【作者】 冯德建；

【导师】 唐茜；

【作者基本信息】 四川农业大学 ， 茶学， 2010， 硕士

【摘要】 铅(Pb)、镉(Cd)既是环境中的主要重金属污染物,又是公认的毒性最强的“五毒”元素,其在自然界中往往伴随存在。当它们在作物体内累积到一定程度时,不仅会严重影响作物的生长发育、产量和品质,还可通过食物链的传递进入人体,对人类的健康造成巨大危害。因此,本实验选取Pb、Cd作为供试污染物,采用室内溶液培养法,初步研究了Pb、Cd及其复合污染对茶树生理生化及吸收积累特性的影响,以期为揭示重金属对茶树的毒害机制和提高茶叶产品的安全性以及为茶树重金属污染的早期预报和综合防治提供一些理论依据与参考。研究结果表明：1、Pb、Cd及其复合污染均可抑制茶树的生长发育并使茶树表现出不同程度的受害症状。单一Pb处理和Pb、Cd复合处理茶树的基本受害症状为：根系逐渐变黑,甚至腐烂,还伴有白色絮凝状物质产生；叶片也失水萎蔫,失绿黄化,焦枯褐变；越冬芽萌发和新梢生长受到严重抑制；茶苗最终死亡。而单一Cd处理的受害症状则表现为：植株中下部叶片轻微失绿黄化和少量脱落,新梢生长也受到抑制,但植株根系却生长正常,并有新根长出,且发芽总数较对照增加明显。Pb、Cd复合污染对茶树的表观毒害程度强于单一Pb、Cd处理。2、Pb、Cd及其复合污染均可不同程度的抑制茶树光合作用。随着Pb、Cd及其复合处理浓度的升高,茶树叶绿素a、叶绿素b、叶绿素总量以及叶绿素a/b比值均持续下降,而光合速率(Pn)、蒸腾速率(Tr)、胞间CO2浓度(Ci)及气孔导度(Gs)等光合作用参数也都随之降低,且Gs和Tr的下降幅度更为明显。Pb、Cd复合污染对茶树光合作用的抑制程度强于单一Pb、Cd处理。3、Pb、Cd及其复合污染对茶树保护酶活性的影响有所不同。单一Pb处理和Pb、Cd复合处理茶树的超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性均随着处理浓度的增加而先升后降,且Pb、Cd复合处理的酶活性变化幅度明显强于单一Pb处理,而单一Cd处理的SOD、POD、CAT活性则呈现持续增加的趋势。同时,各处理茶树叶片的丙二醛(MDA)含量、脯氨酸(Pro)含量和相对电导率也都随着处理浓度的升高而增加,且Pb、Cd复合处理各指标的增加幅度显著高于单一Pb、Cd处理,表明Pb、Cd复合处理对茶树细胞膜的破坏程度明显强于单一处理。4、在Pb、Cd及其复合污染处理下,茶树各部位的Pb、Cd含量均随着处理浓度的增加而不同程度的增加。单一污染时,Pb在茶树体内的移动性较弱,其在茶树体内各部位的积累分布顺序为：吸收根>主根>主茎>枝条>成熟叶片>新梢；而Cd在茶树体内的移动性则较强,其在茶树体内各部位的积累分布顺序则为：吸收根>主根>枝条>成熟叶片>主茎>新梢。而复合处理时,Pb在茶树体内的分布次序依旧表现为：吸收根>主根>主茎>枝条>成熟叶片>新梢,但总体而言,Cd的加入促进了树体各部位对Pb的吸收积累,导致了各部位对Pb的吸收富集能力的改变；而Cd在茶树体内的积累分布次序则发生了改变,低浓度处理时表现为：吸收根>主根>主茎>枝条>成熟叶片>新梢,而高浓度处理时则表现为：主根>吸收根>主茎>枝条>成熟叶片>新梢,Pb的加入抑制了吸收根、枝条、成熟叶片和新梢对Cd的吸收积累,而促进了主根、主茎中Cd含量的增加,改变了茶树体各部位对Cd的吸收富集能力。5、在Pb、Cd及其复合污染处理下,茶树新梢中的各儿茶素组分和氨基酸组分均发生了不同程度的改变,变化规律较为复杂,但儿茶素总量、咖啡碱含量和氨基酸总量则均随着处理浓度的增加而明显降低,且Pb、Cd复合处理各指标的下降幅度更为明显,表明Pb、Cd及其复合污染导致了茶叶品质明显降低。更多还原

