Biostimulant Potential Research Articles

Biostimulant potential of two agrochemical tolerant microalgae isolated from subtropical clay soil

Biostimulant potential of two agrochemical tolerant microalgae isolated from subtropical clay soil

Physiological Effects and Mechanisms of Chlorella vulgaris as a Biostimulant on the Growth and Drought Tolerance of Arabidopsis thaliana.

Microalgae have demonstrated biostimulant potential owing to their ability to produce various plant growth-promoting substances, such as amino acids, phytohormones, polysaccharides, and vitamins. Most previous studies have primarily focused on the effects of microalgal biostimulants on plant growth. While biomass extracts are commonly used as biostimulants, research on the use of culture supernatant, a byproduct of microalgal culture, is scarce. In this study, we aimed to evaluate the potential of Chlorella vulgaris culture as a biostimulant and assess its effects on the growth and drought tolerance of Arabidopsis thaliana, addressing the gap in current knowledge. Our results demonstrated that the Chlorella cell-free supernatant (CFS) significantly enhanced root growth and shoot development in both seedlings and mature Arabidopsis plants, suggesting the presence of specific growth-promoting compounds in CFS. Notably, CFS appeared to improve drought tolerance in Arabidopsis plants by increasing glucosinolate biosynthesis, inducing stomatal closure, and reducing water loss. Gene expression analysis revealed considerable changes in the expression of drought-responsive genes, such as IAA5, which is involved in auxin signaling, as well as glucosinolate biosynthetic genes, including WRKY63, MYB28, and MYB29. Overall, C. vulgaris culture-derived CFS could serve as a biostimulant alternative to chemical products, enhancing plant growth and drought tolerance.

Isolation and Selection of Protein-Rich Mutants of Chlorella vulgaris by Fluorescence-Activated Cell Sorting with Enhanced Biostimulant Activity to Germinate Garden Cress Seeds.

Microalgae are a promising feedstock with proven biostimulant activity that is enhanced by their biochemical components (e.g., amino acids and phytohormones), which turns them into an appealing feedstock to reduce the use of fertilisers in agriculture and improve crop productivity and resilience. Thus, this work aimed to isolate protein-rich microalgal mutants with increased biostimulant activity. Random mutagenesis was performed with Chlorella vulgaris, and a selection of protein-rich mutants were sorted through fluorescence-activated cell sorting (FACS), resulting in the isolation of 17 protein-rich mutant strains with protein contents 19-34% higher than that of the wildtype (WT). Furthermore, mutant F4 displayed a 38%, 22% and 62% higher biomass productivity, growth rate and chlorophyll content, respectively. This mutant was then scaled up to a 7 L benchtop reactor to produce biomass and evaluate the biostimulant potential of this novel strain towards garden cress seeds. Compared to water (control), the germination index and the relative total growth increased by 7% and 19%, respectively, after the application of 0.1 g L-1 of this bioproduct, which highlights its biostimulant potential.

The Biostimulant Potential of Clove Essential Oil for Treating Soybean Seeds

Increasing soybean productivity can be achieved by treating seeds with biostimulants. To this end, an investigation was conducted into the potential of a formulation prepared with clove es-sential oil (CEO) diluted in soybean oil for seed treatment. Soybean seeds were treated with CEO concentrations between 0.5 to 3.0 mL/L, and subjected to germination, vigor, and sanity analyses. The CEO at 1.6 mL/L exhibited favorable outcomes regarding germination, root length, and re-duced fungal infection. In this way, a two-crop field experiment evaluated soybean seeds treated with CEO at 1.6 mL/L. Soybean seeds treated with CEO in the field in 2021/2022 were not different from the controls. However, in 2019/2020, there was a higher percentage of emergence, nodulation, and production of 749 kg/ha more than in the industrial treatment. These results highlight the potential use of CEO as a biostimulant.

