【作者】 付冬冬；

【导师】 梁东丽；

【作者基本信息】 西北农林科技大学 ， 环境科学， 2011， 硕士

【摘要】 全球有10亿人的饮食缺硒,通过饮食补硒是最经济和安全的途径。小麦是第二大粮食作物,也是我国北方人的主食,因此研究如何提高小麦籽粒中硒含量来满足人体对硒的需求具有重要的意义。本文采用盆栽试验和室内分析相结合的方法,选择最重要的粮食作物冬小麦作为供试作物,系统研究了不同外源硒对小麦硒吸收、转运、累积和分布的影响,从植物生理学和土壤硒形态转化两个方面探讨了产生这种影响的机制。同时采用大田喷施硒的方法研究了我国北方麦区6种主栽小麦品种不同喷时期对硒吸收的影响,旨在为采取针对性的措施,提高我国主要麦区小麦籽粒中硒含量,保障人体健康提供依据。取得主要结果如下:1.外源硒抑制了苗期小麦的生长(株高和生物量);而在生长后期,小麦的株高和生物量随外源硒浓度增加表现为先促进后抑制趋势;表明小麦对硒的耐受浓度随生长时间的延长逐渐增大。硒酸钠和亚硒酸钠处理对小麦生物量影响的EC10分别从苗期的1.40和0.28 mg/kg增加到收获期的28.48和4.56 mg/kg。硒酸钠低浓度(≤1 mg/kg)对小麦生长的促进作用及高浓度(≥2.5 mg/kg)对小麦生长的抑制作用均大于亚硒酸钠。小麦籽粒产量随外源亚硒酸钠和硒酸钠浓度的增大呈先升高而后降低趋势,分别在施入亚硒酸钠2.5 mg/kg和硒酸钠1 mg/kg浓度处理时达到最大。产生这种现象的主要原因是低浓度硒处理(亚硒酸钠≤5mg/kg和硒酸钠≤0.5 mg/kg)能促进拔节期小麦叶片中GSH和POD等抗氧化酶活性,显著降低叶片过氧化物质MDA(Se≤2.5 mg/kg)含量;而高浓度硒则导致了小麦的过氧化作用的产生的,引起MDA上升。2.不同价态硒处理对小麦各器官生物量的影响各不相同。在供试的浓度范围内,亚硒酸钠(≤20 mg/kg)各浓度均能提高了小麦各器官的生物量;硒酸钠则在低硒浓度(2.5 mg/kg)时能促进增长,超过此浓度后硒对小麦的生长产生抑制作用。不同价态外源硒处理下,小麦各器官生物量影响权重较大的是叶子和根。硒酸钠和亚硒酸钠处理对小麦各器官硒含量的影响各不相同,亚硒酸钠处理为:根>籽粒>叶子>杆>壳;硒酸钠处理为:叶子>籽粒>壳>杆>根。两者比较不难看出,亚硒酸钠处理虽使得更多的硒富集在小麦根部,但是转运到地上的硒绝大部分进入小麦籽粒。而硒酸钠虽然使得更多的硒转运到地上部分,但是更多的硒富集在小麦叶子中,转移到籽粒中的硒量与亚硒酸钠相近。转移系数分析进一步说明,外源亚硒酸钠处理中,转运到小麦地上的硒中间没有受阻,流向了籽粒。而硒酸钠处理的转运到地上的硒,在麦秆和叶子中都有一定的累积和滞留。3.不同价态硒处理土壤中总硒和各形态硒含量均随着外源硒浓度的升高而升高。但是相对于亚硒酸钠处理来说,硒酸钠处理下小麦土壤中硒含量增加较为缓慢。对于亚硒酸钠来说,非根际土中硒含量低于根际土壤,而对于硒酸钠来说,正好相反,这与硒酸钠处理根系易于吸收和转运硒有关。土壤中各个形态硒均随着外源硒处理浓度的增大而增大,且两者之间呈显著相关关系(P<0.05)。但两种价态硒处理下五种形态硒所占份额大小各不相同,亚硒酸盐主要以可交换态及碳酸盐结合态形式和铁锰氧化物结合态硒存在,而硒酸钠处理则主要为残渣态硒存在。两个价态硒处理土壤中可溶态硒含量均低于10%。除残渣态硒外,小麦各个器官硒含量均与土壤中四个形态硒含量显著相关(P<0.05)。4.小麦大田喷施试验发现,小麦基因型显著的影响了小麦的产量和收获指数,其中西农979和西农889品种小麦的产量和收获指数较高。在拔节期喷施亚硒酸钠比在灌浆期能显著提高小麦的产量。不同小麦品种小麦氮磷钾含量存在差异。喷施亚硒酸钠显著增加了籽粒氮磷的含量,降低了钾的含量。不同品种小麦硒含量差异显著,其中西农889和远丰175品种硒含量高于其他品种,且以灌浆期喷施硒处理中小麦中硒含量显著高于拔节期(P<0.05)。更多还原

