【作者】 陈京都；

【导师】 戴其根； 张洪程；

【作者基本信息】 扬州大学 ， 农产品安全与环境， 2013， 博士

【摘要】 水稻是我国第一大粮食作用,全国约有60%的人口以稻米为主食。我国稻米Cd污染的现象严重,危害了广大人民群众的健康,研究水稻Cd污染具有重要的意义。本研究采用不同基因型水稻,在Cd胁迫下研究了水稻的生长发育、生理活动及其差异,探讨了耐Cd性的生理生化机制。此外还研究了调控措施对水稻Cd吸收的影响。主要研究结果如下：1、不同基因型水稻Cd积累特征及其差异的研究选取秀水63、甬优8号、扬稻6号、两优培九和汕优63,5种有代表性的不同基因型水稻,设置5个Cd浓度梯度,在盆栽条件下研究了水稻Cd吸收和积累的特征。结果表明,植株Cd含量随着水稻生育进程逐渐降低,且不同基因型降低程度不同。水稻地上部各器官Cd含量存在显著地基因型差异。土壤Cd添加量为5mg·kg-1,秀水63籽粒Cd含量仅为0.17mg·kg-1,没有超过国标规定的限值(0.2mg·kg-1),其它品种均超过标准限值,但超标幅度不大,可以认为在Cd中轻度污染土壤中筛选和种植籽粒低积累Cd水稻品种是可行的。水稻籽粒Cd富集能力存在显著地基因型差异,甬优8号富集能力最强,秀水63最弱,而且容易受到土壤Cd浓度的影响,低Cd条件下水稻籽粒富集能力比高Cd条件下强,水稻Cd转运能力也受到环境和土壤Cd浓度共同作用的影响。籽粒Cd含量与各个生育时期植株Cd含量存在显著或极显著的相关关系,且不同基因型水稻的相关系数不同,说明不同生育时期吸收的Cd对籽粒Cd积累的贡献作用不同。供试品种成熟期叶片和茎鞘Cd含量与籽粒Cd含量表现出显著或极显著的相关关系。2、Cd胁迫对不同基因型水稻生长及营养元素吸收的影响采用以上5种有代表性的不同基因型水稻,设置对照和Cd胁迫两种处理,研究了Cd胁迫对不同基因型水稻的生长发育、产量以及Ca、Mg、P和K等矿质营养元素吸收的影响。研究结果表明,Cd胁迫显著地降低了水稻的产量、穗数和结实率,但粒重受影响不显著。Cd胁迫降低了各生育时期的干物质重,其主要表现在生育前中期,随着生育进程逐渐减弱。Cd对水稻生长发育和产量影响存在显著地基因型的差异,汕优63和秀水63受Cd胁迫程度小,耐Cd性强,为Cd耐性品种,两优培九、甬优8号和扬稻6号受Cd胁迫程度大,耐Cd性弱,为Cd敏感性品种。Cd胁迫影响了水稻对Ca、Mg、P和K的吸收和积累,分为促进和抑制两种作用,即促进了Ca的吸收,抑制了Mg、P和K的吸收,同时也影响其在地上部各器官的分配和积累,且存在着基因型的差异。研究发现,Cd耐性品种Ca含量与对照相比增加幅度较Cd敏感性品种大,而在Mg、P和K中没有出现这种现象,以此可以推断,水稻耐Cd性可能与Ca元素代谢存在一定的关系。3、Cd胁迫下不同耐性水稻光合特性、抗氧化酶系统和氮代谢的研究选取以上研究的Cd耐性和Cd敏感性水稻品种,研究了Cd胁迫下水稻不同生育时期光合特性、抗氧化酶活性和氮代谢酶活性的响应及其差异。研究结果表明,Cd胁迫抑制了水稻叶片的Pn,随着水稻的生长发育抑制程度逐渐降低,对Cd耐性品种的抑制程度小于Cd敏感性品种,Cond、Ci和Tr也有类似的表现。Cd胁迫导致膜脂过氧化程度加剧,导致水稻叶片MDA含量的增加,Cd敏感性品种MDA的增加幅度大于Cd耐性品种。Cd胁迫提高了水稻叶片SOD、POD和CAT活性,与CK相比,SOD和CAT在分蘖期和拔节期活性提高程度较为显著,抽穗期和灌浆期的显著性降低,POD分蘖期和拔节期提高程度不显著,抽穗期和灌浆期显著性提高。Cd耐性品种抗氧化酶活性的提高程度大于Cd敏感性品种。氮代谢酶活性也受到Cd胁迫的影响,与CK相比,NR的活性分蘖期和拔节期受到抑制,抽穗期和灌浆期的活性则提高,GS活性则全生育期受到抑制,GOT和GPT活性前中期受到抑制,后期则活性其提高。与Cd敏感性品种相比,Cd胁迫对Cd耐性品种氮代谢酶活性的抑制程度小,而提高程度大。因此可以看出,水稻耐Cd性与光合特性、抗氧化酶和氮代谢酶活性有关。4、不同耐Cd性水稻Cd亚细胞分布和化学形态含量差异的研究采用土培试验,结合蔗糖差速离心法和化学试剂逐级提取法,研究了Cd耐性品种和Cd敏感性品种水稻叶片中Cd的亚细胞分布和不同化学形态的含量及其生育时期的变化。研究结果表明,随着水稻的生长发育,叶片细胞各组分Cd含量逐渐减低。细胞中的Cd大部分积累在细胞壁和可溶性组分中。Cd耐性品种细胞壁和可溶性组分Cd含量显著地高于Cd敏感性品种,细胞器Cd含量显著地低于Cd敏感性品种,在生育前期表现尤为明显。水稻叶片中Cd的化学形态主要以氯化钠提取态为主,其次为醋酸和盐酸提取态,乙醇和水提取态较低,不同生育时期Cd化学形态含量和分布比例会发生变化。与Cd敏感性品种相比,Cd耐性品种移动活性较强的乙醇和水提取态含量和分布比例较低,而难以移动的提取态含量和分布比例较高,在生育前中期表现尤为显著。因此,可以推断水稻耐Cd性与Cd的亚细胞分布和存在的化学形态有关。研究还发现,水稻籽粒Cd含量较高可能与灌浆期细胞可溶性组分含量以及移动活性较强的化学结合形态含量较高有关。5、Cd胁迫下Si对不同Cd积累型水稻Cd耐性和吸收的影响选取两个不同Cd积累型水稻品种,在水培条件下研究了Si对不同Cd浓度胁迫的解毒效应及其机理。研究结果表明,Cd浓度低时Si显著地缓解了Cd对水稻生长的抑制作用,Cd浓度高时Si缓解作用不显著,高积累品种汕优63缓解效果好于低积累品种武育粳3号。与Cd处理相比,Cd低浓度时加Si显著地促进了水稻游离脯氨酸含量和SOD、CAT活性的提高,显著地降低了MDA的含量,汕优63效果好于武育粳3号,在Cd高浓度时显著性下降。Si增加了水稻细胞壁Cd的含量和分布比例,减少了可溶性组分和细胞器的含量和分布比例,降低水稻体内移动活性强的Cd的化学结合态的含量和分布比例,提高了移动活性弱的化学结合态的含量和分布比例,且在低Cd浓度效果好于高Cd浓度,汕优63的效果好于武育粳3号。因此,Si在一定范围内可以通过提高抗氧化酶活性,维持细胞膜稳定以及减少Cd的吸收和运输来缓解Cd对水稻的毒害作用,且存在品种间的差异,高积累型品种缓解效果较低积累型品种好。6、麦秸杆对Cd在水稻-土壤系统中迁移的影响通过室外砂土和黏土的大型土柱栽培试验,研究了麦秸杆对Cd在水稻-土壤中迁移的影响。研究结果表明,随着水稻的生长发育,水稻植株Cd含量逐渐降低,麦秸秆促进了水稻对Cd的吸收,增加了水稻植株Cd的含量,水稻地上部各器官Cd含量也受麦秸影响而增加,籽粒和茎鞘较为显著。麦秸秆可以显著提高土壤中有效态Cd的含量,黏土中的提高程度大于砂土。麦秸秆促进了Cd向籽粒的转运,提高了水稻籽粒Cd的富集系数,与Cd单一处理相比,砂土中添加麦秸秆使籽粒Cd富集系数增加了50%,黏土中增加了61.5%,黏土的提高幅度大于砂土。Cd进入土壤后会随着水分流动向下迁移,砂土中的迁移能力大于黏土,随着土壤深度的增加Cd含量逐渐减少。添加麦秸杆可以降低Cd在土壤中向下迁移的能力,降低幅度黏土大于砂土。因此,Cd污染土壤中添加麦秸促进了Cd在水稻-土壤系统中的向上迁移,阻止了其向下的迁移。7、不同生育期类型水稻对Cd积累的研究以江苏省有代表性的早熟中粳、中熟中粳、迟熟中粳、早熟晚粳和中熟晚粳5种生育期类型的56个粳稻品种为材料,在Cd污染农田中研究了不同生育期类型粳稻品种Cd的积累特性。结果表明,56个供试水稻品种籽粒Cd含量变化范围为0.014～0.054mg·kg-1,水稻籽粒Cd含量在品种间差异显著,其中籽粒Cd含量最高的品种是ELTO,扬粳687、泗阳1382、广陵香粳和武香粳9号籽粒Cd含量最低。不同生育期类型水稻籽粒Cd含量以早熟中粳较高,中熟中粳较低,分别为0.024和0.020mg·kg-1。不同生育期类型水稻籽粒Cd富集系数差异不显著,而转运系数存在生育期类型差异。更多还原

