Abstract
BackgroundSoil salinity has been one of the biggest hurdles in achieving better crop yield and quality. Plant growth-promoting rhizobacteria (PGPR) are the symbiotic heterogeneous bacteria that play an important role in the recycling of plant nutrients through phytostimulation and phytoremediation. In this study, bacterial isolates were isolated from salt-polluted soil of Jhajjar and Panipat districts of Haryana, India. The potential salt-tolerant bacteria were screened for their PGPR activities such as phosphate solubilization, hydrogen cyanide (HCN), indole acetic acid (IAA) and ammonia production. The molecular characterization of potent isolates with salt tolerance and PGPR activity was done by 16S rDNA sequencing. ResultsEighteen soil samples from saline soils of Haryana state were screened for salt-tolerant bacteria. The bacterial isolates were analyzed for salt tolerance ranging from 2 to 10%. Thirteen isolates were found salt tolerant at varied salt concentrations. Isolates HB6P2 and HB6J2 showed maximum tolerance to salts at 10% followed by HB4A1, HB4N3 and HB8P1. All the salt-tolerant bacterial isolates showed HCN production with maximum production by HB6J2. Phosphate solubilization was demonstrated by three isolates viz., HB4N3, HB6P2 and HB6J2. IAA production was maximum in HB4A1 (15.89) and HB6P2 (14.01) and least in HB4N3 (8.91). Ammonia production was maximum in HB6P2 (12.3) and least in HB8P1 (6.2). Three isolates HB6J2, HB8P1 and HB4N3 with significant salt tolerance, and PGPR ability were identified through sequencing of amplified 16SrRNA gene and were found to be Bacillus paramycoides, Bacillus amyloliquefaciens and Bacillus pumilus, respectively. ConclusionsThe salt-tolerant plant growth-promoting rhizobacteria (PGPR) isolated from saline soil can be used to overcome the detrimental effects of salt stress on plants, with beneficial effects of physiological functions of plants such as growth and yield, and overcome disease resistance. Therefore, application of microbial inoculants to alleviate stresses and enhance yield in plants could be a low cost and environmental friendly option for the management of saline soil for better crop productivity.
Highlights
Soil salinity has been one of the biggest hurdles in achieving better crop yield and quality
All samples were collected in sterile polybags and divided in Production of indole acetic acid (IAA) Bacterial isolates were inoculated in nutrient broth enriched with tryptophan (1–2%) and incubated for 24 h at 28 °C on rotary shaker
Isolation of bacteria from saline soils of Haryana, India In the present study, a total of eighteen soil samples from saline soils of Jhajjar and Panipat districts of Haryana state were screened for salt-tolerant bacteria (Fig. 1)
Summary
Soil salinity has been one of the biggest hurdles in achieving better crop yield and quality. The potential salt-tolerant bacteria were screened for their PGPR activities such as phosphate solubilization, hydrogen cyanide (HCN), indole acetic acid (IAA) and ammonia production. The world population is estimated approximately 7.8 billion. This is projected to rise up to 9.7 billion by 2050. The increase in the world’s population has increased the demand of food products [1, 2]. Crop production per unit of land cultivated is unequal to meet the desired demand of food. The change in climate, loss of soil structure, nutrient degradation, draught and soil salinity are the major factors behind the decreased crop yield [2,3,4]. The salinity stress may lead to generation of free radicals such as superoxide ions, hydrogen peroxide (H2O2), and singlet oxygen, decrease in plant defensive enzymes, imbalance in sodium hemostasis, decreased iron uptake, phenols and other trace elements [6,7,8]
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