Biochar immobilized plant growth-promoting rhizobacteria enhanced the physicochemical properties, agronomic characters and microbial communities during lettuce seedling

Ti-Kun Guan; Qiu-Ying Wang; Jia-Shu Li; Hui-Wen Yan; Qing-Jun Chen; Jian Sun; Chao-Jie Liu; Ying-Yan Han; Ya-Jie Zou; Guo-Qing Zhang

doi:10.3389/fmicb.2023.1218205

Biochar immobilized plant growth-promoting rhizobacteria enhanced the physicochemical properties, agronomic characters and microbial communities during lettuce seedling

Front Microbiol. 2023 Jul 5:14:1218205. doi: 10.3389/fmicb.2023.1218205. eCollection 2023.

Authors

Ti-Kun Guan¹, Qiu-Ying Wang^{1

2}, Jia-Shu Li¹, Hui-Wen Yan¹, Qing-Jun Chen¹, Jian Sun³, Chao-Jie Liu¹, Ying-Yan Han¹, Ya-Jie Zou⁴, Guo-Qing Zhang¹

Affiliations

¹ Beijing Key Laboratory for Agricultural Application and New Technique, College of Plant Science and Technology, Beijing University of Agriculture, Beijing, China.
² College of Horticulture, Xinjiang Agricultural University, Urumqi, China.
³ Institute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China.
⁴ Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China.

Abstract

Spent mushroom substrate (SMS) is the by-products of mushroom production, which is mainly composed of disintegrated lignocellulosic biomass, mushroom mycelia and some minerals. The huge output and the lack of effective utilization methods make SMS becoming a serious environmental problem. In order to improve the application of SMS and SMS derived biochar (SBC), composted SMS (CSMS), SBC, combined plant growth-promoting rhizobacteria (PGPR, Bacillus subtilis BUABN-01 and Arthrobacter pascens BUAYN-122) and SBC immobilized PGPR (BCP) were applied in the lettuce seedling. Seven substrate treatments were used, including (1) CK, commercial control; (2) T1, CSMS based blank control; (3) T2, T1 with combined PGPR (9:1, v/v); (4) T3, T1 with SBC (19:1, v/v); (5) T4, T1 with SBC (9:1, v/v); (6) T5, T1 with BCP (19:1, v/v); (7) T6, T1 with BCP (9:1, v/v). The physicochemical properties of substrate, agronomic and physicochemical properties of lettuce and rhizospheric bacterial and fungal communities were investigated. The addition of SBC and BCP significantly (p < 0.05) improved the total nitrogen and available potassium content. The 5% (v/v) BCP addiction treatment (T5) represented the highest fresh weight of aboveground and underground, leave number, chlorophyll content and leaf anthocyanin content, and the lowest root malondialdehyde content. Moreover, high throughput sequencing revealed that the biochar immobilization enhanced the adaptability of PGPR. The addition of PGPR, SBC and BCP significantly enriched the unique bacterial biomarkers. The co-occurrence network analysis revealed that 5% BCP greatly increased the network complexity of rhizospheric microorganisms and improved the correlations of the two PGPR with other microorganisms. Furthermore, microbial functional prediction indicated that BCP enhanced the nutrient transport of rhizospheric microorganisms. This study showed the BCP can increase the agronomic properties of lettuce and improve the rhizospheric microbial community.

Keywords: biochar; lettuce seedling; microbial community; plant growth-promoting rhizobacteria; spent mushroom substrate.