Stimulate Plant Growth Research Articles

Comparative effectiveness of carbon nanoparticles and biochar in alleviating copper stress in corn (Zea mays L.)

The application of carbon nanoparticles (CNPs) and biochar in agriculture for improving plant health and soil quality and alleviating metal stress offers alternative approaches to meet the ever-increasing demand for food. However, poor understanding of their roles in improving crop production under Cu stress represents a significant obstacle to their wide application in agriculture. To clarify how CNPs and biochar affect corn (Zea mays L.) seed germination, seedling growth, plant health, and nutrient uptake under different Cu stress levels, soil-less Petri-dish and greenhouse soil-based bioassays were conducted. The results revealed that CNPs and biochar stimulated corn seed germination and seedling growth. Besides, they were effective in immobilizing Cu2+ sorption in sandy soil and alleviating Cu stress for plant growth, as shown by the increased plant height and dry biomass. The plant nutrient uptake efficiency (NUE) was significantly increased by CNPs, with a maximum increase of 63.1% for N and 63.3% for K at the highest Cu2+ stress level (400 mg Cu2+ L−1). In contrast, non-significant effects on NUE were observed with biochar treatments regardless of Cu stress levels. Interestingly, CNPs significantly increased plant uptake of Cu in the Petri dish test, while biochar inhibited plant uptake of Cu under both experimental conditions. Principle component analysis (PCA) and Pearson correlation analysis indicated that CNPs mitigated Cu stress mainly by elevating antioxidant enzyme activities, enhancing plant photochemical efficiency, and increasing plant uptake of N and K, while biochar was more likely to reduce bioavailability and uptake of Cu in the plant. These findings have great implications for the application of CNPs and biochar as plant growth stimulators and de-toxicity agents in agriculture.

Evaluation of the antimicrobial activity and chickpea growth stimulation effects of green synthesized zinc oxide nanoparticles

Green synthesized nanoparticles are believed to alleviate the detrimental effects of chemical fertilizers and the multidrug resistance of various microbial strains. This study evaluates the use of bush tea-mediated zinc oxide nanoparticles (ZnO NPs) for chickpea fertilization and assesses their cytotoxicity, antioxidant and antibacterial activity. The study demonstrated that the application of ZnO NPs improved the number of leaves, nodules, biomass and yield of chickpea cultivars under glasshouse conditions. The authors suggest that biosynthesized ZnO NPs are a good plant growth stimulant. The control with no nanoparticles application, had higher values of photosynthetic rate and water use efficiency in the Desi genotype whereas for the Kabuli genotype, 25 mg/L showed higher values of stomatal conductance and transpiration efficiency, while 15 mg/L gave the highest water use efficiency and photosynthetic rate. Furthermore, the inhibitory activities of bacteria were reported in which E. coli and S. aureus were the most sensitive bacterial strains. The ZnO NPs also quenched free radicals that demonstrate antioxidant activity. Thus, they can be beneficial to both plants and humans as they reduce oxidative stress that can cause diseases. Furthermore, toxicity to cells was evaluated and ZnO NPs were less toxic to the studied cells with IC50 values of 16.17 µg/mL and 21.30 µg/mL against lung cancer and embryonic cell lines. Thus, the use of ZnO nanoparticles with antimicrobial activity could help fight against several diseases attacking humans and plants.

Glyphosate hormesis stimulates tomato (Solanum lycopersicum L.) plant growth and enhances tolerance against environmental abiotic stress by triggering nonphotochemical quenching.

