喜旱莲子草对Pb、Cd胁迫响应的研究

采用营养液培养法,以喜旱莲子草为对象,选择重金属Pb在浓度梯度0,0.1,10,50,100和200 mg/L条件下,Cd在浓度梯度0,0.01,1,10,20和40 mg/L条件下,研究了不同浓度Pb、Cd单一及复合胁迫对喜旱莲子草生长的影响。结果表明,在试验条件下,对单一Pb及Cd对喜旱莲子草生长及生理影响而言,与对照相比,当Pb处理浓度为0.1 mg/L时,植物最高株高和最长根长分别增加了3.8%和15%。随着Pb处理浓度增加到200 mg/L时,植物生长受到明显抑制,茎叶株高呈显著下降。当Cd处理浓度为1 mg/L时,与对照相比,植物最高株高和最长根长分别增加了9.0%和10.0%,随着Cd处理浓度增加(20~40 mg/L),植物生长受到明显抑制,茎叶株高呈显著下降。随Pb和Cd处理浓度增加,喜旱莲子草叶绿素含量呈下降趋势,POD活性先升后降,MDA含量呈上升趋势,植株体内Pb、Cd积累量呈上升趋势。在研究Pb、Cd对喜旱莲子草生长及生理胁迫的基础上,选择Pb、Cd不同配比浓度,探讨其对喜旱莲子草的复合胁迫作用,研究植物对重金属Pb、Cd富集特性,结果表明,低浓度Pb、Cd处理表现出相互促进吸收富集,高浓度处理表现出相互抑制吸收富集的特性。

Studies on Responses of Alternanthera philoxeroides to Stress of Pb and Cd

Experimental studies focused on stress of heavy metal,e.g.Pb,Cd,singly and Pb and Cd combined on growth of plant Alternanthera philoxeroides,revealing the trend of development and growth of the plant with the increase of concentrations of Pb and Cd in the Hoagland-Arnon cultivation solution.It was shown that growth of Alternanthera philoxeroides was greatly inhibited when Cd concentration increased to the range of 20~40 mg/L;on the contrary,low concentrations of Pb(≤10 mg/L) and Cd(≤1 mg/L) could promote its growth.According to the observations,content of chlorophyll of the plant declined apparently with the increasing of Pb,Cd respectively or Pb and Cd combined,with the peroxidase(POD) activities being up at first and down later and content of malondialdehyde(MDA) increasing;accumulation of Pb and Cd in the plant also tended to increase as well.When treated with low concentration of Pb(≤10 mg/L) Cd accumulation in Alternanthera philoxeroides was enhanced and Cd(≤1 mg/L),and vice versa,treated with Cd in low concentration(≤1 mg/L) Pb accumulation in the plant enhanced;treatment with high concentration of Pb and Cd would each other inhibit their accumulation in the plant.