土壤镉胁迫对田七体内镉分布及富集特性影响

Distribution and accumulation characteristics of cadmium in Panax notoginseng under cadmium stress in soil

关键词:  田七, 镉污染, 累积与分布, 富集系数, 转移系数

Key words:  Panax notoginseng, cadmium stress, accumulation and distribution, enrichment coefficients, transfer coefficients

摘要:

田七(Panax notoginseng)是我国的一种传统珍贵的草本药用植物,其重金属污染问题已经引起广泛关注。为了分析田七不同部位对镉毒害的响应,明确不同浓度镉污染对田七体内镉分布的基本特征以及不同部位的富集特性,以揭示镉胁迫对田七不同部位的影响机制及富集转移特性。该研究在“田七之乡”广西靖西市田七园以3年生田七为材料,土培条件下以不施镉处理为空白对照,设置6个镉浓度(5、10、20、30、40、50 mg·kg^-1)梯度,研究了在不同浓度镉胁迫下田七不同部位镉积累特征以及转移特性。结果表明:在不同器官(叶、茎、剪口、须根、主根)随着镉浓度的增加各器官镉的积累量均显著(P<0.05)增加,呈现出正相关关系。田七不同部位镉含量的分布特征表现:空白对照下田七各器官镉累积分布表现为须根>剪口>主根>茎>叶; 当镉浓度为5、10、20、30、40、50 mg·kg^-1时,田七镉分布表现为剪口>主根>须根>茎>叶; 地下部的镉含量显著高于地上部的镉含量; 随着镉浓度的增加,无论地下部生物富集系数还是地上部生物富集系数均表现为逐渐降低的趋势。

Abstract:

Panax notoginseng is a kind of traditional and precious herbaceous officinal plant in our country. Its heavy metal pollution problem has already caused wide public concern, and the related studies have shown that a certain concentration of cadmium can produce inhibition for the its growth, cadmium stress can reduce its accumulation of saponins, the main pharmacodynamic component, and influence the quality of its medicinal materials. The health risk assessment of cadmium in it showed that the hazard quotient(HQ)was greater than one, which indicates that cadmium in it has non-carcinogenic risk to users. In order to reveal the response of different parts of P. notoginseng to cadmium toxicity, to clarify the basic characteristics of cadmium distribution in it by cadmium pollution of its different concentrations and the enrichment characteristics of its different parts, and to reveal the mechanism of cadmium stress on enrichment and transfer characteristics of its different parts. The triennial P. notoginseng was used as the experimental material in P. notoginseng garden, Jingxi City, Guangxi, under the condition of soil culture, with no cadmium treatment as the blank control and six cadmium concentration gradients(5, 10, 20, 30, 40, 50 mg·kg^-1), the characteristics of cadmium accumulation and transfer in its different parts were analyzed under the stress of different concentrations of cadmium. The results showed that cadmium accumulation in different organs(leaf, stem, scissor, fibrous root and taproot)increased significantly with the increase of cadmium concentration(P < 0.05), showing a positive correlation. The distribution characteristics of cadmium content in different parts of P. notoginseng were as follows: In the blank control group, the cumulative distribution of cadmium in each organ was fibrous root > cut root > tap root > stem > leaf; When the cadmium concentration was 5, 10, 20, 30, 40, 50 mg·kg^-1, the distribution of cadmium was cut root > taproot > fibrous root > stem > leaf; The cadmium content in the underground part was significantly higher than that in the aboveground part, with the increase of cadmium concentration, the bioenrichment coefficient of both under-ground and above-ground parts decreased gradually.