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An attempt was made to evaluate the efficacy of bio-inoculant in single form and as consortium (two or more) involving various treatments (T1 to T12) for the growth performance of Santalum album seedlings. Analysis of growth parameters (at 90th and 180th day) included shoot length (20.4 cm and 52.50 cm), collar diameter (2.88 mm and 4.27 mm), root length (11.76 cm and 26.00 cm), shoot dry weight (8.90 g and 15.18 g), root dry weight (8.10 g and 15.21 g) and total dry weight (16.99 g and 30.39 g). The parameters revealed growth augmentation (shoot length, collar diameter, root length) at 180th day in T12 plants with bio-fertiliser consortia compared to control (T1) (19.80 cm, 3.42 mm, 8.31 cm) and single bio-inoculants (T2) (21.80 cm, 2.83 mm, 11.92 cm). Growth indices, viz., root shoot ratio (0.91 and 1.01), volume index (266.04 and 1462.82) and Dickson's quality index (2.08 and 2.28) at 90th and 180th day, with treatment (T12) involving arbuscular mycorrhizal fungi (AMF) + Azospirillum + Azotobacter + phosphobacteria + potash mobiliser, performed better than control and single bio-inoculant. This study highlights that the efficacy of two or more bio-inoculant in the form of consortium enhances the growth of Santalum album plants in nursery conditions. [ABSTRACT FROM AUTHOR]

Exo-polysaccharides (EPS) possess unique water holding and cementing properties that help in soil aggregation. EPS also increase nutrient uptake in plants, increase water flow across the roots, reduce saline stress by up taking Na+ from soil and increases plant resistance to drought stress. All these factors lead to investigate for eco-friendly and economically reasonable sources of exo-polysaccharides. The exo-polysaccharides secreted by bacteria might play potential role in improvement of agricultural productivity. In the present study, seven bacterial isolates from rice rhizosphere were characterized for their plant growth promoting traits. The isolate NP6 showed most promising results with indole-3-acetic acid production, phosphate solubilization, hydrogen cyanide production, ammonia production, nitrogen fixation along with significant amount of exo-polysaccharides production. The strain was identified as Bacillus cereus by 16S rDNA sequencing method. The co-inoculation of NP6 with pathogenic fungal strain Alternaria alternata showed 86% inhibition of the mycelial growth. For NP6, fructose and peptone were proved to be most optimum carbon and nitrogen sources respectively for exo-polysaccharide production. At a C/N ratio of 20, highest exo-polysaccharides production was observed. In presence of salinity stress NP6 is also able to secrete considerable amount of EPS. All these properties of NP6 make it a candidate to be utilized in large scale exo-polysaccharides production as well as bio-inoculant for improvement of soil condition. [ABSTRACT FROM AUTHOR]

Increase in desiccation is one of the adverse impacts of global climate change that limits the growth of microorganisms including cyanobacteria. Reduction in growth and nitrogen fixation by cyanobacteria due to desiccation is expected to severely restrict their application of cyanobacteria as biofertilizer. Therefore, in the present study the desiccation tolerance potential of ten different species of nitrogen fixing Anabaena strains commonly observed in rice fields was evaluated. The ten different species of Anabaena were grown in BG-11 medium supplemented with polyethylene glycol (10% w/v) and the desiccation tolerance potential was evaluated in terms of several important physiological parameters. Based on the physiological parameters and multivariate analysis the most desiccation tolerant species of Anabaena were identified. Desiccation-tolerant Anabaena fertilissima and Anabaena variabilis showed better growth, chlorophyll, carotenoid, sugar and protein content. They also accumulated the lowest levels of malondialdehyde and peroxides and showed higher superoxide dismutase activity. Physiological parameters such as carotenoid, sugar, nitrogenase activity and proline were also found to contribute significantly to the demarcation of Anabaena sp. and showed positive correlation with chlorophyll. The large diversity observed in the physiological parameters among the different species of Anabaena can be effectively used to screen and select desiccation-tolerant cyanobacteria as bio-inoculants to enhance desiccation tolerance in plants. [ABSTRACT FROM AUTHOR]

