Microbial Inoculants Research Articles

Effect of Exogenous Organic Matter on Phosphorus Forms in Middle-High Fertility Cinnamon Soil.

To slow down the chemical fixation of phosphate fertilizer, reduce the risk of active phosphorus leaching, stimulate the inherent phosphorus resource activity of soil, and improve phosphorus supply capacity. This study utilized a combination of field experiments and indoor chemical analysis. Six types of exogenous organic matter (fulvic acid, biochar, compound microbial fertilizer, high-energy microbial inoculum, pig manure-vermicompost, cow manure-vermicompost) were added based on conventional fertilization. The experiment was conducted under the wheat-maize rotation system in the Huang-Huai-Hai region. Compared with control (CK) without exogenous organic matter (EOM), all the other treatments with EOM had an enhancing effect on the available phosphorus of the cultivated soil. During the maize harvest, the combined application of biochar, pig manure-vermicompost and cow manure-vermicompost treatment significantly increased the content of available phosphorus in 0-20 cm soil by 45.87-56.59% compared with CK. The combined application of fulvic acid, biochar, pig manure-vermicompost and cow manure-vermicompost treatment significantly increased the content of Ca2-P in 0-20 cm soil by 34.04-65.14%. The content of Ca10-P in each treatment with EOM exhibited a lower level compared to CK. EOM could slow down the fixation of phosphorus to some degree. Correlation analysis revealed significant associations between Ca2-P, Ca8-P, Al-P, Fe-P, neutral phosphatase activity, acid phosphatase activity, and the available phosphorus content in the soil. The combined application of fulvic acid, biochar, and cow manure-vermicompost could enhance the activity of neutral and acid phosphatase in topsoil to a certain extent, thereby facilitating the conversion of phosphorus into highly available Ca2-P. EOM could enhance the soil phosphorus availability and decelerate the conversion of soil phosphorus into O-P and Ca10-P forms with low availability. Among all treatments, biochar exhibited the most pronounced efficiency in mitigating phosphorus leaching downward. All the EOMs had the potential to enhance the conversion of phosphorus into soluble phosphorus (Ca2-P), thereby mitigating the chemical fixation of soil phosphorus and ameliorating non-point source pollution caused by phosphorus. EOM enhanced the activity of neutral and acid phosphatase, which was beneficial to the conversion of organic phosphorus to inorganic phosphorus and increasing the content of available phosphorus. All EOMs had good effects on the retention of soil effective phosphorus, among which biochar had the best effect on retaining effective phosphorus in the tillage layer and blocking phosphorus leaching downward.

Exploring polyphosphates in soil: presence, extractability, and contribution to microbial biomass phosphorus

Polyphosphates (Poly-P) are known to fulfil several important physiological functions. Many microorganisms can accumulate large amounts of Poly-P in their biomass. Regardless of these facts, systematic research on Poly-P in soil is missing, probably due to the absence of any method of direct Poly-P quantification. In this study, we attempted to unequivocally prove the presence of Poly-P in the biomass of soil microorganisms and quantify their extractability and contribution to microbial biomass phosphorus. To do so, we combined several approaches that can indicate Poly-P presence in soil microbial biomass indirectly, i.e. growth of soil inoculum on media without phosphorus, associated with measurement of changes in the microbial biomass stoichiometry, and the colour of the microbial suspension stained by the Neisser method. All soil microbial communities exhibited growth on media without phosphorus. As the growth on this media depleted Poly-P content, the biomass carbon to phosphorus and nitrogen to phosphorus ratio increased and the colour of the microbial suspension stained by the Neisser method changed predictively. The associated Poly-P addition experiment indicated that the recovery of added Poly-P from soil in form of soluble reactive phosphorus in sodium bicarbonate extract may reach up to 93% mainly due to abiotic depolymerization. Using a simple stoichiometric model applied to measured data, we calculated that the Poly-P content of microbial biomass in our soils may be up to 45 or 70% of total microbial biomass phosphorus depending on the assumptions applied regarding parameter values. We discuss the magnitude of error associated with the measurement of soil microbial phosphorus due to the high extractability of Poly-P.

