Single Inoculants Research Articles

Combining microorganisms in inoculants is agronomically important but industrially challenging: case study of a composite inoculant containing Bradyrhizobium and Azospirillum for the soybean crop

The increasing global perception of the importance of microbial inoculants to promote productivity and sustainability in agriculture prompts the adoption of bio-inputs by the farmers. The utilization of selected elite strains of nitrogen-fixing and other plant-growth promoting microorganisms in single inoculants creates a promising market for composite inoculants. However, combining microorganisms with different physiological and nutritional needs requires biotechnological development. We report the development of a composite inoculant containing Bradyrhizobium diazoefficiens and Azospirillum brasilense for the soybean crop. Evaluation of use of carbon sources indicates differences between the microbial species, with Bradyrhizobium growing better with mannitol and glycerol, and Azospirillum with malic acid and maleic acid, allowing the design of a formulation for co-culture. Species also differ in their growth rates, and the best performance of both microorganisms occurred when Azospirillum was inoculated on the third day of growth of Bradyrhizobium. The composite inoculant developed was evaluated in five field trials performed in Brazil, including areas without and with naturalized populations of Bradyrhizobium. The composite inoculant resulted in symbiotic performance comparable to the application of the two microorganisms separately. In comparison to the single inoculation with Bradyrhizobium, co-inoculation resulted in average increases of 14.7% in grain yield and 16.4% in total N accumulated in the grains. The performance of the composite inoculant was similar or greater than that of the non-inoculated control receiving a high dose of N-fertilizer, indicating the importance of the development and validation of inoculants carrying multiple beneficial microorganisms.

Effects of Inoculants Producing Antifungal and Carboxylesterase Activities on Corn Silage and Its Shelf Life against Mold Contamination at Feed-Out Phase.

The present study aimed to investigate effects of dual-purpose inoculants (antifungal and carboxylesterase activities) not only on corn silage quality, but also its shelf life against mold contamination at feed-out phase. Corn forage was ensiled for 252 d with different inoculants of the following: control (CON), Lactobacillus brevis 5M2 (5M), Lactobacillus buchneri 6M1 (6M), and mixture of 5M and 6M at 1:1 ratio (MIX). After ensiling, corn silage was contaminated with Fusarium graminearum. Silages applied inoculants had positive effects by increased organic acid and lactic acid bacteria, and decreased undesirable microbes. At feed-out phase, contamination of F. graminearum into corn silage had a negative effect on aerobic stability caused by increased growth of undesirable microbes. However, silages applied inoculants had positive effects by decreased undesirable microbes and extended lactic acid bacteria and aerobic stability. Generally, MIX silage presented better effects on organic acid production, rumen degradation, inhibition of undesirable microbes, and aerobic stability than 5M silage and 6M silage. The present study concluded that application of inoculants into corn silage had positive effects on fermentation characteristics and extended shelf life against mold contamination at feed-out phase. A mixed inoculant appeared to have better effects of antifungal and carboxylesterase than a single inoculant.

Effect of Seed Bio-priming with Trichoderma viride Strain BHU-2953 for Enhancing Soil Phosphorus Solubilization and Uptake in Soybean (Glycine max)

The main objective of our study was to evaluate the effectiveness of Trichoderma viride BHU-2953 as a single inoculant during seed-priming to enhance phosphorus (P) uptake in soybean. A pot experiment was conducted, taking six treatments, in a completely randomized block design to assess the P uptake, root length, apparent phosphorus recovery (APR), rhizospheric phosphatase activity, pH, soil-P status, dehydrogenase activity, and fungal colony-forming unit (CFU g−1) in three different soybean growth stages through seed-priming with T. viride along with graded fertilizer P-doses. Significantly (P < 0.05) higher soil phosphatase activity, dehydrogenase activity, CFU of T. viride, and P-content in soybean vegetative parts were observed in bio-primed treatments as compared to control and RDF (full recommended dose of P-fertilizer without seed-priming), while seed-P (%), APR (%), and root lengths of RDF were found significantly (P < 0.05) lower than bio-primed soybeans with 90% RDF but were at par with 80% RDF. Higher positive correlations between CFU and acid phosphatase (R2 = 0.89, 0.9, and 0.89; P < 0.05) and between CFU and alkaline phosphatase activities (R2 = 0.98, 0.96, and 0.97; P < 0.05) at 30, 50, and 75 DAS indicate that T. viride mediated higher soil phosphatase activities. Higher P-recoveries of bio-primed soybeans, received 90% and 80% RDF, were achieved mainly due to soil applied-P solubilization through enhanced acid phosphatase activities along with better soil exploration by plant roots. Thus, seed-priming with T. viride BHU-2953 can reduce up to 20% of the recommended P-dose in soybeans.