Rhizoremediation involves the use of plants and plant growth promoting rhizobacteria (PGPR) for remediation of contaminated soil. This study evaluated the use of Pseudomonas aeruginosa and Eleusine indica to remediate cadmium-polluted soil. Soil samples were collected around the roots of E. indica and PGPR were isolated and evaluated for their capacity for plant growth promotion. P. aeruginosa was selected for Cd remediation experiment which was based on treatments T1 (control soil), T2 (soil + cadmium), T3 (soil + plant + Cd + Pseudomonas applied 2x monthly) T4 (Soil + Plant + Cd + Pseudomonas applied once). T5 (soil + plant + Cd + Pseudomonas applied 1x monthly) T6 (soil + plant + Cd) and T7 (soil and plant). Cd concentration in soil treatments was equivalent to 8 mg/kg and treatments were monitored for 2 months. Bacterial count, physicochemical parameters, nutrient analyses, and Cd removal were subsequently evaluated. T3 had higher bacterial count and pH values (p < 0.05) relative to other treatments and this could be due to the inoculum addition. Conversely, reduction in electrical conductivity, organic carbon and organic matter observed in T3 could be attributed to improved rhizospheric activities. Again, rhizoremediation was highest (P < 0.05) in T3 (90 %) and this suggests P aeruginosa made bio-absorption of Cd easier for E. indica relative to treatments that do not have the inoculum. This study showed that E. indica together with P. aeruginosa are suitable candidates for phytoremediation of Cd contaminated soils. [ABSTRACT FROM AUTHOR]

Rhizoremediation involves the use of plants and plant growth promoting rhizobacteria (PGPR) for remediation of contaminated soil. This study evaluated the use of Pseudomonas aeruginosa and Eleusine indica to remediate cadmium-polluted soil. Soil samples were collected around the roots of E. indica and PGPR were isolated and evaluated for their capacity for plant growth promotion. P. aeruginosa was selected for Cd remediation experiment which was based on treatments T1 (control soil), T2 (soil + cadmium), T3 (soil + plant + Cd + Pseudomonas applied 2x monthly) T4 (Soil + Plant + Cd + Pseudomonas applied once). T5 (soil + plant + Cd + Pseudomonas applied 1x monthly) T6 (soil + plant + Cd) and T7 (soil and plant). Cd concentration in soil treatments was equivalent to 8 mg/kg and treatments were monitored for 2 months. Bacterial count, physicochemical parameters, nutrient analyses, and Cd removal were subsequently evaluated. T3 had higher bacterial count and pH values (p < 0.05) relative to other treatments and this could be due to the inoculum addition. Conversely, reduction in electrical conductivity, organic carbon and organic matter observed in T3 could be attributed to improved rhizospheric activities. Again, rhizoremediation was highest (P < 0.05) in T3 (90 %) and this suggests P aeruginosa made bio-absorption of Cd easier for E. indica relative to treatments that do not have the inoculum. This study showed that E. indica together with P. aeruginosa are suitable candidates for phytoremediation of Cd contaminated soils.

