Site-Specific Efficacy of Microbial Inoculants on Sunflower Development and Soil Metabolic Activity in Open-Field Trials

Combined microbial inoculation improves plant growth, nutrient acquisition, and soil biological functioning in Opuntia ficus-indica under water deficit

Exploring the Influence of Biofertilizer on Early Plant Growth in A Hydroponic System

Hydroponics provides an efficient alternative to soil-based cultivation by conserving water, minimizing soil-borne diseases, and addressing land constraints. Coco peat serves as an effective growth medium due to its favorable aeration and moisture retention properties, while plant growth-promoting bacteria (PGPB) such as Phosphate-Solubilizing Bacteria (PSB) and Azotobacter are known to enhance nutrient availability through biological mechanisms. The present study investigates the influence of coco peat enriched with PGPB on early-stage plant growth under hydroponic conditions. PSB and Azotobacter were applied individually and as a consortium using seed coat and spray methods to evaluate their effects during the initial stages of plant development. PSB facilitates the solubilization of inorganic phosphates, whereas Azotobacter contributes to nitrogen fixation, potentially supporting early seedling establishment. The experiment was conducted in a controlled hydroponic setup over a short duration, and growth-related physical parameters indicative of early plant response were monitored. The results revealed that the consortium treatment exhibited enhanced early-stage growth parameters compared to individual applications across both treatment methods. The observed improvement in seedling performance suggests an interaction between PSB and Azotobacter during the initial growth phase. As this study represents a preliminary, short-term assessment, conclusions regarding long-term plant performance, crop yield, or reduction in chemical fertilizer dependency would require further experimentation and confirmation of results. However, the findings provide foundational insights into microbial-assisted early growth responses in hydroponic systems and highlight the need for extended-duration and field-scale studies to evaluate long-term agronomic implications.

Synergistic Effects of Organo-Mineral Fertilization and Phosphorus-Solubilizing Bacteria on Soil Biological Activity and Eggplant Growth in Calcareous Soil

This study was conducted to investigate the effects of a commercial microbial fertilizer containing Bacillus megaterium, Pantoea agglomerans and Pseudomonas fluorescens on soil biological properties and plant growth during eggplant (Solanum melongena L.) cultivation under greenhouse conditions in calcareous soils. While 70% of the phosphorus (P) requirement was supplied via fertigation, the remaining 30% was provided through organo-mineral basal fertilization at four reduction levels (0%, 25%, 50%, 100%) combined with microbial inoculation. Soil samples collected prior to the experiment and at 4 different growth stages were analyzed for physical, chemical, and biological properties, while plant samples collected at the end of the harvest were evaluated for pomological and physiological traits. The results indicated that microbial treatments substantially enhanced soil biological activity. Specifically, the full-dose P + microbial treatment (100+) produced the highest urease, alkaline phosphatase, β-glucosidase activities, and total bacterial count. The 100+ treatment also yielded the most pronounced improvements in soil EC, organic matter, total nitrogen, and available P. Plant parameters, including fruit length, peduncle length, dry biomass, soluble solids content, and chlorophyll concentrations, responded positively to P–microbial combinations. The highest leaf phosphorus concentration was obtained from the 100+ treatment, while the maximum total yield was achieved in both the 100 and 100+ treatments. These findings demonstrate that microbial inoculants create a strong synergy with mineral fertilization by enhancing P bioavailability and nutrient use efficiency. Consequently, it was determined that an integrated microbial-chemical fertilization strategy is an effective method for sustainable eggplant production in calcareous soils.

Agronomic, Biochemical and Metabolic Responses of Tomato to Vermicompost and Mineral Fertilization in Loam and Clay Soils

The intensive use of mineral fertilizers in horticultural systems has improved crop productivity but also increased concerns regarding soil degradation and environmental sustainability. In this context, vermicompost derived from buffalo manure may represent a sustainable alternative for nutrient management and organic waste valorization. This study evaluated the effects of four fertilization strategies on tomato (Solanum lycopersicum L.) grown in loam and clay soils: unfertilized control, mineral fertilization, vermicompost applied at an equivalent nitrogen rate, and the residual effect of vermicompost from a previous cauliflower crop. Agronomic performance, fruit quality, carbon and nitrogen metabolism, and antioxidant-related traits were assessed. Mineral fertilization produced the highest marketable yield, reaching 9.68 and 7.69 kg m−2 in loam and clay soils, respectively, mainly through increased fruit number. Direct vermicompost application maintained substantial productivity, with yields of 7.55 and 5.18 kg m−2 in the two soils. The fertilization strategies also induced distinct changes in fruit composition. Mineral fertilization increased total free amino acids to approximately 160 mg g−1 DW, mainly through the accumulation of glutamine, glutamate, asparagine and γ-aminobutyric acid, but was associated with lower soluble solids and antioxidant activity. Vermicompost promoted the highest lycopene concentration, approximately 2.1 mg g−1 DW, in clay soil and maintained intermediate antioxidant activity and amino acid concentrations. Soil texture also influenced carbohydrate partitioning, with greater fructose accumulation in clay soil and greater starch accumulation in loam soil. The residual vermicompost treatment alone did not adequately sustain tomato productivity or metabolic activity, particularly in clay soil. Overall, vermicompost partially replaced mineral fertilization while maintaining satisfactory yield and modulating fruit metabolic quality, although its effectiveness depended strongly on soil texture.

