【作者】 邬飞波；

【导师】 张国平；

【作者基本信息】 浙江大学 ， 作物栽培学与耕作学， 2002， 博士

【摘要】 镉(Cd)是对人类和动植物具有强烈毒害作用的重金属，且是已知的危害最严重的农田污染类型之一。植物对Cd的积累和耐性种间和品种间存在着明显的差异，因此，筛选耐Cd且食用器官Cd积累量低的作物品种，是有效利用自然资源和保证农产品安全生产的重要途径。同时，作物对Cd吸收与积累已证明也与环境和栽培因子有关，因此改进农艺条件也可望降低作物对Cd吸收与积累。但目前有关作物Cd耐性、吸收与累积的基因型差异机理尚不十分清楚，从而限制了相关育种与栽培工作的开展。本研究在明确大麦籽粒重金属含量的基因型差异及基因型和环境效应的基础上，利用水培试验，系统地研究了Cd抑制大麦生长和产量形成以及Cd耐性和吸收及积累基因型差异的生理机理，并探索了减少大麦Cd胁迫和吸收的化学调控技术。 1、大麦籽粒有毒重金属含量的基因型差异及与土壤因子的关系 利用多品种多环境试验，测定分析了浙江省不同地区大麦籽粒重金属的含量。结果表明，部分地区大麦籽粒的Cd和Cr含量接近或超过安全临界值，这与当地土壤有效Cd利Cr含量高、pH低相偶联。籽粒重金属含量的基因型效应亦达显著水平，且环境与基因型存在着显著的互作效应，启示出特定地区选择适宜品种的重要性。大麦籽粒中Cd、Zn、Cr和Mn含量相互间呈显著的正相关，说明有可能筛选培育出多种重金属低积累型的品种(系)。根据试验结果，建立了籽粒Cd、Zn、Cr和Mn浓度与其土壤有效态含量的回归方程，可用于确定安全大麦生产的土壤重金属临界水平。 2、镉胁迫对大麦生长和镉及养分吸收影响的基因型差异 水培耐Cd基因型筛选试验，研究了不同Cd水平下大麦幼苗对Cd和几种矿质元素吸收和积累及生长的影响。结果表明，1μMCd处理显著降低麦苗株高、绿叶数、叶绿素计读数、地上部和根系干重，显著抑制植株对Zn、Mn、Cu的吸收和累积；基因型之间差异显著，无芒六棱受害最重，米麦114、农大3号和浙农1号受害相对较轻。麦苗Cd含量和累积量，以浙农1号最高，米麦114最低。相关分析表明，麦苗生物量与地上部Cd含量、累积量及根系Cd含量呈显著负相关，其中尤以与地上部Cd含量的相关性最强，与根系Cd累积最无显著相关。3、人麦隔吸收动力学的基l刘到筹异 八水上产附（”；I）．＜山八忖巾选以验的从几H二，以（：；】；则，叮个I小＊从！川呗村料，汕、己厂人七村（”；I吸收和似祟们）．（＊川外汁。5．‘收衣叭，对（刀的吸收，4个参试．川种邢符合Mlch。elk－Ment。n模型，且从冲！。间根系的M、v。。x和茎叶的Vm。x无显著差异，们茎叶的k。值州Cd品种显著高丁Cd ＄1感品种，其中米麦114 的Km值比无芒六棱高1．3倍，说明Cd从根系向茎11｝。的转运率可能是影响大麦（：d耐性的重要因素。籽粒＆1欠垦与C；I处川冰个的【、UI分析（刃，1个，V冲11的模型相似，用双例数M01分析泌木能建立MI。七；［，1卜－川。l；I（；；lpwU奠型。M此，凸。丁以认为，籽粒“积累并作足向小的线忡吸收4‘VS过比。JOll ti州遮光降低光凶w】蒸腾强度对籽1。0 Cd的积累兀显丹影响，上芒处川衅”粒u含歇略有卜降，均启小出茎叶小Cd向籽粒的转运是非木质部途径的。植株根、茎M 小C。l积累冕，随Cd处理水平与生河进程而增加，［1．品种l川有lK差异，以尤芒六栓最同，米麦114最低。Cd积累量的籽粒／（地上部＋地下部）比随 Cd处理浓度提高而增加，且 5 p M处理中品种间差异显著，米麦 门 4显著高I浙农人3号和浙农Ic。从米麦114的茎IIJ和根“浓度小于其它3个品种，而籽粒Cd浓度反而较高上看，大麦籽粒的 Cd含量主要决定于 Cd从木质部再运输到穗韧皮部的能力。另外，还建立了籽粒Cd含量与根、茎Ilf Cd含量的回归模型，并HP了安个大麦’卜产不ltd中育则根、茎111、Cd含慰的临界水平。4、儡胁迫对人麦光合竹性影响的基因型差异 C；I胁迫显X彤、w人女！儿光介什川及I’1绿素荧光，5卜MCd处刀＊It著降低光合叶IHi积、1‘1·绿素含鼠、以’川）值和冷光合速率（Pn），减少光合产物积累；显著降低最人荧光产’量（I‘h）、l’SI光化学效率（FV／I‘。）及I，Sll光合电子传递量子效率（中PS），且随h处理时间的延长而显著加重。与叶绿素b川比，H r绿素。对“胁迫更敏感。基旧型问差异显公，Cd敏感基因型无芒六棱受抑制最严重，耐Cd品种浙农 1号。浙农大 3号和米麦 114表现出相对较强的抗性。由结果可得，Cd胁迫降低叶绿素含量、Fv／Fm LL值和巾 PS，破坏了气孔的生理功能，从而导致净光合速率的显著下降，耐Cd基因型在这些光合与荧光特性上对Cd表现为相对较强的耐性。5、隔胁迫对大麦膜脂过氧化及抗氧化酶系统影响的基因型差异 研究了“胁迫对不同大麦品种 SOD。POD、CAT酶活性和 MDA含量的影响。结果表明，l和 5 p M Cd处理显著增加大麦功能叶 SOD、POD和 CAT酶活性，并导致 MDA 11更多还原