Glyphosate is the most widely applied herbicide in the world. Hormesis caused by low glyphosate doses has been widely documented in many plant species. However, the specific adaptative mechanism of plants responding to glyphosate hormesis stimulation remains unclear. This study focused on the biphasic relationship between glyphosate dose and tomato plant growth, and how glyphosate hormesis stimulates plant growth and enhances tolerance to environmental stress. We constructed a hormesis model to describe the biphasic relationship with a maximal stimulation (MAX) of 162% above control by glyphosate at 0.063 g ha-1. Low-dose glyphosate increased photosynthetic pigment contents and improve photosynthetic efficiency, leading to plant growth stimulation. We also found that glyphosate hormesis enhanced plant tolerance to diuron (DCMU; a representative photosynthesis inhibitor) by triggering the nonphotochemical chlorophyll fluorescence quenching (NPQ) reaction to dissipate excess energy stress from photosystem II (PSII). Transcriptomic analysis and quantitative real-time polymerase chain reaction results revealed that the photosynthesis-antenna proteins pathway was the most sensitive to glyphosate hormesis, and PsbS (encoding photosystem II subunit S), ZEP (encoding zeaxanthin epoxidase) and VDE (encoding violaxanthin de-epoxidase) involved in NPQ played crucial roles in the plant response to glyphosate hormesis. These results provide novel insights into the mechanisms of plant hormesis and is meaningful to the application of glyphosate hormesis in agriculture. © 2024 Society of Chemical Industry.

UNLOCKING SUSTAINABLE ECO-FRIENDLY AGRICULTURE: THE ROLE OF PEROXIDE OXIDATION TREATED CASSAVA PROCESSING EFFLUENT IN BOLSTERING CELOSIA ARGENTEA GROWTH PARAMETERS

The study investigated effect of peroxide-oxidation-treated wastewater from the hitherto environmentally problematic cassava processing industry on the growth parameters of Celosia argentea. Peroxide-aeration treated cassava processing wastewater was mixed with groundwater at 25, 50, 75 and 100% concentration. Prepared solutions were applied on Celosia to determine its effect on growth and nutritive quality. The treatment was observed to have stimulated plant growth parameters by 18.28±0.03 cm, 3.85±0.02 mm, 23.80±0.11 and 35.70±0.03 mm2 for plant height, stem girth, number of leaves, and leaf area, respectively at 25% treatment concentration after 62 days from planting. Improvement in macro nutrients such as iron (0.95%), calcium (0.52%), potassium (0.03%) and micro nutrients like manganese (9.34%) and copper (1.07%), with no bioaccumulation of heavy metals were recorded. Conclusively, peroxide-aeration treated cassava processing wastewater offers sustainable, eco-friendly water source for irrigation purposes, as well as fertigation potential for cultivation of Celosia argentea.

Serratia spp. as plant growth-promoting bacteria alleviating salinity, drought, and nutrient imbalance stresses.

In agricultural environments, plants are often exposed to abiotic stresses including temperature extremes, salt stress, drought, and heavy metal soil contamination, which leads to significant economic losses worldwide. Especially salt stress and drought pose serious challenges since they induce ionic toxicity, osmotic stress, and oxidative stress in plants. A potential solution can be the application of bacteria of the Serratia spp. known to promote plant growth under normal conditions Thus the mini-review aims to summarize the current knowledge on plant growth promotion by Serratia spp. (under the conditions of salinity stress, drought, and nutrient deficit) and highlight areas for development in the field. So far, it has been proven that Serratia spp. strains exhibit a variety of traits contributing to enhanced plant growth and stress tolerance, such as phytohormone production, ACC deaminase activity, nitrogen fixation, P and Zn solubilization, antioxidant properties improvement, and modulation of gene expression. Nevertheless, further research on Serratia spp. is needed, especially on two subjects: elucidating its mechanisms of action on plants at the molecular level and the effects of Serratia spp. on the indigenous soil and plant microbiota and, particularly, the rhizosphere. In both cases, it is advisable to use omics techniques to gain in-depth insights into the issues. Additionally, some strains of Serratia spp. may be phytopathogens, therefore studies to rule out this possibility are recommended prior to field trials. It is believed that by improving said knowledge the potential of Serratia spp. to stimulate plant growth will increase and strains from the genus will serve as an eco-friendly biofertilizer in sustainable agriculture more often.