Enhancing nutrient uptake and grapefruit (Citrus paradisi) growth through soil application of beneficial bacteria (Bacillus spp.)

The term plant growth-promoting rhizobacteria (PGPR) refers to a root-associated bacteria that possesses several benefits for soil and the plant. The increasing demand for sustainable food production necessitates a shift towards agricultural practices that mitigate adverse environmental impacts. Excessive use of chemical fertilizers and pesticides has raised concerns, prompting a surge of interest in harnessing the potential of beneficial soil microorganisms, particularly plant growth-promoting rhizobacteria. This study explores the impact of soil inoculation with PGPR treatments on grapefruit seedlings, including a commercial strain of Bacillus velezensis, a fresh inoculum of Bacillus amyloliquefaciens, a mixture of three selected citrus endophytic Bacillus spp. isolates, inorganic fertilizers, and combinations thereof. The aim was to test their ability to enhance growth and nutrient uptake reducing the input of chemical fertilization. Results indicated that the combination of Bacillus velezensis and inorganic fertilization significantly improved soil nutrient availability and enhanced plant growth, surpassing both negative (water) and positive (inorganic fertilization) controls. Shoot and root system biomass showed significant increases from Bacillus velezensis plus inorganic fertilization compared to other treatments. These findings provide insights into management methods that can reduce chemical inputs while promoting plant productivity. The demonstrated benefits of PGPR on grapefruit seedlings highlight a promising approach for future research and applications in sustainable citrus cultivation.

Metagenomics profiling of the microbial community and functional differences in solid-state fermentation vinegar starter (seed Pei) from different Chinese regions.

The starter used in solid-state fermentation (SSF) vinegar, known as seed Pei is a microbial inoculant from the previous batch that is utilized during the acetic acid fermentation stage. The seed Pei, which has a notable impact on vinegar fermentation and flavor, is under-researched with comparative studies on microorganisms. Herein metagenomics was employed to reveal the microbes and their potential metabolic functions of four seed Pei from three regions in China. The predominant microbial taxa in all four starters were bacteria, followed by viruses, eukaryotes, and archaea, with Lactobacillus sp. or Acetobacter sp. as main functional taxa. The seed Pei used in Shanxi aged vinegar (SAV) and Sichuan bran vinegar (SBV) exhibited a higher similarity in microbial composition and distribution of functional genes, while those used in two Zhenjiang aromatic vinegar (ZAV) differed significantly. Redundancy analysis (RDA) of physicochemical factors and microbial communities indicated that moisture content, pH, and reducing sugar content are significant factors influencing microbial distribution. Moreover, seven metagenome-assembled genomes (MAGs) that could potentially represent novel species were identified. There are distinctions in the microbiome and functional genes among different seed Pei. The vinegar starters were rich in genes related to carbohydrate metabolism. This research provides a new perspective on formulating vinegar fermentation starters and developing commercial fermentation agents for vinegar production.

Wheat straw and microbial inoculants have an additive effect on N2O emissions by changing microbial functional groups

AbstractStraw‐decomposing microbial inoculants (MIs) have been increasingly applied to straw‐amended soils. However, the interactive effects and underlying microbial mechanisms of straw and decomposing MIs on nitrous oxide (N2O) emissions remain unclear. Here, a pot experiment with an Aquic Inceptisol was conducted to determine soil N2O emissions and the abundance and composition of microbial functional genes under six amendments: wheat straw (W), Bacillus subtilis MI (B), Streptomyces rochei MI (S), a combination of straw and B. subtilis MI (WB), a combination of straw and S. rochei MI (WS), and a control without wheat straw or MI (C). Compared with the control, the amendments of straw, decomposing MIs, and their combinations decreased soil N2O emissions by 43%, 22–30%, and 46–60%, respectively. Mechanistically, the positive relationship between ammonia‐oxidizing bacteria (AOB) and soil potential nitrification rate (PNR), along with decreased AOB abundance (−36%) following straw and decomposing MI amendments, further suggested that AOB predominated soil nitrification and was responsible for the suppressed nitrification. In addition, straw amendment increased nirK gene abundance (by 48%) and potential denitrification rate (by 11%), while the increase in nosZI gene abundance (+25%) involved in N2O consumption contributed to the decrease in N2O emissions. Overall, the additive effect of straw and decomposing MIs on soil N2O emissions was associated with two amendment‐induced changes in the abundance and composition of AOB and straw‐stimulated the abundance of the nosZI gene. Our results revealed the potential for mitigating N2O emissions following the amendments of straw and MI by influencing soil N2O‐related microbial groups.