Novel microbial consortium formulation as plant growth promoting bacteria (PGPB) agent

PGPB enhance plant growth through nitrogen fixation, IAA production, phosphorus and pottasium solubilization. PGPB as biofertilizer provide an alternative for chemical fertilizer to reduce environmental damage. PGPB in consortium could be more effective instead of single strain inoculant. The aim of this study is to investigate compatibility, design soil bacteria consortium isolated from rubber-Canna intercropping plantation and evaluate the consortium’s potential as biofertilizer. Functional roles of PGPB was tested such as nitrogen fixation, potassium and phosphate solubilization, and IAA production. Detection of pathogenic bacteria was tested by Blood Agar method. Compatibility test was performed by cross streak method. Bacteria were identified using sequencing of 16srRNA gene and verified using BLAST to database of NCBI. The results showed that among 19 bacterial isolates, all showed the nitrogen-fixing activity, G5 had the highest phosphorus and potassium solubilization index, whereas Citrobacter braakii strain 167 produced the highest IAA concentration. Compatibility analysis showed that Citrobacter freundii strain LMG 3246, Citrobacter braakii strain DSM 17596 and G5 are compatible as a bacteria consortium and may developed as biofertilizer. This study found a possible new and beneficial biofertilizer formulation to enhance plant growth and to reduce the application of chemical fertilizer.

Evaluation of two commercial fungal inoculants for improving phosphorus supply to crops grown in soils with contrasting management histories

AbstractTwo fungal inoculants are commercially available in Canada and the USA that target improving plant access to soil phosphorus (P). Arbuscular mycorrhizal fungi and Penicillium bilaiae were used to inoculate wheat, lentil and flax grown in an organically-managed and a conventionally-managed soil. A second crop was grown after freezing the soil to evaluate if the inoculants carried over to a second crop. Crops in the organically managed soil were smaller and took up less P than the same crop in the conventionally managed soil. Inoculation with either inoculant improved shoot growth and P uptake in wheat grown in the organically-managed soil and in lentil grown in the conventionally-managed soil. Co-application of the inoculants was never superior to the single inoculants. Carry-over effects were slight and inconsistent.

Effects of beneficial endophytic fungal inoculants on plant growth and nutrient absorption of trifoliate orange seedlings

Citrus plants heavily depend on soil arbuscular mycorrhizal fungi (AMF), while the application of AMF in citrus is limited because of no propagation in vitro. The present work tried to apply a culturable (in vitro) endophytic fungus Piriformospora indica into trifoliate orange (Poncirus trifoliata) and to compare the role of P. indica in plant growth and nutrient acquisition especially phosphorus (P), relative to an arbuscular mycorrhizal fungus Funneliformis mosseae. After 20 weeks, roots of trifoliate orange could be colonized by P. indica, and both P. indica and F. mosseae existed in roots together. Root fungal colonization and soil easily extractable, difficultly extractable, and total glomalin-related protein concentrations were higher under single F. mosseae inoculation than under single P. indica and dual inoculation of F. mosseae and P. indica. Single or dual microbial inoculant collectively improved plant growth including plant height, leaf number, and leaf, stem, and root biomass, compared with non-inoculation. In addition, single fungal treatment raised the content of root N, P, and Mg, and dual inoculation increased only Mg and B contents. The improvement of P by single microbial inoculant was associated with the fungi-accelerated soil phosphatase activity and the fungi-induced root phosphate transporter genes (PT3, PT5, and PT6) expression levels. The positive effects on growth and nutrients were more significant under single F. mosseae than under single P. indica and dual inoculations. It concluded that P. indica has the stimulated roles in plant growth and P acquisition of trifoliate orange, and thus has more applied potentiality in citriculture than AMF as a biofertilizer.