Composting with efficient microbes is considered a sustainable strategy for effective conversion of agricultural discards into a productive biofertilizer. The present study was designed to isolate fungal strain efficient in releasing hydrolytic enzymes for accelerated decomposition and value addition of press mud (PM). In order to tolerate higher temperatures and pH variations during composting, the analysis specifies the different enzymatic behavior at varied temperature and pH range and the strain was also tested for aflatoxins production to produce biofertilizer safe for crop application. The physicochemical characteristics of PM such as total organic carbon (TOC), C/N ratio, electrical conductivity (EC), cation exchange capacity (CEC), total Kjeldahl nitrogen (TKN), total phosphorus (TP), and total potassium (TK) during composting were also studied as compared to control. The results indicated that among seven fungal isolates, Aspergillus niger (A. niger) PM-4 was selected as the best enzyme producers by producing carboxymethyl cellulase (CMCase) α-Amylase, pectinase, and xylanase at a broader temperature and pH spectrum. Composting of PM with A. niger PM-4 leads to significant reduction in TOC (21.2%), C/N ratio (21.3%), increase in EC (25%), CEC (98%), TKN (10.5%), TP (9.2%), and TK (41%) compared to control with one month maturity duration. The A. niger PM-4 also inhibiting mycotoxin growth (aflatoxins) and its inoculation into PM generated mature biofertilizer with germination index (GI) 96.5% after a month representing a cheaper, effective and sustainable approach for waste utilization. [ABSTRACT FROM AUTHOR]

Summary: There is a growing interest in the use of natural products for crop production and protection. Humic acid is a well-known bioresource that intensifies soil functions and improves crop productivity. This review article provides a synopsis of the humic acid-plant-nematode association and the prospects for using humic acid as an alternative to chemical control of nematodes. Humic acid is known to have toxic and antagonistic effects against many plant-parasitic nematodes, including Meloidogyne spp., Rotylenchulus reniformis , Radopholus similis and Helicotylenchus multicinctus. The required dose for getting significant nematode control ranges from 0.04 to 2.0% concentration. Delivery methods like soil application or drenching, seedling root dip treatment and foliar spray on leaves are effective for nematode control. Humic acid controls plant-parasitic nematodes through various mechanisms including killing juveniles, inhibiting hatching, reducing nematode infectivity and reproduction, and inducing systemic resistance. Humic acid is compatible with bio-inoculants such as Azospirillum spp., phosphobacterium, Bacillus megaterium , Pseudomonas fluorescens , Trichoderma viride , Glomus spp., Pochonia chlamydosporia , Purpureocillium lilacinum and T. asperellum. These attributes of humic acid show a promising potential for use in nematode control. However, further work on bio-efficacy against a broad spectrum of plant-parasitic nematodes is needed. [ABSTRACT FROM AUTHOR]

The untapped microbial communities in medicinal plants can have a genetically varied population with multi-functional plant growth promoting characters. An attempt was made to investigate the effect of bioinoculant, Cohnella sp., Chryseobacterium taklimakanense, Lysobacter soli and Paenibacillus glycanilyticus isolated from the medicinal plant (Hemidesmus indicus) rhizosphere on the growth parameters of Kalmegh (Andrographis paniculata) without chemical fertilizers. A vermicompost carrier based single, dual and multiple bio-inoculant formulation was developed and tested for the survival of individual strains, showed a maximum population of 1 × 106 cells g−1 after 90 days of storage at 28 ± 2 °C invariably in all formulations. The inoculums' efficiency on Kalmegh under greenhouse conditions resulted in boosted growth with the maximum plant height (95.8 cm) in Cohnella sp. application, followed by consortium of all strains recorded 91.5 cm. Flower initiation occurred sooner in plants inoculated with bacterial consortium of all as well in Cohnella sp. alone, consecutively resulted in highest Andrographolide content of 3.06% and 3.50%, respectively. Maximum fresh weight herbage yield of 39.5% and 27.5% (dry weight) was recorded in plants treated with bacterial consortium (Cohnella sp, C. taklimakanense, L. soli and P. glycanilyticus) over non-inoculated control as well the available nitrogen, phosphorus and potassium content. Germination of seed experiment revealed the synergism of bacterial isolates in consortium for promoting plant growth. Further, the quanta of inoculums is reduced by 25 percent in composite inoculation, in turn reduces the fertilizers expenditure and persist until the harvesting stage of the crop with the need to apply once. [ABSTRACT FROM AUTHOR]