Seasonal and spatial characteristics of microbial community in intertidal wetlands: Aspect of microbial coupling

The simultaneous reductions of pollution and carbon are widely concerned in sewage treatment. Various microorganisms with synergies are existed in the intertidal wetlands, which have the potential to be the microbial inoculation used in sewage treatment. In this study, the microorganisms in the reed wetlands of the Yellow River Delta in four seasons and at four layers (0–5, 5–10, 10–15, and 15–20 cm) were investigated by high-throughput sequencing technology. The results showed that the majority of functional bacteria were denitrifying bacteria in the spring and summer. Spring was the primary season for hydrogen autotrophic denitrification, whereas summer was the primary season for sulfur autotrophic denitrification. A range of bacteria connected to one another by cable bacteria cooperated to finish the cycle of several elements in the 10–15 cm layer in autumn. A distinctive characteristic of functional bacteria was the anaerobic methane oxidation mediated by NC10 facultative bacteria in the 0–5 cm layer in winter. The results of this study provide an inspiration for utilizing suitable microbial inoculation to realize the simultaneous reductions of pollution and carbon in the future sewage treatment.

Effect of microbial inoculation on nitrogen transformation, nitrogen functional genes, and bacterial community during cotton straw composting

The effects of microbial agents on nitrogen (N) conversion during cotton straw composting remains unclear. In this study, inoculation increased the germination index and total nitrogen (TN) by 24–29 % and 7–10 g/kg, respectively. Inoculation enhanced the abundance of nifH, glnA, and amoA and reduced that of major denitrification genes (nirK, narG, and nirS). Inoculation not only produced high differences in the assembly process and strong community replacement but also weakened environmental constraints. Partial least squares path modelling demonstrated that enzyme activity and bacterial community were the main driving factors influencing TN. In addition, network analysis and the random forest model showed distinct changing patterns of bacterial communities after inoculation and identified keystone microorganisms in maintaining network complexity and synergy, as well as system function to promote nitrogen preservation. Findings provide a novel perspective on high-quality resource recovery of agricultural waste.

Trophic facilitation in forest restoration: Can Nothofagus trees use ectomycorrhizal fungi of the pioneer shrub Leptospermum?

The benefits of plant-to-plant facilitation in ecological restoration are well recognized, yet the potential for indirect trophic facilitation remains understudied. Nothofagus (southern beech; Nothofagaceae) is an iconic southern hemisphere tree genus that is frequently the focus of ecological restoration efforts. One aspect of Nothofagus ecology that may limit restoration success is the availability of appropriate ectomycorrhizal fungi. It has been suggested that pioneer dual-mycorrhizal hosts such as Leptospermum species (Myrtaceae) could facilitate Nothofagus establishment by providing fungal inoculum, but the capacity for Nothofagus to use Leptospermum ectomycorrhizal fungi is unknown. To investigate potential indirect facilitation, we conducted a common garden pot trial to determine if Nothofagus cliffortioides (mountain beech) can use symbionts from Leptospermum scoparium (mānuka) ectomycorrhizal communities. Nothofagus and Leptospermum seedlings were grown in monoculture and mixed pairs with reciprocal "home" and "away" soil fungal inoculum. ITS2 metabarcoding of eDNA from hyphal ingrowth bags revealed that Nothofagus and Leptospermum inoculum contained different ectomycorrhizal fungal communities, but that half of the common ectomycorrhizal taxa identified were found in both soil types, suggesting generalist fungi exist. Nothofagus was able to form associations with some fungal species originating from Leptospermum inoculum, however, probable spore contamination meant that the proportion of root colonization associated with those species was ambiguous. Root ectomycorrhizal colonization rates were positively associated with seedling biomass, and there was some evidence of a home soil inoculum advantage in Nothofagus, but these effects were minor. Additionally, we found evidence that home inoculum provides a protective advantage against drought stress for Leptospermum seedlings. Our results indicate the potential for using Leptospermum to promote Nothofagus establishment in restoration plantings and highlight the possible benefits of considering fungal mutualists in ecological restoration projects.