【Abstract】 Rice is the first food crop and about60%of population with it as the stable food in China. Rice cadmium pollution is becoming more and more serious, and has threatened the human health seriously. Therefore, it is very important for researching rice cadmium pollution. In this study, the effect of cadmium on the growth and development, physiological activity and their differences were investigated with the different genotypes rice in all stages. Moreover, the methods to regulate cadmium toxicity and absorption were researched. The main results are as follows:1Characteristic of cadmium accumulation and differences in different genotypes riceAn experiment was set to research the different characters of cadmium absorption and accumulation between different genotypes rice in potted condition, with Xiushui63, Yongyou8, Yangdao6, Liangyoupeijiu and Shanyou63et al five different genotypes rice. The results showed that cadmium absorption capacities were different in different growth stage and genotypes rice, the content of cadmium in rice plant reduced gradually with development of rice. Cadmium concentration in grain, leaf and stem were significant difference between different genotypes rice, and increased dramatically with addition of soil cadmium concentration. In this study, cadmium content in grain of Xiushui63was only0.17mg-kg-1when the cadmium concentration of soil was more than5mg-kg-1, which under the limit value (0.2mg-kg-1) by the national standard, others exceed standard limit, but only little. Therefore, it is feasible for screening and cultivating rice variety which the grain accumulation lower cadmium. Abilities of enrich cadmium in grain were significant diversity, Yongyou8was the strangest and Xiushui63was the weakest. They were affected by soil cadmium concentration, which were stranger in low cadmium than high cadmium. The capacities of cadmium transport were influenced by soil cadmium concentration and genotypes interaction. Correlation analysis indicated that there were significant or extremely significant correlations in cadmium content of grain and each growth stage. The correlation coefficients were difference between different genotype rice, which showed that the contributions of cadmium absorption at different growth stage to grain cadmium accumulation were different between genotypes rice. The correlations of cadmium content among stem, leaf and grain were significant or extremely significant in all rice.2Effect of cadmium on growth and absorption of nutrition elements in different genotypes riceA pot experiment was conducted to research the effect of cadmium on growth and absorption of Ca, Mg, P, K. Cadmium was added into soil to form two levels, i.e.0(CK) and25mg-kg-1(Cd tolerance), with Xiushui63, Yongyou8, Yangdao6, Liangyoupeijiu and Shanyou63et al five different genotypes