Salinity is a major environmental stress that limits crop production worldwide. It is well-understood that environmental adaptations, physiological and biochemical traits adjust salinity tolerance in plants, but imparting the knowledge gained towards crop improvement remain arduous. Utilizing the potentially of beneficial microorganisms present in the rhizosphere is an alternative strategy to improve crop production under optimal or stress conditions. The current study aims at examining the ability of plant growth-promoting rhizobacteria (PGPR) in improving coriander growth under salt stress condition. Coriander seeds were inoculated via dual culture of Azospirillum brasiliense and Azotobacter chroococcum, and therefore subjected to four levels of salt stress (0, 40, 80 and 120 mM NaCl) with three replications in a research greenhouse. Seventy-five days after sowing, when leaves fully developed, leaf samples were collected and the traits were measured. The results indicated that the dual inoculation improved chlorophyll a and b content, in comparison to the un-inoculated plants. The dual inoculation increased grain yield, stem fresh and dry weights by 11.6, 11.3 and 17.2%, respectively; it also enhanced total plant fresh and dry weights by 6.1 and 10.2%, respectively, as compared to control. As a result, the dual inoculation significantly improved catalase (CAT), but decreased ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) enzymes activities, as compared to control plants. Salt stress significantly increased (CAT) activity in the leaves, whereas it resulted in significant reduction in (APX) and (GPX) activity, especially in inoculated plants. Furthermore, dual inoculation decreased Na and subsequently increased K concentration in coriander leaves comparing with untreated plants. Overall, these results indicate that the PGPRs has improved coriander growth under control as well as salt stress conditions. Thus, PGPR can could significantly contribute to solve the coriander plant production problems caused by high salinity.

Changes in temperature and moisture as a result of climate forcing can impact performance of planted trees. Tree performance may also be sensitive to new soil conditions, for example, brought about by seeds germinating in soils different from those colonized by ancestral populations. Such "edaphic constraint" may occur with natural migration or human‐assisted movement. Pinus ponderosa seedlings, sourced from one location ("home" site), were grown across a field environmental gradient in either their original home soil or in soils from two different "away" sites. Seedlings were inoculated with site‐specific soil organisms by germinating seeds in living soil. After 6 months, the inoculated seedlings were transplanted into sterilized soils from the home or away sites. This experimental design allowed us to uncouple the importance of abiotic and biotic soil properties and test (1) how biotic and abiotic soil properties interact with climate to influence plant growth and stress tolerance, and (2) the role of soil biota in facilitating growth in novel environments. Seedlings grew least in hotter and drier away sites with away soil biota. Home soil biota ameliorated negative impacts on growth of hotter and drier away sites. Measurements of photosynthetic rate, stomatal conductance, and chlorophyll florescence (Fv/Fm) suggest that edaphic constraint reduced growth by increasing tree water stress. Results suggest that success of Ponderosa pine plantings into warming environments will be enhanced by pre‐inoculation with native soil biota of the seed source. [ABSTRACT FROM AUTHOR]

Nowadays, microorganisms that display plant growth promoting properties are significantly interesting for their potential role in reducing the use of chemical fertilizers. This research study proposed the isolation of the actinobacteria associated with arbuscular mycorrhizal fungi (AMF) spores and the investigation of their plant growth promoting properties in the in vitro assay. Three actinobacterial strains were obtained and identified to the genus Streptomyces (GETU-1 and GIG-1) and Amycolatopsis (GLM-2). The results indicated that all actinobacterial strains produced indole-3-acetic acid (IAA) and were positive in terms of siderophore, endoglucanase, and ammonia productions. In the in vitro assay, all strains were grown in the presence of water activity within a range of 0.897 to 0.998, pH values within a range of 5–11, and in the presence of 2.5% NaCl for the investigation of drought, pH, and salt tolerances, respectively. Additionally, all strains were able to tolerate commercial insecticides (propargite and methomyl) and fungicides (captan) at the recommended dosages for field applications. Only, Amycolatopsis sp. GLM-2 showed tolerance to benomyl at the recommended dose. All the obtained actinobacteria were characterized as plant growth promoting strains by improving the growth of chili plants (Capsicum flutescens L.). Moreover, the co-inoculation treatment of the obtained actinobacteria and AMF (Claroideoglomus etunicatum) spores could significantly increase plant growth, contribute to the chlorophyll index, and enhance fruit production in chili plants. Additionally, the highest value of AMF spore production and the greatest percentage of root colonization were observed in the treatment that had been co-inoculated with Streptomyces sp. GETU-1.