Plant Growth-Promoting Rhizobacteria Isolated from Degraded Habitat Enhance Drought Tolerance of Acacia (Acacia abyssinica Hochst. ex Benth.) Seedlings.

Drought stress (DS) is the most impacting global phenomenon affecting the ecological balance of a particular habitat. The search for potential plant growth-promoting rhizobacteria (PGPR) capable of enhancing plant tolerance to drought stress is needed. Thus, this study was initiated to evaluate the effect of inoculating Acacia abyssinica seedlings with PGPR isolated from rhizosphere soil of Ethiopia to enhance DS tolerance. The strains were selected based on in vitro assays associated with tolerance to drought and other beneficial traits such as salinity, acidity, temperature, heavy metal tolerances, biofilm formation, and exopolysaccharide (EPS) production. The strains with the best DS tolerance ability were selected for the greenhouse trials with acacia plants. The results indicate that out of 73 strains, 10 (14%) were completely tolerant to 40% polyethylene glycol. Moreover, 37% of the strains were strong biofilm producers, while 66 (90.41%) were EPS producers with a better production in the medium containing sucrose at 28 ± 2°C and pH 7 ± 0.2. Strains PS-16 and RS-79 showed tolerance to 11% NaCl. All the strains were able to grow in wider ranges of pH (4–10) and temperature (15–45°C) and had high tolerance to heavy metals. The inoculated bacterial strains significantly (p ≤ 0.05) increased root and shoot length and dry biomass of acacia plants. One of the strains identified as P. fluorescens strain FB-49 was outstanding in enhancing DS tolerance compared to the single inoculants and comparable to consortia. Stress-tolerant PGPR could be used to enhance acacia DS tolerance after testing other phytobeneficial traits.

Inoculation of drought-stressed wheat plant (Triticum aestivum L.) with single and combined inoculants of Arbuscular mycorrhizal fungi

The current study aimed to compare between inoculation of wheat plant with a single and combinations of several species of Arbuscular mycorrhizal fungi (AMF), and promoting its growth under water stress conditions. In a greenhouse experiment, the effect of three AMF species on wheat plant growth was studied using single-inoculations with Glomus monosporum, G. mosseae and Gigaspora gigantean, and mixtures of various AMF species. Moreover, inoculation of wheat plant with pair of AM fungi composed mainly of; SN (G. monosporum and Gigaspora gigantean) and AA (G, monosporum and Glomus mosseae) were investigated. Current findings indicate that inoculation with AMF belonging to different families was more effective in improving plant growth than AMF from the same genus and with mono-inoculation. Results showed that plant height inoculated with SN and AA increased by 27.30% and 24.95; respectively, while inoculation with Gigaspora gigantean (GG), G. mosseae (GS) and G. monosporum (GM) increased by 16.01%, 14.6% and 6.83%, respectively. Number of spikes/plant, spike length, number of spikelet/spike, 1000-grain weight and grain yield/plant of wheat plants inoculated with AMF increased significantly, compared with the non-inoculated control plants under water stress. In addition, current results demonstrated that inoculation with SN had relatively higher impact on promoting the growth of wheat plants followed by AA and GG, suggesting that inoculation with AMF consisting of different species may have a better effect than single inoculations. Furthermore, it is observed also that SN; which are combination from different genera have better effect on wheat plant growth, compared to that of AA from the same genus but of different species.

Influence of Funneliformis mosseae enhanced with titanium dioxide nanoparticles (TiO2NPs) on Phaseolus vulgaris L. under salinity stress.