Growth and Physiological Responses of Petunia to Chitosan and Arbuscular Mycorrhizal Fungi Under Sustained Water Content Reduction

Reducing irrigation inputs is essential for sustainable container crop production; however, the ability of biostimulants to mitigate the effects of deficit irrigation on ornamental crop quality and postharvest often may be crop-specific, product-specific, and application-specific. Two independent experiments were conducted to evaluate whether chitosan applied as a substrate amendment or arbuscular mycorrhizal fungi (AMF) applied during germination could improve growth, physiology, and postharvest performance of petunia ( Petunia milliflora ‘Picobella TM Pink’) under sustained water content reduction. Plants were grown under three container capacity (CC) treatments (100%, 70%, and 40%) combined with chitosan application timing (no application, week 1, or week 3) or AMF application (with or without). After production, plants were exposed to postharvest environments at 30 °C or 40 °C for 2 weeks. The growth index and canopy area decreased by 10% to 40% relative to plants grown at 100% CC under 70% and 40% CC; however, flower coverage percentage remained unaffected during production. Water use reduced by 20% at 70% CC and by up to 50% at 40% CC, while irrigation water use efficiency (IWUE) was maintained with all CC treatments. In the AMF experiment, plants grown at 40% CC with AMF exhibited the highest IWUE and increased root colonization under severe deficit irrigation. Photosynthetic pigment concentrations were generally maintained under deficit irrigation, whereas malondialdehyde concentrations temporarily increased at week 4 under 40% CC, indicating increased oxidative stress. Neither chitosan nor AMF consistently enhanced plant growth or reduced biochemical stress indicators under the evaluated conditions. Chitosan application timing strongly influenced plant responses, with week 3 applications reducing growth and increasing oxidative stress across CC treatments. During the postharvest evaluation, temperature was the primary factor affecting plant performance, with plants maintained at 40 °C exhibiting lower flower coverage and canopy area compared with plants maintained at 30 °C. The combination of deficit irrigation and chitosan application showed limited potential to improve postharvest heat tolerance, whereas AMF application did not improve postharvest performance. Overall, petunia demonstrated substantial tolerance to sustained deficit irrigation, and 70% CC appeared to be a practical strategy for reducing irrigation inputs while maintaining marketable crop quality.

Rhizosphere Engineering Using a Native Pseudomonas veronii Improves Soil Functioning in Degraded Calcisol

The degradation of Calcisols in the arid regions of Central Asia constrains sustainable agricultural production because of low organic matter content, poor aggregate stability, nutrient limitations, and increasing climatic stress. This study evaluated a rhizosphere engineering approach based on the native plant growth-promoting bacterium Pseudomonas veronii Ps-S/Sh-1503/2022 for the rehabilitation of degraded Calcisols. Four-year field experiments (2022–2025) using Sorghum bicolor assessed plant growth, rhizosphere microbial indicators, physiological responses, pathogen suppression, crop productivity, and implementation feasibility through economic and environmental assessments. Inoculation with P. veronii increased root depth by 45%, improved aboveground biomass, increased the ratio of culturable bacteria to Fusarium spp. from 6.1 to 10.3, and reduced Fusarium abundance by 29.4%. Structural equation modeling suggested that trophic support (42.1%), aggregate stabilization (27.4%), biocontrol (23.3%), and defense-related responses (7.2%) were the principal pathways associated with soil rehabilitation. Economic assessment indicated that the combined inoculation and mineral fertilization treatment provided the highest profitability, while environmental assessment estimated potential reductions in mineral fertilizer use and greenhouse gas emissions. These findings suggest that rhizosphere engineering using a native P. veronii strain represents a promising, economically viable, and climate-smart approach for improving the biological functioning of degraded Calcisols and supporting sustainable agricultural production.