中文摘要：

为了研究汞对小麦幼苗叶片、根和萌发种胚的蔗糖酶（Inv）和苯丙氨酸解氨酶（PAL）活性的影响,采用水培法,用不同浓度的Hg2＋对小麦进行浸种处理,测定小麦在不同时间和不同器官的Inv和PAL活性,结果表明,随着Hg2＋浓度的递增,小麦幼苗叶片、根和萌发种胚中,酸性和中/碱性Inv的活性都呈先上升而后下降的趋势,小麦幼苗叶片、根和萌发种胚的PAL的活性也呈先上升而后下降的趋势。不同器官的两种酶活性相比,快速生长的叶片和根部的酶活性都比萌发种胚的高。低浓度Hg2＋（≤0.100 mmol/L）对小麦幼苗的Inv和PAL活性有短暂的促进作用,高浓度Hg2＋（≥0.200 mmol/L）对Inv和PAL活性有显著的抑制作用。当Hg2＋浓度为0.100 mmol/L时,各种Inv和PAL活性达到最大,由此推断,此浓度是影响小麦幼苗生长的阈值浓度。

英文摘要：

In order to study the effect of mercury on the activities of invertase（Inv） and phenylalanine ammonia-lyase（PAL）in leaves,roots and germinating embryos of wheat seedlings,different concentrations of Hg2＋were used for seed soaking treatment and then the Inv and the PAL activities of wheat at different processing times and organs were determined.Results showed that with the concentration of Hg2＋ increasing,the acidic and neutral/alkaline Inv activities all trended to rise first and then fall in the leaves,roots and germinating embryos.PAL activity also presented the same tendency.In different organs,the enzyme activities in the fast growth leaves and roots were higher than those in the germinating embryos.In conclusion,low concentration of Hg2＋（≤0.100mmol/L） had short-term promoting action,while high concentration of Hg2＋（≥0.200mmol/L） had significantly inhibition on the activities of Inv and PAL.The activities of Inv and PAL reached the maximum at Hg2＋concentration of 0.100mmol/L,which was a threshold concentration affecting the growth of wheat seedlings.