The Arbuscular mycorrhizal fungi (AMF) (Funneliformis mosseae), are the most widely distributed symbiont assisting plants to overcome counteractive environmental conditions. In order to improve the sustainability and the activity of AMF, the use of nanotechnology was important. The main objective of this study was to investigate the effect of titanium dioxide nanoparticles (TiO2NPs) on the activity of AMF in common bean roots as well as its activity under salinity stress using morphological and molecular methods. The activity of AMF colonization has increased in the presence of TiO2NPs especially for arbuscule activity (A%), which increased three times with the presence of TiO2NPs. The improvement rate of Funneliformis mosseae on plant growth increased from 180% to 224% of control at the lowest level of salinity and increased from 48% to 130% at higher salinity level, respectively. The AMF dependencies for plant dry biomass increased in the presence of TiO2NPs from 277% in the absence of salinity to 465 and 883% % at low and high salinity levels, respectively. The presence of AMF co-inoculated with TiO2NPs resulted in increasing the salinity tolerance of plants at all levels and reached 110% at salinity level of 100 mM NaCl. Quantitative colonization methods showed that the molecular intensity ratio and the relative density of paired inocula AMF Nest (NS) or chitin synthases gene (Chs) with TiO2NPs were higher significantly P.>0.05 than single inoculants of AMF gene in roots under the presence or the absence of salinity by about two folds and about 40%. Hence, the positive effect of TiO2NPs was confined to its effect on AMF not on bean plants itself.

Relevance of Plant Growth Promoting Microorganisms and Their Derived Compounds, in the Face of Climate Change

Climate change has already affected food security in many parts of the world, and this situation will worsen if nothing is done to combat it. Unfortunately, agriculture is a meaningful driver of climate change, through greenhouse gas emissions from nitrogen-based fertilizer, methane from animals and animal manure, as well as deforestation to obtain more land for agriculture. Therefore, the global agricultural sector should minimize greenhouse gas emissions in order to slow climate change. The objective of this review is to point out the various ways plant growth promoting microorganisms (PGPM) can be used to enhance crop production amidst climate change challenges, and effects of climate change on more conventional challenges, such as: weeds, pests, pathogens, salinity, drought, etc. Current knowledge regarding microbial inoculant technology is discussed. Pros and cons of single inoculants, microbial consortia and microbial compounds are discussed. A range of microbes and microbe derived compounds that have been reported to enhance plant growth amidst a range of biotic and abiotic stresses, and microbe-based products that are already on the market as agroinputs, are a focus. This review will provide the reader with a clearer understanding of current trends in microbial inoculants and how they can be used to enhance crop production amidst climate change challenges.

Towards Better Understanding of the Interactions and Efficient Application of Plant Beneficial Prebiotics, Probiotics, Postbiotics and Synbiotics.

It is well known that a gram of soil contains thousands of individual microbial taxa including bacteria, fungi, protists, oomycetes and viruses. Many of them play the main role in ecosystem functioning determining soil fertility and provide plant growth promotion and disease suppression, (van der Heijden et al., 2008; Glick, 2012; Serna-Chavez et al., 2013; Maron et al., 2018). However, after many years of chemical fertilization, soils lost their natural fertility, plant diversity and microbial richness (Huang et al., 2019). In addition, an increasing number of stress factors are observed such as salinity, alkalinity/acidity, contamination, nutrient deficiency or overload of chemical fertilizers, drought, soil erosion due to climate change, and various biotic factors (Fitzpatrick et al., 2019). The use of plant beneficial microorganisms (PBM) to mitigate these 0problems in cultivated crop production is now a common practice particularly in the modern, sustainable agriculture and in the context of increasing world population and environmental and climate concerns (Shilev et al., 2019). During the last 20–30 years, a large number of microorganisms have been isolated, characterized and tested as biofertilizers and biocontrol agents in controlled and natural conditions. The results confirmed the beneficial effect of the selected microorganisms on plant growth and health, enhancing nutrient content and improving soil properties. Now, the emphasis of the scientific activity in the field of microbial inoculants is on developing environmentally friendly and efficient microbial formulations and analyse how the introduced microorganisms affect microbial community, diversity, and the specific plant–microorganisms interactions, which determine the plant holobiome functioning (Berg et al., 2017). Therefore, at this moment, at least two major lines of research can be distinguished: the first one deals with holobiome/hologenome studies including molecular mechanisms and genetic regulation (and epigenetic mechanisms) of beneficial microbiota (Corbin et al., 2020) and, another important line of research on the process of establishing a plant beneficial microbiome includes development of efficient single or multiple microbial inoculants. A combination of pro- and postbiotics could be applied to manage and stimulate the existing beneficial microbiome.

