Application Of Microbial Inoculants Research Articles

Effects of Microbial Inoculants Combined with Chemical Fertilizer on Growth and Soil Nutrient Dynamics of Timothy (Phleum pratense L.)

Microbial inoculants derived from plant growth-promoting rhizobacteria (PGPR) offer eco-friendly alternatives to traditional chemical fertilizers, maintaining microbiota balance in agricultural systems. However, limited research has explored the combined effects of microbial inoculants and chemical fertilizers on crop growth and soil properties. In this study, we investigated seven fertilizer combinations, ranging from no fertilizer to various proportions of chemical fertilizers with microbial inoculants, on timothy (Phleum pratense L.) growth, chlorophyll content, soil properties, enzyme activities, and soil microbial communities. A randomized block design was employed to analyze these effects. The results indicate that the combination of 85% chemical fertilizer with microbial inoculants significantly increased timothy yield and chlorophyll content. In addition, a reduction to 55% chemical fertilizer in conjunction with microbial inoculants resulted in comparable yield to that of 100% fertilizer with no inoculants. The microbial inoculants treatments notably elevated soil catalase, urease, acid phosphatase, and invertase activities, along with soil fast-acting nutrient content. The sequencing results show that the abundance of beneficial bacteria increased, while that of fungi decreased in the soil rhizosphere after the application of microbial inoculants. This study underscored the potential of microbial inoculants combined with reductions in chemical fertilizers to enhance soil microbiology, nutrient content, and beneficial microbial abundance while suppressing pathogenic fungi, thereby promoting timothy growth and yield. These findings provide a theoretical basis for the use of microbial inoculants in sustainable agricultural practices, providing valuable insights for optimizing microbial inoculants and chemical fertilizer formulations to mitigate the sustainability challenges posed by conventional fertilizers.

Bioremediation of toxic metals and Limnocharis flava (L.) Buchenau growth in acidic contaminated soil supported by microbial inoculants

An in situ pot experiment was carried out in a net house to study the combined effect of a mixture of microbial inoculants at different levels of 0, 1, 1.5, 2, 2.5, and 3 g/kg in dry soil with Limnocharis flava (L.) Buchenau plants grown on agricultural land contaminated with lead (Pb) and cadmium (Cd). The results showed that plant growth, fresh inflorescence yields and accumulation of Pb and Cd in L. flava plant parts gradually increased with increasing levels of the applied microbial inoculants in the contaminated soil. The highest total content of Pb and Cd was determined in roots (6.63–32.46 and 0.12–0.72 mg/kg dw), followed by stems and leaves (1.20–3.08 and 0.04–0.09 mg/kg dw) and inflorescence parts (0.012–0.120 and 0.011–0.065 mg/kg fw). The application of microbial inoculants in the range of 2–2.5 g/kg dry soil stimulated the growth and fresh inflorescence yields of L. flava, increased the accumulation of Pb and Cd in inedible parts, ensuring safety for edible parts of L. flava plants in accordance with QCVN8-2:2011/BYT and FAO/WHO regulations. The results of the present work indicate that the flexibility of Pb and Cd can be increased when soil is mixed with microbial inoculants. Long term ex situ experiments are needed to investigate the impact of microbial inoculants mixed with biochar, minerals and nanomaterial for phytomanagement of soil contaminated with multiple metals.

Identification of Native Root Nodulating Bacteria from Mucuna (Mucuna pruriens L.)

Background: Mucuna (Mucuna pruriens L.) is an annual herbaceous climber, grown as a medicinal, green manure, cover and smothering crop. The mucuna seeds contains L-DOPA (L-3, 4 dihydroxy phenylalanine), a non-protein amino acid, extensively used for Parkinson and hypertensive drug. Injudicious application of nitrogenous fertilizers leads to deterioration of soil quality which results into loss of crop yield and quality. The application of microbial inoculant containing efficient native rhizobia enhances the nodular properties, N2-fixation and soil quality. Therefore, Rhizobium strain associated with mucuna was isolated, biochemically characterized and identified. The 16SrRNA sequencing revealed that Sinnorhizobium mililoti, a gram negative symbiotic nitrogen fixing bacteria is present in root nodules of mucuna. Methods: Root nodules were extracted from mucuna grown at ICAR- Krishi Vigyan Kendra, Doddaballapura Taluk, Bengaluru Rural District, Karnataka, then cultured, screened and characterized in the laboratory. The 16SrRNA sequencing and phylogenetic analysis was done to identify the native rhizobial strain. Result: Identification of native root nodulating bacteria through 16SrRNA sequencing concluded that Sinnorhizobium mililoti strain associated with the root nodules of Mucuna (Mucuna pruriens L.).