【Abstract】 It is estimated that between 500 and 1000 million people worldwide may be deficient in Se. Growing plants enriched with selenium could be an effective and safe way to reduce dietary deficiencies and increase health benefits. Wheat is the second important crop in China, and it is also a staple food crop for northern people. Therefore, there is a significant impotance for study of increasing selenium content in wheat grain.In this thesis, a pot experiment was carried out to investigate the uptake, accumulation, distribution and translocation of selenium(Se4+ & Se6+) in winter wheat, the main food crop in north China., and elucidate the phenomenon from the aspects of plant physiology and transformation of soil selenium fractionation. In addition, a field experiments was conducted to research accumulation of selenium in six main varieties of winter wheat in north China, and wheat was sprayed with selenium(Se4+ & Se6+)solution at different growth periods. The aim was to provide database for rational supplement selenium in the main wheat-producing areas in China. The results was described as below:1. At seeding stage, wheat height and biomass was significantly lower in the selenium treated soil than that without added selenium. However, at the late growth periods, wheat height and biomass first increased with the increase of soil selenium concentration, and then decreased. The tolerance to selenium improved with the wheat growth. The 10% effective concentration(EC10) of wheat in selenate and selenate treated soil increased from 1.42 and 0.28 mg/kg at seeding stage to 28.48 and 4.56 mg/kg at harvest time, respectively. The stimulated(≤1 mg/kg) or inhibited (≥2.5 mg/kg) effect of selenate on wheat height and biomass was significantly greater than that of selenite. Wheat seed yield increased with the increase of soil selenite-Se and selenate-Se concentration, and peak at 2.5 mg/kg(selenite) and 1mg/kg(selenate). Physiological metabolism analysis of winter wheat leaves showed that lower concentration of selenium in soil (Se (Ⅳ)≤5mg/kg and Se (Ⅳ)≤0.5mg/kg) stimulated the activity of GSH and POD, and decreased MDA (Se≤2.5mg/kg) contents significantly. However, high concentration of selenium induced the produce of lipid peroxides, and the content of MDA increased.2. Added selenium increased the biomass of various wheat organs in all tested selenite levels and≤2.5 mg/kg selenate treatment, while it decreased the biomass when selenate concentration was more than 2.5 mg/kg. Among various wheat organs, leaves and roots was affected greatest by exogenetic selenite and selenate. Contents of selenium in wheat organs varied in the following order: root > seed > leaf >wheat straw > glume in selenite treatment, while it was leaf > seed > glume > wheat straw > root in the selenate treatment. More selenium was transported from root to the aerial parts in selenate treatment than selenite treatment. However, the transported selenium mainly accumulated in the leaf in selenate treatment, while it could easily be assimilated and entered the seed. Transport factor further indicated this view.3. Soil selenium concentration increased more slowly with the increase of exogenetic selenium in the selenate treatment than that in the selenite treatment. Non-rhizosphere soil had more selenium than rhizosphere soil in selenate treatment, while the opposite was in the selenite treatment. Selenium concentration of various fractionation increased significantly with the increase of exogenetic selenium(P<0.05). Exchangeable selenium, selenium bound to carbonate and iron and manganese oxides bound selenium were the main selenium fractionation in selenite treatment, while it mainly was residual selenium in selenate treatment. concentration of soluble selenium was lower than 10% both in selenite and selenate treatment. contents of selenium in wheats had significantly correlation with the soil selenium fractionation except for residual form(P<0.05).4. Field experiment showed that wheat genotype had significantly effect on the wheat yield and harvest index. Particularly, the yield and harvest index of XN-979 and XN-889 were higher than the other wheat varieties. Spraying selenium at jointing stage increased wheat yield more than spraying selenium at filling stage. Contents of nitrogen, phosphorus and potassium in wheat varied greatly in different wheat varieties. Spraying selenate solution increased contents of nitrogen and phosphorus in wheat seed, but decreased the content of potassium. Selenium contents in different wheat varieties had significant difference. XN-889 and YF-175 accumulated more selenium than the other wheat varieties, and wheat accumulated more selenium when spraying selenium at filling stage than spraying selenium at jointing stage.更多还原