Search Results (133)

Systemic biologicals have emerged as a disruptive technology for overcoming the limitations of conventional biologicals. The effectiveness of systemic and conventional biological products in improving the growth and yield of two carrot cultivars was compared. Carrot plants were inoculated with either systemic or conventional biofertilizers and nematicides, and various growth parameters and yields were compared. As expected, the first indicator of the proper functioning of the systemic biofertilizer was increased chlorophyll content (two-variety averages: systemic = 17.1, conventional = 11.8, control = 10.9 mg g⁻¹ FW). The results indicated the superior performance of the systemic biologicals in carrot production. The two-variety average yield increased by 11.92 t ha⁻¹ (32%) in plants inoculated with systemic biologicals compared with the control plants and by 6.62 t ha⁻¹ (15.4%) compared with plants inoculated with conventional products (p ≤ 0.05). For the biological nematicides, the two-variety average damage rate was 10.15% in plants treated with the systemic bionematicide, 21.15% in plants treated with the conventional bionematicide, and 31.6% in non-inoculated plants. Analyses revealed the presence of microorganisms in plants inoculated with systemic biologicals, although beneficial fungi were detected at relatively low levels. In conclusion, systemic products offer a more robust and consistent technology for improving crop health and yield and are considered the next generation of biologicals. Full article

Microorganism inoculants are becoming increasingly essential in sustainable agriculture because they improve nutrient availability, promote plant growth, inhibit disease, and increase crop tolerance to environmental stresses. Nonetheless, their field performance is frequently hampered by poor storage survival, low rhizosphere establishment, and susceptibility to harsh climatic conditions. Encapsulation technologies provide an effective solution by encapsulating microbial cells in a biodegradable matrix, extending shelf life, increasing vitality, and allowing for controlled release in the soil. This review focuses on four agriculturally significant microorganisms: Azotobacter chroococcum, Azospirillum brasilense, Pseudomonas brassicacearum, and Trichoderma harzianum. Their modes of action, including nitrogen fixation, phytohormone synthesis, pathogen inhibition, and stimulation of plant defense responses, are reviewed alongside recent advances in encapsulation strategies. Alginate-based formulations and proposed potential multi-species microbial consortia are discussed as promising strategies for improving inoculant performance. However, the successful development of multifunctional potential microbial formulations requires further investigation of microbial compatibility, formulation stability, synchronized release behaviour, and long-term storage performance before broad agricultural implementation can be achieved. Full article

Brazilian cattle production relies predominantly on pasture systems, many of which are degraded by nutrient depletion, particularly nitrogen deficiency. Plant growth-promoting bacteria (PGPB) offer a sustainable strategy to improve pasture productivity, but their effects are often host-specific and remain poorly explored in Paspalum. This study evaluated the effect of inoculation with Azospirillum brasilense strains CNPSo 2083 (=Ab-V5) and CNPSo 2084 (=Ab-V6) and Pseudomonas fluorescens strain CNPSo 2719 (=CCTB 03), applied by seed inoculation or leaf spray, on the root morphology and shoot growth of four Paspalum accessions under controlled axenic greenhouse conditions, evaluated in an early growth stage at 35 days after emergence. Genotype-specific responses were the central finding of this study: Paspalum malacophyllum BGP-293 showed negligible responses to inoculation, whereas BGP-486—of the same species—increased root dry weight by up to 43% and root tissue density by up to 30% in all inoculated treatments. In Paspalum regnellii BGP-112, seed inoculation produced stronger root responses than foliar spray, increasing root dry weight by up to 38% and root area by up to 40%. In Paspalum rojasii BGP-149, inoculation induced root architectural remodeling without increasing root biomass—root area increased by up to 92% and total root length by up to 97%, relative to the control—indicating an efficient root-foraging strategy. P. fluorescens favored root-foraging traits and tissue density, whereas A. brasilense preferentially stimulated root-hair elongation. These accession-level contrasts, rather than a single generalizable trend, are the main contribution of this work: they support tailored, genotype-specific PGPB strategies for sustainable tropical pastures. Full article