Biocompatibility of Brazilian native yeast-derived sophorolipids and Trichoderma harzianum as plant-growth promoting bioformulations

The replacement of agrochemicals by biomolecules is imperative to mitigate soil contamination and inactivation of its core microbiota. Within this context, this study aimed at the interaction between a biological control agent such as Trichoderma harzianum CCT 2160 (BF-Th) and the biosurfactants (BSs) derived from the native Brazilian yeast Starmerella bombicola UFMG-CM-Y6419. Thereafter, their potential in germination of Oryza sativa L. seeds was tested. Both bioproducts were produced on site and characterized according to their chemical composition by HPLC-MS and GC-MS for BSs and SDS-PAGE gel for BF-Th. The BSs were confirmed to be sophorolipids (SLs) which is a well-studied compound with antimicrobial activity. The biocompatibility was examined by cultivating the fungus with SLs supplementation ranging from 0.1 to 2 g/L in solid and submerged fermentation. In solid state fermentation the supplementation of SLs enhanced spore production, conferring the synergy of both bioproducts. For the germination assays, bioformulations composed of SLs, BF-Th and combined (SLT) were applied in the germination of O. sativa L seeds achieving an improvement of up to 30% in morphological aspects such as root and shoot size as well as the presence of lateral roots. It was hypothesized that SLs were able to regulate phytohormones expression such as auxins and gibberellins during early stage of growth, pointing to their novel plant-growth stimulating properties. Thus, this study has pointed to the potential of hybrid bioformulations composed of biosurfactants and active endophytic fungal spores in order to augment the plant fitness and possibly the control of diseases.

CaIAA2-CaARF9 module mediates the trade-off between pepper growth and immunity.

To challenge the invasion of various pathogens, plants re-direct their resources from plant growth to an innate immune defence system. However, the underlying mechanism that coordinates the induction of the host immune response and the suppression of plant growth remains unclear. Here we demonstrate that an auxin response factor, CaARF9, has dual roles in enhancing the immune resistance to Ralstonia solanacearum infection and in retarding plant growth by repressing the expression of its target genes as exemplified by Casmc4, CaLBD37, CaAPK1b and CaRROP1. The expression of these target genes not only stimulates plant growth but also negatively impacts pepper resistance to R. solanacearum. Under normal conditions, the expression of Casmc4, CaLBD37, CaAPK1b and CaRROP1 is active when promoter-bound CaARF9 is complexed with CaIAA2. Under R. solanacearum infection, however, degradation of CaIAA2 is triggered by SA and JA-mediated signalling defence by the ubiquitin-proteasome system, which enables CaARF9 in the absence of CaIAA2 to repress the expression of Casmc4, CaLBD37, CaAPK1b and CaRROP1 and, in turn, impeding plant growth while facilitating plant defence to R. solanacearum infection. Our findings uncover an exquisite mechanism underlying the trade-off between plant growth and immunity mediated by the transcriptional repressor CaARF9 and its deactivation when complexed with CaIAA2.

Trichoderma spp.: characteristics and applications

Trichoderma is the genus of a cosmopolitan fungus, common in different types of environments or agroecosystems. It has different properties that give it beneficial qualities and functions, which is why it is given different uses, for example, as a biocontrol agent, through induced or direct systemic resistance, as a plant growth stimulant, improving the absorption of water and nutrients and producing phytohormones, as a bioremediator, among others. The objective of this work was to compile knowledge of the characteristics of the genre Trichoderma and the different applications it can have

Potential use of Ulva intestinalis-derived biochar adsorbing phosphate ions in the cultivation of winter wheat Tristicum aestivum

