【作者】 于肇端；

【导师】 曹辰兴；

【作者基本信息】 山东农业大学 ， 蔬菜学， 2010， 硕士

【摘要】 镉(Cd)是极易富集的重金属元素之一,近年来,随着工业生产的迅猛发展、农业污水灌溉及化肥农药的大量使用,致使我国很多地方土壤中镉含量超标,导致作物生长受抑制,影响产量。黄瓜(Cucumis sativus L.)和油菜(Brassica campestris L.)是我国主要的蔬菜作物,但易发生重金属(如镉)毒害。NO是生物体中的一种重要的氧化还原信号分子,可参与植物生长、发育、抗病、抗逆等生理过程。本试验采用水培的方法,研究了镉对黄瓜和油菜幼苗的伤害抑制机理,并探讨了外源NO供体硝普钠(Sodium nitroprusside, SNP)对黄瓜及油菜幼苗镉毒害的缓解效应。主要研究结果如下:1.随Cd浓度增加,黄瓜和油菜幼苗生长受到明显抑制,光合色素含量降低;Cd处理使黄瓜净光合速率(Pn)和气孔导度(Gs)下降,而胞间二氧化碳浓度升高,叶绿素荧光参数Fv/Fo、Fv/Fm、ΦPSII降低,并随着Cd离子浓度的增大,降低程度越严重;丙二醛(MDA)和脯氨酸(Pro)含量随着Cd处理浓度的增大而增加;超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性也有不同程度的下降;随着Cd处理浓度的增加POD活性也发生变化,与对照相比,镉毒害黄瓜幼苗的POD活性在低浓度100μmol·L-1时增大,在高浓度的Cd处理时降低,并随着Cd处理浓度的增大,其降低程度越显著,而镉毒害油菜幼苗的POD活性随着Cd处理浓度的增大而增大,结果表明,300μmol·L-1的Cd浓度胁迫效果最为显著。2.外源NO明显缓解了Cd对黄瓜、油菜幼苗生长的抑制,与Cd处理相比,其株高、茎粗等生长指标明显增大;SNP处理使Cd胁迫下黄瓜、油菜幼苗的光合色素含量显著提高;Pn、Fv/Fo、Fv/Fm升高,ΦPSII也得以缓解;SOD、CAT、POD活性也显著升高;SNP处理降低了Cd胁迫下黄瓜、油菜幼苗的MDA和Pro含量,缓解了Cd胁迫,结果表明,300μmol·L-1浓度的SNP缓解效果最为显著。但SNP的缓解效果还是有一定差异的,说明SNP副产物对幼苗生长也有抑制作用;铁氰化钾SF作为氰化物提供CN-模拟SNP副产物对幼苗的影响,从而也证明了SNP对Cd胁迫的缓解作用。3.抑制剂(抑制剂1为L-硝基精氨酸(Nitro-L-arginine),抑制剂2为钨酸镁(Magnesium tungstate-325 mesh))的处理,使黄瓜幼苗的株高和茎粗减小;黄瓜幼苗叶片的叶绿素含量明显降低;其叶片荧光参数Fv/Fo、Fv/Fm、ΦPSII显著降低;抑制剂的加入使POD活性明显降低,使MDA和脯氨酸含量增加,这表明抑制剂抑制了SNP对Cd胁迫黄瓜幼苗生长的缓解作用,加重了Cd胁迫引起的活性氧的伤害,可以看出外源NO供体SNP对Cd胁迫的缓解作用。更多还原

【Abstract】 Cucumber (Cucumis sativus L.) and Chinese cabbage (Brassica campestris L.) are main vegetables, planted widely in greenhouse and outdoor in China. Cadmium is one of the most aggressive and persistent heavy metals that may be present in natural environments as a by-product of human activities; among them, application of phosphoric fertilizers, pesticides and sewage farming constitute the major Cd inputs into agricultural soils. Cd concentration in soil is over standard in many places. Excess Cd inhibited the growth and yield of plants, including cucumber. Nitric oxide (NO) is a versatile signal molecule that functions through interaction with cellular targets via either redox or additive chemistry, and is involved in many key physiological processes of plants, such as growth, development, disease resistance and stress resistance. In this experiment, we studied the effects and the mechanism of that NO alleviate the toxic hazard that Cd to cucumber and chinese cabbage. The main results were as follows:1 Plant growth, chlorophyll and carotenoid contents, net photosynthetic rate (Pn) and stomatal conductance (Gs) of cucumber and chinese cabbage decreased with increasing concentration of Cd, while intracellular CO2 (Ci) significantly increased. The primary maximum photochemical efficiency of PSII(Fv/Fm), the maximum yield of the photosystem II photochemical reactions (Fv/Fm) and the quantum yield of photosysytem II electron transport (ΦPSII) were significantly inhibited by excess Cd, and was more significant with the increasing concentration of Cd. MDA and Pro contents, increased, superoxide dismutase (SOD) and catalase (CAT) activities decreased with the increasing concentration of Cd. Low concentration of Cd increased POD activity while high concentration dramatically inhibited its activity. The results showed that the Cd concentration of 300μmol·L-1 had the most significant effect.2 Application of SNP significantly alleviated the inhibition of plant growth of cucumber and chinese cabbage seedlings under Cd stress, and increased the contents of photosynthetic pigment significantly. Pn, Fv/Fm, Fv/Fo,ΦPSII and activities of SOD, CAT and POD increased with application of SNP, whereas MDA content decreased with application of SNP. The results showed that 300μmol·L-1 concentration of SNP had the most significant relief effect. However the application of SNP was different, this indicated that the by-products of SNP had inhibition. Potassium ferricyanide (SF) as the by-products of simulates SNP, which offered CN- affected the seedlings.3 Application of inhibitors significantly decreased photosynthetic pigment content, Pn, Fv/Fm, Fv/Fo,ΦPSII, and POD activity. At the same time, inhibitors increased the content of MDA and Pro, which indicated that inhibitors aggravated the stress of Cd to cucumber and chinese cabbage seedling. Thus, we can see that application of SNP was an effective way to alleviate the toxic hazard of Cd to cucumber and chinese cabbage seedlings.更多还原