A New Model Describing Copper Dose⁻Toxicity to Tomato and Bok Choy Growth in a Wide Range of Soils.

Bao Jiang,Yibing Ma,Guangyun Zhu,Jun Li

doi:10.3390/ijerph16020264

Abstract

Phytotoxicity thresholds for heavy metals are derived from dose–response curves, which show the relationships between exposure dose and toxicity response. However, the results of tests or observations are commonly based on total heavy metal concentration, not the exposure dose that causes phytotoxicity; additionally, the phytotoxicity response differs with plant species. In the present study, the ethylenediaminetetraacetic acid (EDTA)-extractable copper (Cu) concentration was determined in order to evaluate Cu extractability. As two important horticultural food crops in Asia, tomato (Lycopersicon esculentum ‘Meifen No. 1’) and bok choy (Brassica rapa var. chinensis ‘Susheng 28’) were used to investigate Cu phytotoxicity in a wide range of Chinese soils with and without leaching treatment, after which relationships between Cu phytotoxicity thresholds based on EDTA-extractions and soil properties were established. The phytotoxicity thresholds showed that biomass of bok choy was more sensitive to Cu than tomato. Multiple linear regression analyses showed that soil factors, including organic carbon (OC), citrate dithionate extractable manganese (CD-Mn), cation exchange capacity (CEC), and CaCO3 explained over 85% of the variance in Cu phytotoxicity thresholds. The EDTA-extractable Cu dose–response relationships were further improved by incorporating soil properties. The new phytotoxicity predictive models indicated soil properties (soil pH, OC, CEC, and oxalate-extractable Mn) and EDTA-extractable Cu concentration explained more than 90% of the variance in the phytotoxicity response of tomato and bok choy biomass. The new phytotoxicity predictive models could be used to develop a reasonable remediation strategy for contaminated soils.

Highlights

Continuing accumulation of copper (Cu) in surface soils, in agricultural lands, will increase the risk of phytotoxicity, and eventually threaten environment security [1]
Phytotoxicity Thresholds Based on ethylenediaminetetraacetic acid (EDTA)-Extractable Cu for Tomato and Bok Choy
The leaching factors, which were defined as the ratio of leached phytotoxicity threshold (EC10-EDTA or EC50-EDTA) to the corresponding unleached phytotoxicity threshold, were

Summary

Introduction

Continuing accumulation of copper (Cu) in surface soils, in agricultural lands, will increase the risk of phytotoxicity, and eventually threaten environment security [1]. Heavy metal accumulation in soils is of concern in agricultural production due to adverse effects on growth (due to phytotoxicity) and environmental health [2]. As an indispensable food group, vegetables play important roles in agricultural production. Research on the phytotoxicity of heavy metals to vegetables has attracted more attention. Dulce DC)) shoot growth was significantly inhibited at Cu concentrations above 150 mg·kg−1 in soils. Gharbi et al [4] found that lettuce (Lactuca sativa) and spinach (Spinacia oleracea) appeared chlorotic when it was exposed to concentrations of Cu ranging from 250 to 1000 mg·kg−1 in sandy loam

Methods

Results

Conclusion