【作者】 朱志勇；

【导师】 李友军；

【作者基本信息】 河南科技大学 ， 生态学， 2011， 硕士

【摘要】 通过水培小麦试验,对小麦幼苗进行Cd处理,设置CK、低、中、高Cd (0、30、60、90μmol/L)四个处理浓度,研究Cd对小麦幼苗的生物学效应及幼苗体内Cd吸收和积累情况,探讨洛旱6号、矮抗58、豫麦25、豫麦18、中育10号、豫农949、新麦21、许农5号、洛麦23等9个品种小麦苗期镉耐性的差异。从苗期镉耐性不同的9个品种当中选取镉耐性强的洛旱6号和中育10号、镉耐性中等的新麦21和矮抗58、镉耐性弱的豫麦18和洛麦23等6个小麦品种,结合大田试验,设置CK、低、中、高Cd (0、10、50、100 mg/kg)四个处理浓度,探讨镉胁迫下不同镉耐性小麦品种在灌浆期间生长、干物质积累、产量的特征,同时研究小麦对Cd吸收和分配的特征及镉胁迫对小麦吸收和积累其它金属元素的影响,揭示不同镉耐性小麦品种的生理生化机制。主要结果如下:1、Cd对小麦幼苗生长及生物量积累的影响表现为低Cd处理促进了部分品种的生长、生物量积累,中、高Cd处理呈抑制作用。灌浆期间,Cd导致小麦生长、各器官干物质和氮素的积累、转运受阻,叶面积指数下降,进而抑制了小麦的籽粒灌浆速率及产量。其中,镉耐性强的品种在灌浆期间受Cd抑制程度较镉耐性弱的品种小。2、灌浆期间,镉胁迫抑制了小麦旗叶叶绿素、旗叶和籽粒可溶性糖、旗叶和籽粒可溶性蛋白及籽粒淀粉的合成和积累,其抑制程度因品种而异。其中,6个品种小麦籽粒可溶性糖含量、籽粒淀粉含量、旗叶可溶性蛋白含量相对值大小与其镉耐性大小不太一致。同时,镉胁迫小麦籽粒的谷蛋白、高分子量谷蛋白亚基(HMW-GS)、低分子量谷蛋白亚基(LMW-GS)含量整体上呈下降趋势。说明镉胁迫导致小麦籽粒的加工品质下降,镉耐性大的品种,籽粒品质受影响较小。3、幼苗期间,叶片POD活性随着Cd处理浓度增加和处理时间延长有不同程度的增加,且Cd对POD活性激活效应有一定的界限,其临界浓度值因品种而异。所有品种小麦叶片的脯氨酸含量随着Cd处理浓度升高和处理时间的延长而逐渐升高,升高的幅度因品种而异。灌浆期间,镉胁迫下小麦旗叶POD和SOD的活性整体上呈下降趋势,其抑制程度因品种和处理浓度而异。有部分品种的POD和SOD活性在低镉处理下有所升高。POD和SOD同工酶谱显示,低、中Cd浓度诱导或抑制了低分子量同工酶表达从而影响POD的活性,对高分子量区的POD同工酶影响较小;高Cd处理下高分子量区和低分子量区POD同工酶的表达,从而抑制POD的活性。Cd对大部分小麦品种SOD活性的影响是因为低分子量区的SOD同工酶表达受到诱导或抑制。4、小麦幼苗体内Cd含量随着Cd处理浓度的升高而增大,且根部Cd含量高于地上部的。但是Cd积累量却不与Cd处理浓度呈正比,低、中Cd处理下Cd积累量最大,根部的Cd积累量大于地上部的。灌浆期间,各器官Cd含量总体是随着土壤Cd浓度增加而上升,各器官Cd积累量受到对应器官生物量和Cd含量的共同作用,积累量最高点存在较大差异。各器官Cd含量和积累量大小依次为籽粒>茎鞘>叶片。Cd含量与积累量与苗期耐镉性大小顺序不大一致,耐镉性弱的洛麦23籽粒Cd含量最高。镉胁迫下,小麦各器官Zn、Mn、Cu、Fe等金属元素的吸收和积累都受到不同程度的影响。5、9个小麦品种的苗期耐镉性大小依次为:豫农949>洛旱6号、豫麦25>中育10号>新麦21>矮抗58、许农5号>豫麦18>洛麦23;6个小麦品种在灌浆期间的耐镉性大小依次为:洛旱6号、中育10号>新麦21>矮抗58>豫麦18>洛麦23。苗期耐镉性大小与灌浆期间耐镉性基本一致。更多还原

