Bio Inoculants Research Articles

Effect of Organic Sources of Nutrients and Bio Inoculants on Diversity of Microbes in Chickpea (Cicer arietinum L.)

A field experiment was conducted during two consecutive seasons of 2022-23 and 2023-2024 at Research Farm, Department of environmental science, college of Sehore, Mansarovar Global university Sehore (MP). The experiment was laid out in a split plot design with sixteen treatment combinations and replicated thrice. The study on the effect of organic sources of nutrient and bio-inoculants on diversity of microbe under chickpea. It is clear from the data that the highest microbial cells count like Rhizobium (16.43 x 106 cfu/g soil) (cfu- colony forming unit), PSB (Phosphate solubilizing bacteria) (19.03 x 106 cfu/g soil) was recorded under application of vermicompost @ 2 t ha-1 followed by FYM (farm yard manure) @ 5 t ha-1 along with Rhizobium and PSB (12.25 x 106 cfu/g soil) and (17.72 x 106 cfu/g soil), respectively. Whereas, highest fungi and actinomycetes count were observed under FYM @ 5 t ha-1 in combination with bio-inoculants and recorded 41.30 x 104 cfu/g and 12.92 x 103 cfu/g soil, respectively followed by vermicompost @ 2 t ha-1 with same inoculants. Whereas the lowest population of fungi was recorded under control along with combined application of bio-fertilizers (29.23 x 104 cfu/g and 7.25 x 103 cfu/g soil).

In vitro P–solubilization activity of halophilic fungi in salt–affected soils and their potential as bio–inoculants

In vitro P–solubilization activity of halophilic fungi in salt–affected soils and their potential as bio–inoculants

Effect of Staggered Planting and Application of Bioinoculants on the Phosphatase Enzyme Activity in the Rhizospheric Soil of Gladiolus cv. White Prosperity

The experiment consists of growing white prosperity cultivar of gladiolus at four different planting times (1st fortnight of October, 2nd fortnight of October, 1st fortnight of November and 2nd fortnight of November) and with eight different treatments of bio inoculants. The experiment was laid out in randomized block design with three replications. Among the different bio inoculants treatment, T8 treatment (RDF + Azotobacter + PSB + Mycorrhiza) proved best with respect to maximum phosphatase enzyme activity when compared to other treatments and among different time of plantings, 1st fortnight of October was the best planting time for gladiolus in terms of maximum phosphatase enzyme activity.

Bioinoculants for growth enhancement of aromatic plants: Artemisia pallens and Origanum majorana

The use of fertilizers is a common practice to improve soil fertility and increase crop yields. Chemical fertilizers have played a significant role in increasing crop yields, but their widespread use has led to environmental degradation and soil depletion. The continuing challenges in agro-ecosystem and environment require more sustainable solutions than chemical fertilizers. In recent years, there has been a growing interest in the use of biofertilizers as a sustainable alternative to chemical fertilizers. Biofertilizers are natural substances that improve soil fertility, modify soil microbiota and enhance plant growth. Cyanobacteria are one of the well-known bio inoculants for paddy crops. However, the use of cyanobacteria for other plants has not been very well documented. We screened certain cyanobacteria isolated from different natural environments as biofertilizers for certain aromatic plants. Artemisia pallens and Origanum majorana are two plants with aromatic compound productions. The aim of this study was to screen for enhancement in the growth and propagation of the plants for their yield using bio inoculants. Further air-dried, powdered plant materials of the aerial parts of A pallens and O. majorana were extracted using solvents ranging in polarity from non-polar (n-hexane), semi-polar (chloroform) and polar (acetone, methanol). These extracts were tested for antioxidant activity, several plant extracts showed antioxidant activity, with water exhibiting the greatest levels. The purpose of the experiment was to investigate the effects of bioinoculants on the growth of the test plant. Our observation showed that all the tested cyanobacterial strains i.e. KM1, KM2 and VM1, VM2, the bioinoculants, enhanced plant growth to various levels. KM1 and KM2 exhibited a greater ability to increase plant growth. This demonstrates that Artemisia's and Origanum’s growth and herbage output may be successfully enhanced by the use of cyanobacterial bioinoculants.