Contrasting effects of commercial and native arbuscular mycorrhizal fungal inoculants on plant biomass allocation, nutrients, and phenolics

Societal Impact StatementAs the global population increases, the need to feed more people must be met while simultaneously conserving the long‐term sustainability of our agroecosystems. There is mounting interest and discussion around the application of arbuscular mycorrhizal fungal (AMF) inoculants to enhance crop growth, nutrient uptake, and pest resistance. However, the effects of AMF inoculation are variable and context dependent. This study found that a multi‐species AMF inoculant had a stronger effect on plant biomass allocation and chemistry than a single AMF species inoculant, however, neither of these had a stronger effect than re‐inoculating plants with a field‐sourced native AMF community.

Non-rhizobial Root Nodule Endophytic Yeast, Candida tropicalis VYW1 Impacts Germination, Nodulation behavior and Metabolic flux in Blackgram (Vignamungo L.)

Nodule associated endophytic yeasts have attracted much attention dueto its potential plant growth-promoting activities and protecting legumecrops from both biotic and abiotic stress. The present study evaluated thepotential role of an endophytic yeast Candida tropicalis VYW1 in modulatinghost fitness (blackgram) both as a single inoculant and co-inoculant withRhizobium sp. VRE1. The results showed that nodule associated endophyticyeast C. tropicalis VYW1 when co-inoculated with Rhizobium sp. VRE1significantly increased the germination percent (100%), root (34.6 cm),and shoot length (32.8 cm). The vigor index was also maximum (4250) inthe treatment that received the co-inoculation of Rhizobium sp. VRE1 andC. tropicalis VYW1 besides registering enhanced hydrolytic enzyme,α - amylase, and protein content in seeds. Metabolite profiling of bacterialprimed seed exudates revealed 30 diverse compounds belonging to theclasses viz., sugars, amino acids, organic acids, flavones, prenol lipids,and fatty acids. The blackgram seeds primed with co - inoculants releasedhydroxyl benzoic acid and galactopyranose, which act as potential chemoattractantsand involves in the lectin complement pathway regulatingfructose mannose metabolism. These metabolites lead to a significantincrease in germination and nodulation in blackgram seedlings. Hence,the study suggests the scope of enhancing the fitness of blackgram usinga co-inoculant comprising of C. tropicalis VYW1 and Rhizobium sp. VRE1.

Combinations of different arbuscular mycorrhizal fungi improve fitness and metal tolerance of sorghum in ultramafic soil

Research on arbuscular mycorrhizal fungi (AMF) in ultramafic soils has principally focused on ecological restoration whereas little attention has been given to agriculture. The present study aims at understanding if mixtures of different AMF species from a New Caledonian ultramafic soil induced a better plant fitness and lower contents of potentially toxic metals in aerial parts of a crop plant than single species inoculants. Sorghum vulgare plants were inoculated using six AMF species separately and in different mixtures of these species in a glasshouse experiment in ultramafic soil. The tested inocula showed very different effects on plant fitness. Results highlight that, when sorghum is grown in ultramafic soil, AMF mixes were more efficient than single species inoculation in alleviating abiotic stresses by reducing translocation of potentially toxic metals to the aerial part of the plant and thereby improving the fitness of the plants. Our findings point out the utility of arbuscular mycorrhizal biotechnology for agricultural ultramafic soils.

Rhizobacteria producing ACC deaminase mitigate water-stress response in finger millet (Eleusine coracana (L.) Gaertn.).