Continuous cropping obstacles (CCOs) seriously constrain tomato yield and quality in facility agriculture, primarily due to rhizosphere microbial imbalance. Indigenous synthetic microbial communities (SynCom) offer superior colonization and stability compared to single strains. This study aimed at constructing a simplified SynCom from indigenous rhizobacteria in Northwest China to alleviate tomato CCOs. A total of 155 rhizobacterial strains (29 genera) were isolated. Sixteen strains with significant growth-promoting effects were selected through seedling assays. Based on the carbon source niche overlap index (NOI > 70%) with Ralstonia solanacearum QL-Rs1115, eight candidate strains were retained. Using the broken-stick model, 29 simplified SynComs were constructed. SynCom28, composed of six functionally complementary strains (Azospirillum brasilense, Massilia niabensis, Enterobacter hormaechei, Chryseobacterium sp., Priestia megaterium and Pseudomonas brassicacearum), showed the best performance. Pot experiments revealed that SynCom28 reduced the bacterial wilt disease index to 32.41, with a biocontrol efficacy of 41.72%. Greenhouse trials under continuous cropping demonstrated that SynCom28 significantly increased seedling Dickson quality index (DQI), stem diameter and biomass. Fruit yield increased by 12.98–15.30% across the 2nd to 4th cropping cycles (p < 0.05). Fruit quality parameters were also enhanced, with soluble sugar, lycopene, and vitamin C contents increasing by 47.22–65.07%, 33.07–81.71% and 80.56–166.67%, respectively. In conclusion, the indigenous simplified SynCom28 effectively alleviates tomato CCOs, enhancing growth, yield, and quality while suppressing bacterial wilt, providing a promising strategy for sustainable facility agriculture. Full article

Nitrogen (N) is a key nutrient for upland rice (Oryza sativa L.), and plant growth-promoting rhizobacteria (PGPR) have been investigated as a sustainable strategy to improve plant nutrition and crop performance. This study evaluated the effects of N topdressing and PGPR inoculation on leaf chlorophyll index (LCI), leaf nutrient concentrations, and yield components in upland rice. A field experiment was conducted in a randomized block design (4 × 6 factorial) with four N rates (0, 40, 80, and 120 kg ha⁻¹) and five PGPR strains (Azospirillum brasilense, Nitrospirillum amazonense, Bacillus subtilis, Priestia aryabhattai, and Methylobacterium symbioticum), plus a non-inoculated control. No significant interaction between N rates and PGPR inoculation was observed. Nitrogen increased leaf phosphorus (P), potassium (K), and magnesium (Mg) concentrations and panicle number; however, it also increased unfilled grains, reduced grain weight, and did not affect grain yield. Azospirillum brasilense increased LCI by 25.7%. Bacillus subtilis and A. brasilense increased leaf N, K, Mg, copper (Cu) and manganese (Mn) concentrations. Azospirillum brasilense, B. subtilis, N. amazonense, and P. aryabhattai reduced unfilled grains, increased grain weight and grain yield by up to 10.7%, whereas M. symbioticum did not differ from the control in grain yield. Under the conditions of this study, nitrogen was not limiting for grain yield, and all strains, except M. symbioticum, were associated with increases in grain yield and changes in plant nutritional status. Full article

Water scarcity is one of the main constraints on maize production in semiarid regions, making it essential to adopt management strategies that reconcile water savings, crop resilience, and economic viability. This study evaluated the effects of deficit irrigation strategies integrated with the use of bioinputs on physiological, productive, and economic parameters of maize grown under field conditions in the Brazilian semiarid region over two growing seasons (2023 and 2024). The experiment was conducted using a randomized complete block design with a split-plot arrangement. Irrigation strategies comprised full irrigation (FI; 100% of crop water requirements), continuous deficit irrigation (RD50%; 50% throughout the crop cycle), and stage-specific controlled deficit irrigation (50%) imposed during the vegetative (CDV50%), flowering/grain formation (CDF50%), and grain-filling (CDG50%) stages, while seed treatments involved inoculation with Bacillus aryabhattai, coinoculation with B. aryabhattai + Azospirillum brasilense, and control treatments. Physiological variables, yield components, water use efficiency, the crop sensitivity coefficient to water deficit (Ky), and economic indicators were assessed. Controlled deficits irrigation, particularly under CDV50%, maintained grain yield comparable to FI (6465.80 kg ha⁻¹, in second growing season), whereas RD50% reduced yield in 26%. Inoculation treatments enhanced gas exchange, carboxylation efficiency, and water use efficiency, resulting in higher agricultural income under specific production systems. The CDV50% strategy combined with coinoculation showed the greatest potential as a sustainable approach for maize production in semiarid environments and reduced the water use by up to 18.9%. Full article