Evaluation of Various Inoculation Methods on the Effect of Beauveria bassiana on the Plant Growth of Kiwi and on Halyomorpha halys Infestation: A Two-Year Field Study.

In this study, the bioinsecticidal action of a commercial formulation with Beauveria bassiana was evaluated on the new sucking pest in Greece: Halyomorpha halys, of the kiwifruit. Additionally, the biostimulant potential of the same formulation was studied on kiwi growth. The application was performed in three different ways in a commercial field of kiwi crop A. deliciosa "Hayward" field in Arta, Greece: (i) trunk spray, (ii) root injection, and (iii) trunk inoculation. During the 2 years seasons of the experiment, weekly measurements of the H. halys population were determined. The insect is sucking plants nutrients; therefore, the total chlorophyll content in the leaves of the treatments was recorded weekly. In addition, the percentage of infested kiwifruits was estimated at the end of the experiment. Moreover, to study the biostimulant potential of the formulation, growth measurements on stems and leaves were performed during the experiment. Finally, at the kiwi harvest point, the fruit biomass, dimensions, and weight were obtained, and the leaves' proline content was evaluated. The results encourage us to further study this EPF formulation as the bioinsecticidal effect was noted by the reduction in H. halys population, and biostimulant action was perceived by the higher plant biomass.

In-depth metabolite characterization of seaweed-based plant biostimulants: Insights into bioactive components

Biostimulants derived from Kappaphycus alvarezii are renowned for sustainable agricultural enhancement, yet the exploration of numerous other tropical algae remains uncharted. This study aimed to unravel the metabolite diversity, bioactivities, and potential plant biostimulant properties of extracts derived from Kappaphycus alvarezii (KAE), Gracilaria debilis (GDE), and Sargassum cinctum (SCE). Two-year field trials showcased a significant boost in maize grain yields, indicating the biostimulant potential of each extract.Application of 7.5 % seaweed extract concentration substantially increased grain yields by 32 %, 29 %, and 31 % over the control for KAE, GDE, and SCE in the first-year trial and by 31 %, 28 %, and 32 % in the second year. Even a lower concentration of 2.5 % resulted in an increase in grain yield over the control. High-resolution chromatographic techniques coupled with tandem mass spectrometry (MS/MS) revealed 198, 202, and 191 compounds in KAE, GDE, and SCE, respectively. GC–MS profiling further unveiled 23, 21, and 12 metabolites, respectively. The extracts from red and brown seaweeds harbored distinct metabolites with low similarities to each other. These extracts contained a spectrum of compounds, including glycerol, glycine, valine, ellagic acid, cromakalim, genistein, 1,4-β-d-glucan, polyamines, n1-acetylspermine, mannose, propionic acid, benzoic acid, glycine, coumaric acid, hydroxycinnamic acids, and resveratrol. These compounds, known for their potent bio-stimulatory properties in various crops when applied exogenously in pure forms. This study transcends the conventional understanding of seaweed extract efficacy by shedding light on lesser-known metabolites which might have potential biostimulant roles. In contrast to the well-established components traditionally associated with seaweed extracts, this exploration highlights the need to test the biological activities of several other overlooked compounds spanning diverse classes.

Unlocking the potential of Euglena gracilis cultivated in piggery wastewater: biomass production, nutrient removal, and biostimulant potential in lettuce and tomato plants

Unlocking the potential of Euglena gracilis cultivated in piggery wastewater: biomass production, nutrient removal, and biostimulant potential in lettuce and tomato plants