Biochemical and metabolic signatures are fundamental to drought adaptation in PGPR Enterobacter bugandensis WRS7.

Drought alone causes more annual loss in crop yield than the sum of all other environmental stresses. There is growing interest in harnessing the potential of stress-resilient PGPR in conferring plant resistance and enhancing crop productivity in drought-affected agroecosystems. A detailed understanding of the complex physiological and biochemical responses will open up the avenues to stress adaptation mechanisms of PGPR communities under drought. It will pave the way for rhizosphere engineering through metabolically engineered PGPR. Therefore, to reveal the physiological and metabolic networks in response to drought-mediated osmotic stress, we performed biochemical analyses and applied untargeted metabolomics to investigate the stress adaptation mechanisms of a PGPR Enterobacter bugendensis WRS7 (Eb WRS7). Drought caused oxidative stress and resulted in slower growth rates in Eb WRS7. However, Eb WRS7 could tolerate drought stress and did not show changes in cell morphology under stress conditions. Overproduction of ROS caused lipid peroxidation (increment in MDA) and eventually activated antioxidant systems and cell signalling cascades, which led to the accumulation of ions (Na+, K+, and Ca2+), osmolytes (proline, exopolysaccharides, betaine, and trehalose), and modulated lipid dynamics of the plasma membranes for osmosensing and osmoregulation, suggesting an osmotic stress adaption mechanism in PGPR Eb WRS7. Finally, GC-MS-based metabolite profiling and deregulated metabolic responses highlighted the role of osmolytes, ions, and intracellular metabolites in regulating Eb WRS7 metabolism. Our results suggest that understanding the role of metabolites and metabolic pathways can be exploited for future metabolic engineering of PGPR and developing bio inoculants for plant growth promotion under drought-affected agroecosystems.

Effect of Different Formulations of Bio Inoculants on Growth and Yield of Red gram

Effect of Different Formulations of Bio Inoculants on Growth and Yield of Red gram

Rhizobium mayense sp. Nov., an efficient plant growth-promoting nitrogen-fixing bacteria isolated from rhizosphere soil

The nitrogen-fixing bacterium has great prospects in replacing synthetic fertilizers with biofertilizers for plant growth. It would be a useful tool in eradicating chemical fertilizers from use. Five nitrogen-fixing bacteria were isolated from the Tea and Groundnut rhizosphere soil out of which RSKVG 02 proved to be the best. The optimized condition of RSKVG 02 was found to be pH 7 at 30 °C utilizing 1% glucose and 0.05% ammonium sulfate as the sole carbon and nitrogen source. Plant growth-promoting traits such as IAA and ammonia were estimated to be 82.97 ± 0.01254a μg/ml and 80.49 ± 0.23699a mg/ml respectively. Additionally, their phosphate and potassium solubilization efficiency were evaluated to be 46.69 ± 0.00125 b mg/ml and 50.29 ± 0.000266 mg/ml. Morphological, and biochemical methods characterized the isolated bacterial culture, and molecularly identified by 16 S rRNA sequencing as Rhizobium mayense. The isolate was further tested for its effects on the growth of Finger millet (Eleusine coracana) and Green gram (Vigna radiata) under pot conditions. The pot study experiments indicated that the bacterial isolates used as bio inoculants increased the total plant growth compared to the control and their dry weight showed similar results. The chlorophyll content of Green gram and Finger millet was estimated to be 19.54 ± 0.2784a mg/L and 15.3 ± 0.0035 mg/L which suggested that Rhizobium sp. Possesses high nitrogenase activity. The enzyme activity proved to use this bacterium as a biofertilizer property to enhance soil fertility, efficient farming, and an alternative chemical fertilizer. Therefore, Rhizobium mayense can be potentially used as an efficient biofertilizer for crop production and increase yield and soil fertility.