Saline irrigation water is increasingly used in arid and coastal regions, posing serious constraints to soil health and wheat yield, particularly in saline–sodic soils. A two-season field experiment was conducted to evaluate the effects of compost, biofertilizers (Azospirillum brasilense and Azotobacter chroococcum), and their combinations on soil physicochemical properties, microbial activity, wheat growth, yield, and physiological traits under two irrigation water salinity levels (3 and 6 dS m⁻¹). Two wheat varieties differing in salt tolerance (Miser 4 and Sakha 95) were tested. Salinity significantly increased soil EC and ESP and reduced plant growth, yield, and nutrient content, while integrated bio-organic treatments markedly alleviated these adverse effects. Compost combined with Azotobacter chroococcum markedly improved soil physical conditions, enhanced microbial biomass carbon, reduced sodicity indicators, and promoted wheat productivity across both seasons. Multivariate analyses including principal component analysis (PCA), redundancy analysis (RDA), and self-organizing maps (SOMs) revealed a strong positive association between yield traits, microbial activity, and soil fertility, and negative correlations with salinity stress indicators. The results demonstrate that combining compost with biofertilizers induces both immediate and residual improvements in saline–sodic soils, enhances wheat resilience to salinity stress, and offers a sustainable approach for improving cereal production under salt-affected environments. Full article

Strawberry powdery mildew, caused by Podosphaera aphanis, severely impacts the yield and quality of strawberry fruit and necessitates sustainable control strategies. Here, we assessed the growth and hormone content of strawberry seedlings (Fragaria × ananassa ‘Hongyan’) to evaluate the abilities of four plant growth-promoting bacteria (PGPB), Azospirillum brasilense, Phytobacter diazotrophicus, Variovorax soli, and Microbacterium phyllosphaerae, in a 42-day consecutive culture. Among all treatments, our results showed that the strains V. soli and M. phyllosphaerae increased the seedling biomass by 25.6–25.8% and decreased the disease index by 30–32.5% compared to the control. Moreover, the strain M. phyllosphaerae could produce 22.32 μg·mg⁻¹ indole-3-acetic acid (IAA) after 24 h in a consecutive culture system and still maintain the IAA at 8.12 ng·mg⁻¹ in seedlings. In addition, the salicylic acid (SA) and jasmonic acid (JA) hormones of the seedlings increased by 293% and 35.3% after inoculating with V. soli and M. phyllosphaerae, respectively. Further analysis of the coordination between plant hormones and plant growth showed that the accumulation of SA might have had a positive relation with biomass, whereas JA was negative under powdery mildew infection. These findings highlight that the V. soli and M. phyllosphaerae strains could offer the dual benefits of growth promotion and different defense strategies against powdery mildew for sustainable strawberry production. Full article

The high cost of nitrogen (N) fertilizers has increased interest in sustainable alternatives, such as inoculation with Azospirillum brasilense, to improve forage production. This study evaluated the agronomic performance, yield, nutritional composition, and fermentation profile of giant sorghum silage from crops inoculated with A. brasilense under different N rates. A randomized block design was adopted in a 5 × 2 factorial arrangement, with five N rates (0, 50, 100, 200, and 400 kg ha⁻¹) and the presence or absence of A. brasilense inoculation, with four replicates. Nitrogen rates significantly affected plant height and stem diameter, with maximum values observed at 200 kg ha⁻¹ N. An interaction between inoculation and N rates was detected for first-cycle yield, in which inoculated plants showed reduced productivity at 200 and 400 kg ha⁻¹ N. Total yield was higher in non-inoculated treatments and was maximized at 200 kg ha⁻¹ N, representing a 29.42% increase compared with the unfertilized control. Crude protein concentration increased with increasing N rates, while in vitro dry matter digestibility was influenced only by N fertilization. Inoculation did not improve agronomic performance and negatively affected yield at higher N rates, although both inoculation and N fertilization influenced protein and fiber contents of sorghum silage. Under the edaphoclimatic conditions of the Brazilian Amazon, A. brasilense inoculation is not recommended for giant sorghum cultivation, whereas the application of 200 kg ha⁻¹ N was the most effective strategy to maximize yield. Full article