In this work, the properties of biochar produced from green macroalga Ulva intestinalis by pyrolysis were studied at temperatures of 300, 500, and 700 °C. This biochar was characterized in terms of multielemental composition, BET surface area, total pore volume, and biosorption properties toward phosphate ions. Biochar produced at 700 °C–25 m2/g had the highest surface area. The kinetics and isotherms of sorption processes of phosphate ions as sorbate by these sorbents were investigated. Modified biochar was able to remove 84.3% of phosphate ions from wastewater, whereas non-modified biochar—only 40.6%. Hence, biochar enriched with phosphate ions can serve as a valuable soil amendment. Pot experiments performed on winter wheat (Triticum aestivum) with a 3% addition of dry Ulva intestinalis, pristine biochar, and Mg-modified biochar enriched with phosphate ions showed that these amendments stimulated plant growth (length and fresh weight of plants) as well as enlarging the chlorophyll content in leaves. Our results indicate that the production of biochar (pristine and Mg-impregnated) is a sustainable option to valorize the biomass of seaweeds, and to recycle phosphorus from wastewater.Graphical

Influence of preparations on photosynthetic activity of brewing barley (Hordeum vulgare L.) plants and quality indicators of grain

Plant growth regulators and microfertilizers stimulate the accumulation of chlorophyll by plants, increase the photosynthetic activity of chloroplasts and the net productivity of photosynthesis, and contribute to increasing the resistance of crops to diseases and adverse environmental factors. The aim of the work was to study the effect of preparations on the photosynthetic activity the plants of spring barley varieties in order to achieve the proper quality of the grown products. In the research, barley plants of the spring brewing direction of the varieties Sebastian (Seyet Planteforedling I/S, Denmark) and Salomi (SAATEN Union, France) were used, which were treated with plant growth stimulator Vimpel 2, complex microfertilizer ORACUL multicomplex, a mixture of Vimpel 2 + ORACUL multi-complex and control area — water treatment. The article presents the results that show that the content of the sum of chlorophylls a and b in spring barley leaves under the influence of preparations Vimpel 2 and ORACUL multicomplex plays a major role in increasing the productivity of the crop. Accumulation of protein and starch in spring barley grains is one of the most important indicators for growing varieties of brewing value. In all variants of the study, the accumulation of protein in the grain turned out to be within acceptable limits for malting barley (8.75–10.02%), only in the control variant it remained too low. The use of preparations Vimpel 2 and ORACUL multicomplex in a mixture contributes to the accumulation of starch in spring barley grains of both studied varieties. At the same time, treatment with only growth promoter or only micro-fertilizer stimulates the accumulation of starch in the grain compared to the control, but remains at a low level for the brewing industry. The most active growth of the assimilation surface of spring barley plants in all phases of growth was observed after treatment with Vimpel 2 mixture in combination with ORACUL multicomplex. The conducted studies established a significant influence of microfertilizers and growth stimulants on the photosynthetic potential of spring barley crops. During the entire vegetation period of spring barley, the highest photosynthetic potential of crops (FPP) — 859.2 m2/ha×day was determined in the Sebastian variety with the addition of microfertilizer and growth stimulator. The high-quality work of the leaf apparatus of plants is determined by the net productivity of photosynthesis (NPP). The highest PPF index was observed on the Sebastian variety in the variant treated with a mixture of microfertilizer and growth stimulator, which is 27% higher than in the control variant. Therefore, spring barley grain of the required quality can be obtained only under the conditions of optimal combination of the use of preparations of different spectrum of action.

MCNTs/ZnO nanocomposite-fabricated nanosensor for 1-naphthyleacetic acid electroanalysis and its applications

