Plant growth-promoting rhizobacteria as a sustainable tool for enhancing growth and germination of Chrysopogon aucheri in degraded arid rangelands of Pothwar, Pakistan

Hina Tariq, Lubna Ansari, Aamir Saleem, Rifat Hayat, Farah Naz, Aliya Tariq

Abstract


Plant growth-promoting rhizobacteria (PGPR) play a crucial role in enhancing plant productivity and sustainability by improving nutrient availability and promoting growth. This study aimed to isolate, characterize, and evaluate rhizosphere bacteria from Chrysopogon aucheri for their potential as PGPR. A total of 85 bacterial isolates were obtained and subjected to morphological, biochemical, and molecular characterization. Based on colony morphology, Gram reaction, cell shape, and biochemical tests, ten distinct isolates were selected. These isolates were further screened for plant growth-promoting traits, including indole-3-acetic acid (IAA) production, phosphate solubilization, siderophore, and ammonia production. Among them, strains UUHH-1, UUHH-5, and UUHH-8 exhibited the highest PGP potential, with UUHH-1 (Bacillus subtilis) producing 80.78 ± 1.5 µg ml-1 IAA and the largest phosphate solubilization halo (70.25 ± 5.50 mm2). Molecular identification using 16S rRNA gene sequencing confirmed UUHH-1 as B. subtilis, UUHH-5 as B. cereus, and UUHH-8 as B. mojavensis. In vivo evaluation of C. aucheri seedlings demonstrated that bacterial inoculation significantly enhanced growth parameters compared with uninoculated controls. Strain UUHH-1 showed the greatest enhancement in shoot length (38.33 ± 3.51 cm), root length (46.73 ± 1.53 cm), and biomass accumulation, followed by UUHH-5 and UUHH-8. These findings highlight the effectiveness of selected Bacillus strains in promoting plant growth and suggest their potential as sustainable biofertilizers. Integration of PGPR with organic amendments like vermicompost further supports nutrient availability and bacterial survival. Overall, this study identifies UUHH-1, UUHH-5, and UUHH-8 as promising PGPR candidates for sustainable enhancement of C. aucheri growth.


Keywords


PGPR, Chrysopogon aucheri, Arid rangelands, Soil restoration, Seed germination

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DOI: https://doi.org/10.33804/pp.010.02.6086

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