Phosphate-solubilizing bacteria (PSB) improve plant nutrition by solubilizing insoluble phosphorus compounds in alkaline calcareous soils thus improve plant growth of both leguminous and non-leguminous crops. In the present study, two promising PSB strains Bacillus aryabhattai S10 and Bacillus subtilis ZM63 were evaluated for their potential to improve plant growth and nutritional status of mungbean and maize crops. The experiment was conducted in pots under wire house conditions following completely randomized design (CRD) with three replications. The results revealed that co-inoculation with Bacillus aryabhattai S10 and Bacillus subtilis ZM63 exhibited an increased nodulation in mungbean which was measured in terms of nodules number, and nodules fresh and dry weight as compared to sole inoculation. This co-inoculation of bacterial strains also increased plant growth and nutritional status of mungbean and maize crops. It increased nitrogen (N) concentration up to 142 and 18%, phosphorus (P) concentration up to 90 and 43%, and potassium (K) concentration up to 71 and 44%, in shoots of mungbean and maize crops, respectively. It is concluded that the tested PSB strains Bacillus aryabhattai S10 and Bacillus subtilis ZM63 have the potential to be used as promising bio-inoculants to maximize plant growth and nutritional status of the crop for sustainable production. [ABSTRACT FROM AUTHOR]

In smallholder farms of Côte d’Ivoire, particularly in the northeast of the country, Cajanus cajan (pigeonpea) has become an important crop because of its multiple beneficial facets. Pigeonpea seeds provide food to make ends meet, are sold on local markets and aerial parts serve as forage for animals. Since it fixes atmospheric nitrogen in symbiosis with soil bacteria collectively known as rhizobia, C. cajan also improves soil fertility and reduces fallow time. Yet, seed yields remain low mostly because farmers cannot afford chemical fertilizers. To identify local rhizobial strains susceptible to be used as bio-inoculants to foster pigeonpea growth, root nodules were collected in six fields of three geographically distant regions of Côte d’Ivoire. Nodule bacteria were isolated and characterised using various molecular techniques including matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS) and DNA sequencing. These molecular analyses showed that 63 out of 85 nodule isolates belonged to two major clades of bradyrhizobia, one of which is known as the Bradyrhizobium elkanii super clade. Phylogenies of housekeeping (16S-ITS-23S, rpoB) and symbiotic (nifH) genes were not always congruent suggesting that lateral transfer of nitrogen fixation genes also contributed to define the genome of these bradyrhizobial isolates. Interestingly, no field-, plant- or cultivar-specific effect was found to shape the profiles of symbiotic strains. In addition, nodule isolates CI-1B, CI-36E and CI-41A that belong to distinct species, showed similar symbiotic efficiencies suggesting that any of these strains might serve as a proficient inoculant for C. cajan.