Synergistic interaction of Piriformospora indica and microbial inoculants on symbiotic potential, plant nutrition and productivity of chickpea (Cicer arietinum)

The present study was carried out during the winter season of 2011–12 and 2012–13 at Indian Agricultural Re search Institute, New Delhi, to evaluate the efficacy of microbial bioinoculants in chickpea (Cicer arietinum L.) us ing combinatorial approach. A group of microbial inoculants (Mesorhizobium ciceri). Phosphate-solubilizing micro organisms and plant growth-promoting rhizobacteria) in presence and absence of P fertilizer was used to testify its synergistic effect with Piriformospora indica on symbiotic traits, growth and yield of chickpea under field condi tions. Significant differences were observed with respect to symbiotic potential and other associated parameters with combined inoculation. Inoculation with Mesorhizobium ciceri enhanced nitrogenase activity and leghemoglobin content significantly over un-inoculated control. Significant improvement in N and P nutrition with combined inoculation amended with 30 kg P/ha emphasized the beneficial effect of these and similar trend was reflected in productivity enhancement as well.

Heat Stress in Indian Mustard (Brassica juncea L.): A Critical Review of Impacts and Adaptation Strategies

Indian mustard, a member of the Brassicaceae family, is a cool-season crop cultivated extensively in various agro-ecological conditions, contributing significantly to vegetable oilseed production. However, being a thermosensitive and C3 plant [1], Indian mustard is highly susceptible to high-temperature stress, particularly during critical developmental stages [2]. High temperatures disrupt physiological, morphological, and biochemical mechanisms essential for plant growth and development. From altered chlorophyll content and osmotic water potential to impaired photosynthesis and reduced seed oil accumulation, heat stress detrimentally affects various aspects of Indian mustard physiology. This comprehensive review examines the impacts of heat stress on Indian mustard, a significant oilseed crop, and explores adaptation strategies to mitigate its adverse effects. Additionally, heat stress during reproductive stages leads to flower abortion, reduced fertility, and poor seed development, significantly impacting yield potential. To cope with heat stress, plant response mechanisms involve intricate signaling pathways, leading to cellular readjustments at transcriptome, epigenome, proteome, and metabolome levels. Breeding approaches, including conventional techniques and advanced molecular tools like CRISPR/Cas-based genome editing, offer promising avenues for developing heat-tolerant cultivars. Integration of multi-omics approaches aids in identifying stress-responsive genes and metabolic pathways crucial for adaptation. Agronomic strategies, such as nutrient management and microbial inoculation, play vital roles in mitigating heat stress effects and enhancing plant resilience. Collaborative efforts and interdisciplinary research are essential to deepen our understanding of heat stress responses and develop sustainable solutions to ensure oilseed crop productivity and food security in the face of climate change. This review underscores the urgency of addressing heat stress challenges in Indian mustard cultivation and highlights the need for concerted efforts to develop effective adaptation strategies for sustainable agriculture.