【Abstract】 Pb and Cd are not only the major heavy metal pollutants in the environment but also the two of the most recognized toxic and harmful environmental elements, they usually concomitantly exist in the nature. When they accumulate to a certain extent in the crops, they will not only seriously affect the growth, yield and quality of the crops, but also can enter the body through the food chain, and cause great harm to the human health. Therefore, this study selected Pb and Cd as the pollutants, the Pb, Cd and their compound pollution on the physiological, biochemical effects and their absorption, accumulation characteristics of tea plants were preliminary studied with indoor solution culture, to provide some theoretical basises and references for revealing the toxicity and patience mechanisms of heavy metals, improving the safety of tea products and the early warning and integrated control of heavy metals. The results show that:1、Pb, Cd and their compound pollution could inhibit the growths of tea plants and make tea plants damaged with different degrees of symptoms. The basic symptoms of tea plants under single Pb treatment and Pb, Cd compound pollution were that the roots blacked gradually, and even decayed, accompanied by white flocculate engendered; the leaves withered with losing water, and yellowed, browned, scorched; the winter buds and the growths of the new shoots were seriously inhibited; and finally, the tea plants dead. But the symptoms of single Cd treatment on tea plants were different, they were that the middle and lower parts of tea plant leaves lightly appeared etiolation and bit shed, the length and weight of the new shoots were was also inhibited, but the growth of the roots were normal, and there were some new roots growing, the total number of buds significantly increased compared with the control. The damages of Pb, Cd compound treatment on the symptoms of tea plants were all much stronger than the single Pb, Cd treatment.2、Pb, Cd and their compound pollution could significantly reduce the photosynthesis of tea plants. With the concentrations of Pb, Cd and their compound treatment increasing, the contents of chlorophyll a, chlorophyll b, total chlorophyll in tea plants and the ratio of a/b all reduced all the time, while the photosynthetic rate (Pn), transpiration rate (Tr), intercellular CO2 concentration (Ci) and stomatal conductance (Gs) also reduced, even the stomatal conductance (Gs) and transpiration rate (Tr) reduced more. The inhibition leveles of Pb, Cd compound treatment on the photosynthesis of tea plants were much stronger than single Pb, Cd treatment.3、The effects of Pb, Cd and their compound pollution on the protective enzymatic activities of tea plants wrer different. With the concentrations of Pb and Pb, Cd compound treatment increasing, the SOD, POD, CAT activities increased at first and then decreased, and the rangeabilities of enzymatic activities under Pb, Cd compound treatment were significantly stronger than single Pb treatment, but the SOD, POD, CAT activities of single Cd treatment increased all the time. In addition, the contents of MDA, proline and the relative conductivity in tea leaves increased obviously with the concentrations of Pb, Cd and their compound treatment increasing, and the increasing number of Pb, Cd compound treatment were more evident, mean that the cell membrane damages of Pb, Cd compound treatment on tea plants were stronger than single Pb, Cd treatment.4、Under Pb, Cd and their compound treatment, the contents of Pb and Cd in different parts of tea plants differently increased with the concentrations of Pb, Cd and their compound treatment increasing. Under single treatment, the mobility of Pb in the tea plants was weak, its accumulation and distribution order in the tea parts was absorbing roots> main roots> main stems> tender stems> mature leaves>new shoots; but the mobility of Cd in the tea plants was much stronger, its accumulation and distribution order in the tea parts was absorbing roots> main roots> tender stems> mature leaves> main stems>new shoots. But under Pb, Cd compound treatment, although the accumulation and distribution order of Pb in the tea parts was still absorbing roots> main roots> main stems> tender stems> mature leaves>new shoots, but overall, the accession of Cd promoted the tea parts to absorb and accumulate Pb, and changed the Pb accumulation capacity of tea plants too; however the accumulation and distribution rule of Cd in the tea parts was changed, it was absorbing roots> main roots> main stems> tender stems> mature leaves>new shoots while lower concentrations, but it was main roots> absorbing roots> main stems> tender stems> mature leaves>new shoots while higher concentrations, the accession of Pb suppressed the absorbing roots, tender stems, mature leaves, new shoots to absorb and accumulate Cd, but promoted the contents of Cd in main roots and main stems, and changed the Cd accumulation capacity of tea plants too.5、Under Pb, Cd and their compound treatment, the catechins components and amino acids components in new shoots changed differently, but the contents of total catechins, caffeine and amino acids decreased obviously with the concentrations of Pb, Cd and their compound treatment increasing, and the decrease extents of Pb, Cd compound treatment were more obviouser, mean that Pb, Cd and their compound treatment could significantly reduce the quality of tea.更多还原