Toxic effects of copper on Chinese cabbage and its ecological health parameter

Copper is an essential element for the health of plants.But excessive copper has a detrimental negative effect on plant growth.Therefore,the diagnosis of soil copper contamination is one of the most important component parts in soil cleanup processes.This study was conducted to determine the toxic effect of Cu pollution on Chinese cabbage(Brassica Chinensis) growth,and on its physiological activity.Shoots and roots production,malondialdehyde(MDA),superoxide dismutase(SOD) and proline of Chinese cabbage were used as bioindicators of the toxic effect of Cu.The inhibition of physiological activity and biomass by different Cu concentrations ranging from 0 to 400 mg/kg soil was described by a mathematical model in order to calculate the ecological limitation value of Cu pollution.In the present study,84% decrease of fresh shoot mass was observed at 400 mg/kg Cu loading.Similarly trend was found in root.Increased Cu loading caused a linear decrease of SPAD value.Nearly 2/3 of Cu is retained by the roots and only 1/3 is transported to the shoots.Cu concentrations lower than 100 mg/kg has a trend to promote the increases of root volume,root surface area,and root length.However,higher Cu loading(>200 mg/kg) significantly reduced the length,volume,and surface area of Chinese cabbage root.In the work reported here,it seems that proline is highly susceptible to Cu toxicity.The proline and SOD were affected severely not only by low concentration of external Cu(200 mg/kg).There was a stimulation of MDA content at high Cu level.A much higher ED10 value threshold(171 mg/kg) was calculated and demonstrated the necessity of phototoxicological test according to different soil conditions.A similar quantity of Cu was calculated from fresh base of Chinese cabbage shoot mass.