Plant growth-promoting rhizobacteria mediated moisture stress alleviation in the early stages of Rice (Oryza sativa L.) variety CO 51

Drought is one of the abiotic stresses that have a significant impact on agricultural growth across the world. Plant growth-promoting rhizobacteria (PGPR) inoculation in rice plants may be a viable and environmentally acceptable method of sustaining the development and yield of drought-stressed rice plants. The current study focused on the alleviation of drought in the early stages of rice variety CO 51 using PGPR isolated from the rhizosphere of xerophytes. The seeds were treated with bio inoculants and subjected to different moisture stress levels (10%, 20% and 30%) using PEG 6000. The seeds treated with bio inoculants exhibited higher germination percentage and growth traits such as shoot length root length and fresh weight, especially seeds treated with Bacillus velezensis VKSB5 (MT729963), and Bacillus altitudinis MLSB2 (MT729964) over uninoculated plants. This was found to be due to the increased proline accumulation and antioxidant activity in these seedlings, which plays a major role in drought alleviation by altering the osmotic potential and by its ROS scavenging mechanism. Hence this study provides evidence for the effective drought ameliorating ability of these cultures during the initial growth stages of rice. Further studies can contribute to the development of effective bio-inoculants for the mitigation of drought in rice.

Investigating the diversity of bacterial endophytes in maize and their plant growth-promoting attributes.

Maize is a widely known crop in cereals for its importance as staple food, and the endophytic bacteria which dwell within the maize tissues may have impact on the yield and quality of crop. In this study, endophytic bacteria associated with maize were characterized based on their plant growth promoting traits and identified at molecular level to provide valuable information for developing a microbial consortium to enhance the productivity of crop. The bacterial strains having multi-trait plant growth promoting attributes were studied quantitatively, and highest phosphate solubilization was shown by the isolate KL3E1 (573µg/mL), while K solubilization has reported maximum of 39mg/L by the isolate PdS3E1, IAA production was found maximum by the isolate LL3E1 (165μg/mL), and maximum siderophore production (93%) was shown by the isolate VaR3E1 and exopolysaccharide production was found highest by LS3E3 (65mg/L). The efficient isolates identified by 16S rRNA gene sequencing were found as Gordonia hongkongensis, Microbacterium hydrothermale, Kosakonia radicincitans, Kosakonia cowanii, Priestia megaterium, Priestia aryabhattai, Klebsiella pneumoniae, Cellulosimicrobium funkei, Bacillus licheniformis, Pantoea dispersa, Pseudomonas aeruginosa, and Methylorubrum populi. The results showed that these multi-trait plant growth promoting endophytic bacterial isolates could be used as bio inoculants for sustainable improvement of maize crop productivity.

Exploration of plant growth-promoting endophytic bacteria from the crops grown in sodic soils

Isolation of the potential endophytic bacteria from plants that are grown in sodic soils, their diversity and screening their plant growth-promoting activities for testing their efficiency as bio inoculants for the problem soils were studied. Twelve different isolates were selected out of 35 endophytic bacterial isolates on the basis of their richness in the endophytic population of different crop plants and the nucleotide sequences of 16S rRNA genes were observed. The endophytic bacteria for their plant growth-promoting traits such as nitrogen fixation, IAA production, ACC deaminase production, phosphate solubilization, siderophore secretion and antifungal activity were assessed. The best performing strains were evaluated using principal component analysis (PCA). The phylogenetic tree from the endophytic bacterial isolates of different crops grown in sodic soil was categorized into three clusters i.e. Firmicutes, β-Proteobacteria and γ- Proteobacteria. The PCA results identified two potential endophytic strains viz., Ma11 (Bacillus mojavensis) and Ri 2 (Pseudomonas fluorescens) from sodic soil-grown crops. The present findings revealed that the isolates, Ma 11 and Ri 2 were capable of improving crop growth under sodicity. These multifaceted endophytic bacterial isolates would be developed as new inoculants which will be highly suitable for sodic soils. Bangladesh J. Bot. 51(2): 271-280, 2022 (June)

Biopriming of Durum Wheat Seeds with Endophytic Diazotrophic Bacteria Enhances Tolerance to Fusarium Head Blight and Salinity.