The fate and biostimulant potential of metal lactates in silt loam soil

AbstractConventional farming practices have negatively impacted micronutrient fertility and overall soil health. Metal lactates are an organic micronutrient amendment that provide both a labile carbon substrate as well as mineral nutrition for plant and microbial growth. To determine the ability of metal lactates to provide readily available micronutrients, Zn, Cu, Mn, Ni, and Co in lactate and chloride salt form were amended to soils and incubated for 28 days. Operationally defined speciation was determined using sequential extraction on samples incubated for 1, 5, or 28 days. The results show a comparable distribution of metals in chloride and lactate form; however, differences were detected in water‐soluble and exchangeable Ni and Zn at each timepoint. For example, in the water exchangeable fraction, there was 2.6%–2.9% less Ni and 0.2%–0.3% less Zn in the metal lactate‐treated soil compared to soil treated with metal chlorides. Furthermore, carbonate‐bound Ni averaged 4.1% and 4% less in metal lactate‐treated soils as compared to metal chloride‐treated soils on days 1 and 5, and Cu decreased 2.9%–3.3% during the treatment period for the lactate‐bound form. Additionally, microbial phospholipid fatty acid (PLFA) was performed and found a stimulatory effect of metal lactates on bacterial biomass with an increase of 12%–18% relative to the metal chloride treatment. Results from this study support the use of metal lactates as a sustainable alternative to conventional fertilizers by providing bioavailable micronutrients for plant nutrition in addition to a labile carbon source to support the growth of microbial populations.

Novel rapid screening assay to incorporate complexity and increase throughput in early-stage plant biological testing

The search for new biological products with a positive impact on crop performance is typically initiated by laboratory based in vitro assays. However, live plants and their associated microbes are often removed from in vitro testing assays as a way to reduce biological complexity (variation) and facilitate molecular techniques in the pursuit of uncovering mode-of-action (MoA) mechanisms. Nevertheless, when studying biological candidates intended for use in agriculture, it is essential to incorporate this complexity and validate mechanisms under conditions as close to in situ as possible in order to understand the capacities and MoA of the biologicals in the intended application environments. To address this paradox, we have developed a high-capacity early-stage plant assay that incorporates a live non-sterile plant while also enabling molecular MoA investigations, and that can be conducted in laboratories without greenhouse facilities. The high-capacity design features plants grown in 8-chamber transparent boxes to allow for multiplex imaging and increased biological replicates for greater statistical power. The transparent box design allows the visualization of shoots, roots, tagged-microbes, or visible substrates, and further non-destructive access to shoots or roots for sampling. The boxes are held in racks that hold eight plant boxes during growth in a 19 by 17 cm space, further increasing the throughput to >670 plants per m2 and easing the logistical challenges of plant assays. Furthermore, the box can support various levels of microbial complexity with the option to select the plant growth medium that meets experimental objectives, as well as using sterile or non-sterile seeds. A script-based post-imaging quantification was developed to automate image processing and allow for individual plant readings, further enabling increased statistical confidence. As proof of concept, we use the high-capacity plant system to evaluate the biocontrol potential of Pseudomonas protegens and the biostimulation potential of Pseudomonas koreensis, and are in both cases able to show statistically significant differing plant biomass between treatments under these closer-to-nature conditions. We further demonstrate that the high-capacity plant system is suitable for paired molecular investigations by performing metabolomics and qPCR DNA quantification directly from the plant box to explore in situ chemical MoA, as well as confirm the survival of the P. protegens strains to validate their role in the improved plant phenotype. In conclusion, the study presents a modular high-capacity plant assay system that enables increased throughput functional testing of microbial biocontrol and biostimulant candidates in planta. This novel assaying system saves time, reduces human error, provides quantitative and non-destructive in planta data, and can be used in laboratories without greenhouse facilities. We therefore believe it provides a potent early-stage testing option that bridges in vitro and greenhouse testing, and will expedite the discovery of superior next-generation biological products in agriculture.

