石灰性土壤铅镉交互作用下小麦重金属吸收特性及机理研究

According to the data on national soil pollution situation: there are more than 0.2 billion acres of arable land slightly contaminated by heavy metals. How to achieve the goal of the safe utilization of this type of arable land and ensure food quality and safety, is the problem which need to solve urgently in China. In this study, the difference in chemistry form, organic and sub-cellular distribution of lead and cadmium among different genotypes of wheat is compared using field, pot and hydroponic experiment. Meanwhile, low lead and cadmium accumulation and high accumulation of wheat selected previously, was used in the experiment. Mitochondrial damage of cell walls, cell membranes and mitochondrion in roots and leaves would be observed under transmission electron microscopy. The objectives are to ascertain the difference among wheat varieties, and give an insight to the traits of uptake, transport and accumulation of lead and cadmium by different genotypes of wheat. The data in this study could provide a technical support for the screening of low accumulation varieties in calcareous soil.

据全国土壤污染状况己公布的数据推算：全国约有2亿多亩耕地受重金属轻微轻度污染。如何实现这类耕地的安全利用，保障粮食品质安全，是当前我国粮食生产中迫切需要解决的问题。本项目旨在铅镉交互污染条件下，通过不同基因型小麦大田、盆栽和实验室水培等的对比试验，分析测定重金属铅、镉在小麦体内不同器官及化学存在形态、亚细胞分布特征以及抗性酶活性等多项指标的响应差异，同时用透射电镜观察不同小麦品种根尖和叶片细胞壁、细胞膜、线粒体的损伤情况，对比前期筛选的铅、镉低积累和高积累小麦间区别，揭示不同基因型小麦品种间对各种铅、镉胁迫条件的回避、吸收、转运及积累规律，以期初步建立针对石灰性土壤轻微污染、轻度污染条件下，低积累小麦品种的筛选依据，为低积累品种的筛选提供理论依据。

如何实现污染耕地的安全利用，保障粮食品质安全，是当前我国粮食生产中迫切需要解决的问题。本项目针对石灰性土壤，旨在确定不同小麦品种对单一铅、镉胁迫及铅、镉复合污染胁迫响应的细胞学机制，探讨不同基因型小麦在各种胁迫条件下铅、镉的运移和积累机制。结果表明：1）铅镉共存条件下，铅具有较弱的活性。改良剂的施加能显著降低土壤DTPA提取态铅、镉含量，促使其向难溶态的可氧化态、残渣态转化，这一特性有助于降低铅、镉在小麦籽粒的富集。2）以西农979、众麦998、豫农201为供试品种，高浓度的Pb能促进部分小麦品种对Cd的吸收，表现为协同作用。3）就Cd在小麦中的化学形态而言，Cd主要以氯化钠提取态和去离子水提取态为主。Si处理可以通过区隔化作用增强小麦对Cd的耐受能力，但是Si的作用与Cd的浓度和小麦部位等因素有关。4）Cd胁迫可减少小麦的生物量，并对小麦生长造成毒害作用。无论是锌预处理还是瞬时处理都能显著降低小麦根表对镉的吸收通量。上述相关结果可以为铅镉污染土壤上探寻低积累小麦品种提供参考。