K Fertilizers Reduce the Accumulation of Cd in Panax notoginseng (Burk.) F.H. by Improving the Quality of the Microbial Community

Yue Shi; Lisha Qiu; Lanping Guo; Jinhui Man; Bingpeng Shang; Rongfeng Pu; Xiaohong Ou; Chunyan Dai; Pengfei Liu; Ye Yang; Xiuming Cui

doi:10.3389/fpls.2020.00888

K Fertilizers Reduce the Accumulation of Cd in Panax notoginseng (Burk.) F.H. by Improving the Quality of the Microbial Community

Front Plant Sci. 2020 Jun 26:11:888. doi: 10.3389/fpls.2020.00888. eCollection 2020.

Authors

Yue Shi^{1

2}, Lisha Qiu³, Lanping Guo⁴, Jinhui Man¹, Bingpeng Shang¹, Rongfeng Pu¹, Xiaohong Ou¹, Chunyan Dai¹, Pengfei Liu¹, Ye Yang¹, Xiuming Cui¹

Affiliations

¹ Yunnan Provincial Key Laboratory of Panax notoginseng, Key Laboratory of Panax notoginseng Resources Sustainable Development and Utilization of State Administration of Traditional Chinese Medicine, Kunming Key Laboratory of Sustainable Development and Utilization of Famous-Region Drug, Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China.
² College of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China.
³ Analysis and Test Center, Kunming University of Science and Technology, Kunming, China.
⁴ Chinese Medica Resources Center, China Academy of Chinese Medicinal Sciences, Beijing, China.

Abstract

The high background value of cadmium (Cd) in the Panax notoginseng planting soil is the main reason for the Cd content in P. notoginseng exceeding the limit standards. The main goal of this study was to reveal the mechanism by which potassium (K) reduces Cd accumulation in P. notoginseng from the perspective of the influences of soil microbial communities on soil pH, total organic matter (TOM) and cation exchange capacity (CEC). Pot experiments were conducted to study the effects of different types and amounts of applied K on the Cd content in P. notoginseng, and on the soil pH, TOM, CEC, and bioavailable Cd (bio-Cd) content in soil. Field experiments were conducted to study the effects of K₂SO₄ fertilizer on the microbial community, and its correlations with the soil pH, TOM and CEC were analyzed. A moderate application of K₂SO₄ (0.6 g⋅kg^-1) was found to be the most optimal treatment for the reduction of Cd in the pot experiments. The field experiments proved that K fertilizer (K₂SO₄) alleviated the decreases in pH, TOM and CEC, and reduced the content of bio-Cd in the soil. The application of K fertilizer inhibited the growth of Acidobacteria, but the abundances of Mortierellomycota, Proteobacteria and Bacteroidetes were promoted. The relative abundances of Acidobacteria and Proteobacteria in the soil bacteria exhibited significant negative and positive correlations with pH and CEC, respectively. In contrast, the relative abundance of Mortierellomycota was found to be positively correlated with the pH, TOM and CEC. The bio-Cd content was also found to be positively correlated with the relative abundance of Acidobacteriia but negatively correlated with the relative abundances of Proteobacteria and Mortierellomycota. The application of K fertilizer inhibited the abundance of Acidobacteria, which alleviated the acidification of the soil pH and CEC, and promoted increase in the abundances of Mortierellomycota, Proteobacteria and Bacteroidetes, which ultimately increased the soil TOM and CEC. Soil microorganisms were found to mitigated decreases in the soil pH, TOM, and CEC and reduced the bio-Cd content in the soil, which significantly reduced the accumulation of Cd in P. notoginseng.

Keywords: Panax notoginseng; bioavailable; cadmium; potassium; soil microorganism.