Zinc oxide nanoparticles and multiwalled carbon nanotubes were mixed to create a novel carbon paste electrode known as MCNTs/ZnO/CPE—a substance that stimulates plant growth. This electrode was designed to investigate the effects of NAA. Various techniques, including cyclic voltammetry (CV) and square wave voltammetry (SWV), were employed to assess the stability and electrochemical properties of the MCNTs/ZnO/CPE electrode. The study aimed to examine the electrochemical behavior of NAA on MCNTs/ZnO/CPE to investigate its potential application in plant development. The experiment results provided valuable insights into the complementary effects of NAA and the electrode materials, paving the way for future advances in plant bioelectrochemistry. At a pH of 3.0, the more significant peak current indicates the effective electron transfer between the PB solution and the MCNTs/ZnO/CPE sensor. The sensor's outstanding catalytic activity at this pH further suggests its potential for various electrochemical applications. Actual samples, such as water, fruits, vegetables, and soil, were analyzed using the SWV method. ZnO/CPE, bare CPE, MCNTs/CPE, and MCNTs/ZnO/CPE all had peak currents of 4.044 µA, 10.40 µA, 12.91 µA, and 16.52 µA, respectively. The peak potentials for bare CPE, ZnO/CPE, MCNTs/CPE, and MCNTs/ZnO/CPE were all found to be 1.19 V, 1.19 V, 1.18 V, and 1.15 V, respectively. All the experiments were carried out at 25 s of optimum accumulation time. The detection limit was determined to be 1.1 nM, and the linear range is 0.2 × 10−8 to 7.0 × 10−6 M. The surface area of the unmodified CPE was determined to be 0.04 cm2, whereas the surface area of the modified CPE was determined to be 0.13 cm2. The mean value of the rate constant (ks) for the anodic reaction was 2.8 × 10−3 cm s−1. In addition to electro-kinetic factors like the effect of temperature and the heterogeneous rate constant, the electro-oxidation of NAA was examined about several parameters, including electron contribution, accumulation duration, pH, energy of activation, scan rate, and transfer coefficient.

Foliar Application of Tropical Trees Leaf Extract for Improve Growth and Yield of Blackgram [Vigna mungo (L). Hepper

Blackgram (Vigna mungo L.), the most important pulse crop is grown throughout India. The productivity of blackgram in India is relatively low compared to the world's average productivity. Nowadays for improving productivity foliar spraying of nutrients plays a major role. The available synthetic formulations for foliar spraying are polluting and highly expensive. Hence, the leaf extracts of tropical trees can be utilized as an alternative source since they have enormous bioactive compounds able to stimulate plant growth and improve productivity without any harmful effects. Therefore, the present study was conducted on a sandy loam farm of The Indian Agriculture College, Radhapuram from March 2023 to May 2023 to evaluate the effect of leaf extracts like Moringa oleifera (Moringa), Annona squamosa (Custard apple) and Nerium oleander (Nerium) at different concentration viz., 5% and 10% on cultivation of blackgram crop, variety VBN 8. The results revealed that foliar spraying of Moringa oleifera leaf extract @ 10% + RDF significantly improves the growth components like plant height (27.87 cm and 34.6 cm at 35 DAS and 50 DAS respectively), LAI (2.87 and 4.06 at 35 DAS and 50 DAS respectively), dry matter accumulation (141 g/m2 and 266 g/m2 at 35 DAS and 50 DAS respectively), Crop growth rate (5.77 and 8.33 g/m2/day at 20 to 35 DAS, 35 to 50 DAS respectively), Relative Growth Rate (0.064, 0.042 g/g/day at 20 to 35 DAS, 35 to 50 DAS respectively) and yield attribute like average number of pods per plant (36.9) and seed yield (648 kg/ha) over other treatments and it was on par with RDF + Foliar application of Custard apple leaf extract @ 10%.

Dynamic root microbiome sustains soybean productivity under unbalanced fertilization

Root-associated microbiomes contribute to plant growth and health, and are dynamically affected by plant development and changes in the soil environment. However, how different fertilizer regimes affect quantitative changes in microbial assembly to effect plant growth remains obscure. Here, we explore the temporal dynamics of the root-associated bacteria of soybean using quantitative microbiome profiling (QMP) to examine its response to unbalanced fertilizer treatments (i.e., lacking either N, P or K) and its role in sustaining plant growth after four decades of unbalanced fertilization. We show that the root-associated bacteria exhibit strong succession during plant development, and bacterial loads largely increase at later stages, particularly for Bacteroidetes. Unbalanced fertilization has a significant effect on the assembly of the soybean rhizosphere bacteria, and in the absence of N fertilizer the bacterial community diverges from that of fertilized plants, while lacking P fertilizer impedes the total load and turnover of rhizosphere bacteria. Importantly, a SynCom derived from the low-nitrogen-enriched cluster is capable of stimulating plant growth, corresponding with the stabilized soybean productivity in the absence of N fertilizer. These findings provide new insights in the quantitative dynamics of the root-associated microbiome and highlight a key ecological cluster with prospects for sustainable agricultural management.

