Selection and Bioassay of Halotolerant Nitrogen-Fixing Endophytic Bacteria for Promoting Rice Seedlings (Oryza sativa L.) under Saline Conditions

Plant growth promotion of rice (Oryza sativa L.) with root endophytic bacteria, isolated from wild Solanaceous medicinal plants Solanum nigrum L., Solanum sisymbriifolium Lam., and Solanum virginianum L.

Rhizobium spp. strains improve the physiological attributes of Mimosa tenuiflora (Willd.) Poiret seedlings under different water contents

Rhizobium spp. inoculation is a strategy to promote plant growth and enhance drought tolerance, particularly in semiarid environments. This study evaluated the morphological and physiological responses of Mimosa tenuiflora (Willd.) seedlings inoculated with Rhizobium spp. under different water contents. Seeds were collected from 12 naturally growing mother trees (Patos, Paraíba, Brazil). No specific genotype or cultivar was used. A completely randomized experiment was conducted in a 5 × 2 factorial design with four replicates, comprising five treatments (inoculation with three Rhizobium spp. strains: CA19PT, RO19PT, and MK17PT; nitrogen fertilization; and a non-inoculated control) under two water-content levels (40% and 80% of pot capacity). M. tenuiflora seedlings were grown in 3 dm³ pots for 90 days, after which growth, biomass production, nodulation, relative water content (RWC), and gas exchange parameters were evaluated. The results demonstrated that physiological variables were influenced by the treatments and water availability, whereas growth variables were affected only by water availability. Among the evaluated treatments, inoculation with strain CA19PT showed physiological responses comparable to those observed under nitrogen fertilization. Even under low water availability (40% pc, seedlings maintained adequate hydration levels, with an increase in root biomass. Inoculation with selected Rhizobium isolates, particularly CA19PT, improved the physiological performance of M. tenuiflora seedlings under contrasting water-content conditions. Physiological responses observed in seedlings inoculated with CA19PT were comparable to those obtained with nitrogen fertilization. Additionally, seedlings grown under higher water content (80% pc exhibit better overall growth, whereas reducing water content to 40% pcstimulates root growth.

Greenhouse and field evaluation of bacterial endophytes from Cannabis sativa and Chelidonium majus reveals beneficial stage-dependent growth and yield responses in common bean

Bacterial endophytes are increasingly recognized for their ability to enhance plant growth and productivity through multiple physiological and biochemical mechanisms. However, how these responses are coordinated across plant developmental stages and translate into final crop performance remains unclear. This study evaluated previously characterized bacterial endophytes belonging to Bacillus subtilis (BS-114, BS-120) and Pseudomonas wadenswilerensis (PPW-26) as plant growth-promoting agents in yellow bean under in vitro , greenhouse, and field conditions. Bacterial treatments enhanced early developmental responses relative to the non-inoculated control (NC), with BS-114 increasing germination (+19.1%) and seedling total root length (+71.3%), while PPW-26 increased root biomass (+61.7%). Under greenhouse conditions, BS-114 improved reproductive development, increasing bud count (+47.4%), immature pod count (+60.2%), and pod fresh mass (+42.1%). Cell-free extracts reproduced several of these beneficial effects, with the BS-114 cell-free extract (BS-114E) producing the highest cumulative pod fresh mass (+94.2%), suggesting the contribution of extracellular components to reproductive performance. Physiological and gene-expression analyses further indicated that treatment responses were not attributable to a single pathway. Among the measured gas-exchange parameters, photosynthetic rate increased (+175.8%) and stomatal conductance increased (+306.9%). Gene expression analyses showed treatment-specific upregulation of selected genes, with N-fixation-related expression ( nifH ) reaching +5.62 log 2 FC (49.31×) with the BS-114 live-cell treatment (BS-114L), while hormone-related responses were characterized by coordinated upregulation of auxin signaling-related expression +5.24 log 2 FC (37.89×) and cytokinin-related expression patterns consistent with increased biosynthesis and reduced degradation. Field validation showed that all treatments increased yield relative to NC, with the BS-114+BS-120 consortium achieving a +32.65% increase, which was comparable to NPK (+37.76%), despite limited shifts in soil microbial diversity and moderate variation in soil nutrients. Together, these findings indicate that the evaluated bacterial treatments improved plant performance through coordinated responses across multiple biological levels and plant developmental stages, supporting their application as plant growth-promoting agents under controlled and field conditions.

Integration of novel endophytic diazotrophs with reduced nitrogen fertilization improves nitrogen uptake and productivity in sugarcane in subtropical India

Improving drought tolerance in pre-sprouted sugarcane through inoculation with plant growth-promoting bacteria: assessment of biochemical activity, nutrient uptake, and physiological performance

Pre-sprouted sugarcane seedlings are increasingly used to ensure uniform crop establishment; however, their performance is highly constrained by water deficit under climate change scenarios. This research evaluated whether a consortium of Bacillus licheniformis (FMCH001) and Bacillus subtilis (FMCH002) could mitigate drought stress by improving root development, soil microbial activity, and plant nutritional and physiological responses under different water regimes. The experiment was conducted in a randomized block design using a 4 × 2 factorial scheme, with four water regimes (20, 40, 60, and 80% of field capacity) and two inoculation treatments (with and without bacteria), with four replicates. Bacillus inoculation alleviated the adverse effects of water deficit, particularly under severe water restriction (20, 40, and 60% of field capacity), by increasing root length, surface area, volume, and diameter. Inoculated treatments showed higher arylsulfatase, β-glucosidase, acid phosphatase, and urease activities, indicating enhanced soil microbial functioning. These responses were associated with increased leaf concentrations of N, P, K, Ca, Fe, and Zn. Furthermore, inoculated plants exhibited improved photosynthetic performance, including higher PSII efficiency, electron transport rate, net CO 2 assimilation, water use efficiency, and carboxylation efficiency, contributing to better establishment and development throughout the sugarcane growth cycle. Inoculation with Bacillus subtilis and Bacillus licheniformis mitigated the effects of water deficit in pre-sprouted sugarcane seedlings by promoting root development, enhancing soil microbial activity, and increasing nutrient acquisition, thereby improving plant mineral nutrition and photosynthetic performance.

Evaluation of the Azotofertil Biostimulant as a Nitrogen-Based Fertilization Strategy for Solanum lycopersicum L. and Capsicum annuum L.

The continuous growth of the global population and the need to ensure food security require the development of sustainable agricultural technologies capable of maintaining crop productivity while reducing environmental impact. Nitrogen-fixing bacteria belonging to the genera Azotobacter and Azospirillum have attracted increasing interest due to their ability to improve plant nutrition and stimulate physiological processes associated with growth and productivity. The aim of the present study was to evaluate the effect of the commercial biostimulant Azotofertil, based on Azotobacter chroococcum and Azospirillum lipoferum, on the agrophysiological response of tomato and pepper plants, in comparison with conventional nitrogen and phosphorus fertilization. A field experiment was conducted using a randomized block design with three fertilization treatments and three biological replicates for each crop species. Soil pH, cultivable Azotobacter spp. populations, plant height, photosynthetic pigment content, vitamin C content, and total yield were evaluated. Data were analyzed using one-way analysis of variance (ANOVA), followed by Duncan’s multiple range test (p < 0.05) and Pearson correlation analysis. The application of Azotofertil significantly increased the abundance of cultivable Azotobacter spp., photosynthetic pigment content, and vitamin C content, while no statistically significant differences were observed for soil pH or plant height. The most pronounced effect was observed for photosynthetic pigment content, which increased by 26% in tomato and by 21% in pepper compared to the control.