Efficacy of different rhizobia strains with specific common beans landraces in biological nitrogen fixation

Bean production in Tanzania barely meets half of the domestic demand because of low yield attributed to low fertility, nitrogen being the most common deficient. The use of rhizobia inoculants can substantially increase bean yields. However, less than 1% of the farming population is aware of inoculants. The aim of the study was to evaluate the efficacy of different rhizobia strains with specific common beans landraces in biological nitrogen fixation and yields. Four experiments were conducted during in a screen house at Sokoine University of Agriculture (SUA). Two experiment consisted Leonard jar and the other two were pot experiments in which the soil used were either sterilized or unsterilized. The landraces collected were Kasuka Nywele, Msafiri and Manjano from Mbeya; Nyayo, Soya and Kachumbaa from Arusha; and Kabungu, Nyamungu and Karanga from Morogoro. Two sets of Leonard jars were arranged in completely randomized block design in triplicate and the other two pot experiments were arranged in split split plot design. Inoculants in pot experiments used were Nitro-SUA, Underwood Biostacked as commercial and native. Landrace were the main plot, soil sterilization as a sub plot and inoculants as sub sub plot replicated three times. Data were subjected to analysis of variance using GENSTAT software. Significance differences in N2 fixation were observed among all landraces in all experiments, promising results were observed from Nyayo, Nyamungu, Msafiri and Kabungu. Native rhizobia had comparable symbiotic effectiveness to commercial inoculants in unsterilized soils and vice versa in sterilized soils conditions though soil sterilization was not significant. The findings on this study provide rooms for further research especially on the promising landraces to nodulation and explore their effectiveness.

Bacillus velezensis YXDHD1-7 Prevents Early Blight Disease by Promoting Growth and Enhancing Defense Enzyme Activities in Tomato Plants.

Bacillus velezensis is well known as a plant growth-promoting rhizobacteria (PGPR) and biocontrol agent. Nevertheless, there are very few reports on the study of B. velezensis on tomato early blight, especially the biocontrol effects among different inoculation concentrations. In this study, an IAA-producing strain, Bacillus velezensis YXDHD1-7 was isolated from the tomato rhizosphere soil, which had the strongest inhibitory effect against Alternaria solani. Inoculation with bacterial suspensions of this strain promoted the growth of tomato seedlings effectively. Furthermore, inoculations at 106, 107, and 108 cfu/mL resulted in control efficacies of 100%, 83.15%, and 69.90%, respectively. Genome sequencing showed that it possesses 22 gene clusters associated with the synthesis of antimicrobial metabolites and genes that are involved in the production of IAA. Furthermore, it may be able to produce spermidine and volatile compounds that also enhance plant growth and defense responses. Our results suggest that strain YXDHD1-7 prevents early blight disease by promoting growth and enhancing the defense enzyme activities in tomato plants. This strain is a promising candidate for an excellent microbial inoculant that can be used to enhance tomato production.

Fungal communities are passengers in community development of dune ecosystems, while bacteria are not.

An increasing number of studies of above-belowground interactions provide a fundamental basis for our understanding of the coexistence between plant and soil communities. However, we lack empirical evidence to understand the directionality of drivers of plant and soil communities under natural conditions: 'Are soil microorganisms driving plant community functioning or do they adapt to the plant community?' In a field experiment in an early successional dune ecosystem, we manipulated soil communities by adding living (i.e., natural microbial communities) and sterile soil inocula, originating from natural ecosystems, and examined the annual responses of soil and plant communities. The experimental manipulations had a persistent effect on the soil microbial community with divergent impacts for living and sterile soil inocula. The plant community was also affected by soil inoculation, but there was no difference between the impacts of living and sterile inocula. We also observed an increasing convergence of plant and soil microbial composition over time. Our results show that alterations in soil abiotic and biotic conditions have long-term effects on the composition of both plant and soil microbial communities. Importantly, our study provides direct evidence that soil microorganisms are not "drivers" of plant community dynamics. We found that soil fungi and bacteria manifest different community assemblies in response to treatments. Soil fungi act as "passengers," that is, soil microorganisms reflect plant community dynamics but do not alter it, whereas soil bacteria are neither "drivers" nor "passengers" of plant community dynamics in early successional ecosystems. These results are critical for understanding the community assembly of plant and soil microbial communities under natural conditions and are directly relevant for ecosystem management and restoration.