The aim of the study was to examine the influence of single and consortia treatments of drought tolerant rhizobacteria producing ACC deaminase together with additional plant growth promoting (PGP) characteristics on finger millet growth, antioxidant and nutrient concentration under water-stressed and irrigated (no stress) conditions. These rhizobacteria belong to the Variovorax sp. Achromobacter spp. Pseudomonas spp. and Ochrobactrum sp. The single inoculant of RAA3 (Variovorax paradoxus) and a consortium inoculant of four bacteria, i.e., DPC9 (Ochrobactrum anthropi), DPB13 (Pseudomonas palleroniana), DPB15 (Pseudomonas fluorescens) and DPB16 (Pseudomonas palleroniana), significantly boosted the overall growth parameters and nutrient concentrations in leaves of finger millet. Moreover, elevated levels of the reactive oxygen species scavenging enzymes-superoxide dismutase (17.3%, 11.6%), guaiacol peroxidase (38.7%, 22.2%), catalase (33.7%, 21.3%) and ascorbate peroxidase (18.2%, 10.0%); cellular osmolytes-proline (41.5%, 25.0%), phenol (44.5%, 37.5%); higher leaf chlorophyll (64.4%, 30.8%) and a reduced level of hydrogen peroxide (50.7%, 59.5%) and malondialdehyde (48.4%,72.5%) were noted, respectively, after single inoculation of RAA3 and a consortium treatment by strains DPC9 + DPB13 + DPB15 + DPB16, in contrast with non-treated plants mainly under water-stressed conditions. This finding clearly illustrates that PGPB that express ACC deaminase along with additional PGP traits could be an efficient approach for improving plant health in environments, where agricultural practices are reliant on rain for water.

Co-existence of Leclercia adecarboxylata (LSE-1) and Bradyrhizobium sp. (LSBR-3) in nodule niche for multifaceted effects and profitability in soybean production.

The present study was designed with the objective of improving growth and nodulation of soybean [Glycine max (L.) Merill] with co-inoculation of native Bradyrhizobium sp. (LSBR-3) (KF906140) and non-rhizobial nodule endophytic diazotroph Leclercia adecarboxylata (LSE-1) (KX925974) with multifunctional plant growth promoting (PGP) traits in cereal based cropping system (Rice-Wheat). A total of 40 endophytic bacteria from cultivated and wild sp. of soybean were screened for multifarious PGP traits and pathogenicity test. Based on PGP traits, antagonistic activities and bio-safety test; L. adecarboxylata (LSE-1) was identified with 16 S rRNA gene sequencing along with the presence of nifH (nitrogen fixation) and ipdc (IAA production) genes. Dual inoculant LSE-1 and LSBR-3 increased indole acetic acid (IAA), P & Zn-solubilization, 1-aminocyclopropane-1-carboxylate deaminase (ACCD) activity, siderophore, biofilm formation and exo-polysaccharides in contrast to single inoculation treatment. Further, assessment of dual inoculant LSBR-3 + LSE-1 improved growth parameters, nodulation, soil enzymes activities, nutrient accumulation and yield as compared to single as well as un-inoculated control treatment under field conditions. Single inoculant LSBR-3 improved yield by 8.84% over control. Further, enhancement of 4.15% grain yield was noticed with LSBR-3 + LSE-1 over LSBR-3 alone treatment. Application of LSBR-3 + LSE-1 gave superior B:C ratio (1.29) and additional income approximately 116USDha-1 in contrast to control treatment. The present results thus, is the first report of novel endophytic diazotroph L. adecarboxylata (LSE-1) as PGPR from Indian conditions particularly in Punjab region for exploiting as potential PGPR along with Bradyrhizobium sp. (LSBR-3) in soybean.

Synergism of Pseudomonas aeruginosa (LSE-2) nodule endophyte with Bradyrhizobium sp. (LSBR-3) for improving plant growth, nutrient acquisition and soil health in soybean.