In smallholder farms of Côte d'Ivoire, particularly in the northeast of the country, Cajanus cajan (pigeonpea) has become an important crop because of its multiple beneficial facets. Pigeonpea seeds provide food to make ends meet, are sold on local markets, and aerial parts serve as forage for animals. Since it fixes atmospheric nitrogen in symbiosis with soil bacteria collectively known as rhizobia, C. cajan also improves soil fertility and reduces fallow time. Yet, seed yields remain low mostly because farmers cannot afford chemical fertilizers. To identify local rhizobial strains susceptible to be used as bio-inoculants to foster pigeonpea growth, root nodules were collected in six fields of three geographically distant regions of Côte d'Ivoire. Nodule bacteria were isolated and characterized using various molecular techniques including matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS) and DNA sequencing. These molecular analyses showed that 63 out of 85 nodule isolates belonged to two major clades of bradyrhizobia, one of which is known as the Bradyrhizobium elkanii super clade. Phylogenies of housekeeping (16S-ITS-23S, rpoB) and symbiotic (nifH) genes were not always congruent suggesting that lateral transfer of nitrogen fixation genes also contributed to define the genome of these bradyrhizobial isolates. Interestingly, no field-, plant-, or cultivar-specific effect was found to shape the profiles of symbiotic strains. In addition, nodule isolates CI-1B, CI-36E, and CI-41A that belong to distinct species, showed similar symbiotic efficiencies suggesting that any of these strains might serve as a proficient inoculant for C. cajan. [ABSTRACT FROM AUTHOR]

Bio-inoculants have potential role in plant growth promotion. The present study evaluated the potential of Pseudomonas strains as bio-inoculants in wheat on the basis of plant growth promotion and physiological characterization. The 16S rRNA gene sequencing and phylogenetic analysis revealed that four isolated strains belonged to genus Pseudomonas. These strains were positive for phosphorus solubilization and indole acetic acid production, whereas only two strains were positive candidate for their nitrogen fixing ability as determined by presence or absence of nifH gene through amplification from polymerase chain reaction. The pot experiment showed that the integrated use of Pseudomonas strains as co-inoculant and 50% applied mineral fertilizers enhanced the maximum wheat growth and development from 58 to 140% for different shoot and root growth parameters. The strain NCCP-45 and NCCP-237 were closely related to Pseudomonas beteli and Pseudomonas lini, respectively. These isolated strains can be used to increase crop productivity by using as a bio-fertilizer inoculum. [ABSTRACT FROM AUTHOR]

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This study was conducted to examine the effects of the combined application of rhizobial strains and plant growth-promoting rhizobacteria at different ratios on growth and salt tolerance of lucerne. Vegetative growth, relative water content, photosynthetic pigments and organic and inorganic solute contents in leaves were measured after 6 weeks of sowing. The results showed that bacterial inoculation significantly increased shoot and root dry weight, leaf number and relative water content whereas salinity reduced the growth of plants mainly in root dry weight and leaf area. However, the obtained results showed a significant improvement in the growth under salt stress of inoculated plants compared to non-inoculated ones. Regarding photosynthetic pigments, inoculation and salt induced significant variations in the total chlorophyll content, whereas changes in carotenoids remained insignificant. The inoculated plants accumulated less sodium and chloride and maintained a constant potassium content compared to non-inoculated plants. This would imply that the bacteria have retained Na and Cl and so have consequently limited their translocation to the leaves and have promoted selectivity of K ions relative to Na. The levels of organic solutes and soluble proteins were not significantly affected in most plants by both salt and bacterial inoculation, suggesting that they are not directly involved in the strategy of salt tolerance of Lucerne. These results indicate that inoculation with these plant growth promoting rhizobacteria could mitigate the adverse effects of soil salinity on growth of lucerne suggesting that these species could be used as bio-inoculants to increase productivity in arid and semi-arid lands. [ABSTRACT FROM AUTHOR]