Tripartite interactions among free‐living, N‐fixing bacteria, arbuscular mycorrhizal fungi, and plants: Mutualistic benefits and community response to co‐inoculation

AbstractInteractions between arbuscular mycorrhizal (AM) fungi and free‐living nitrogen fixers (FLNF) occur in the rhizosphere where they can enhance plant nutrient acquisition, impact plant growth, and affect soil processes. Tripartite mutualism commonly occurs between nodule‐forming plants, symbiotic diazotrophs, and AM fungi, and can occur between non‐nodulating plants, FLNF, and AM fungi. However, information on the extent of, and controls on, tripartite mutualism in non‐nodulating plant systems is limited to a small number of crop plants and culturable microbial inoculum, mostly in greenhouse growing conditions. We conducted a systematic literature review to synthesize the current understanding of the responses of plants, AM fungi, and FLNF to co‐inoculation, as well as the conditions affecting tripartite mutualism and the magnitude and range of benefits conferred. Our review shows that plants generally benefit from co‐inoculation with AM fungi and FLNF taxa, but benefits are highly variable and context dependent, ranging from 94% reduction in plant shoot biomass to 255% increase in total plant biomass. Additionally, the presence of AM fungi can increase abundance of FLNF and the presence of FLNF can increase AM fungal root colonization, but these responses also vary widely. Major factors influencing variation in response to co‐inoculation by all organisms include plant phenology/age, soil type and nutrient availability, and partner pairing. There is potential for leveraging these tripartite mutualisms to improve plant productivity and soil microbial function, but successful application is more likely with a thorough understanding of the environmental and mechanistic controls on these relationships and testing of field‐scale implementation.

Enhancing drought tolerance in Indian mustard (Brassica juncea) through microbial inoculants under varying irrigation regimes

A field experiment was conducted during the winter (rabi) seasons of 2020–21, 2021–22 and 2022–23 at College of Agriculture, Sri Karan Narendra Agriculture University, Jobner, Rajasthan to identify the appropriate bacterial strains and irrigation levels to enhance drought tolerance and productivity in Indian mustard [Brassica juncea (L.) Czern.]. The experiment was laid out in a split plot design assigning irrigation treatments (no irrigation, 50% deficit irrigation and normal level of irrigation) in main plots and microbes (MRD-17, MKS-6, Biophos and Biophos+, CRIDAMI-I, CRIDA MI-II and control) in sub plots. Results demonstrated that normal level of irrigation (2 irrigations) yielded superior outcomes in terms of plant height, dry matter accumulation, yield attributes, viz. seed yield (1542 kg/ha), stover yield (3677 kg/ha), relative water content (70.72%), protein content (18.1%), oil content (38.7%), water use efficiency (7.50 kg/ha-mm), net returns (₹52529/ha) and B:C ratio (2.07). This was significantly higher compared to 50% deficit irrigation and no irrigation treatments. Among microbial inoculants, CRIDA MI-II exhibited the highest impact on growth and yield attributes, viz. seed yield (1312 kg/ha), stover yield (3262 kg/ha), protein content (17.2%), water use efficiency (5.88 kg/ha-mm), net returns (₹42294/ha) and B:C ratio (1.72). Notably, it was statistically comparable to the effects of CRIDA MI-I and Biophos and Biophos+ across most parameters. The comprehensive results of this study advocated the strategic implementation of both optimal irrigation practices and microbial inoculants as a sustainable approach to enhance productivity and drought tolerance in Indian mustard, particularly in the arid and semi-arid regions of Rajasthan.

Enhancing drought tolerance in Indian mustard (Brassica juncea) through microbial inoculants under varying irrigation regimes