rice. The results showed that the yield, panicle number, filled spikelet rate were reduced significantly under cadmium stress, but the reduction of grain weight was not significant. Rice dry matter production was restrained by cadmium and weakened gradually with growing process. There was difference in affecting by cadmium between different genotype rice. The growth of Shangyou63and Xiushui63affected by cadmium were less, which indicated their resistances to cadmium were strong. The growth of Liangyoupeijiu, Yongyou8and Yangdao6affected by cadmium were more, which indicated their resistances to cadmium were weak. The result also indicated that the affect of cadmium stress on mineral nutrient concentrations in shoot differed types and mineral nutrients. When exposed to cadmium stress, reduced effect could be noted for K, P and Mg, thus resulting in reduced concentration. On the other hand, increased effect was found for Ca. It was not only affected rice absorbing Ca, Mg, P and K, but also affect its distribution and accumulation on the organs of ground parts under cadmium stress, which existed difference between different genotypes rice. Compared with CK, the Ca content in cadmium resistence strong varieties increased larger than resistence weak, but not in Mg, P and K. This indicated that maybe there was a relationship in cadmium resistence and calcium metabolism.3Research on differences of photosynthetic characteristics, antioxidant and Nitrogen metabolism enzymes in different resistence rice under cadmium stressAn experiment was set to research the responses and differences of photosynthetic characters, antioxidants and nitrogen metabolism enzymes activities under cadmium stress in different growth stage with different cadmium resisitence rice varieties. The results indicated that photosynthetic rate was restrained by cadmium and the extent of inhibition reduced following development of rice. The extents of restrain in resistance varieties were lower than sensitive. Stomatal conductance, intercellular CO2concentration and transpiration rate had the similar performance. Cadmium lead to membrane lipid peroxidat more severe which promoted MDA content increased, and cadmium sensitivity varieties increased more than resistance varieties. The activities of antioxidant enzymes were promoted by cadmium such as SOD, CAT and POD, which resistance promoted more than sensitive. Compared with CK, SOD and CAT activity increased more significant in tillering and jointing stage than in heading and filling stage, and POD activity was opposite. Nitrogen metabolism enzymes activities were also affected by cadmium. Compared with CK, nitrate reductases activities were restrained in tillering and jointing stages but were promoted in heading and filling stage under cadmium stress. Glutamine synthetases activities were inhabited in whole growth period. Glutamic oxalacetic and glutamic-pyruvic transaminases were inhabited in early and medium stage and promoted in later stage. Compared with sensitive varieties, the inhibitions of nitrogen metabolism enzymes