黑麦草生长过程中有机酸对镉毒性的影响

研究了低分子量有机酸草酸、柠檬酸、乙酸及高分子量有机酸胡敏酸对黑麦草(Lolium Loinn)生长过程中Cd毒性的影响.结果表明,随着低分子量有机酸浓度增加,Cd毒性有所增强,致使黑麦草中的叶绿素含量降低及黑麦草的生物量降低,递降顺序是草酸＜乙酸＜柠檬酸.而施入胡敏酸后,Cd毒性逐渐减弱,黑麦草中的叶绿素含量及黑麦草生物量逐渐增加.对低分子量有机酸而言,无论迁移到黑麦草茎叶中,还是迁移到黑麦草根系中的Cd,随着施入的有机酸浓度增加,增加顺序为柠檬酸＞乙酸＞草酸.对胡敏酸而言,迁移到黑麦草茎叶和根系中的Cd,随着施入的胡敏酸浓度增加,Cd含量减少,说明其具有降低Cd毒性的作用.另外,根系中Cd含量明显高于茎叶中Cd含量,由此得知,黑麦草根系对Cd有较强的富集作用,并阻止Cd向茎叶中迁移.

Effects of organic acids on the toxicity of cadmium during ryegrass grwth

Effects of low molecular weight organic acids(oxalic acid, citric acid, and acetic acid) and higher molecular weight organic acid(humic acid) on the toxicity of Cd during ryegrass growth were studied. The results showed that Cd toxicity enhanced gradually with increasing the concentration of low molecular weight organic acids, and led to the decreasing of chlorophyll concentration in ryegrass plant and the biomass of ryegrass. The sequence of this influence was: oxalic acid < acetic acid < citric acid. On the contrary, Cd toxicity was reduced as a result of addition of humic acid, and the concentration of chlorophyll in ryegrass shoots and the biomass of ryegrass increased consequently. The concentration of Cd in roots and shoots of the ryegrass increased with increasing the concentration of low molecular weight organic acids, and the sequence of this influence was: citric acid > acetic acid > oxalic acids. The concentration of Cd decreased gradually as a result of increasing the concentration of humic acid, which means humic acid could reduce the toxicity of Cd on ryegrass. Furthermore, the concentration of Cd was higher in roots than in shoots, which indicated that the roots of ryegrass could prevent transport of Cd from roots to shoots and reduce Cd accumulation in the shoots.