There is growing interest in the use of bio inoculants based on plant growth-promoting bacteria (PGPB) to promote plant growth under biotic and abiotic stresses. Here, we provided a detailed account of the effectiveness of a number of endophytic PGPB strains, isolated from the roots of the halophyte Salicornia brachiata in promoting durum wheat growth and enhancing its tolerance to salinity and fusarium head blight (FHB) disease. Bacillus spp. strains MA9, MA14, MA17, and MA19 were found to have PGPB characteristics as they produced indole-3-acetic acid, siderophores, and lytic enzymes, fixed free atmospheric nitrogen, and solubilized inorganic phosphate in vitro. Additionally, the in vivo study that involved in planta inoculation assays under control and stress conditions indicated that all PGPB strains significantly (p < 0.05) increased the total plant length, dry weight, root area, seed weight, and nitrogen, protein, and mineral contents. Particularly, the MA17 strain showed a superior performance since it was the most efficient in reducing disease incidence in wheat explants by 64.5%, in addition to having the strongest plant growth promotion activity under salt stress. Both in vitro and in vivo assays showed that MA9, MA14, MA17, and MA19 strains were able to play significant PGPB roles. However, biopriming with Bacillus subtilis MA17 offered the highest plant growth promotion and salinity tolerance, and bioprotection against FHB. Hence, it would be worth testing the MA17 strain under field conditions as a step towards its commercial production. Moreover, the strain could be further assessed for its plausible role in bioprotection and growth promotion in other crop plants. Thus, it was believed that the strain has the potential to significantly contribute to wheat production in arid and semi-arid regions, especially the salt-affected Middle Eastern Region, in addition to its potential role in improving wheat production under biotic and abiotic stresses in other parts of the world.

IMPORTANCE OF BIO FERTILIZERS AS ALTERNATIVE SOIL FERTILITY AMENDMENTS

There is a current interest in agrarian sustainability with soil microorganisms instead of agro-chemicals. Key constraints in the use of bio fertilizers are; inadequate awareness about bio inoculants and lack of promotion network and publicity among the end users. This review discusses current technical information a way of creating awareness in order to promote the use of bio fertilizers. Publon, Google Scholar, Science Direct and Microsoft Academic data bases were used for the review 2021. Research and review articles published from 2019 onwards were considered as current information for the review. The findings of the review are that; both primary and secondary macronutrients can be provided by bio fertilizers. Potential microbes are; free-living nitrogen fixing bacteria and cyanobacteria, symbiotic nitrogen-fixing bacteria and fungi such as mycorrhiza. Other important functions of bacteria are; conferring to plants the ability for salt tolerance, lignin degradation and remediation of heavy metals from the soil. Bio Compost, vermicompost and termite soil with their rich microorganism content can be used as bio fertilizers for soil nutrient increase. In order to reap maximum benefit from bio fertilizers there is need to formulate them in appropriate materials. Apart from addition of nutrients to the soil, bio fertilizers play an important role in plant health, conclusion. This paper has brought to the fore the need to improve rhizosphere management in a sustainable way particularly at this point in time when there are strong indications that it has deteriorated in the face of continued use of chemical fertilizers.

Effect of Arbuscular Mycorrhizal Fungi and Bio - Inoculants on Germination and Seedling Growth of Carica papaya L. Var. Gujarat Junagadh Papaya-1

Background: Glomus intraradices fungi and three bio-inoculants (Pseudomonas fluorescens, Trichoderma viride, and Trichoderma harzianum) are known to have certain beneficial effects on germination and seedling growth of several tropical fruit crops. A pot study was conducted to evaluate the effects of arbuscular mycorrhizal (AM) fungi and bio inoculants on seed germination and seedling growth of a papaya cultivar Gujarat Junagadh Papaya-1 at regional horticultural research station (RHRS), ASPEE College of Horticulture and Forestry (ACHF), Navsari Agricultural University, Navsari, Gujarat, India.&#x0D; Methods: The seeds of papaya were sown in the Monsoon season (June-Aug 2019) in polybags. The seeds of papaya were coated by AM fungi (G. intraradices), three bio inoculants, and their combinations. There were 9 treatments including control treatment.&#x0D; Results: An application of T. harzianum was found to be the most effective on seed germination and seedling growth by enhancing germination percentage (89%) along with early emergence (6 days) and consolidating all the growth parameters. T. harzanium was also effective on underground plant parts such as tap root length and diameter. The combination of all four bio-inoculants also gave significant results. Results from this study could be helpful for the West Indian fruit growers by enhancing the opportunities to use bioagents for sustaining their farming systems.