activities in resistance varieties by cadmium were less and promotion were more. In conclusion, the rice resistance to cadmium stress may have relation with photosynthesis, antioxidants and nitrogen metabolism enzymes activities.4Differences of subcelluar distribution and chemical forms in different cadmium resistence riceA soil culture experiment combined with the method of soucrose differential centrifugation and chemical reagent stepped extraction was carried out to research the subcellular distribution and chemical forms of cadmium and change with growth development in rice leaves, and the differences between cadmium resistive and sensitive rice varieties were compared. The results showed that with rice growing, the cadmium content in all fractions of rice leaves reduced, and most of cadmium accumulated in cell wall and soluble substance. Compared with sensitive varieties, resistive varieties had significant higher cell wall and soluble fraction of cadmium and significant lower organelle fraction of cadmium in leaves, especially at early stage. The greatest amount of cadmium in leaves was in the extraction solution of NaCl, followed HAC and HCl, ethanol and water were lower. Concentration and percent distribution of cadmium in different extractions would change at different growth stage. Compared with sensitive varieties, cadmium content and distribution in ethanol and water extraction, which had stronger mobile activity, of resistive varieties were lower, and the extraction which difficult to move were higher. This performance was particularly significant at early stage. Therefore, the capacities of rice resistance to cadmium have relation with the subcellular distribution and chemical forms of cadmium in rice. The study also found that high cadmium content in grain may have relationship with the higher soluble fraction and mobility stronger extraction in rice in filling stage.5Effect on cadmium tolerance and absorption in two cadmium accumulation rice types by siliconThe alleviation effect of silicon on cadmium toxicity to rice plants was investigated using a hydroponic experiment with three cadmium levels, two silicon levels and two different cadmium accumulated rice types. The result indicated that the inhibition were greatly alleviated due to silicon addition to the culture in low cadmium treatment but no significant in high. The alleviated effect in Shangyou63was better than Wuyujing3. Compared with the plant treated with cadmium alone, silicon addition markedly increased praline content and SOD and CAT activities, reduced MDA content, which was better in Shangyou63than Wuyujing3, in low cadmium treatment and the function declined in high cadmium treatment. The cadmium content and percent distribution of cell wall was increased and the content and percent distribution of soluble and organelle were reduced by silicon addition. Moreover, by addition silicon, on one hand, the content and percent distribution of the extractions, which had stronger mobile activity, were reduced. On other hand the extractions, which were difficult to