污水与镉复合胁迫对玉米幼苗抗氧化酶活性的影响

摘要

To investigate the influence of sewage and cadmium (Cd) compound stress on crop growth mechanism,by using laboratory hydroponic technology,ultraviolet spectrophotometer and graphite furnace atomic absorption spectrometry,the paper studied the variation of maize seedlings of antioxidant enzyme activity led by the compound stress.The results showed that compared with their own CK,single and compound stress processions had an promoting effect (P ＜ 0.05) on maize seedlings germination when the Cd2+ concentration was 0 ～ 10 rag/L,but no effect on plant height and root length.On the contrary,when the Cd2+ concentration was 10 ～50 rag/L,it had no effect on maize seedling germination,but an obvious inhibition effect on plant height and root length (P ＜ 0.001).Compared with their own CK,Cd2+ in both two treatments could induce the increase of the four kinds of antioxidant (SOD,POD,GST,CAT) of maize seedlings activity.With the increase of concentration of Cd2+,enzyme activity changed into double phases:low concentration increased slowly,high concentration increased rapidly.Compared with Cd single treatment,the change of the four kinds of enzyme activity in the compound stress showed no significant differences when the Cd2+ concentration was between 0 ～ 10 mg/L (P ＞0.05),while the compound treatment was significantly higher than single treatment (P ＜ 0.05) when the Cd2+ concentration was 10 ～50 mg/L.Single and compound stress could cause maize seedling Cd accumulation,compound treatment was higher than the single treatment with the same concentration of Cd2+,with increasing concentration of Cd2+,Cd content of maize seedlings increased in both treatment showed a double stage:it increased rapidly when the Cd2+ concentration was 0 ～ 10 rag/L,while slowly when the Cd2+ concentration was 10 ～ 50 mg/L.At low concentration of Cd2+,sewage could alleviate the harm to the maize seedlings by the heavy metal Cd,and the harm deepened when the Cd2+ concentration was high.The concentration of Cd2+ in 5 ～ 10 mg/L range was a sensitive point of maize seedling antioxidant enzyme activity.The compound pollution of sewage and high concentration of Cd2+ to human health should be highly attention.%为了探讨污水与镉(Cd)复合胁迫对作物生长的影响机制,采用实验室水培技术、紫外分光光度和石墨炉原子吸收法,对复合胁迫致玉米幼苗抗氧化酶活性的变化进行了研究.结果表明,与各自空白对照相比,单一和复合胁迫在Cd2+质量浓度为0～ 10 mg/L时,对玉米种子萌发均有显著促进作用(P＜0.05),但对株高和根长没有影响;在Cd2+质量浓度为10～ 50 mg/L时,对玉米种子萌发没有影响,但对株高和根长则存在明显的抑制作用(P＜0.001).与各自空白对照相比,2个系列Cd2+均能诱导玉米幼苗超氧化物歧化酶(SOD)、过氧化物酶(POD)、谷胱甘肽-S-转移酶(GST)、过氧化氢酶(CAT)4种抗氧化酶活性的增加,且随着Cd2+浓度的增大,酶活性变化均呈现双阶段性:低浓度增加缓慢,高浓度增加迅速;与Cd单一胁迫相比,复合胁迫4种酶活性的变化,在Cd2+为0～10 mg/L时,没有显著差异(P＞0.05),在Cd2+为10 ～ 50 mg/L时,均为复合胁迫显著高于单一胁迫(P＜0.05).单一和复合胁迫均会导致玉米幼苗Cd积累,且Cd2+质量浓度相同时,复合胁迫高于单一胁迫;在2个系列中,随着Cd2+质量浓度的增大,玉米幼苗Cd含量上升亦呈现双阶段性,Cd2+为0～ 10 mg/L时增加迅速,为10 ～ 50 mg/L时增加缓慢.污水在Cd2+质量浓度较低时可以缓解重金属Cd对玉米幼苗的危害,Cd2+质量浓度较高时,则加剧对玉米幼苗的危害;Cd2+为5～ 10 mg/L是污水与Cd复合胁迫诱导玉米幼苗抗氧化酶活性变化的敏感点,污水与高浓度Cd2+复合胁迫对人体健康的影响应引起高度关注.