and simulated acid rain.The activities of SOD increased significantly after seedlings exposed to single metal ion Al,Pb or Cd and simulated acid rain,but decreased markedly after exposure to the combination of three metal ions and simulated acid rain.POD activity increased significantly in all treatment groups,however CAT activity decreased at the same time.The results showed that the combination of simulated acid rain and metal ion caused oxidative stress in plants,and higher toxicity occurred after seedlings exposed to the combination of simulated acid rain and three metal ions.