move, were increased. This effect which in low cadmium treatment was better than high treatment and Shangyou63was better than Wuyujing3. In conclusion, silicon alleviated the cadmium toxicity may through enhancing the capacity of defense against oxidative stress and reducing absorption and transportation. There were differences in that alleviation between different varieties, the high cadmium accumulated varieties was better than low.6Effect of wheat straw on cadmium remove in rice-soil systemThe experiment of rice cultivated in sandy and clay soil columns were conducted under outdoor condition to investigate the effects of wheat straw on cadmium remove in rice-soil systems in artificial cadmium-contaminated soils. The results indicated that cadmium content of rice reduced gradually with growth development. Addition wheat straw promoted rice to absorbing cadmium and increasing content of overground organs which were significant in grain and stem. Compared with Cd treatment, addition wheat residue led to increasing contents of cadmium availability significantly which was greater in caly than in sandy soil. Wheat straw promoted the cadmium transporting into grain and increasing the concentration factor. Compared with Cd treatment, the concentration factor increased50.0%and61.5%in sandy and clay soils by adding straw, respectively. Cadmium entered into soil and removed downward with water flow and the cadmium migrated ability in sandy was greater than clay. With soil depth increasing, cadmium content became less and less. Wheat straw reduced the cadmium migrated ability which in clay soil was greater than in sandy soil. In conclusion, wheat straw in cadmium contamination soil promoted cadmium migrating up, but restrained migrating down.7Accumulation of cadmium in japonica rice varieties with different growth period typesThe experiment was set to investigate the accumulation characteristics of cadmium in rice of different growth types in cadmium pollution farmland, with early-(125-135d), medium-(136-145d), and late-maturing (146-155d) medium japonica as well as early-(156-165d) and medium-maturing (166-175d) late japonica varieties. The result showed that the range of grain Cadmium content was0.014-0.054mg-kg-1for56rice varieties. The content of cadmium in grain showed significant variances among rice varieties, the highest variety are ELTO, the lowest varieties were Yangjing687, Siyang1382, Guanglingxiangjing and Wuxiangjing9. There was also difference in the content of cadmium of rice among different growth types. The content of cadmium in grain of early-maturing medium japonica was the highest and medium-maturing medium japonica was the lowest, were0.024and0.020mg-kg-1respectively. Concentration factor and transference coefficient were the important characteristic indexes in screening the low cadmium accumulating varieties of rice. In this research, the accumulation factors were different but not significant among different growth types rice. The transference coefficient showed significant difference among different growth types rice.更多还原