A field experiment was conducted during the winter (rabi) seasons of 2020–21, 2021–22 and 2022–23 at College of Agriculture, Sri Karan Narendra Agriculture University, Jobner, Rajasthan to identify the appropriate bacterial strains and irrigation levels to enhance drought tolerance and productivity in Indian mustard [Brassica juncea (L.) Czern.]. The experiment was laid out in a split plot design assigning irrigation treatments (no irrigation, 50% deficit irrigation and normal level of irrigation) in main plots and microbes (MRD-17, MKS-6, Biophos and Biophos+, CRIDAMI-I, CRIDA MI-II and control) in sub plots. Results demonstrated that normal level of irrigation (2 irrigations) yielded superior outcomes in terms of plant height, dry matter accumulation, yield attributes, viz. seed yield (1542 kg/ha), stover yield (3677 kg/ha), relative water content (70.72%), protein content (18.1%), oil content (38.7%), water use efficiency (7.50 kg/ha-mm), net returns (₹52529/ha) and B:C ratio (2.07). This was significantly higher compared to 50% deficit irrigation and no irrigation treatments. Among microbial inoculants, CRIDA MI-II exhibited the highest impact on growth and yield attributes, viz. seed yield (1312 kg/ha), stover yield (3262 kg/ha), protein content (17.2%), water use efficiency (5.88 kg/ha-mm), net returns (₹42294/ha) and B:C ratio (1.72). Notably, it was statistically comparable to the effects of CRIDA MI-I and Biophos and Biophos+ across most parameters. The comprehensive results of this study advocated the strategic implementation of both optimal irrigation practices and microbial inoculants as a sustainable approach to enhance productivity and drought tolerance in Indian mustard, particularly in the arid and semi-arid regions of Rajasthan.

Inoculation and tracking of beneficial microbes reveal they can establish in field-grown potato roots and decrease blemish diseases

In a three-year field study, we inoculated two potato varieties with a selection of four beneficial microbial strains (i.e. Rhizophagus irregularis MUCL41833, Trichoderma asperelloides A, Pseudomonas brassicacearum 3Re2-7 and Paraburkholderia phytofirmans PsJN), alone or in combination. Plants were grown under rainfed or irrigated conditions, and potato yield and development of several diseases were evaluated. The microbial inoculants were traced in the root system at different stages of crop development via molecular markers. Whatever the water supply, the inoculants had no effect on yield. Conversely, some of the inoculants were able to lower the incidence and/or severity of several blemish diseases, namely common scab-associated symptoms (CSAS) and silver scurf/black dot-associated symptoms (SSAS). Microbial consortia were more efficient in decreasing symptoms compared to single strain inoculations. The best control was obtained with the combination of R. irregularis and P. brassicacearum, which reduced the incidence of CSAS by 22% and severity of SSAS by 21%. Root tracking revealed that P. brassicacearum and P. phytofirmans PsJN were able to establish in the root system of the potato, while only P. brassicacearum was detected from emergence until flowering of the plants.

Interactions of Microbial Inoculations with Fertilization Options and Crop Establishment Methods on Modulation of Soil Microbial Properties and Productivity of Rice

A field investigation was undertaken to assess the interactive effects of different crop establishment methods (CEMs) and microbial formulations in field conditions. The two year experiment was carried out in kharif season (June to October) of both 2013–14 and 2014–15 at Research Farm of ICAR-Indian Agricultural Research Institute, New Delhi India. The CEMs studied consist of puddled transplanted rice (PTR), system of rice intensification (SRI) and aerobic rice system (ARS); while microbial formulations consist of Anabaena sp. (CR1)+Providencia sp. (PR3) consortium (MC1) and Anabaena–Pseudomonas biofilm formulation (MC2). The microbial inoculation was applied with 75% recommended dose of nutrients (RDN) (90 kg nitrogen ha-1 and 19.35 kg phosphorus ha-1) and compared with 100% RDN. Soil microbiological properties showed significantly higher values in SRI in the first year; while in the second year, SRI and PTR remained on par and superior to ARS. Among the combinations of nutrient supplements, application of Anabaena–Pseudomonas biofilm formulation (MC2) with 75% RDN was superior in terms of all microbiological attributes studied [acetylene reduction activity (ARA), soil chlorophyll, soil dehydrogenase activity, microbial biomass carbon and alkaline phosphatase activity]. Application of microbial inoculation led to an increase in milled rice yield from 230 to 240 kg ha-1. Among the different combinations of CEMs and inputs investigated the application of 75% RDN+MC2+zinc (Zn) (soil applied 5 kg Zn ha-1 through zinc sulphate heptahydrate) in SRI can be a judicious option to maximize rice yield and soil health.