Biostimulation Potential of Nypa fruticans Ash on Indegenous Heterotrophic Bacteria and Fungi for Enhanced Remediation of Hydrocarbon Polluted Soil at B. Dere, Rivers State, Nigeria

This study was designed to evaluate the biostimulation potential of Nypa feuticans ash on the growth of indigenous heterotrophic bacteria and fungi for enhanced remediation of hydrocarbon polluted soil at B. Dere, Rivers State, Nigeria in an ex-situ experiment, using the completely randomized split plot experimental design. 2kg of oil polluted soils were treated with 10g, 20g, 30g, 40g, 50g and 60g of Nypa fruticans ash and monitored for biostimulation and growth of indigenous biodegrading heterotrophic bacteria (THBC) and fungi (THFC). The results of four months post residual and cumulative effect on treated soil showed optimum improvement of microbial load at 60g/2kg treatment of Nypa fruticans ash. Findings on THBC for post residual treatment soil ranged from 0.1×10⁵ to 8.0 ×10⁴ cfu/g, while the THFC ranged from 0.1×10⁴ to 3.0 ×10⁴ cfu/g. THBC for post cumulative treated soil ranged from 2.7 ×10⁵ to 9.0 ×10⁴ cfu/g, while THFC ranged from 0.2 × 10⁴ to 3.0 ×10⁴ cfu/g. Three bacteria genera isolated from the post treated soil ware Bacillus spp. (36.3%), Clostridium spp (33.4%) and staphylococcus spp. (30.3%), while two fungi genera namelyYeast spp. (58%) and Muccor spp. (42%) were isolated from the post treated soil. The high-count THB and THF recorded in both residual and cumulative treated soil compared to the oil polluted untreated soil is attributed to Nypa fruticans ash capacity to neutralize the toxic effects of the crude oil on the microbial population by rapid improvement of the soil physiochemical properties, favoring the growth of indigenous microorganisms in the soil. This study has shown that treatment of crude oil polluted soil with Nypa fruticans ash at 60g/2kg showed optimum improvement which enhanced the biostimulation and growth of indigenous petroleum degrading microorganism.

Bacteria from the skin of amphibians promote growth of Arabidopsis thaliana and Solanum lycopersicum by modifying hormone-related transcriptome response

Plants and microorganisms establish beneficial associations that can improve their development and growth. Recently, it has been demonstrated that bacteria isolated from the skin of amphibians can contribute to plant growth and defense. However, the molecular mechanisms involved in the beneficial effect for the host are still unclear. In this work, we explored whether bacteria isolated from three tropical frogs species can contribute to plant growth. After a wide screening, we identified three bacterial strains with high biostimulant potential, capable of modifying the root structure of Arabidopsis thaliana plants. In addition, applying individual bacterial cultures to Solanum lycopersicum plants induced an increase in their growth. To understand the effect that these microorganisms have over the host plant, we analysed the transcriptomic profile of A. thaliana during the interaction with the C32I bacterium, demonstrating that the presence of the bacteria elicits a transcriptional response associated to plant hormone biosynthesis. Our results show that amphibian skin bacteria can function as biostimulants to improve agricultural crops growth and development by modifying the plant transcriptomic responses.

Biostimulation of sulfate reduction for in-situ metal(loid) precipitation at an industrial site in Flanders, Belgium

A 30-month pilot study was conducted to evaluate the potential of in-situ metal(loid) removal through biostimulation of sulfate-reducing processes. The study took place at an industrial site in Flanders, Belgium, known for metal(loid) contamination in soil and groundwater. Biostimulation involved two incorporations of an organic substrate (emulsified vegetable oil) as electron donor and potassium bicarbonate to raise the pH of the groundwater by 1–1.5 units. The study focused on the most impacted permeable fine sand aquifer (8–9 m below groundwater level) confined by layers of non-permeable clay. The fine sands exhibited initially oxic conditions (50–200 mV), an acidic pH of 4.5 and sulfate concentrations ranging from 600 to 800 mg/L. At the central monitoring well, anoxic conditions (−200 to −400 mV) and a pH of 5.9 established shortly after the second substrate and reagent injection. Over the course of 12 months, there was a significant decrease in the concentration of arsenic (from 2500 to 12 μg/L), nickel (from 360 to <2 μg/L), zinc (from 78,000 to <2 μg/L), and sulfate (from 930 to 450 mg/L). Low levels of metal(loid)s were still present after 34 months (end of study). Mineralogical analysis indicated that the precipitates formed were amorphous in nature. Evidence for biologically driven metal(loid) precipitation was provided by compound specific stable isotope analysis of sulfate. In addition, changes in microbial populations were assessed using next-generation sequencing, revealing stimulation of native sulfate-reducing bacteria. These results highlight the potential of biostimulation for long-term in situ metal(loid) plume treatment/containment.

