Pb胁迫对双穗雀稗生长、抗氧化酶活性及Pb富集的影响

Effects of Pb Stress on Growth and Antioxidative Enzymes Activity of Paspalum distichum L. and its Pb Uptake

以消落带适生植物双穗雀稗(Paspalum distichum L.)为试验材料,通过水培试验,研究了Pb胁迫对双穗雀稗生长、抗氧化酶活性及其对Pb富集的影响。结果表明,低浓度(≤400μmol/L)Pb胁迫对双穗雀稗生长有促进作用,根系耐性指数大于1,叶绿素含量明显增加,抗氧化保护酶系统超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性提高;当Pb浓度>400μmol/L时,双穗雀稗生长受到抑制,叶尖发黄,根系耐性指数小于1,叶片叶绿素含量下降,SOD、POD、CAT活性均呈下降趋势。在200μmol/L Pb胁迫下,随胁迫时间延长,叶片叶绿素含量及SOD、POD、CAT活性均先升高后降低,在12 d时达到最大。双穗雀稗主要通过地下部和地上部迁移富集Pb,迁移富集量与水体中Pb浓度表现为明显的线性正相关,转运系数小于1,不属于Pb超积累植物,但能明显降低水体中的Pb浓度,因而双穗雀稗既是消落带植被重建的优良物种,也能较好修复水体中的Pb污染。

The hydro-fluctuation belt plant Paspalum distichum L. was taken as material,the effects of Pb stress on the growth and antioxidative enzymes activity of Paspalum distichum and its Pb enrichment were investigated by hydroponic experiment. The results showed that the growth of Paspalum distichum could be improved under low concentration of Pb stress （ ≤400 μmol/L） ,the root tolerance index was greater than one,the chlorophyll content in leaves increased obviously, and the activity of SOD, POD and CAT in- creased. When the concentration of Pb in water was greater than 400μmol/L, the growth of Paspalum dis- tichum was inhibited,the leaf tip becomed yellow,the root tolerance index was less than one, the chloro- phyll content in leaves decreased obviously, and the activity of SOD, POD and CAT decreased. Under 200 μmol/L Pb stress,the chlorophyll content and the activity of SOD,POD and CAT increased first and then decreased with the increase of the stress time,which reached the peack after 12 days. The enrichment and transportation of Pb was found mainly in the root and culm of Paspalum distichum. The enrichment and transportation amount were positively related with the Pb concentration, and the transmission coefficients of Pb was smaller than one, indicating Paspalum distichum was not Pb-hyperaccumulator, but Paspalum ditichum had the ability to repair heavy metal Pb pollutions, and it was the good plants for the river waterecosystem restoration.