【Abstract】 Cadmium (Cd) is one of the most deleterious heavy metals to both plants and animals, and its contamination in soil has turned into one of the most trouble agricultural and environmental issues worldwide. Genetic variation in Cd uptake and tolerance exists between and within plant species. Consequently, it is one of the best cost-effective and efficient approaches to develop Cd-tolerant genotypes with low Cd accumulation in edible parts so as to alleviate health risks associated with Cd exposure and guarantee food safety and make full use of natural resource. Meanwhile, it has been demonstrated that Cd absorption and accumulation in crops is a function of the complex interaction of soil, plant and environmental and farming factors that influence their phyto-availability. It would thus be beneficial to reduce Cd uptake and accumulation in crops by improving agronomic practices. To breed Cd-tolerant genotype or improve agronomic practices, it is important to find out the potential of Cd accumulation in existing genotypes and their physiological responses/mechanism to Cd exposure. However, there is little information about the genotypic difference in Cd tolerance, uptake and accumulation, and which has in some extent limited the developments of its related breeding and cultivation programs to prevent Cd accumulation in plants. This investigation was carried out to study the physiological mechanism of genotypic difference in Cd- uptake, accumulation and tolerance of barley and detrimental effects of Cd on growth and yield formation, based on the research of genotypic variation of kernel Cd concentration and its genotype Location effect, by using four levels of Cd hydroponic experiments. Meanwhile, the possibility of reducing Cd uptake and accumulation in crops by application of chemical regulators were also studied in this investigation. The major results were summarized as follows:1. Genotypic variation in kernel heavy metal concentrations in barley and as affected by soil factorsGenotypic variation in kernel heavy metal concentrations was studied for barley cultivars grown in six locations of Zhejiang, China. These sites covered a wide range of soil and climate. The results showed that barley kernels produced at some sites contained heavymetals, such as Cd and Cr, higher than the maximum permitted concentration (MFC). Soil properties such as pH and EDTA-extractable heavy metal content played an important role in heavy metal uptake and accumulation in barley. Data from the six soils showed that the soil in Ningbo was lower in pH and contained the highest EDTA- Cd, Cu, and Cr, causing significantly higher kernel Cd, Cu and Cr concentrations in barley grains. Kernel Cd, Zn, Cr, Mn and Fe concentrations were closer to EDTA-extractable corresponding metal contents than to soil pH. Significant cultivar effects were identified, but these were less than the site effects. Meanwhile, although Genotype x Location effect existed, genotypes performed consistently across six locations. Therefore, it is important to select suitable cultivars for special regions. Positive relationship between kernel Cd, Zn, Cr and Mn found in this study indicated the potential to screen or develop low heavy metal accumulation cultivars or lines. In addition, regression equations between kernel Cd, Zn, Cr, Mn and Fe concentrations and its EDTA-extractable contents were established and suggested to be used in predicting soil critical levels of these metals for safe barley production.2, Cultivar differences in growth of barley seedlings and their Cd and nutrient uptake under various Cd levelsA hydroponic experiment was carried out to examine genotypic differences of barley in the uptake/accumulation of Cd and some mineral elements, plant development and biomass accumulation under different Cd levels. The results showed that plant height, leaf number, SPAD value and biomass accumulation of shoot/root were significantly reduced in the plant grown in luM Cd nutrient solution compared with control, and the absorption of Zn, Mn and更多还原