Adoption of arbuscular mycorrhizal fungi and biochar for alleviating the agro-physiological response of lavander (Lavandula angustifolia L.) subjected to drought stress

Increasing the productivity of crops in water deficit circumstances is of great significance in order to face the challenge of securing global food production. Nowadays, the use of biochar (BC) and arbuscular mycorrhizal fungi (AMF) are considered as one of the most effective methods for empowering plants to deal with drought stress. However, the literature regarding the effects of the simultaneous use of AMF+BC on plants under drought stress is scarce. Hence, the present study was conducted to consider the combined application of AMF and biochar on the physiological and biochemical properties of lavender under various levels of irrigation. The first factor includes three irrigation regimes of 90 % field capacity (FC), 60 % FC, and 30 % FC, respectively, corresponding to normal irrigation, mild and severe drought stress. The second factor included a fertilizer or microbial inoculant source, which were respectively: no inoculation (control), inoculation with AMF, BC, and co-application of AMF along with BC. The highest nutrient, chlorophyll and carotenoid content, and fresh, and dry weight of lavender were recorded under normal irrigation conditions with combined application of AMF+BC. The combined application of AMF+BC was significantly effective in increasing the activity of antioxidant enzymes against oxidative damage caused by drought stress and in reducing the accumulation of proline and malondialdehyde. An increase in phenolic, flavonoid, and concentration of essential oil was observed under mild stress and using AMF+BC, while the highest essential oil yield was recorded under a normal irrigation regime and treated with AMF+BC. The highest content of linalool, camphor, borneol, and linalyl acetate was obtained in mild stress by adding AMF+BC. It can be concluded that the use of AMF+BC combination treatment may be a useful strategy to improve the quantity and quality of lavender EO in drought-stress circumstances.

The effect of low-intensity laser radiation on the sensitivity of Staphylococcus aureus to some halogen-containing azaheterocycles

The rapid rate of acquisition and spread of resistance to antibiotics by microorganisms leads to the search and investigation of new ways of combating infectious agents. Being a modern, minimally invasive method with an almost complete absence of side effects, the use of low-intensity laser radiation can be considered as one of the alternatives to traditional antibiotic therapy. At the same time, the search for new chemical compounds with pronounced antimicrobial activity is also promising. The impact of low-intensity laser of the red spectrum (λ = 660 nm) on the sensitivity of a clinical isolate of Staphylococcus aureus to newly synthesized halogen- and chalcogen-halogen-containing derivatives of the quinazoline and benzothiazole series was studied using the serial microdilutions method with the determination of minimal inhibitory and minimal bactericidal concentrations. To evaluate the antimicrobial properties of the investigated substances in dynamic, we investigated their activity two months after the synthesis with subsequent comparison to freshly synthesized compounds. The research results indicate that the most pronounced antimicrobial effect was shown by trichlorotelluromethylthiazoloquinazolinium chloride and propargylthiobenzothiazolium hexachlorotellurate. Evaluating the dynamics of the activity of the studied compounds, it was noted that the absolute majority of substances retained their properties, which indicates their stability. When evaluating the effect of irradiation of microbial inoculum with low-intensity laser radiation on the susceptibility to chemical compounds, an increase in the sensitivity of irradiated microorganisms to some investigated chemicals was noted compared to similar non-irradiated microbial suspensions. In the case of 2 out of 9 studied chemical compounds we noted a 2- to 4-fold decrease in the minimal inhibitory concentration for irradiated microbial suspensions. A decrease in the minimal bactericidal concentration after irradiation was noted for one of the substances. In the cases of butynylthiobenzothiazolium hexabromotellurate, and tribromotelluromethylthiazoloquinazolinium bromide, decrease of both minimal inhibitory and minimal bactericidal concentrations in the irradiated inoculum was observed. The above shows that low-intensity laser radiation under certain parameters increases the susceptibility of microorganisms to antimicrobial agents.