Effect of Microbial Consortia Inoculation and Chemical Fertilizers on Growth Parameter and Nodulation of Soybean (Glycine max L. merill.) and Chickpea (Cicer arietinum L.)

Microbial consortia inoculation and chemical fertilizers significantly impact plant growth parameters. Microbial consortia contribute to soil health by enhancing nutrient availability and promoting plant growth, while chemical fertilizers provide essential nutrients. In this study, an Field Experiment was conducted during two successive years in Kharif and Rabi 2020-21 and 2021-22 consecutively on effect of microbial consortia inoculation and chemical fertilizers on productivity and soil properties in soybean chickpea sequence on vertisol at research farm of department soil science and agricultural chemistry Vasantrao Naik Marathwada Agricultural University, Parbhani (MAH) India. The Soil of experimental site was classified as vertisol (Typic Haplustert) dominant montmorillonite type with kaollinite and illite mineral alkaline in reaction. Experimental treatments consist of four levels of laboratory evaluated microbial cultures (Bradyrhizobium, Mesorhizobium, Bacillus megaterium, Pseudomonas striata, Thiobacillus thioxidant) and uninoculated control and four levels of chemical fertilizers (100 % RDF, 75 % RDF, 50 % RDF and Control i.e. (without fertilizers)). Seed treatment of soybean and chickpea was done with microbial consortia immediate before sowing and chemical fertilizers were applied at the time of sowing as per treatments. The results revealed that the application of microbial inoculants with chemical fertilizers showed significant effect on biometric attributes and nodulation of soybean and chickpea. The microbial consortia Rhizobium spp.+ Pseudomonas striata inoculation has highest plant height, shoot weight, root length, number of nodule, fresh weight of nodules, and dry weight of noduels in both crops as compared to uninoculated control. However, the application of chemical fertilizer i.e. N,P and K 100% RDF obviously increased the height, shoot weight, number of nodulation, and fresh weight of nodules in respect of both soybean and chickpea crops. The chemical fetilizers N,P and K are applied in the form of Urea, single super phosphate and muriate of potash respectively.

Effects of straw-returning combined with application of microbial inoculants on soil aggregates and related nutrients

We analyzed the particle size distribution of soil aggregates in 0-20 and 20-40 cm soil layers of rice-wheat rotation field based on a field plot test with two treatments, conventional straw returning (CK) and straw returning with the addition of straw decomposition promoting microbial inoculants (IT). We evaluated the water stability indices of soil aggregates (the number of soil water stable large aggregates R0.25, the average weight diameter MWD, and the geometric average diameter GMD), and measured the contents of soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) in the soil aggregates of ＜0.053, 0.053-0.25, 0.25-1, ＞1 mm. The results showed that: 1) The number of aggregates ＜0.053, 0.053-0.25, ＞0.25 mm in the 0-20 and 20-40 cm soil layers under IT decreased by 10.0% and 6.8%, increased by 3.0% and 5.7%, and 17.9% and 26.1% compared with CK, respectively. IT effectively increased R0.25, MWD, and GMD by 26.4%, 20.0%, 18.2% and 18.2%, 10.5%, 10.0% in 0-20 and 20-40 cm soil, respectively. 2) Compared to CK, the TP content of 0.25-1 mm aggregates in 0-20 and 20-40 cm soil under IT was significantly increased by 40.3% and 37.5%, respectively, without difference in TN and SOC contents. There was no significant difference in nutrient contents of the other aggregates between the treatments. The contents of SOC and TN in large aggregates (>0.25 mm) were higher than those in silty aggregates (<0.053 mm). Compared to CK, the cumulative contribution rates of SOC, TN and TP of <0.053 mm aggregates under IT were decreased in two soil layers. There was no significant difference in the nutrient cumulative contribution rates of 0.053-0.25 mm aggregates between treatments. The cumulative contribution rates of SOC, TN, and TP of large aggregates (>0.25 mm) under IT were 32.1%, 19.6%, 52.8% and 22.8%, 11.8%, 42.9% higher than those under CK in 0-20 and 20-40 cm soils, respectively. 3) The number of <0.053 mm aggregates was significantly negatively correlated with SOC and TP contents, while that of 0.053-0.25 mm aggregates was negatively correlated with nutrient content. The number of large aggregates (>0.25 mm) were significantly positively correlated with SOC, TN, and TP contents. In conclusion, straw returning with microbial-inoculant addition could promote the formation of soil macroaggregates (>0.25 mm), and improve the water stability of soil aggregates, increasing nutrient contents in soil macroaggregates, with the nutrients transferring from silty aggregates to macroaggregates.