The present study was aimed to assess the scope of native potential endophyte Pseudomonas aeruginosa (LSE-2) strain (KX925973) with recommended Bradyrhizobium sp. (LSBR-3) (KF906140) for synergistic effect to develop as consortium biofertilizer of soybean. A total of 28 non-rhizobial endophytic bacteria were isolated from cultivated and wild sp. of soybean. All isolates were screened for multifarious PGP traits viz. Indole-3-acetic acid (IAA), phosphate (P) and zinc (Zn) solubilization, siderophore, cell wall degrading enzymes and pathogenicity. Compatible of LSBR-3 and LSE-2 enhanced IAA, P-solubilization, 1-aminocyclopropane-carboxylate deaminase and biofilm formation over the single inoculant treatment. Further, consortium was evaluated in vivo for growth, symbiotic traits, nutrient acquisition, soil quality parameters and yield attributes of soybean. Improvement in growth parameters were recorded with dual inoculant LSBR-3 + LSE-2 as compared to LSBR-3 alone and un-inoculated control treatments. Significantly (p ≥ 0.05) high symbiotic and soil quality parameters (phosphatase and soil dehydrogenase activity) was recorded with LSBR-3 + LSE-2 at vegetative and flowering stage as compared to LSBR-3 alone and un-inoculated control treatments. Single inoculation of LSBR-3 improved grain yield by 4.25% over the un-inoculated control treatment, further, enhancement in yield was recorded with consortium inoculant (LSBR-3 and LSE-2) by 3.47% over the LSBR-3 alone. Application of consortium inoculant (LSBR-3 + LSE-2) gave an additional income of Rs. 5089/ha over the un-inoculated control treatment. The results, thus strongly suggest that endophytic diazotroph LSE-2 can be used as potent bio-inoculant along with LSBR-3 as bio-enhancer for improving soybean productivity in a sustainable system.

Assessment of native single and dual inoculants of Mesorhizobium SP. and endophytic rhizobacteria for plant growth promotion in chickpea

Assessment of native single and dual inoculants of <i>Mesorhizobium</i> SP. and endophytic rhizobacteria for plant growth promotion in chickpea

English

Abundance and unmanaged agriculture residues lead to unutilized resource waste and environmental pollution. Application of microbial technology to manage agriculture waste could produce value-added product. A preliminary study on biodegradation of rice straw using different potential microorganisms was tested under controlled environment. Three different inoculant cultures were used to observe their efficiency in rice straw degradation. Combination cultures microorganisms coding AMB1 shows the potential degrading activity, which reduces the hemicellulose of rice straw by 50% from the raw material. The highest cellulase activity at 1.5 U/mL was also observed in rice straw treatment with AMB1 than single inoculant fungi and commercial microbial product. Overall, the results suggested that the biodegradation of rice straw could be improved by using combination culture. The ability of these cultures to enhance biodegradation shows potential to fasten the decomposing period and may be used to manage agriculture waste. Key words: Cellulase, lignin, agriculture waste, biodegradation.

The Effect of Plant Growth Promoting Rhizobacteria (PGPR) on Germination and Seedling Growth of Sorghum bicolor L. Moench

Germination is the first important step of the plant growth in the land. The germination and growth of sorghum in marginal land can be optimized by inoculating with PGPR (inoculants), hydrogel and CMC (carriers). The aim of the research was to evaluate the response of germination and seedling growth of sorghum using PGPR inoculation with hydrogel and CMC as carriers (in vitro) and pots containing sterile sand (in vivo). The experiment used PGPR (Azospirillum lipoferum 1103D, Azotobacter chroococcum 4103D, and Bacillus sp. 3D), and hydrogels as the reserve water, as well as carboxymethyl cellulose (CMC) as the adhesive media. The results showed that the combination of PGPR-mix (Azospirillum, Azotobacter, Bacillus) with hydrogels as bio-organic fertilizer and CMC as carriers has promoted the growth of the roots, shoots and vigour index of in vitro sorghum germination, as well as increased the root length, shoot length and total dry weight of sorghum seedlings in pots containing sterile sand. The best result of in vitro experiment (root length = 8.67 cm; shoot length = 12.6 cm; and vigor index = 2127.00) was obtained by sorghum seed inoculated with single PGPR inoculant (A. lipoferum) with carrier of CMC. The root length, shoot length and total dry weight of the highest sorghum seedlings were obtained by PGPR-mix inoculants without carriers (46.5 cm, 12 cm, and 0.477 g), PGPR-mix with carrier of CMC (48.67 cm, 15.67 cm, and 0.431 g), and PGPR-mix with carrier of hydrogel (48.67 cm, 15 cm, and 0.430 g).