Cd、Cr、Pb复合胁迫下小麦植株重金属的积累与分布

为了预测重金属复合胁迫对小麦的危害,采用溶液培养、田间土柱栽培等毒理试验方法,分析了小麦幼苗期及成熟期Cd、Cr、Pb在植株不同器官的富集,并对小麦受重金属胁迫的安全限量值进行了研究。结果表明,①Cd、Cr、Pb二元或三元胁迫条件下,小麦幼苗期植株各器官对重金属的富集浓度均极显著高于单一胁迫处理,说明复合胁迫加剧了重金属向小麦体内的迁移累积。成熟期小麦对Cd、Cr、Pb的富集比较依赖于土壤中相应Cd、Cr、Pb的浓度水平,其他两种重金属的协同作用在根系所占比例大约为5.09%～21.66%。②各器官中重金属的富集表现:幼苗期为根系>叶鞘>叶片,成熟期为根系>茎叶>籽粒。但幼苗期复合胁迫促进了重金属向地上部分的转移。③幼苗期植株各器官对重金属富集系数的大小为Cr>>Pb>Cd,表明幼苗期小麦根系对Cr的富集能力最强;植株地上部分的重金属平均富集量Cd为68.68%、Cr为51.63%、Pb为70.83%,说明Cd、Pb运输到地上部的能力较强。成熟期Cd在小麦地下、地上各器官的转移速率最快,Cr次之,而Pb转移到籽粒中去的量很少。

Accumulation and Distribution of Heavy Metals in Wheat on Combined Stress of Cd, Cr and Pb

In order to forecast the harm of combined stress by heavy metal on wheat the experiments including hydroponic and soil column culture were carried out to study the enrichment of Cd,Cr,and Pb in different organs of wheat at different growth stages,and their critical value of stress.The results indicated that: ① Comparing with the effects of single stress,the heavy metal accumulation in wheat seedling plant was significantly higher under combined stress by Cd,Cr,and Pb.This fact indicated that the migration and accumulation of heavy metal in wheat plant were stimulated by combined stress.The enrichment capacities of Cd,Cr and Pb at wheat mature stage relied on the concentrations of Cd,Cr and Pb in soil.The proportion of synergistic action by two other heavy metals was about 5.09%-21.66% in roots of wheat.② The order of heavy metal accumulation in wheat organs was as root > leaf sheath > leaf at seedling,and root > stem and leaf > seed at mature stage,but the combined stress promote the migration of heavy metal from root to above ground organs at seedling stage.③ The concentration coefficient of heavy metal in different wheat organs at seedling period was Cr>>Pb>Cd in order.In above ground part,the average accumulative amount of Cd,Cr and Pb was 68.68%,51.63% and 70.83%,respectively.it suggested that plant had the strongest capability to extract and transfer Cd and Pb to the aerial part at seedling stage;At mature stage,Cd had the highest transfer rate in all organs,followed by Cr.However,the amount of Pb in grain was very little.④Critical content of harmful heavy metal stress of Cd in wheat cultivated in loessal cinnamon soil was 3.14 μg·g-1,and this value could be used as an important reference of safety standard for wheat growth.