中文摘要：

重金属Cd作为毒性较高的环境毒物，不仅危害植物的生长和发育，也对人类健康带来严重威胁。水杨酸（Salicylicacid，SA）作为一类新型植物生长调节物质，在诱导植物抗性方面起重要调节作用。以莴苣笋王一号为试验材料，研究了不同浓度SA处理对Cd胁迫下莴苣种子萌发的效应及其生理机制。结果表明，Cd胁迫条件下，莴苣种子萌发受到影响，表现为发芽势、发芽指数、活力指数和根长明显降低。Cd胁迫还可引起氧化胁迫产生，并造成膜脂过氧化伤害。不同浓度SA对cCd胁迫下莴苣种子萌发和幼苗生长的缓解作用不同，表现为低促高抑效应，以0．1mmol／L的SA效果最好。SA处理能缓解Cd对种子萌发和幼苗生长的伤害与植株体内CAT、APX、SOD和GPX等抗氧化酶活性变化有关。

英文摘要：

Cadmium（Cd） was a highly toxic and persistent environmental poison,its increasing level in soil environment exerted a wild range of adverse effects on plants and even the healthy of human beings by food chains. Salicylic acid（SA） ,considered as a hormone-like substance,played an important role in modulation of acclimation responses for plant. The possible effects of SA on lettuce seeds germination and seedlings growth under Cd stress were studied. The results showed that the quality of seed germination and seedling growth were significantly inhibited under Cd stress, especially for root length, vigor index, etc. Moreover, Cd stress could lead to oxide stress and high level of lipid peroxidation. Different concentrations of SA had different roles on seed germination and seedling growth under Cd stress and low concentrations of SA could enhance the germination and seedlings growth,however, high concentration had a inhibition effect. Our results showed the protection role of 0.1 mmol/L SA was best for seed germination and seedling growth,respectively. Alleviating the cadmium toxicity in seed germination and seedling growth by SA was due to modulating the activities of CAT,APX,SOD and GPX.