中文摘要：

采用营养液培养方法,研究了外源柠檬酸（0.5、5mmol.L-1）和草酸（0.5、5mmol.L-1）对不同浓度Pb（0、100、500mg.L-1）胁迫下马蔺（Irislactea var.chinensis）生长和生理的影响。结果表明,与单独Pb胁迫相比,加入5mmol.L-1的柠檬酸显著促进了马蔺株高的生长;草酸的加入缓解了500mg.L-1Pb胁迫对马蔺根生长的影响;加入0.5mmol.L-1的草酸缓解了500mg.L-1Pb胁迫对马蔺地上部生长的影响,并显著增加了100和500mg.L-1Pb胁迫下马蔺的地下部干质量;0.5mmol.L-1的柠檬酸能显著增加100mg.L-1Pb胁迫下马蔺叶片SOD酶活性;0.5和5mmol.L-1柠檬酸和0.5mmol.L-1草酸均能显著增加100mg.L-1Pb胁迫下马蔺体内POD酶活性;5mmol.L-1的柠檬酸和0.5mmol.L-1的草酸均缓解了500mg.L-1Pb胁迫对马蔺光合色素的影响;0.5和5mmol.L-1的柠檬酸和0.5mmol.L-1的草酸均能缓解由100和500mg.L-1Pb胁迫引起马蔺叶片细胞膜的损伤。

英文摘要：

A hydroponic experiment was conducted to study the effects of exogenous citric acid （0.5 and 5 mmol·L-1） and oxalic acid （0.5 and 5 mmol·L-1） on the growth and physiology of Iris lactea var.chinensis under 100 and 500 mg·L-1 Pb stress.Comparing with Pb stress alone,adding 5 mmol·L-1 of citric acid promoted the shoot growth of I.lactea var.chinensis significantly.The addition of oxalic acid mitigated the impact of 500 mg·L-1 Pb stress on the root growth of I.lactea var.chinensis.Adding 0.5 mmol·L-1 of oxalic acid alleviated the 500 mg·L-1 Pb stress on the shoot growth,and increased the root dry mass significantly under 100 and 500 mg·L-1 Pb stress.The SOD activity in I.lactea var.chinensis leaves under 100 mg·L-1 Pb stress was increased significantly by adding 0.5 mmol·L-1 of citric acid,and the POD activity of I.lactea var.chinensis under 100 mg·L-1 Pb stress was increased significantly by adding 0.5 and 5 mmol·L-1 of citric acid or 0.5 mmol·L-1 of oxalic acid.The impact of 500 mg·L-1 Pb stress on the photosynthetic pigments of I.lactea var.chinensis was alleviated by the addition of 5 mmol·L-1 of citric acid or 0.5 mmol·L-1 of oxalic acid.Adding 0.5 and 5 mmol·L-1 of citric acid or 0.5 mmol·L-1 of oxalic acid reduced the membrane damage of I.lactea var.chinensis leaves under 100 and 500 mg·L-1 Pb stress.