Potencial bioestimulante de Azospirillum brasilense e nicotinamida para cultivo hidropônico de abóbora

ABSTRACT The application of biostimulants in agriculture has been studied to increase production while using smaller physical spaces and agricultural inputs to increase sustainability in production systems. Despite the promising results, there is a need to study the effects of joint applications of these products, identifying possible interactions during crop development. Thus, this study aimed to verify the biostimulant potential of the isolated and combined use of nicotinamide and Azospirillum brasilense during the initial growth of pumpkin plants in hydroponic cultivation. A completely randomized design with six treatments and four replicates was performed. The treatments were composed by the combination of the application of nicotinamide (foliar) and A. brasilense (foliar or applied in the hydroponic solution). Treatments increased the gas exchanges, particularly the assimilation rate and carboxylation efficiency, being superior to the control treatment. However, for growth characteristics, the isolated application of nicotinamide favored the development of the shoot and, when combined with A. brasilense via foliar, increased root growth. Thus, the application of nicotinamide and A. brasilense alone or together enhances the growth and gas exchanges of pumpkin plants grown in a hydroponic system, especially when using foliar application of A. brasilense. Whereby its action can be referred to as a biostimulant effect. Furthermore, the application method affects the efficiency and compatibility of the products applied. Therefore, foliar application is recommended.

Algae Extracts in Horticulture: Characterization of Algae-Based Extracts and Impact on Turnip Germination and Radish Culture

Algae are rich in nutrients and bioactive compounds, playing a crucial role as biostimulants for plants, enhancing growth and resilience. Four algae-based extracts were tested: the raw extract of red macroalgae Calliblepharis jubata (CJ), Ulasco (UA), Grasco (GR) and “AgriAlgae Foliar” (AA), the latter with microalgae. The extracts were evaluated for their physicochemical parameters (pH, electrical conductivity and solids), macro and microelements, phenolic compounds and antioxidants. Afterwards, seed germination trials were carried out with turnip seeds (Brassica rapa var. cymosa L.), and pot trials were carried out with Cherry Belle (Flora Lusitana, Cantanhede, Portugal) radish plants (Raphanus sativus L.), to verify the biostimulant potential of the extracts in horticulture. In the pot trials, all the treatments led to better yields and nutritional quality. The UA 0.12 extract influenced the heaviest roots (40.32 ± 11.89 g), on average, and the GR 0.10 extract in roots with the highest percentage of proteins (1.866 ± 0.004% dm), phenolic compounds (0.12121 mg eq. gallic acid/g fm) and antioxidants (0.0754 ± 0.0000 mg eq. ascorbic acid/g fm). The radishes treated with the AA 0.003 extract showed the greatest uniformity, the healthiest leaves, with the highest flavonoid content and the heaviest aerial part (19.52 ± 5.99 g). All the extract treatments resulted in a visible mitigation of abiotic stress and consequently better results, showing that these can be crucial for sustainable agriculture.