Rhizobiome Transplantation: A Novel Strategy beyond Single-Strain/Consortium Inoculation for Crop Improvement.

The growing human population has a greater demand for food; however, the care and preservation of nature as well as its resources must be considered when fulfilling this demand. An alternative employed in recent decades is the use and application of microbial inoculants, either individually or in consortium. The transplantation of rhizospheric microbiomes (rhizobiome) recently emerged as an additional proposal to protect crops from pathogens. In this review, rhizobiome transplantation was analyzed as an ecological alternative for increasing plant protection and crop production. The differences between single-strain/species inoculation and dual or consortium application were compared. Furthermore, the feasibility of the transplantation of other associated micro-communities, including phyllosphere and endosphere microbiomes, were evaluated. The current and future challenges surrounding rhizobiome transplantation were additionally discussed. In conclusion, rhizobiome transplantation emerges as an attractive alternative that goes beyond single/group inoculation of microbial agents; however, there is still a long way ahead before it can be applied in large-scale agriculture.

Effects of microbial inoculants on agronomic characters, physicochemical properties and nutritional qualities of lettuce and celery in hydroponic cultivation

Leafy vegetables are rich in nutrients such as vitamins and dietary fiber, which are essential to people's daily diet. Microbial inoculants play an important role in promoting plant growth and nutritional qualities. In this study, two combined microbial inoculants of Arthrobacter pascens BUAYN-122 and Bacillus subtilis BUABN-01 were applied in the hydroponic system for lettuce (Lactuca sativa L.) and celery (Apium graveolens L.) cultivation. After harvesting, the agronomic characters, physicochemical properties and nutritional qualities of lettuce and celery were determined. The paper aimed to evaluate the application of the combined microbial inoculants on hydroponic cultivation of lettuce and celery. The results showed that the microbial inoculants significantly improved the aboveground fresh weight, underground fresh weight, root length, leaf length and leaf number of both lettuce and celery. The root dehydrogenase activity, net photosynthetic rate, stomatal conductance and total chlorophyll content of the two vegetables were significantly improved, indicating that the microbial inoculation can promote the root nutrient uptake and leaf photosynthesis. Furthermore, the microbial inoculants could significantly increase the total protein, vitamin C and total phenol contents of lettuce and celery, anthocyanin and total flavonoid contents of lettuce, and soluble sugar and total dietary fiber contents of celery. The results of this study confirmed that the application of microbial inoculants in hydroponics systems can promote the yield and the quality of lettuce and celery.

The Application of endophytic halotolerant bacteria in modulating the development of maize seedlings under salinity

Salinity stress has negative effects on plants physiologically as well as lowering productivity. Application of microbial inoculant as seed treatment is one of the bio-techniques that have proved to be efficient in enhancing salinity resilience in agriculture, especially for seedling development. This study aims to determine the effect of inoculation of halotolerant bacteria consortium on the development of maize seedlings under saline stress. The experiment used four different bacterial consortia namely B5 (two species of phosphate solubilizing bacteria); B6 (phosphate solubilizing bacteria, and ACC deaminase producing bacteria); B7 (phosphate solubilizing bacteria and nitrogen-fixing bacteria) and B9 (phosphate solubilizing bacteria, ACC deaminase producing bacteria and nitrogen-fixing bacteria). The salinity stress was conducted by adding NaCl with a concentration of 0, 50, 100, and 150 mM to the Hoagland nutrient solution as a germination medium. The inoculation bacteria increased the root length, root number, shoot length, fresh weight, and chlorophyll content of Pioneer maize seedling up to 25% at salinity stress treatment 150 mM NaCl. The highest increase in seedlings growth parameters was observed on seedlings inoculated by B5, B7, and B9 under a salinity treatment of 150 mM.

Natural variation of Macrocystis pyrifera gametophyte germplasm culture microbiomes and applications for improving yield in offshore farms.