【Abstract】 A hydroponics experiment was set up to cultivate wheats which treated by four Cd concentrations, the concentrations were 0, 30, 60, 90μmol/L, was carried out to study bioeffects of cadmium on wheats, Cd absorption and accumulation, even dicussed Cd tolerance of different genotypic wheats. After that, a field experiment was set up, which using 6 genotypic wheats with different Cd tolerances treated by four Cd concentrations, such as 0, 10, 50, 100 mg/kg, to study effects of cadmium on their growthes, biomasses and yields in filling stage, discussed characteristics of Cd and other metallic elements absorbed and distributed in wheats, and revealed physiological and biochemical mechanisms. The main results are as follows.Firstly, there was a difference on effects of Cd on growthes and biomasses of seedlings, however, their average values were descending with Cd concentration ascending. The low Cd concentration promoted a part of wheats growing more quickly and accumulated more biomasses than controls’, both growthes and biomasses of wheats exposed in middle and high Cd concentrations were less than controls’. As a whole, Cd depressed growthes, biomasses, leaf area indexes and accumulations of nitrogen of wheats in filling stage, to make matters worse, the yields of wheats were depressed because of Cd. The degrees of depressions were different among genotypics, genotypics with low Cd tolerance beared more poison from Cd than genotypics with high Cd tolerance.Secondly, contents of chlorophyll in flag leaves, soluble sugar in flag leaves and grains, soluble protein in flag leaves and grains and amylum in grains were depressed by Cd. Orders of relative values of soluble sugar in grains, amylum in grain and soluble proteins were different from Cd tolerances’. The contents of glutelin, HMW-GS and LMW-GS were on a descending trend on the whole, however, the ratio of HMW and LMW on an ascending trend. The results indicated that processing quality of grains treated by Cd became worse, and there were some relations between Cd tolerances and grains processing quality.Thirdly, POD activities of leaves in most of seedlings enhanced with Cd concentration ascending and treated time extending. Prolines of leaves in all seedlings were enhancing with different velocities. During filling stage, a part of wheats’POD and SOD activities enhanced in low Cd concentration, on the while, the POD and SOD activities were restrained. The isozymogram of POD and SOD indicated that effects of Cd on POD and SOD happened in enzyme protein synthesis stage.Fourthly, during seedling stage, Cd contents in up ground part and down ground part were increasing when aggravating Cd stress level, and Cd contents in down ground part were more than up ground part’s. The highest Cd accumulations were not in highest Cd concentration, but in middle concentration. Most of Cd accumulated in down ground part. In filling stage, Cd content of each organ increased when the Cd concentration ascend. The highest accumulations of each organ happened in different Cd concentrations, because they affected by biomasses and Cd contents of the genotype’s organ. Both orders of Cd contents and accumulations in organs were grains > stem-sheathes> leaves. As a whole, other metallic elements, such as Zn, Mn, Cu, Fe, their contents and accumulations in wheats were depressed.Last, the order of Cd tolerances of seedlings is Yumai 949 > Luohan 6, Yumai 25 > Zhongyu 10 > Xinmai 21 > Aikang 58, Xunong 5 > Yumai 18 > Luomai 23, and the order of Cd tolerances showed in filling stage is Luohan 6, Zhongyu 10> Xinmai 21 > Aikang 58> Yumai 18 > Luomai 23. There was no difference between Cd tolerances showed in seedling stage and filling stage.更多还原