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不同土壤中镉对大麦和多年生黑麦草毒性阈值的研究
王子萱,陈宏坪,李 明,杨新萍
南京农业大学资源与环境科学学院
摘要:
根据不同终点、不同农田土壤的植物毒性测试可为基于生态毒理效应的土壤镉(Cd))环境质量标准值的修订提供基础数据。以大麦和黑麦草为供试植物,研究了中国14种不同农田土壤,添加多水平外源Cd对大麦根的相对伸长量和黑麦草的发芽率、地上部生物量的影响,并结合Log-Logistic分布函数模型确定不同土壤中大麦和黑麦草Cd毒性的剂量-效应关系和毒性阈值(EC50、EC10)),也测定了黑麦草地上部的Cd含量。结果表明,外源Cd含量在0 ~ 200 mg/kg时,大麦根长随土壤Cd含量的增加显著降低,EC50值为7.8 ~ 61.7 mg/kg,EC10值为0.2 ~ 5.4 mg/kg,均与土壤pH显著正相关。外源Cd含量在0 ~ 500 mg/kg时,黑麦草地上部生物量随土壤中Cd含量的增加呈先上升(5 mg/kg))后下降(≥ 25 mg/kg))趋势,EC50值为29.7 ~ 499.7 mg/kg,EC10值为4.4 ~ 200.0 mg/kg,二者与土壤性质均无显著相关性。与对照相比,外源Cd含量为5 ~ 25 mg/kg时,外源添加Cd对黑麦草种子发芽有促进作用,当外源Cd含量为500 mg/kg时,仅有5种土壤中种子发芽率明显下降。黑麦草地上部Cd含量随着外源Cd含量(0 ~ 100 mg/kg))的增加而显著升高。黑麦草地上部对土壤Cd的富集程度与土壤pH极显著负相关。黑麦草具有作为草坪草中Cd污染修复植物的潜力。大麦对土壤Cd污染胁迫比黑麦草更为敏感,总体上,pH是影响土壤Cd植物毒性的重要因素。
关键词:    大麦  多年生黑麦草  毒性阈值  超积累植物
DOI:10.13758/j.cnki.tr.2019.06.015
分类号:X53
基金项目:公益性行业(农业)科研专项(201403014)资助。
Toxicity Thresholds of Cadmium to Barley and Perennial Ryegrass as Determined by Root-Elongation and Growth Tests in Soils
Wang Zixuan1, Chen Hongping1, Li Ming1, Yang Xinping2
1.College of Resources and Environmental Sciences, Nanjing Agricultural University;2.College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing
Abstract:
The toxicity thresholds of Cd to higher plants in various soils are determined using root-elongation, emergence and growth of higher plants tests with the aim of providing fundamental data for the revision of soil environmental quality standards of Cd in soils of China. Fourteen different soils with various properties and barley and perennial ryegrass were selected in this study, the dose-response curves and the toxicity thresholds were investigated using Log-Logistic distribution models based on the ISO 11269-1 root-elongation test and on the ISO 11269-2 emergence and growth of higher plants test in soils. Cd concentrations in shoot of the ryegrass seedlings were also determined in this study. The results indicated that the relative root elongation (%) of barley significantly decreased with the increase of Cd concentrations (0-200 mg/kg) in soils. The half inhibiting concentration (EC50) and the 10% effect concentration (EC10) of Cd to the relative root elongation of barley varied significantly from 7.8 to 61.7 mg/kg and from 0.2 to 5.4 mg/kg among the tested soils, respectively. The values of EC50 and EC10 increased obviously with rising soil pH. In the test range (0-500 mg/kg Cd) the shoot biomass of perennial ryegrass increased at lower concentrations (5 mg/kg) and then significantly decreased at higher concentrations (≥ 25 mg/kg). The EC50 and the EC10 of Cd to the shoot biomass of perennial ryegrass varied significantly from 29.7 to 499.7 mg/kg and from 4.4 to 200.0 mg/kg among the tested soils, respectively. There was no correlation between soil factors and the EC50 or EC10 of Cd to the shoot biomass of ryegrass in soils. Lower concentrations of Cd (5-25 mg/kg) promoted seed germination of perennial ryegrass, but when Cd concentration was more than 50 mg/kg there was slightly inhibition of seed germination and the inhibition peaked when Cd concentration was 500 mg/kg in five of the studied soils. Soil pH was found to be the major property influencing Cd accumulation in shoots of ryegrass. In general, Cd sensitiveness of barley is higher than perennial ryegrass which represents hyper-accumulative ability for Cd, soil pH is the main soil factor affecting Cd toxicity to higher plants in soils. The conclusions of this study could provide reference for plants breeding on Cd contaminated soil.
Key words:  Cadmium  Barley  Perennial ryegrass  Toxicity threshold  Hyper-tolerant grass

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