With national interest in seaweed-based biofuels as a sustainable alternative to fossil fuels, there is a need for tools that produce high-yield seaweed cultivars and increase the efficiency of offshore farms. Several agricultural studies have demonstrated that the application of microbial inoculants at an early life stage can improve crop yield, and there is an opportunity to use similar techniques in seaweed aquaculture. However, there is a critical knowledge gap regarding host-microbiome associations of macroalgae gametophytes in germplasm cultures. Here, we investigate the microbial community of Macrocystis pyrifera gametophyte germplasm cultures that were used to cultivate an offshore farm in Santa Barbara, California and identify key taxa correlated with increased biomass of mature sporophytes. This work provides a valuable knowledge base for the development of microbial inoculants that produce high-biomass M. pyrifera cultivars to ultimately be used as biofuel feedstocks.

A Comparative Analysis of Microbe-Based Technologies Developed at ICAR-NBAIM Against Erysiphe necator Causing Powdery Mildew Disease in Grapes (Vitis vinifera L.).

Globally, Erysiphe necator causing powdery mildew disease in grapevines (Vitis vinifera L.) is the second most important endemic disease, causing huge economic losses every year. At present, the management of powdery mildew in grapes is largely dependent upon the use of chemical fungicides. Grapes are being considered as one of the high pesticide-demanding crops. Looking at the residual impact of toxic chemical pesticides on the environment, animal, and human health, microbe-based strategies for control of powdery mildew is an emerging technique. It offers an environment-friendly, residue-free, and effective yet safer approach to control powdery mildew disease in grapes. The mode of action is relatively diverse as well as specific to different pathosystems. Hence, the aim of this study was to evaluate the microbe-based technologies, i.e., Eco-pesticide®, Bio-Pulse®, and Bio-Care 24® developed at the Plant-Microbe Interaction and Rhizosphere Biology Lab, ICAR-NBAIM, Kushmaur, against grape powdery mildew and to integrate these technologies with a safer fungicide (sulfur) to achieve better disease control under organic systems of viticulture. The experiments were conducted at four different locations, namely, the vineyards of ICAR-NRCG, Rajya Draksha Bagayatdar Sangh (MRDBS), and two farmers' fields at Narayangaon and Junnar in the Pune district of Maharashtra. A significantly lower percent disease index (PDI) was recorded on the leaves of grape plants treated with Eco-Pesticide®/sulfur (22.37) followed by Bio-Pulse®/sulfur (22.62) and Bio-Care 24®/sulfur (24.62) at NRCG. A similar trend was observed with the lowest PDI on bunches of Eco-pesticide®/sulfur-treated plants (24.71) followed by Bio-Pulse®/sulfur (24.94) and Bio-Care®/sulfur (26.77). The application of microbial inoculants singly or in combination with sulfur has a significant positive impact on the qualitative parameters such as pH, total soluble solids (TSS), acidity, berry diameter, and berry length of the grapes at different locations. Among all the treatments, the Bio-Pulse®/sulfur treatment showed the highest yield per vine (15.02 kg), which was on par with the treatment Eco-Pesticide®/sulfur (14.94). When compared with the yield obtained from the untreated control, 2.5 to 3 times more yield was recorded in the plants treated with either of the biopesticides used in combination with sulfur. Even in the case of individual inoculation, the yield per vine was approximately two times higher than the untreated control and water-treated plants across the test locations. Results suggested that microbial technologies not only protect grapevines from powdery mildew but also enhance the quality parameters with increased yield across the test locations.

Effects of different types of microbial inoculants on available nitrogen and phosphorus, soil microbial community, and wheat growth in high-P soil.