This study is Part II of a five-year (2018–2022) field trial in western Portugal evaluating the effects of three microbial biofertilizers—Mycoshell^® (Glomus spp. + humic/fulvic acids), Kiplant iNmass^® (Azospirillum brasilense, Bacillus megaterium, Saccharomyces cerevisiae), and Kiplant All-Grip^® (Bacillus megaterium, Pseudomonas spp.)—applied at different dosages alongside two mineral fertilizer regimes, T100 (full dose) and T70 (70% of T100, alone or combined with biofertilizers), on the physiological performance of ‘Gala Redlum’ apple trees. Part I had shown that Myc4 (Mycoshell^®, 4 tablets/tree), iNM6, and iNM12 (Kiplant iNmass^®, 6 and L ha⁻¹, respectively) consistently enhanced fruit growth, yield, and selected quality traits. While Part I showed clear agronomic gains, Part II demonstrates that these improvements occurred without significant alterations in seasonal photosynthetic performance, canopy reflectance, or chlorophyll fluorescence parameters over five years, highlighting the contrast between observed yield improvements and physiological stability. Seasonal monitoring of physiological traits—including specific leaf area (SLA), chlorophyll content index (CCI), gas exchange (A_n, g_s, E, C_i), spectral indices (NDVI, OSAVI, SIPI, GM2), and chlorophyll fluorescence (OJIP). It is clear that physiological values remained largely stable across biofertilizer treatments and years. Importantly, this stability was maintained even under a 30% reduction in mineral fertilizer (T70), indicating that specific microbial biofertilizers can sustain physiological resilience under reduced nutrient inputs, thereby providing a physiological basis for the yield-enhancing effects observed and supporting their integration into fertilizer reduction strategies in Mediterranean orchards. Full article

Wheat (Triticum aestivum L.) sustains global caloric intake, but its productivity in Andean highlands is constrained by soil fertility and input reliance. This study represents one of the first field-based evaluations of biofertilizers under high-altitude, rainfed Andean conditions, addressing a major knowledge gap in low-input mountain agroecosystems. This study evaluated three seed-applied biofertilizers—Azospirillum brasilense, Trichoderma viride (Trichomax), and an anchovy (Engraulis ringens) based liquid biofertilizer, compared with an untreated control and a soil-test mineral fertilization benchmark in rainfed wheat (Triticum aestivum L.) cv. INIA 405 in the central Andes of Peru. A 5 × 5 Latin square design (25 plots) was established under farmer-realistic conditions. At physiological maturity (Zadoks 9.5), plant height, spike length, grains per spike, thousand-grain weight, test weight, root dry mass, and grain yield were recorded. Mineral fertilization achieved the highest yield (1.20 ± 0.79 t ha⁻¹), nearly doubling the control (0.60 ± 0.47 t ha⁻¹). Notably, A. brasilense delivered an intermediate yield of 0.90 ± 0.64 t ha⁻¹, representing a 50% increase over the control—accompanied by a marked rise in root dry mass. T. viride and the anchovy-based input yielded 0.85 ± 0.59 and 0.81 ± 0.59 t ha⁻¹, respectively. Grain physical quality remained stable across treatments (thousand-grain weight ≈ 42 g; test weight 68–75 kg hL⁻¹). Trait responses were complementary: root dry mass increased with mineral fertilization and A. brasilense, whereas spike length increased with mineral fertilization and the anchovy-based input. Overall, the evidence supports biofertilizers, particularly A. brasilense, as effective complements that enable partial fertilizer substitution within integrated nutrient-management strategies for sustainable wheat production in Andean rainfed systems. Full article

Quinoa (Chenopodium quinoa Willd.) is a strategic crop for climate-smart agriculture in the Andes, yet yield gains are constrained by soil degradation and low-input systems. We tested whether synergistic bioinoculation with a plant growth-promoting rhizobacterium (Azospirillum brasilense) and an arbuscular mycorrhizal fungus (Glomus iranicum var. tenuihypharum) enhances root function and grain productivity under field conditions. A split-plot RCBD was conducted in Ayacucho, Peru (2735 m a.s.l.) using four cultivars, Blanca de Junín (BJ), INIA 441 Señor del Huerto (SH), INIA 415 Pasankalla (RP) and INIA 420 Negra Collana (NC) and four treatments: uninoculated control, Azospirillum, Glomus and co-inoculation. Vegetative, root and yield traits were quantified; ANOVA, Tukey/Dunnett contrasts, correlations and PCA were applied. Co-inoculation consistently outperformed single inoculants, increasing root diameter, length, branching, dry weight and volume dry weight, while also enlarging panicle dimensions and raising grain weight per panicle and thousand-seed weight. Grain yield reached 4.94 ± 0.59 t ha⁻¹ under co-inoculation, almost triple that of the control (1.71 ± 0.28 t ha⁻¹) and about 1.5 times higher than single inoculations. Genotypic effects were pronounced; BJ and SH combined superior root biomass with higher yield, RP maximized grain size and hectoliter weight, whereas NC responded weakly. Significant genotype × treatment interactions indicated cultivar-dependent microbiome benefits. Correlation and PCA linked root biomass and stem/panicle architecture to yield formation, positioning co-inoculation along trait vectors associated with belowground vigor and productivity. These results demonstrate a robust microbial synergy that translates root gains into yield, supporting co-inoculation as a scalable, low-input strategy for sustainable intensification of quinoa in highland agroecosystems. Full article