Theoretical study of the working body of a centrifugal type mixing plant

Relevance. The use of fertilizers in the agro-industrial complex is an important means to ensure sustainable development, food and environmental security. The scientific application of various types of fertilizers can reduce the negative impact on natural ecosystems, as well as optimize the use of resources and take into account the individual needs of each plant. Due to the balanced composition and biological modification by chelate complexes, fertilizer mixture has increased biological efficiency and stimulate plant growth. At the same time, there is an urgent task of obtaining mixtures that have a high degree of uniformity. In this connection, the requirements for the mixing equipment are very high, since the structural and kinematic parameters are the most important factors affecting the stability of the mixing process and the uniformity of the final mixture.Methods. Based on the analysis of existing mixing plants, the authors proposed the concept of a centrifugal type mixing plant with a working body in the form of a conical surface. In the course of the research, the processes occurring during the operation of the working body, the proposed centrifugal mixer, were studied using methods of mathematical analysis, graphical and mathematical modelling.Results. As a result of the research, it was found that the greatest influence on the change in the absolute velocity of the granules is exerted by the circumferential velocity of the granules, which is largely determined by the rotation frequency and parameters of the conical surface. In turn, it was found that over time, the angle between the direction of the absolute velocity of the fertilizer granules and the forming conical surface tends to the direction of the circumferential velocity, while with increasing rotation frequency, this indicator changes more rapidly.

Sustainable agriculture through rhizosphere bacteria for plant growth promotion, nutrient acquisition, and stress alleviation

Rhizosphere bacteria are attracting a lot of interest in sustainable agriculture because of their capacity to stimulate plant growth, improve nutrient uptake, and reduce stress in plants. A review of recent discoveries in the field of using rhizosphere bacteria for these advantageous agricultural techniques is given in this article. Rhizosphere bacteria facilitate plant growth by solubilizing inaccessible elements like phosphorus, potassium, zinc, and manganese by producing a variety of enzymes and organic acids. Furthermore, these bacteria support plant nutrition by fixing atmospheric nitrogen, a necessary component for plant growth and development. Moreover, some rhizosphere bacterial strains can inhibit plant diseases, which lessen the need for artificial chemical pesticides. Rhizosphere bacteria have improved plant stress tolerance by producing stress-related substances, including phytohormones and osmoprotectants. These bacteria also give rise to systemic resistance in plants, successfully allowing them to survive various biotic and abiotic challenges. Concerning climate change and environmental variations, this rhizosphere bacteria-mediated stress reduction component holds a tremendous potential for sustainable agriculture. But for rhizosphere bacteria-based agricultural techniques to be successfully utilized, a thorough grasp of their variety, ecological relationships, and mode of action are necessary. Optimizing application techniques, formulating bioinoculants, and considering environmental aspects are crucial for consistent and dependable outcomes through rhizosphere bacteria.

Effects of Coconut Water and Banana Homogenate on Shoot Regeneration of Meyer Lemon (Citrus × meyeri)

Meyer lemon (Citrus × meyeri) is a hybrid citrus fruit from the Rutaceae family, originating from China. It is well-known for its distinctive appearance and flavor, as well as its health-nourishing nutrients. Micropropagation is an efficient alternative in the multiplication of plant stocks suitable for the commercial scale. The inclusion of organic additives in culture media has been found to provide a cost-effective option as a plant growth stimulant for in vitro plant development. The current study intends to assess the effects of coconut water and banana homogenate in the regeneration of Meyer lemon. In vitro, shoots were treated in half-strength Murashige and Skoog media fortified with 2 mg/L 6-benzylaminopurine with varying concentrations of coconut water and banana homogenate without sucrose. Results revealed that the treatment of 30% coconut water and 40 g/L banana homogenate resulted in the greatest proliferation of new shoots (3.00 ± 0.873 and 1.57 ± 0.297, respectively), whereas treatment of 40% coconut water resulted in the greatest shoot elongation of 0.239 ± 0.026 cm. The current study suggested the incorporation of coconut water and banana homogenate as potential substitutes for carbon sources and growth stimulants in the regeneration of Meyer lemon.