Irrational application of chemical fertilizers causes soil nutrient imbalance, reduced microbial diversity, soil diseases, and other soil quality problems and is one of the main sources of non-point pollution. The application of microbial inoculant (MI) can improve the soil environment and crop growth to reduce problems caused by irrational application of chemical fertilizers. Field experiments were carried out in high-phosphorus soils to study the effects of the addition of various MIs combined with chemical fertilizers on soil properties, wheat growth, and soil microbial composition and structure. The MIs consisted of one fungal agent: Trichoderma compound agent (TC) and five bacterial agents, namely soil remediation agent (SR), anti-repeat microbial agent (AM), microbial agent (MA), plant growth-promoting rhizobacteria (PG), and biological fertilizer agent (BF). The wheat yield increased by 15.2-33.4% with the addition of MIs, and PG with Bacillus subtilis as the core microorganism had the most obvious effect on increasing the production (p < 0.05). For the entire growth period of wheat, all MIs applied significantly increased the available nitrogen (AN) (p < 0.05) but did not significantly affect the available phosphorus (AP). BF has the best effect on increasing AN in the soil. The 16S rRNA sequencing results indicated that the dominant phyla of soil bacteria were Proteobacteria, Acidobacteria, Bacteroidetes, Actinobacteria, and Verrucomicrobia. The addition of MIs increased the relative abundance of Acidobacteria, Actinobacteria, Chloroflexi and decreased Proteobacteria and Bacteroidetes. The diversity of soil bacterial community (Chao1) was significantly higher in the soil added with TC than that added with BF (p < 0.05). All bacterial agents significantly enriched various genera (p < 0.05), while the fungal agent (TC) did not enrich the genera significantly. pH and AN, but not TP, were closely related to the dominant bacteria phylum in high-P soil. The application of MIs improved AN in soil, increased the wheat yield, and changed the relative abundance of the soil dominant phylum, and these changes were closely related to the type of MIs. The results provide a scientific basis for rational use of different types of MIs in high-P soil.

Effects of cutting stage and bacterial inoculant on quality of the red clover silage

In this paper, the influence of cut at two maturity stages (the beginning of the flowering stage and mid bloom stage and bacterial inoculant ?Silko za lucerku? (contains Lactobacillus plantarum and Pediococcus spp.) on the quality of red clover silage were presented. The commercial cultivar Nada selected at the Bc Institute in Zagreb was used for investigation. The silage was examined in mini-silos (glass jars of 1.5 l volume with plastic fermentation valve) in the laboratory. The chemical composition, energy and fermentation characteristics of silages were analyzed 90 days after ensiling. The values of dry matter, acid (ADF) and neutral detergent fibre (NDF), lactic acid and pH were significantly lower, while the crude protein content, total digestible nutrients (TDN), relative feed value (RFV), ammonia nitrogen in total nitrogen (NH3-N/TN), acetic and butyric acids were significantly higher in the first cutting stage. The inoculation with inoculant ?Silko za lucerku? improved the chemical, energy and fermentation parameters of silages. Inoculant-treated silage had lower contents of ADF, NDF, NH3-N/TN, acetic and butyric acids and pH, and higher contents of dry matter, crude protein, TDN, RFV and lactic acid than control. Accordingly, timely cutting stage and application of microbial inoculant can contribute to a lesser loss of nutritional value of the forage and promote silage quality.

Screening and application of microbial inoculants for sludge composting in expressway service area of northwest China

Taking sludge in northwest China’s expressway service area as the research object, four dominant strains, including Bordetella sp. M05, Ochrobactrum sp. M06, Bacillus subtilis M07 and Staphylococcus sciuri M09, were obtained through specific screening. These microbes were prepared into inoculants and effectively promoted sludge composting. The time for the fermentation temperature of the composting process to reach 50°C was 3 days earlier than that of the control group. The high temperature (&gt;50°C) lasted for 12 days and the highest temperature reached 63.5°C. After composting, the product was dark in color, free from odor, and the contents of organic matter, nitrogen, phosphorus and potassium increased by 44.1%, 125.9%, 311.1% and 269.2%, respectively, which made the composted product meet standards of GB/T 23486–2009 Sludge for Landscaping.

Use of microbial inoculants during cultivation maintain the physiological, nutritional and technological quality of fresh-cut romaine lettuce

Nutrition-sensitive agriculture is a novel concept in the agri-food system, which considers the implementation of techniques able to guarantee the nutritional value of the produce, the sustainability of the production and, at the same time, to reduce the ecological impact of agricultural practices. These principles can be also introduced in the fresh-cut market with the aim of maintaining the produce quality during shelf life. In this context, the use of bio-based products is rapidly increasing for improving economic and environmental sustainability of cropping systems during cultivation and shelf life. The aim of this work was to evaluate the effects of three different bacterial-based formulations (Paenibacillus pasadenensis, Bacillus amyloliquefaciens, Pseudomonas syringae) applied during romaine lettuce cultivation by monitoring the changes of several quality indexes at harvest and during storage. Results showed that the application of microbial inoculants during romaine lettuce cultivation contributed to the maintenance of nutritional, functional and perceived quality attributes of leaves during shelf life. The microbial inoculants prevented the development of postharvest fungal pathogen B. cinerea. Moreover, the study evidenced different modes of action of the different inoculants and, in the case of Pseudomonas syringae 260-02 application, a direct involvement of ascorbic acid-mediated antioxidant mechanisms was observed.

