田間條件下小白菜對外源Cd的動態吸收特征

摘要[目的]探究田間條件下小白菜對外源Cd的動態吸收特征，為Cd污染土壤上蔬菜安全生產提供理論依據。[方法]采用田間微區試驗，共設4個Cd濃度處理，即0（CK）、1、2、5 mg/kg，每處理3次重復，研究外源Cd對小白菜生長的影響及小白菜對外源Cd的動態吸收特征。[結果]隨著外源Cd濃度的升高及生長時期的延長，Cd對小白菜生長的抑制加重。5 mg/kg處理55 d時，小白菜的根長、株高、生物量較CK下降幅度均達到最大。任一Cd濃度下小白菜的Cd含量在前45 d快速增加，45 d后增速放緩，地下部Cd含量在55 d達到最大值，地下部平均Cd含量是地上部的1.62倍。[結論]Cd對小白菜的生長作用受Cd污染濃度、生長時期雙重影響，且不同外源Cd濃度下小白菜各部位對Cd的吸收在不同生長時期呈現動態差異。

關鍵詞田間條件；外源鎘；小白菜；動態吸收

中圖分類號S634.3；X173文獻標識碼

A文章編號0517-6611（2017）10-0067-04

Study on the Dynamic Accumulation of Exogenous Cadmium in Brassica chinensis L. under Field Conditions

YANG Shiyan（College of Resource，Sichuan Agriculture University，Chengdu，Sichuan 611130）

Abstract[Objective]To investigate the dynamic absorption characteristics of Brassica chinensis L. under field conditions，and to provide the theoretical basis for the safe production of vegetables on Cd contaminated soil.[Method]Set 4 Cd concentration treatments，namely，0（CK），1，2，5 mg/kg，each treatment for 3 times.The Cd effects on the growth of Brassica chinensis L. and the dynamic accumulation of exogenous Cd in Brassica chinensis L. was studied by field microplot experiments.[Result]The results showed that with the increase of exogenous Cd concentration and the extension of growth period，Cd inhibited the growth of Brassica chinensis L..The root length，plant height and biomass of Brassica chinensis L. reached the maximum value at 55 d under treatment of 5 mg/kg.The Cd content in Brassica chinensis L. increased rapidly at the first 45th days，while the rising tendency slowed down after the 45th days.However，the root was 1.62 times the Cd absorption of aboveground parts signally.[Conclusion]The Cd effects on the growth of Brassica chinensis L. were affected by the different concentrations of Cd and the growth stages of Brassica chinensis L.，also the accumulation of Cd in different parts of Brassica chinensis L. appeared dynamic discrepancy on account of different growth stages under varied concentrations of Cd.

Key wordsField conditions；Exogenous cadmium；Brassica chinensis L.；Dynamic accumulation

土壤作為環境的重要載體，殘留在土壤中的重金屬會導致土壤質量惡化，嚴重影響農作物生長及品質安全[1-3]。曾希柏等[4]研究發現，我國約93%的菜地受重金屬污染且各省均有分布。相較于其他重金屬元素，Cd的生物毒性更強，更易為蔬菜所富集，進而通過食物鏈威脅人類健康[5]。曹仁林等[6]研究表明，我國污灌區受Cd污染菜地面積占所有重金屬超標土地面積的56.90%，且蔬菜Cd超標率高達10.23%，降低蔬菜可食部分Cd含量，實現蔬菜安全生產已引發廣泛關注。一般，低濃度Cd對植物生長有適當刺激作用，高濃度Cd對植物生長有明顯毒害作用[7-8]。已有研究表明，Cd對蔬菜生長影響較大，可顯著減少蔬菜株高、根長、地下部和地上部的干重、鮮重[9]，且葉菜類蔬菜吸收Cd的能力高于果菜類[10]。……