Selection of Carrier Materials to Formulate Bioinoculant Package for Promoting Seed Germination

Biofertilizers are a novel technique for Indian agriculture that has the potential to address many of the shortcomings of chemical-based technology. Plant growth-promoting (PGP) traits such as IAA, P-solubilization, ACC deaminase, NH3, HCN, EPS, siderophore synthesis, and biofilm formation have been demonstrated in two salt-tolerant PGPR, BST YS1 42 (Bacillus cereus) and CHR JH203 (Bacillus marisflavi). They are most commonly utilized to make carrier-based compositions. This study aimed to evaluate how different carrier-based formulations of salt-tolerant PGPR performed in seedlings of pea and maize plants. The chosen PGPR was mass replicated in the lab and put into seedlings via a variety of carriers, including charcoal powder, dry pea peel powder, tea leaf powder, hay+2%peptone, and cowdung powder. The influence of bio inoculants on seedling growth of Pisum sativum and Zea mays seedlings was investigated. There was a substantial variation in seedling germination in both pea and maize. The result was different depending on the type of carrier materials utilized in the bioformulation process. The results showed that seedling germination was better with the bioformulation made with charcoal and tea leaf powder. As a result, we believe it might be used to alleviate abiotic stresses in a cost-effective and environmentally friendly manner.

Plant growth-promoting rhizobacteria (PGPR) and its mechanisms against plant diseases for sustainable agriculture and better productivity

Plant growth-promoting rhizobacteria (PGPR) are specialized bacterial communities inhabiting the root rhizosphere and the secretion of root exudates helps to, regulate the microbial dynamics and their interactions with the plants. These bacteria viz., Agrobacterium, Arthobacter, Azospirillum, Bacillus, Burkholderia, Flavobacterium, Pseudomonas, Rhizobium, etc., play important role in plant growth promotion. In addition, such symbiotic associations of PGPRs in the rhizospheric region also confer protection against several diseases caused by bacterial, fungal and viral pathogens. The biocontrol mechanism utilized by PGPR includes direct and indirect mechanisms direct PGPR mechanisms include the production of antibiotic, siderophore, and hydrolytic enzymes, competition for space and nutrients, and quorum sensing whereas, indirect mechanisms include rhizomicrobiome regulation via. secretion of root exudates, phytostimulation through the release of phytohormones viz., auxin, cytokinin, gibberellic acid, 1-aminocyclopropane-1-carboxylate and induction of systemic resistance through expression of antioxidant defense enzymes viz., phenylalanine ammonia lyase (PAL), peroxidase (PO), polyphenyloxidases (PPO), superoxide dismutase (SOD), chitinase and β-glucanases. For the suppression of plant diseases potent bio inoculants can be developed by modulating the rhizomicrobiome through rhizospheric engineering. In addition, understandings of different strategies to improve PGPR strains, their competence, colonization efficiency, persistence and its future implications should also be taken into consideration.

Influence of bio inoculants and plant growth regulators on growth yield and yield attributes of Radish (Raphanus sativus) variety-sweta

Influence of bio inoculants and plant growth regulators on growth yield and yield attributes of Radish (Raphanus sativus) variety-sweta

Synthetic Microbial Community (SynCom) for Sustainable Agriculture

Agricultural sustainability is possible only when reducing crops’ dependency on chemical fertilizers, improving crops’ ability to grow on marginal soil types, and improving their resilience against biotic and abiotic stresses. Though bio inoculants play a crucial role in agricultural sustainability, they are still limited due to low reproducibility in fields due to different crops and cultivars, soil types, and agro-ecological conditions. Traditionally, inoculants are developed through a single isolate study model, i.e., in vitro screening of strains for plant-growth promotion, omitting their interaction with the host plant and soil ecosystem. Hence, a paradigm shift is needed in developing the inoculant to improve the microbe-mediated crop fitness and productivity. In this paper, we framework the synthetic microbial community (SynCom) as a potential resource for developing ecology-based inoculants to augment nutrient acquisition, drought mitigation, and pathogen resistance of crops to ensure sustainability.