Application of innovative biostimulants for growth and quality improvement in vegetable and ornamental crops

Research objective: This research aims to evaluate the biostimulant potential of some innovative products that can improve germination, growth and protection from biotic stresses on some vegetable and ornamental species. Materials and Methods: The experiments, which started in October 2022, were conducted in the CREA-OF greenhouses in Pescia (Pt), on Cichorium intybus and Crassula rupestris plants. The experimental groups were: i) group control, irrigated with water and previously fertilised substrate; ii) biofertiliser Ecklonia maxima, dilution 1:1000, 5 ml of this dilution once a week per plant; iii) Elixir lite, irrigated with water and substrate previously fertilised; iv) Immuno pro group, irrigated with water and substrate previously fertilised; Harvest boost group, irrigated with water and substrate previously fertilised. On 23 January 2024, plant height, number of leaves, vegetative weight, root volume and length, number of microorganisms and pH of the substrate were determined. In addition, the mortality of the plants in the nursery was assessed. Results and Discussion: The experiment showed that the use of biostimulants can significantly improve the vegetative and root growth of Cichorium intybus and Crassula rupestris plants. In general, a significant increase in plant height, vegetative and root weight and root length was observed, particularly in the Elixir lite treatment. There was also a significant increase in the microbial colonisation of the substrate with all innovative biostimulant treatments, while the pH remained practically unchanged. The Immuno pro treatment was the best in terms of reducing plant mortality in all two plant species. Biostimulants are widely used in horticulture because we often work with short-cycle crops, varying from a few weeks to a few months. The rapid succession of different crops implies a constant supply of nutrients and intensive use of soil. More intensive horticulture in particular often benefits from the effect of biostimulant treatments due to the increased resource use efficiency of the crops. Foliar biostimulants are mainly used by farmers to increase the production of both leaf and fruit vegetable crops. The positive effects of their use are exerted both on increasing the content of secondary metabolites and on a general improvement of nutrient uptake efficiency. These biological effects can be attributed to the presence in biostimulants of polysaccharides, extracted from algae, such as alginates and carrageenan, which are responsible for two important biological actions: sequestering or slowly releasing nutrients. In fruit vegetables, biostimulants can also improve the homogeneity of flowering and fruit size, as reported for peppers. Commercial biostimulants have increased the unit yield of many leafy vegetable species by acting on nutrient uptake by the plant. Conclusions: In horticultural production, in open field and in protected crops, the application of biostimulants is aimed at achieving one or more of the following objectives: to favour a rapid emergence of seedlings in direct sowing crops or a rapid overcoming of the transplanting crisis; to precociate the entry into production; to increase growth, flowering, fruit set and fruit growth; to improve product quality; to increase the efficiency of nutrient use and tolerance to environmental stresses.

Microorganisms and algae (GEA soil) use in the cultivation of onion (Allium cepa L.) and garlic (Allium sativum L.)

Research objective: This research aims to evaluate the biostimulant potential of an innovative microbial product on the development of onion (Allium cepa L.) and garlic (Allium sativum L.) bulbs and roots under controlled conditions Materials and Methods: The experiments began in early July 2022 (mean temperature 22.5 °C), were carried out price experimental greenhouses of the CREA-OF of Pescia (Pt), Tuscany, on bulbs of onion (cv “Rossa di Tropea”) and garlic (cv “Bianco Polesano”). The bulbs were placed in pots ø 14 cm; 40 bulbs for thesis divided into replicas of 20 bulbs each, for all onion and garlic. The three experimental theses in cultivation were: i) group control irrigated with water and previously fertilised substrate; biofertiliser Ecklonia maxima irrigated with water and previously fertilised substrate; Gea soil (GEA) group irrigated with water and substrate previously fertilised. On 26 January 2024, bulbs weight, bulb diameter, roots weight, number of microorganisms were determined. In addition, the mortality of the bulbs in the nursery was assessed. Results and Discussion: The experiment showed that the use of biostimulants based on microorganisms and algae can significantly improve the size, weight and root growth of onion and garlic bulbs. In particular, the GEA soil thesis showed a significant increase in bulb length, weight and root growth compared to Ecklonia maxima and the untreated control thesis. There was also a significant increase in microbial colonisation of the substrate with GEA soil, a very interesting aspect that certainly had an effect on the growth of onion and garlic bulbs. The micro-organisms also by direct stimulation on the plants or by colonisation of the substrate significantly reduced bulb mortality in Gea soil, compared to BIOAL and the control. In recent years, horticulture has had to face the challenge of economic and environmental sustainability, reducing fertiliser use while adopting strategies to increase water use efficiency. Numerous forecasting models have shown that in the next 30 years many production areas could become semi-arid and among these is the Mediterranean basin, where many horticultural crops are grown. Increasing water use efficiency in this context appears essential for the development of sustainable horticulture. Many microorganisms or fungi can promote the plant's utilisation of nutrients and water in the soil. There are numerous strains of bacteria that promote root growth and are classified according to whether they act at the rhizosphere and rhizoplane level. Conclusions: Microbial biostimulants can be a valuable strategy to mitigate environmental stresses that have been emphasised by climate change in recent years. Microbial biostimulants, by increasing the biodiversity of the agro-ecosystem and creating long-lasting symbiotic relationships with the plant, are, in fact, a sustainable and effective solution to prevent the reduction in productivity caused by abiotic stresses and to optimise the use efficiency of human inputs in the agrarian ecosystem.