Restoring degraded microbiome function with self-assembled communities.

The natural microbial functions of many soils are severely degraded. Current state-of-the-art technology to restore these functions is through the isolation, screening, formulation and application of microbial inoculants and synthetic consortia. These approaches have inconsistent success, in part due to the incompatibility between the biofertilizer, crop, climate, existing soil microbiome and physicochemical characteristics of the soils. Here, we review the current state of the art in biofertilization and identify two key deficiencies in current strategies: the difficulty in designing complex multispecies biofertilizers and the bottleneck in scaling the production of complex multispecies biofertilizers. To address the challenge of producing scalable, multispecies biofertilizers, we propose to merge ecological theory with bioprocess engineering to produce 'self-assembled communities' enriched for particular functional guilds and adapted to a target soil and host plant. Using the nitrogen problem as an anchor, we review relevant ecology (microbial, plant and environmental), as well as reactor design strategies and operational parameters for the production of functionally enriched self-assembled communities. The use of self-assembled communities for biofertilization addresses two major hurdles in microbiome engineering: the importance of enriching microbes indigenous to (and targeted for) a specific environment and the recognized potential benefits of microbial consortia over isolates (e.g. functional redundancy). The proposed community enrichment model could also be instrumental for other microbial functions such as phosphorus solubilization, plant growth promotion or disease suppression.

Combined effects of chemical fertilization and microbial inoculant on nutrient use efficiency and soil quality indicators

Microbial inoculant based on beneficial bacteria is a complementary management tool to increase vegetable production. However, its integration with chemical fertilization has been poorly studied. The present study evaluated the effects of microbial inoculant separately and in combination with chemical fertilization on lettuce under greenhouse conditions. An experiment was performed in pots using a completely randomized design. The microbial inoculant was applied at three fertilization levels. Soil response evaluated variables were: available N and P, total soil bacteria, soil enzymatic activities, and N leaching. Agronomic variables measured were: aerial biomass, chlorophyll content, and nutrient foliar contents. Microbial inoculant had a significant impact on soil total bacteria concentration. The application of reduced chemical fertilization and microbial inoculant had a similar effect in terms of soil nutrient availability and soil enzymatic activities as the complete fertilization. Nitrogen leaching was strongly dependent on chemical fertilization rate. Treatment application decreased chlorophyll concentration compared to the control. The application of microbial inoculant and chemical fertilization increased foliar N and P contents improving their uptake. The combined addition of microbial inoculant with chemical fertilization increases the bacteria concentration without altering enzymatic activities, maintaining similar soil nutrient levels and improving N and P uptake in lettuce. Future studies could be performed in lettuce to determine the impact under different growth stages and different soil conditions.

Integrated nutrient management in cowpea with the application of microbial inoculants

Indian livestock sector is one of the largest in the world and fodder is vital component of profitable animal production. Legumes are one of the predominant crops of mixed crop-livestock systems providing highly nutritious fodder as well as contributing soil fertility. Nevertheless, the fodder production and quality in the country is not adequate to meet out the prerequisite of growing livestock population. Optimum nutrition is thus required for getting the maximum forage yield and quality. Nutrient Management is propounded as a promising strategy for addressing such challenges. Microbial inoculants being an important component of integrated nutrient management are eco-friendly and economical sources of nutrient. The benefit of combining organic and inorganic sources of nutrients in integrated nutrient management has proved superior to the use of each component individually. Thus, the present review will feature the need of integrated nutrient management, plant growth promoting rhizobacteria as microbial inoculants, role of microbial inoculants in integrated nutrient management of various leguminous crops and emerging examples of integrated nutrient management in cowpea. The realization attained from literature assessed herein will further help to understand the role of microbial inoculants in integrated nutrient management.

Effect of microbial inoculants on fermentation quality and aerobic stability of sweet potato vine silage.