Trichoderma cf. asperellum and plant-based titanium dioxide nanoparticles initiate morphological and biochemical modifications in Hordeum vulgare L. against Bipolaris sorokiniana

BackgroundSpot blotch is a serious foliar disease of barley (Hordeum vulgare L.) plants caused by Bipolaris sorokiniana, which is a hemibiotrophic ascomycete that has a global impact on productivity. Some Trichoderma spp. is a promising candidate as a biocontrol agent as well as a plant growth stimulant. Also, the application of nanomaterials in agriculture limits the use of harmful agrochemicals and helps improve the yield of different crops. The current study was carried out to evaluate the effectiveness of Trichoderma. cf. asperellum and the biosynthesized titanium dioxide nanoparticles (TiO2 NPs) to manage the spot blotch disease of barley caused by B. sorokiniana and to assess the plant’s innate defense response.ResultsAloe vera L. aqueous leaf extract was used to biosynthesize TiO2 NPs by reducing TiCl4 salt into TiO2 NPs and the biosynthesized NPs were detected using SEM and TEM. It was confirmed that the NPs are anatase-crystalline phases and exist in sizes ranging from 10 to 25 nm. The T. cf. asperellum fungus was detected using morphological traits and rDNA ITS analysis. This fungus showed strong antagonistic activity against B. sorokiniana (57.07%). Additionally, T. cf. asperellum cultures that were 5 days old demonstrated the best antagonistic activity against the pathogen in cell-free culture filtrate. Also, B. sorokiniana was unable to grow on PDA supplemented with 25 and 50 mg/L of TiO2 NPs, and the diameter of the inhibitory zone increased with increasing TiO2 NPs concentration. In an in vivo assay, barley plants treated with T. cf. asperellum or TiO2 NPs were used to evaluate their biocontrol efficiency against B. sorokiniana, in which T. cf. asperellum and TiO2 NPs enhanced the growth of the plant without displaying disease symptoms. Furthermore, the physiological and biochemical parameters of barley plants treated with T. cf. asperellum or TiO2 NPs in response to B. sorokiniana treatment were quantitively estimated. Hence, T. cf. asperellum and TiO2 NPs improve the plant’s tolerance and reduce the growth inhibitory effect of B. sorokiniana.ConclusionSubsequently, T. cf. asperellum and TiO2 NPs were able to protect barley plants against B. sorokiniana via enhancement of chlorophyll content, improvement of plant health, and induction of the barley innate defense system. The present work emphasizes the major contribution of T. cf. asperellum and the biosynthesized TiO2 NPs to the management of spot blotch disease in barley plants, and ultimately to the enhancement of barley plant quality and productivity.

Mitigation of salt stress in lettuce by a biostimulant that protects the root absorption zone and improves biochemical responses.