In the present investigation four carriers -bagasillo, peat, charcoal and coal were evaluated for the production of bioinoculants. The bacteria used for bioinoculant development were Rhizobium trifolii (MTCC-905) and Rhizobium meliloti (MTCC-100). Both bacterial strains were inoculated in all the four carriers separately. The bacterial population was determined in each carrier up to six month storage. Baqasillo maintain maximum population count 9.39 and 9.40 log cfu/gm for Rhizobium trifolii (MTCC-905) and Rhizobium meliloti (MTCC-100) respectively while coal supported minimum population count 7.28 for Rhizobium meliloti and 7.58 for Rhizobium trifolii. Finally the impact of six month stored inoculants on plant productivity was determined. Bagasillo with Rhizobium meliloti enhanced the seedling biomass by 47% while with Rhizobium trifolii by 55%. Peat and charcoal with Rhizobium meliloti enhanced the seedling biomass by 34% and 28 % respectively and with Rhizobium trifolii by 45 % and 30 % respectively. Coal with Rhizobium meliloti showed 08 % increase of seedling biomass and with Rhizobium trifolii seedling biomass was enhanced by 10 %. The bagasillo-based inoculant was much better than any other carrier-based inoculant taken in the study in enhancing the seedling biomass and the nodule number. The present study suggested the use of bagasillo as an efficient and cheaper carrier material. [ABSTRACT FROM AUTHOR]

In the present investigation five carriers - alginate beads, charcoal, sand, sawdust and sugarcane bagasse were evaluated for the production of bioinoculants. The bacteria used for bioinoculant development were Rhizobium leguminosarum AV1amp+tet+ and Pseudomonas fluorescens ERN2amp+strep+. Both bacterial strains were inoculated in all the five carriers separately and in combination with each other (co-inoculants). The bacterial population was determined in each carrier up to six month storage. Sawdust proved to be the best carrier in maintaining the bacterial population for both individual and co-inoculation. Finally the impact of six month-stored inoculants on plant productivity was determined. The co-inoculants containing both rhizobial and pseudomonad population proved much better in enhancing the seedling biomass and the nodule number. The sawdust-based co-inoculant and monoinoculant was much better than any other carrier-based inoculant taken in the study. The present study suggests the use of co-inoculants over mono-inoculants. [ABSTRACT FROM AUTHOR]

Potassium solubilizing bacteria were isolated from soil samples on potassium aluminum silicate amended agar medium. The bacterial strain B15 recorded the highest potassium solubilization in agar (solubilization index = 2.82) as well as in broth (soluble K = 82.012 μg ml−1) medium. It was identified through 16S rDNA nucleotide sequencing as, Enterobacter hormaechei 1110BP. The strain besides potassium solubilization was also found to have nitrogen fixation and phosphate solubilization abilities. The production of bio-inoculant with this strain was done using locally available agro residues such as wheat bran, sorghum (jowar) bran, and molasses. The usage of agro residues as a nutrient medium in the production of potash bio-inoculant is a novel approach. It is cost-effective as well as environment friendly and it could help to minimize the pollution problems. In the study, response surface methodology was applied for designing the bio-inoculant medium to attain high cell numbers (CFUml−1) and prolonged survival of Enterobacter hormaechei 1110BP. A comparison between the expenses on the synthetic nutrient medium and agro-residue nutrient medium of bio-inoculants reveals that synthetic medium incurs nearly 116.13 times excess than agro-residue medium. Thus, the production of multifarious potash solubilizing Enterobacter hormaechei 1110BP bio-inoculants using locally accessible agro residues is a highly economical and eco-friendly approach for sustainable agriculture. • Enterobacter hormaechei 1110BP is a potent K solubilizer. • Usage of agro residues for liquid K solubilizing bio-inoculant formulation. • Usage of agro residues help to minimize pollution problems and cost-effective. • Formulation of K bio-inoculants medium using RSM to attain high CFU. • Enterobacter hormaechei 1110BP can also provide N and P to plants. [ABSTRACT FROM AUTHOR]

