Comparative analysis of the seed germination of pakchoi and its phytoremediation efficacy combined with chemical amendment in four polluted soils

Abstract

The seed germination plant growth parameters and level of heavy metal accumulation were investigated in pakchoi cultured in four contaminated soils with different levels of heavy metals supplemented with citric acid (CA) or calcium phosphate (CP). Results showed that the seed germination energy, germination percentage and germination index parameters were similar, while the seed vigor (SV) significantly (p < 0.05) decreased as the soil pollution level increased. The lengths of the shoots and roots presented the same trend as SV. All the seedlings grew in heavily polluted soil without any amendments before harvesting; therefore, no plant material was available for subsequent analyses. The photosynthesis parameters of pakchoi cultured in lightly polluted soil without amendment (LPS), lightly polluted soil with CA (LPSA) and moderately polluted soil with CP (MPSP) were similar. The concentrations of Pb, Zn, Mn, Cu and Cd in the shoots, roots and whole plants were in the order of MPSP > LPSA > LPS. Pakchoi cultured in MPSP showed the most promising results in terms of plant height, biomass and heavy metal accumulation. Pakchoi presented the highest translocation and bioaccumulation factors for Cd and the lowest for Pb.

Highlights

1. Soil pollution and the type of chemical amendment had no effect on the seed germination of pakchoi.

2. Citric acid addition in lightly polluted soil improved pakchoi growth and heavy metal extraction.

3. Pakchoi cultured in moderately polluted soil with calcium phosphate amendment presented the highest biomass and heavy metal concentration.

Graphical Abstract

Keywords:

• Chemical amendment
• plant growth
• seed germination

Acknowledgements

We thank Beijing Ruimeide Environmental Remediation (BRER) Co., LTD for their previous remediation work in Side village, which provide the opportunity for us to undertake this study; we also thank Mr Xiaolong Lin of BRER for sampling soil.

Notes

1 According to the available concentration of HMs and the amendment types, the soils were referred to as LPS, LPSA, IPSA and HPS according to arbitrary distinction.

Additional information

Funding

This project was supported by National Key Research and Development Program of China [2017YFD0801500], National Science Foundation of China [41661077; 41967019], Guangxi Science and Technology Development Project of Major Projects of Guangxi [Guike AA17204047-3], and Guangxi Natural Science Foundation [2018JJA150018].