Horticultural crops constantly face abiotic stress factors such as salinity, which have intensified in recent years due to accelerated climate change, significantly affecting their yields and profitability. Under these conditions, it has become necessary to implement effective and sustainable solutions to guarantee agricultural productivity and food security. The influence of BALOX®, a biostimulant of plant origin, was tested on the responses to salinity of Lactuca sativa L. var. longifolia plants exposed to salt concentrations up to 150 mM NaCl, evaluating different biometric and biochemical properties after 25 days of treatment. Control plants were cultivated under the same conditions but without the biostimulant treatment. An in situ analysis of root characteristics using a non-destructive, real-time method was also performed. The salt stress treatments inhibited plant growth, reduced chlorophyll and carotenoid contents, and increased the concentrations of Na+ and Cl- in roots and leaves while reducing those of Ca2+. BALOX® application had a positive effect because it stimulated plant growth and the level of Ca2+ and photosynthetic pigments. In addition, it reduced the content of Na+ and Cl- in the presence and the absence of salt. The biostimulant also reduced the salt-induced accumulation of stress biomarkers, such as proline, malondialdehyde (MDA), and hydrogen peroxide (H2O2). Therefore, BALOX® appears to significantly reduce osmotic, ionic and oxidative stress levels in salt-treated plants. Furthermore, the analysis of the salt treatments' and the biostimulant's direct effects on roots indicated that BALOX®'s primary mechanism of action probably involves improving plant nutrition, even under severe salt stress conditions, by protecting and stimulating the root absorption zone.

Complete genome sequences of Rhizobium sp. strain SL42 and Hydrogenophaga sp. strain SL48, microsymbionts of Amphicarpaea bracteata

This study comprehensively analyzed two distinct rhizobacterial strains, Rhizobium sp. SL42 and Hydrogenophaga sp. SL48, through whole genome de novo sequencing. Isolated from root nodules of Amphicarpaea bracteata, a native legume related to soybean, they were selected to explore beneficial rhizobacteria from native plant relatives. Utilizing Illumina and Nanopore sequencers and MaSuRCA assembly, their complete genetic information was elucidated. Rhizobium sp. SL42 has a 4.06 Mbp circular chromosome and two plasmids with 60% GC content, while Hydrogenophaga sp. SL48 exhibits a 5.43 Mbp circular chromosome with 65% GC content. Genetic analysis identified them as new species, supported by ANI values (77.72% for SL42 and 83.39% for SL48) below the threshold. The genomic analysis unraveled a plethora of genes encoding diverse metabolic functions, secretion systems for substance transport, quorum sensing for coordination, and biosynthetic gene clusters suggesting the production of bioactive compounds. These functional properties contribute to plant growth stimulation, reflecting the symbiotic relationship of rhizobacteria with plants, potentially involving nitrogen fixation and growth-promoting compounds. This research contributes valuable knowledge about plant-microbe interactions and plant growth promotion by these two strains of rhizobacteria.

Silver nanoparticles and silver/silica nanocomposites: Impacts on Z. mays L. growth, nutrient uptake and soil health

Although silver nanoparticles (Ag NPs) are widely employed in diverse industries, including agriculture, concerns about their adverse effects on plants at higher concentrations prompt exploration of alternatives, such as Ag/SiO2 NCs. Adding nano SiO2 is anticipated to create a complex with Ag+ ions, potentially decreasing their release into the environment and mitigating toxicity. The potential of Ag/SiO2 NCs as plant growth stimulants remains understudied to date. In this context, the study evaluates the impact of Ag/SiO2 NCs on 30-day-old Z. mays plants compared to Ag NPs at 100 and 200 ppm concentrations and on soil health. Soil health analysis revealed that both Ag NPs and Ag/SiO2 NCs supported the proliferation of P-solubilizing and N-fixing bacteria. Bioaccumulation analysis reveals higher Ag content in plants treated with Ag/SiO2 NCs, attributed to reduced agglomeration. Ag NPs exhibited concentration-dependent toxicity as 200 ppm hindered Z. mays growth, chlorophyll levels and absorption of P, Mg and K, whereas 100 ppm was found to be stimulatory. In stark contrast, Ag/SiO2 NCs demonstrated a remarkable capacity to mitigate Ag toxicity. The beneficial impact of Ag/SiO2 NCs on growth metrics, chlorophyll levels, lipid peroxidation, antioxidant enzyme activity and nutrient absorption was observed at both 100 and 200 ppm. However, it was more pronounced at 100 ppm concentration. This suggests that incorporating SiO2 in NCs may counteract the toxic effects of Ag, possibly through the complexation of Ag+ and a slower release mechanism.