Nowadays, microorganisms that display plant growth promoting properties are significantly interesting for their potential role in reducing the use of chemical fertilizers. This research study proposed the isolation of the actinobacteria associated with arbuscular mycorrhizal fungi (AMF) spores and the investigation of their plant growth promoting properties in the in vitro assay. Three actinobacterial strains were obtained and identified to the genus Streptomyces (GETU-1 and GIG-1) and Amycolatopsis (GLM-2). The results indicated that all actinobacterial strains produced indole-3-acetic acid (IAA) and were positive in terms of siderophore, endoglucanase, and ammonia productions. In the in vitro assay, all strains were grown in the presence of water activity within a range of 0.897 to 0.998, pH values within a range of 5–11, and in the presence of 2.5% NaCl for the investigation of drought, pH, and salt tolerances, respectively. Additionally, all strains were able to tolerate commercial insecticides (propargite and methomyl) and fungicides (captan) at the recommended dosages for field applications. Only, Amycolatopsis sp. GLM-2 showed tolerance to benomyl at the recommended dose. All the obtained actinobacteria were characterized as plant growth promoting strains by improving the growth of chili plants (Capsicum flutescens L.). Moreover, the co-inoculation treatment of the obtained actinobacteria and AMF (Claroideoglomus etunicatum) spores could significantly increase plant growth, contribute to the chlorophyll index, and enhance fruit production in chili plants. Additionally, the highest value of AMF spore production and the greatest percentage of root colonization were observed in the treatment that had been co-inoculated with Streptomyces sp. GETU-1. [ABSTRACT FROM AUTHOR]

Salinity is a major environmental stress that limits crop production worldwide. It is well-understood that environmental adaptations, physiological and biochemical traits adjust salinity tolerance in plants, but imparting the knowledge gained towards crop improvement remain arduous. Utilizing the potentially of beneficial microorganisms present in the rhizosphere is an alternative strategy to improve crop production under optimal or stress conditions. The current study aims at examining the ability of plant growth-promoting rhizobacteria (PGPR) in improving coriander growth under salt stress condition. Coriander seeds were inoculated via dual culture of Azospirillum brasiliense and Azotobacter chroococcum , and therefore subjected to four levels of salt stress (0, 40, 80 and 120 mM NaCl) with three replications in a research greenhouse. Seventy-five days after sowing, when leaves fully developed, leaf samples were collected and the traits were measured. The results indicated that the dual inoculation improved chlorophyll a and b content, in comparison to the un-inoculated plants. The dual inoculation increased grain yield, stem fresh and dry weights by 11.6, 11.3 and 17.2%, respectively; it also enhanced total plant fresh and dry weights by 6.1 and 10.2%, respectively, as compared to control. As a result, the dual inoculation significantly improved catalase (CAT), but decreased ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) enzymes activities, as compared to control plants. Salt stress significantly increased (CAT) activity in the leaves, whereas it resulted in significant reduction in (APX) and (GPX) activity, especially in inoculated plants. Furthermore, dual inoculation decreased Na and subsequently increased K concentration in coriander leaves comparing with untreated plants. Overall, these results indicate that the PGPRs has improved coriander growth under control as well as salt stress conditions. Thus, PGPR can could significantly contribute to solve the coriander plant production problems caused by high salinity., (© 2020 Published by Elsevier Ltd.)

This study emphasizes the beneficial role of rhizo-competitive Bacillus spp. isolated from rhizospheric and non-rhizospheric soil in plant growth promotion and yield improvement via nitrogen fixation and biocontrol of Sclerotium rolfsii causing foot rot disease in Eleusine coracana (Ragi). The selection of potent rhizobacteria was based on plant-growth-promoting attributes using Venn set diagram and Bonitur scale. Bacillus pumilus MSTA8 and Bacillus amyloliquefaciens MSTD26 were selected because they were effective in root colonization, rhizosphere competence, and biofilm formation using root exudates of E. coracana L. rich with carbohydrates, proteins, and amino acids. The relative chemotaxis index of the isolates expressed the invasive behavior of the rhizosphere. During pot and field trials, the consortium of the rhizobacteria in a vermiculite carrier increased the grain yield by 37.87%, with a significant harvest index of 16.45. Soil analysis after the field trial revealed soil reclamation potentials to manage soil nutrition and fertility. Both indexes ensured crop protection and production in eco-safe ways and herald commercialization of Bacillus bio-inoculant for improvement in crop production and disease management of E. coracana .