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Acta Prataculturae Sinica ›› 2022, Vol. 31 ›› Issue (7): 50-63.DOI: 10.11686/cyxb2021233

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Screening of rhizosphere growth promoting bacteria and their application in tailings improvement

Yi-chao CHEN1(), Xiao-ying SUN1,2, Zhi-jie XIE1,2, Pan ZHOU1, Lu ZHANG1, Xue-li GAO1, Dong LI1(), Xiao-feng LIU1   

  1. 1.Chengdu Institute of Biology,Chinese Academy of Sciences,Chengdu 610041,China
    2.College of Life Sciences,University of Chinese Academy of Sciences,Beijing 100049,China
  • Received:2021-06-16 Revised:2021-09-27 Online:2022-07-20 Published:2022-06-01
  • Contact: Dong LI

Abstract:

This research was aimed at developing economic and effective methods which have strong applicability and adoption prospects for tailings improvement and vegetation restoration using plant growth-promoting rhizobacteria (PGPR). PGPR from tailings primary environments were screened and a single factor pot experiment with a control and eight treatments was conducted to test their effects on seed germination and growth of Achillea millefolium. The treatments were: an assembly of mixed PGPR (B), biochar (C), manure (F) and their combinations [BC, BF, CF, a compound treatment of B, C and F (BⅠCF), and BⅡCF (the same as BⅠCF, but with doubled mixed PGPR content)]. Measurements included rhizosphere microbial community composition, tailings nutrients, and for plant tissues, enzyme activities and the total amount and distribution of tailings nutrients including total nitrogen and available phosphorus and potassium. The screened PGPR comprised KSB1 (Pseudomonas sp.), KSB2 (Pseudomonas sp.), KSB7 (Pseudomonas sp.) and KSB21 (Rhizobium sp.) selected for their ability to fix nitrogen, dissolve phosphorus, hydrolyze potassium, synthesize indoleacetic acid or secrete 1-aminocyclopropane carboxylic acid deaminase. The pot experiment showed that: 1) The abundance of Pseudomonas and Rhizobium in the rhizosphere environment and the phosphatase activity in tailings can be increased by inoculating mixed PGPR. 2) The effect on tailings nutrients and the growth of A. millefolium of adding biochar alone, was not obvious. 3) The application of manure promoted the growth of A. millefolium, enhanced the activities of tailings enzymes, and significantly increased the abundance of CyanobacteriaP<0.01), the total amount of nitrogen in the potted system, and the total amount of available phosphorus and potassium. 4) Compared with F alone, both the BF and CF treatments further improved various measures of A. millefolium growth and tailings enzyme activity. In addition, the total nitrogen in the potted system in the BF treatment increased by 11.18%, and the total available phosphorus and potassium increased by 22.54% and 22.00% respectively, while the total available potassium only increased by 8.32% in CF. 5) The various measures for BICF and BIICF treatments were generally higher than other treatments. Compared with BICF, BIICF had significantly improved indicators including alkaline hydrolysable nitrogen, phosphatase activity and A. millefolium biomass and the total nitrogen in the pot system increased by 9.54%, the total potassium content of the A. millefolium plant tissues increased by 19.12%, and the relative abundances of Cyanobacteria and Pseudomonas were increased by 51.96% and 13.62%, respectively. 6) Under these experimental conditions, neither inoculating with mixed PGPR nor adding biochar alone resulted in any significant effect on tailings improvement or vegetation restoration; manure played a key role in improving the nutrient supply of tailings and promoting the growth of A. millefolium.This work indicates the benefits of mixed PGPR and biochar are directly related to the application of manure. The BIICF treatment is effective in tailings improvement and the mixed PGPR at least play the role in enhancing nitrogen fixation, phosphorus solubilization and potassium solubilization, and strengthening the potassium absorption and utilization ability of A. millefolium.

Key words: tailings improvement, plant growth promoting rhizobacteria, biochar, Achillea millefolium