Plant growth promotional studies of novel PGPR strains isolated from the rhizosphere of Neolamarckia cadamba (Roxb.)Bosser plantations in Narasipuram, Tamil Nadu

Forests of Indian subcontinent are one of the biodiversity hot spots of the world. They are the second-largest inland use next to agriculture, yet possess a high degree of endemism. Plantation forestry in India was initiated mainly for the production of industrial raw materials as well as fuelwood and fodder from exotic species. The increase in demand for industrial raw material has spurred the rise in plantations of fast-growing native tree species. Neolamarckia cadamba (Roxb.) Bosser is a native tree species whose wood has been largely used in the pulpwood and pencil industry for making boards, plywood, packing cases, tea-boxes, carving and turnery articles. Supplementation of these native trees with effective bio inoculants will improve and maintain the soil fertility and sustainability in the natural soil ecosystem besides providing economic benefits. In the present study, the diversity of PGPR was assessed in the rhizosphere of N. cadamba plantations in Narasipuram, Coimbatore, Tamil Nadu. 33 PGPR isolates from N. cadamba rhizosphere were isolated viz. four species of Azotobacter, three species of Azospirillum and six different PSB species. The isolates were studied for their plant growth promotional abilities such as Indole Acetic Acid (IAA) production and phosphate solubilization.

Pre-Sowing Seed Treatment with Bio Inoculants and Micronutrients on Growth, Yield and Yield Attributing Traits of Lentil

The field experiment entitled “Pre sowing seed treatment of bio inoculants and micronutrients on growth, yield and yield attributing traits of lentil (Lens culinaris L.)” var. Shekhar Masoor-2 was conducted during rabi at central reseach field of the Department of Genetics and Plant Breeding, Sam Higginbottom University of Agriculture, Technology &amp; Sciences, Prayagraj, Uttar Pradesh, India during 2020 - 2021. The experiment consisted of 13 treatments which was laid in Randomized Block Design (RBD). Results revealed that seeds treated with T12 (Rhizobium + PSB + KMB + ZnSO4 + Ammonium molybdate) recorded maximum values in growth parameters viz., field emergence (%) 88.72%, plant height at 30, 60, 90 DAS with 6.97, 23.33, 45.2 cm Days to 50% flowering (72.67days), number of branches 5.07 branches per plant, number of pods per plant with 64.07 pods per plant, number of seeds per pod 1.85 seeds per pod. Similar results are observed in yield paramters where highest seed yield per plant was observed in T12 (Rhizobium + PSB + KMB + ZnSO4 + Ammonium molybdate) with 3.79 g and seed yield per plot 107.4 g.

Photosynthetic Based Technology For The Bioremediation Of Domestic Sewage Water Using Anoxygenic Bacteria

Bioremediation employs the use of naturally occurring organisms to break down hazardous substances into less toxic or non-toxic substances. The conventional treatment method of domestic sewage water is expensive and generates waste sludge that requires further handling and the problem of disposal of sludge into the environment is risky as it has a high potential to pollute the environment. The development of a simple and cost effective process allows the implementation of bioremediation in a safer and effortless manner. Therefore in this investigation microbiological and chemical analyses were very useful to suggest the best ways to improve bioremediation limits in domestic sewage water. In the study indigenous anoxygenic phototrophic bacteria were isolated from domestic sewage water to treat domestic sewage waste water, to develop a costeffective process for bioremediation. Domestic sewage water was analyzed for different physico-chemical parameters such as pH, Temperature, TDS, TSS, TS, DO, BOD, COD, total sulphate and chlorides using bio inoculants of anoxygenic phototrophic bacteria isolated and domestic sewage water in an suitable light, pH and temperature conditions. The results showed that among the 3 anoxygenic phototrophic bacteria isolated; isolate RP2 (Rhodopseudomonas palustris) could grow well at pH 8, temperature 30°C and also reduce more pollutant parameters in domestic sewage water during bioremediation in the period of four consecutive weeks at the rate of 80%.