ObjectiveThis study was conducted to evaluate the effect of homo or hetero fermentative inoculants on fermentation quality and aerobic stability of sweet potato vine (SPV) silage containing Italian ryegrass hay as moisture absorbent.MethodsThe SPV was harvested at 15% dry matter, mixed with Italian ryegrass hay at 1:1 ratio on a fresh weight basis, and chopped to 3 to 5 cm length. After then, the chopped forage mixture was ensiled into 20-L mini silos in quadruplicate for 7, 48, and 100 days after application of microbial inoculants at 1.2×105 colony forming units (cfu)/g of forage following: no inoculant (CON), Lactobacillus plantarum as a homo fermentative (LP), Lactobacillus buchneri as a hetero fermentative (LB), and mixture of LP and LB at 1:1 ratio as a combo fermentative (MIX).ResultsThe LP and MIX silages had lowest pH (p<0.001) on 7 and 48 days, while MIX and CON silages had greatest lactate concentrations (p<0.05) on 7 and 48 days, respectively. Acetate concentrations were highest (p<0.01) in LB and MIX silages on 7 days, and in LB silage on 48 days, while lactate to acetate ratios were lowest (p<0.001) in LB silages. The chemical compositions and nutrient digestibility of silage ensiled for 100 days was not affected by inoculants. On 100 days of ensiling, LB silage had lowest (p<0.01) lactate concentration and lactate to acetate ratio, but highest acetate concentration. Aerobic stability was highest (p<0.001) in LB silage followed in MIX silage. On contrast, LB silage had lowest (p<0.05) lactic acid bacteria and mold.ConclusionThe results indicated that application of LB solely had a better effect on aerobic stability than not only LP, but also MIX. However, LP application did not show beneficial effects from the viewpoints of fermentation quality and aerobic stability compared to CON.

Growth response of litchi to arbuscular mycorrhizal co-inoculation with Trichoderma viride, Azotobacter chroococcum and Bacillus megatarium

To examine the microbial cooperation in the rhizosphere as reflected in terms of growth response of young trees (< 5 years) of litchi (Litchi chinensis), field experiments were conducted during 2012–2015 at ICAR-National Research Centre on Litchi, Muzaffarpur. The microbial inoculants consisting of arbuscular mycorrhizal fungi (AMF), Trichoderma viride (TR), Azotobacter chroococcum (AZ) and Bacillus megatarium (BM) along with their combinations were compared with application of recommended dose of fertilizers (RDF). The data revealed that AMF in combination with other microbial inoculants resulted in significantly higher increase in growth parameters viz., tree height, tree girth, tree spread, leaf area and leaf chlorophyll content. Growth response produced by combination of AMF + AZ + TR were the best or statistically at par (p = 0.05) with AZ + TR for most of the parameters. Similarly, significant higher root biomass, volume and density were observed with application of microbial inoculants. While AMF positively influenced the increase in population of T. viride and A. chroococcum, it negatively influenced the increase of population of B. megatarium which corroborated with the observed growth response of litchi trees. Thus, the studies not only confirmed the positive response of AMF and A. chroococcum reported in different crop species but also demonstrated a synergistic response of AMF with A. chroococcum and T. viride in litchi under field conditions.

Improving Crop Yield and Nutrient Use Efficiency via Biofertilization—A Global Meta-analysis

The application of microbial inoculants (biofertilizers) is a promising technology for future sustainable farming systems in view of rapidly decreasing phosphorus stocks and the need to more efficiently use available nitrogen (N). Various microbial taxa are currently used as biofertilizers, based on their capacity to access nutrients from fertilizers and soil stocks, to fix atmospheric nitrogen, to improve water uptake or to act as biocontrol agents. Despite the existence of a considerable knowledge on effects of specific taxa of biofertilizers, a comprehensive quantitative assessment of the performance of biofertilizers with different traits such as phosphorus solubilization and N fixation applied to various crops at a global scale is missing. We conducted a meta-analysis to quantify benefits of biofertilizers in terms of yield increase, nitrogen and phosphorus use efficiency, based on 171 peer reviewed publications that met eligibility criteria. Major findings are: (i) the superiority of biofertilizer performance in dry climates over other climatic regions (yield response: dry climate +20.0 ± 1.7%, tropical climate +14.9 ± 1.2%, oceanic climate +10.0 ± 3.7%, continental climate +8.5 ± 2.4%); (ii) meta-regression analyses revealed that yield response due to biofertilizer application was generally small at low soil P levels; efficacy increased along higher soil P levels in the order arbuscular mycorrhizal fungi (AMF), P solubilizers, and N fixers; (iii) meta-regressions showed that the success of inoculation with AMF was greater at low organic matter content and at neutral pH. Our comprehensive analysis provides a basis and guidance for proper choice and application of biofertilizers.