Biostimulant potential of Brazilian macroalgae: seasonal variations and effects on early growth and germination of lettuce

Biostimulant potential of Brazilian macroalgae: seasonal variations and effects on early growth and germination of lettuce

Isolation and characterization of soil cyanobacteria and microalgae and evaluation of their potential as plant biostimulants

Background and AimsBiocrusts are found on soil surface resulting from an association between soil particles and microorganisms. Photoautotrophic cyanobacteria and microalgae are pioneers on biocrusts formation, promoting soil stability, nutrients availability and water retention, leading to the development of other communities. This work aimed at isolating and characterizing cyanobacteria/microalgae from biocrusts (Central Portugal) and to assess their potential as plant biostimulants, as well as obtaining an insight into their mechanism(s) of action.MethodsMicroorganisms were isolated through successive spread plating/serial dilutions and characterized using genetical analysis/morphological traits. An initial screening was performed using exudates from each microorganism and two plant species, Arabidopsis thaliana and Lolium multiflorum. Subsequently, the selected microorganisms were tested as a consortium in hydroponic systems. Biometric and biochemical parameters were evaluated for both plant species.ResultsThe consortium microorganisms belong to genera often found in soils/biocrusts: Trichocoleus, Nodosilinea, Microcoleus (filamentous cyanobacteria), Nostoc (diazotrophic heterocystous cyanobacteria), and Klebsormidium (filamentous microalga), and some of them have the capacity to produce phytohormones and/or siderophores. The consortium showed biostimulant potential in hydroponic cultures, promoting plant growth and enhancing physiological productivity related parameters. Stress related parameters revealed that the microorganisms did not lead to a stressful situation. However, a significant increase in proline was observed, endorsing a role of this molecule in this process.ConclusionThis study contributes to the knowledge on the biodiversity of cyanobacteria and microalgae from Portuguese soils and highlights their potential as biostimulants, constituting a step forward towards understanding the molecular mechanisms behind this effect.

Systematic study on the effect of seaweed fertilizer on the growth and yield of Vigna radiata (L.) R. Wilczek (Mung bean)

