Amelioration effect of salt-tolerant plant growth-promoting bacteria on growth and physiological properties of rice ( Or

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ORIGINAL PAPER

Amelioration effect of salt‑tolerant plant growth‑promoting bacteria on growth and physiological properties of rice (Oryza sativa) under salt‑stressed conditions Patel Prittesh1 · Patel Avnika1 · Patel Kinjal1 · Hardik Naik Jinal1 · Krishnan Sakthivel2 · Natarajan Amaresan1  Received: 12 April 2020 / Revised: 4 June 2020 / Accepted: 20 June 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract For sustainable agriculture in saline soil, extensive exploitation of salt-tolerant plant growth-promoting (PGP) bacteria and other symbiotic bacteria is required. This study was carried out to evaluate the efficiency of native salt-tolerant rice rhizobacteria for plant growth promotion under salt stress. A total of 188 bacteria were screened for assessing salt-tolerant capacity and nine isolates tolerating 12% NaCl (w/v) concentration were selected. Biochemical and molecular identification revealed that the salt-tolerant bacteria belonged to Bacillus sp, Exiguobacterium sp, Enterobacter sp, Lysinibacillus sp, Stenotrophomonas sp, Microbacterium sp, and Achromobacter sp. The increase in NaCl concentration from 2 to 4% decreases the PGP activities such as IAA production, P solubilization, K solubilization, and nitrate reduction. The effects of inoculation of salt-tolerant bacteria on the growth and different physiological properties of rice (Oryza sativa) were studied. It was found that the salinity affected the root and shoot length of the control plants; however, bacterial inoculant were found to effectively promote the growth of paddy under salinity stress. Further, bacterial inoculants substantially enhanced total chlorophyll, proline, total phenol, and oxidative damage such as electrolyte leakage and membrane stability index under salt stress. This study suggests that salt-tolerant PGP bacteria may be used for cultivation of O. sativa in salinized agricultural lands. Keywords  Salinity · Synergism · Rice · Chlorophyll · Plant growth promotion

Introduction Rice (Oryza sativa L.) belonging to grass family of Graminae is an important cereal crop for the farmer and is a primary food source worldwide. Rice is cultivated on about one-tenth of the earth’s arable land with a total area of 150 M ha (Viraktamath et al. 2011). India is the second largest producer of rice after China. Although modern agriculture has become much advanced, farmers from arid, semiarid, and coastal regions are facing salinity problem Communicated by Erko Stackebrandt. * Natarajan Amaresan [email protected] 1



C.G. Bhakta Institute of Biotechnology, Uka Tarsadia University, Maliba Campus, Bardoli, Surat, Gujarat 394 350, India



Division of Field Crop Improvement and Protection, Central Island Agricultural Research Institute, Andaman and Nicobar Islands, Port Blair 744 101, India

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for successful cultivation of rice. At global level, the saline soils are increasing at a rate of 7% (Mark and Romola 2003). The soils having electrical conductivity (EC) of > 4 dS/m are considered as saline soils (Pierzynski et