J Appl Microbiol. 2022;133:943–959. wileyonlinelibrary.com/journal/jam | 943 © 2022 Society for Applied Microbiology. Received: 29 December 2021 | Revised: 31 March 2022 | Accepted: 21 April 2022 DOI: 10.1111/jam.15589 ORIGINAL ARTICLE Efficacy of organic-based carrier material for plant beneficial rhizobacteria application in okra under normal and salt-affected soil conditions Muhammad Tahir 1 | Muhammad Shahid 2 | Farrukh Nawaz 3 | Iftikhar Ahmad 1 | Muhammad Ijaz 3 | Abu Bakr Umer Farooq 1 | Muhammad Akram 1 | Umaira Khalid 3 | Tahir Naqqash 4 | Shehzad Mehmood 1,5 | Muhammad Mubeen 1 | Muhammad Sarfaraz 1 | Yasir Abbas 6 1 Department of Environmental Sciences, COMSATS University Islamabad, Vehari Campus, Islamabad, Pakistan 2 Department of Bioinformatics and Biotechnology, Government College University, Faisalabad, Pakistan 3 College of Agriculture, Bahauddin Zakariya University, Bahadur Sub- Campus Layyah, Multan, Pakistan 4 Institute of Molecular Biology and Biotechnology, Bahauddin Zakariya University, Multan, Pakistan 5 Department of Plant Sciences, Quaid-e-Azam University Islamabad, Islamabad, Pakistan 6 Functional Materials Laboratory (FML), School of Materials Science and Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, China Correspondence Muhammad Tahir, Department of Environmental Sciences, COMSATS University Islamabad, Vehari Campus, Islamabad, Pakistan. Email: muhammad_tahir@cuivehari. edu.pk Funding information Higher Education Commission Islamabad, Pakistan (HEC, Islamabad, Pakistan), Grant/Award Number: 8047/ Balochistan/NRPU/R&D/HEC/2017 Abstract Aims: Plant beneficial rhizobacteria (PBR) improve salt tolerance and plant yield in vegetable plants by producing 1-aminocyclopropane-1-carboxylate-deaminase, indole-3-acetic acid and phosphate solubilization. Organic-based carrier material is needed to ensure the PBR's uniform application, distribution, survival and function- ing in a variety of fields. The PBR also use carbon present in the carrier as food and energy source. The selection of a suitable organic-based carrier material for the ap- plication of the PBR in normal and saline soils always has received less attention. The current study compared the PBR suitability of different organic-based carrier materials (biochar, biogas residues [BGRs] and coconut powder) and evaluated their effects on okra productivity under normal and saline soil conditions. Methods and Results: In a pot experiment, the PBR strain Bacillus sp. MR-1/2 (ac- cession number, MG548383) was applied with/or without organic-based carrier ma- terials to okra grown in three different soils: S1 (EC 1.0 dS m −1 ), S2 (EC 3.0 dS m −1 ) and S3 (EC 5.0 dS m −1 ). The experiment was set up in a completely randomized design with five replicates in factorial arrangement. Results indicated that in soil S1, PBR + BGR increased the number of pods per plant, plant dry weight and in- dole compounds by 64%, 68% and 17% while reduced the electrolyte leakage (ELL), malonaldehyde (MDA) contents and stress ethylene level by 17%, 55% and 38%, re- spectively over the PBR application without any carrier. Similarly, in soil S2, the treatment PBR + BGR increased the number of pods by 81%, plant dry weight by 40% and indole compounds by 13% while reduced the ELL by 17%, MDA contents by 50% and stress ethylene by 30% over the PBR alone treatment. In soil S3, PBR + bio- char increased the number of pods by 51%, plant dry weight by 62% and indole com- pounds by 20%, while reduced the ELL by 21%, MDA by 40% and indole compounds by 54% over the PBR alone treatment. Conclusions: Results concluded that in soil S1 and S2 (normal soils), BGR as carrier for PBR showed best results, while in soil S3, biochar as carrier for PBR resulted in enhanced potassium (K + ) and calcium (Ca +2 ) uptake and increased the productivity of okra. Downloaded from https://academic.oup.com/jambio/article/133/2/943/6989187 by guest on 20 January 2023