Seaweed (Marine algae) extracts have been reported to be beneficial to plants for early seed germination, better plant growth, improved crop yield, and also in preventing biotic and abiotic stress. They are naturally rich in plant growth-promoting factors like microelements, organic matter, vitamins, and fatty acids and can be a low-cost alternative to conventional N:P:K fertilizers and expensive organic farming techniques. Herein, the seaweed fertilizer (SF) have prepared by using three seaweeds, viz., Turbinaria ornata (TSF), Ulva intestinalis (USF), and Portieria hornemannii (PSF). The formulation was evaluated for biostimulant potential by performing a pot culture on Vigna radiata (L.) R. Wilczek, along with aqueous control, chemical fertilizer control (CFC), and organic manure control (OMC). The plants were treated with various groupings (individual and combination) of SF at six different concentrations. The study revealed that PSF (30%) stimulates maximum seed germination and an upsurge in plant growth (shoot length (28%), root length (120%), leaf count (53%), leaf area (62%), fresh weight (41%), and dry weight (54%)), pigment concentration (carotenoid (80%), chlorophyll a (29%), and chlorophyll b (41%)), and biochemical parameters of the leaves (carbohydrate (18%), protein (21%), amino acids (21%), phenolic content(49%)) when compared with aqueous control. The study revealed an 85% surge in the quantity of grains (15.568 g/plant) upon treatment with 30% PSF compared with aqueous control (8.413 g/plant). Followed by 30% (USF + PSF), 30% (TSF + PSF), and 40% PSF, have exhibited 75%, 73%, and 72% increase, respectively, compared with aqueous control. The nutrient uptake study exhibited that 30% PSF improves the efficiency of mineral uptake in V. radiata (L) plants. The results suggest that the tested SF, especially PSF, could be a low-cost and environmentally safe fertilizer. Based on this study, the formulated PSF could be used alone or partially replaced with commercial fertilizers to reduce the total cultivation cost.

Moringa Leaf Extract Mitigates the Adverse Impacts of Drought and Improves the Yield and Grain Quality of Rice through Enhanced Physiological, Biochemical, and Antioxidant Activities.

Agriculture, around the globe, is facing great challenges including the need to increase the production of nutrient-dense food and to withstand climate change's impact on water and soil conservation. Among these challenges, drought stress is considered the most overwhelming danger for the agriculture sector. Organic plant growth ingredients are frequently used to enhance the growth and production of field crops cultivated in normal and unfavorable conditions. The present study was designed to explore whether leaves extracted from various landraces of Moringa could play a defensive role against drought stress in rice. Seedlings were grown under three water conditions, i.e., normal conditions (control; 100% field capacity), moderate (75%), and severe drought (50%). Leaf extracts obtained from four Moringa landraces were used as foliar spray at the tillering, panicle initiation, and grain filling stages of cultivating rice plants. The levels of water stress negatively influenced photosynthetic pigment synthesis, gas exchange traits, antioxidant activities, and yield and grain quality parameters. Leaf extracts, at the rate of 3%, from all the landraces significantly enhanced the biochemical, physiological, and yield-related attributes of rice plants under normal and unfavorable growth conditions. Particularly, leaf extract from the Faisalabad landrace was the most effective biostimulant to increase photosynthetic (8.2%) and transpiration (13.3%) rates, stomatal conductance (8.3%), chlorophyll a (15.9%) and b (9.7%) contents, and carotenoids (10.4%) as compared to water spray. The maximum photosynthesis rate was observed at 14.27 µmol CO2 m-2 s-1 via application of leaf extract from the Faisalabad landrace followed by the DG Khan (13.92 µmol CO2 m-2 s-1) and Multan (13.9 µmol CO2 m-2 s-1) landraces, respectively. Improved grain yield (25.4%) and grain quality (an increase of 10.1% in amylose with a decrease of 2.8% in amylopectin) in rice plants along with enzymatic activities such as catalase (21.2%), superoxide dismutase (38.6%), and ascorbate peroxidase (24.3%) were observed at the peak after application of leaf extract from the Faisalabad landrace. The maximum grain yield of 53.59 g per plant was recorded when using Faisalabad landrace leaf extract and the minimum (40 g) using water spray. It is concluded from the findings of the current experiment that leaf extract from the Faisalabad landrace possesses higher biostimulant potential than other landraces and can be applied to mitigate the adverse impacts of drought stress with higher productivity and improved grain quality of rice.