【作者】 刘素纯；

【导师】 肖浪涛； 廖柏寒；

【作者基本信息】 湖南农业大学 ， 植物学， 2006， 博士

【摘要】 重金属污染是当今污染面积最广、危害最大的环境问题之一。土壤中重金属污染不仅退化土壤肥力，降低作物的产量与质量，恶化水环境，并通过食物链危害人的健康和生命安全。因此，重金属污染方面的研究一直是当前学术界的热点。本文以黄瓜幼苗为材料，研究了铅污染对黄瓜幼苗生长发育、内源激素、多胺、水杨酸、抗氧化保护系统及其他生理生化反应的影响，主要研究结果如下： 1．铅对黄瓜种子萌发、早期生长及生理生化特性的影响 铅在黄瓜幼苗中的吸收分布存在差异，所吸收的铅大部分积累在根系，只有少部分向上运输到茎和叶部。黄瓜幼苗叶和根中吸收铅量的随铅质量浓度增强而增加。铅溶液对种子萌发产生抑制作用并且表现为随铅质量浓度的增加抑制作用增强。 100～200mg·L^-1硝酸铅溶液对黄瓜幼苗的生长有促进作用；300～900mg·L^-1硝酸铅溶液对黄瓜幼苗生长产生抑制且抑制作用随铅质量浓度的增加而增加。高质量浓度铅诱导不定根产生。此外还发现铅处理的黄瓜幼苗其干重与铅质量浓度呈负相关。 100～700mg·L^-1硝酸铅溶液可增加叶片叶绿素的含量，当铅质量浓度增至900mg·L^-1时，叶绿素含量开始下降。铅处理下叶片中栅栏组织和海绵组织排列变得紧密，尤其是栅栏组织由1层增加为2～3层。 铅处理使得黄瓜幼苗体内的MDA和脯氨酸含量明显增加，其含量增加与铅质量浓度呈正相关。细胞膜的透性增加，与MDA含量的变化趋势相一致。 2．铅对黄瓜幼苗地上部抗氧化保护系统的影响 用100～500mg·L^-1硝酸铅溶液处理黄瓜幼苗，其地上部的SOD活性随着处理时间的延长到7d呈现出大幅度上升，达到一个高峰值后急剧下降（低于对照），而且随着铅质量浓度的增加SOD活性也相应地增加。900mg·L^-1硝酸铅溶液处理黄瓜幼苗地上部的SOD活性随着处理时间的延长呈先升高（高于对照）后降低（低于对照）的趋势。SOD同工酶的酶条带数和表达量与铅质量浓度呈负相关，更多还原

【Abstract】 Heavy metal pollution is one of the most serious environmental problems in recent years. Heavy metal pollution in soil degenerates soil fertility, decreases crop yield and product quality, deteriorates water environment, and endangers human health through food chain. Study on heavy metal pollution became one of the hottest academic areas. The cucumber seedling were used to study how the lead （Pb） contamination impacts on the growth and development of cucumber seedlings, especially the change of endogenous phytohormones, polyamines, antioxidation protection enzyme system, biochemical and physiological characteristics. The main results are as follows:1. Effects of lead on germination, early growth and development, some physiological and biochemical characteristics of cucumber seedlingsThe absorption and distribution of lead was different in cucumber seedlings. Lead absorbed mainly accumulates in root, while a small portion was transported to stems and leaves. The lead amount in leaves and roots of cucumber seedling increased under the exogenous lead treatment. It was also found that the germination was promoted within lead mass concentration range of 100-200 mg·L^-1 and hold down under lead mass concentration 300⁹00mg·L^-1Growth accelerating of cucumber seedlings was observed within range 100²00mg·L^-1 lead mass concentration, meanwhile growth was restrained under lead mass concentration of 300⁹00mg·L^-1, and the restraining impact was getting more obvious with the increase of lead mass concentration. High mass concentration of lead induced adventitious roots. Dry weight of cucumber seedling was negatively related to lead mass concentration under lead treatment.Chlorophyll amount in leaves increased within lead mass concentration range of 100-700mg·L^-1, but chlorophyll amount decreased when the lead mass concentration reached 900mg·L^-1 Palisade tissue and spongy tissue in leaves became more tighter arrangment, especially palisade tissue layers increased from one to three.MDA and proline amounts in cucumber seedlings increased continually with increase of lead mass concentration, and they were positively related to lead mass concentration. Cell membrane permeability increased with the increase of lead mass concentration, and the transformation tendency was in conformity with MDA change.2. Effect of lead on antioxidation protection enzyme system in aerial parts of cucumber seedlingWithin lead mass concentration of 100⁵00mg·L^-1, SOD activity in aerial parts更多还原