Lima bean (Phaseolus lunatus L.), an important legume in semiarid environments, often exhibits low yield, requiring strategies to enhance symbiotic nitrogen fixation and nutrient-use efficiency. This study evaluated the effects of single and combined inoculation with Bradyrhizobium elkanii (strain BR 2003) and Azospirillum brasilense (strain Ab-V5) on nitrogen metabolism, nutrient uptake, plant growth, and residual soil fertility in P. lunatus. Four varieties were subjected to four treatments: control (nitrogen fertilization), single inoculation with B. elkanii or A. brasilense, and co-inoculation. All inoculation strategies significantly increased root nodulation, nitrogen assimilation, and the accumulation of key macronutrients. Root nodulation increased from 1 to 12 nodules per plant in the control treatments to up to 277 nodules per plant under inoculation, while shoot nitrogen content increased by up to 91% in ‘Raio de Sol’ and 87% in ‘Cearense’. Increases in P and K were also observed, including a 48% increase in shoot P in ‘Manteiga’ and up to a 100% increase in shoot K in ‘Raio de Sol’, whereas root K increased by up to 90% under co-inoculation. The ‘Raio de Sol’ and ‘Manteiga’ varieties exhibited the most pronounced increases in growth and biomass. Additionally, inoculation improved post-cultivation soil indicators, including pH and available P and K in specific genotype-microbe combinations, and reduced electrical conductivity. These results demonstrate the strong contribution of microbial inoculation to nitrogen assimilation and nutrient acquisition, supporting its use as a promising alternative to conventional nitrogen fertilization in lima bean cultivation. Full article

Quinoa (Chenopodium quinoa Willd.) is valued for its resilience to abiotic stress; however, germination and seedling establishment remain highly sensitive to salinity. While its salt tolerance at later growth stages has been well studied, strategies to improve early development under high salinity are limited, and the role of halotolerant plant growth-promoting bacteria (PGPB) in quinoa has not been systematically investigated. This study assessed the ability of three Azospirillum brasilense strains (BR-11001, BR-11002, and BR-11005) to increase the germination and seedling performance of the cultivar ‘BRS Piabiru’ under saline stress. A 3 × 4 factorial design with three bacterial treatments and four NaCl concentrations (0, 150, 300, and 450 mM) was conducted in a completely randomized arrangement, with four replicates per treatment. Seeds were surface sterilized, inoculated, and incubated at 18 °C under constant light for 10 days. Elevated salinity (≥300 mM NaCl) drastically reduced germination and seedling vigor in the controls. Inoculation with BR-11002 significantly alleviated salinity-induced damage, sustaining over 84% germination at 450 mM and increasing seedling biomass at 300 mM. These findings highlight the potential of halotolerant A. brasilense, particularly BR-11002, as bioinoculants to promote quinoa establishment in salt-affected soils, supporting sustainable agriculture and food system resilience. Full article

Nitrous oxide is a potent greenhouse gas, with N fertilizers being one of its major sources. Plant growth-promoting bacteria have been used to mitigate N₂O emissions by improving N use efficiency in plants. In addition, some of these microorganisms are capable of reducing N₂O to N₂, a process that could be further explored as a complementary mitigation strategy. This study aimed to test whether Azospirillum brasilense strains Ab-V5 and Ab-V6, and strain Wa3, as well as Nitrospirillum viridazoti strain BR 11145, already used in commercial inoculants for N-fertilized crops and known to carry the nosZ gene encoding nitrous oxide reductase, could act as biological sinks for this gas. In the pot experiment, soils fertilized with N and inoculated with N. viridazoti exhibited consistently lower N₂O emissions, but not when A. brasilense strains were used. The mitigation effect was observed both in bare soil (72% emission reduction) and in the presence of millet plants (60% emission reduction), confirming the ability of N. viridazoti strain BR 11145 to consume N₂O. In a field experiment conducted with maize, inoculation with N. viridazoti again reduced N₂O fluxes during the first two weeks after fertilization compared with the urea-only treatment. However, no significant differences were detected comparing emission factors, whose calculation requires consideration of the entire monitoring period, thereby adding more variability. While N₂O mitigation was observed, no significant effects of inoculation or N fertilization were found on maize growth or yield. Nonetheless, the consistent reduction in N₂O emissions achieved with N. viridazoti strain BR 11145 suggests that inoculants with this bacterium represent a promising biological sink for N₂O, offering a novel nature-based solution to enhance the sustainability of tropical crop management. Full article