The study was conducted over the 2023 and 2024 growing seasons at the Central Laboratory for Agricultural Climate of the Agricultural Research Center in Giza Governorate, Egypt. Uniform geranium seedlings were planted in plastic pots in sandy soil during the first week of March, thinned to three plants per pot after 45 days and maintained in a greenhouse. Plants were harvested twice in each season, at 90 and 180 days after planting, with the second harvest recording higher values for most growth and yield measures.

Five treatments were evaluated in a completely randomized design with four replicates per treatment. The control received a complete Hoagland nutrient solution, while the other treatments received weekly applications through irrigation water of Azolla extract at 50% or 75%, or Moringa leaf extract at 5% or 10%. Each replicate consisted of eight pots with three plants per pot. Fresh Azolla extract was prepared by boiling washed biomass in distilled water, whereas fresh Moringa extract was produced by blending leaves with distilled water, filtering the mixture and centrifuging it at 8,000 × g for 15 minutes.

Both plant-based extracts significantly enhanced vegetative growth relative to the control, with 10% Moringa producing the highest values. In the second harvest, plants receiving this treatment reached 114.5 cm in the first season and 119.6 cm in the second, compared with fold increases of 2.5 and 2.6. Branch numbers increased by 2.1- to 2.3-fold, fresh biomass by 2.0- to 2.1-fold and dry biomass by 2.0- to 2.1-fold. Treatment and harvest effects on the growth variables were generally significant at P ≤ 0.001, although some treatment-by-harvest interactions were not significant.

Photosynthetic pigments also increased under extract application. With 10% Moringa at the second harvest, chlorophyll a reached 0.8 and 0.9 mg g−1 fresh weight, chlorophyll b reached 0.4 and 0.5 mg g−1, and carotenoids reached 0.6 mg g−1 in the two seasons. Compared with the control, the treatment was associated with 1.7-fold higher chlorophyll a, 2-fold higher chlorophyll b and 1- to 1.3-fold higher carotenoids. The treatment and harvest effects were significant for chlorophyll a at P ≤ 0.001, for chlorophyll b at P ≤ 0.05 and for carotenoids at P ≤ 0.01, without significant treatment-by-harvest interactions for these pigments.

Essential oil content was higher at the first harvest, but essential oil yield per plant was greater at the second harvest. The highest oil yield under 10% Moringa was 1.4 g per plant in the first season and 1.7 g per plant in the second, representing increases of 1.4- to 2.3-fold relative to the control; oil content rose by 1.1- to 1.4-fold. Gas chromatographic analyses identified citronellol, geraniol and α-gurjunene as major constituents, with oxygenated monoterpenes forming the dominant chemical group. Under 10% Moringa at the second harvest, citronellol reached 774.2 mg per plant, geraniol was associated with a 3.3-fold increase over the control, α-gurjunene increased 2.7-fold and total oxygenated monoterpenes increased 2.3-fold.

Leaf chemical measures generally rose with extract treatment and were higher at the second harvest. At the second harvest with 10% Moringa, total phenolics reached 16.6 and 19.3 mg g−1 dry weight in the two seasons, 1.5- and 1.6-fold above control values. Flavonoids increased by 1.6- to 1.9-fold, while free-radical scavenging inhibition reached 62.34% and 60.2%, representing 1.7- and 1.8-fold increases. Total carbohydrate content was reported as 1.3-fold higher than the control, and crude protein content increased by 1.5-fold in the first season and 1.8-fold in the second.

The treatments also increased plant-tissue concentrations and total uptake of nitrogen, phosphorus and potassium. With 10% Moringa at the second harvest, nitrogen uptake reached 3.6 and 3.7 g per plant in the two seasons, compared with fold increases of 3.1- to 3.6-fold over control. Potassium uptake increased by 2.9- to 3.3-fold, while phosphorus uptake was reported as 5- to 25-fold higher. Because larger nutrient uptake figures reflect both tissue concentrations and total biomass, these values cannot be interpreted independently of the observed increase in plant growth.

The authors proposed that the extracts improved geranium performance through effects on nutrition, photosynthetic activity and secondary metabolism, while successive cutting stimulated regrowth and altered physiological and biochemical processes. They also cautioned that larger-scale field and economic studies are needed to establish commercial feasibility, and that the industrial applicability of the changes in essential oil composition requires further research. The findings therefore come from a greenhouse experiment using potted plants over two seasons, rather than from an open-field trial or commercial production assessment, and the tested extract concentrations should not be assumed to produce the same results under field conditions.

Subject of Research: Effects of Azolla and Moringa extracts on geranium growth, physiology, nutrients and essential oil production in sandy soil

Article Title: Response of geranium to soil applications of Azolla and Moringa extracts: effects on growth, essential oil and physiological parameters

Article References: Abd-Rabbu, H. S., Aboud, F. S., & Khalid, K. A. (2026). Response of geranium to soil applications of Azolla and Moringa extracts: effects on growth, essential oil and physiological parameters. BMC Plant Biology, 26(1), Article 1623. https://doi.org/10.1186/s12870-026-09900-0

Image Credits: AI Generated

DOI: 10.1186/s12870-026-09900-0

Keywords: geranium, Azolla, Moringa, sandy soil, biostimulants, essential oil, plant growth, nutrient uptake, greenhouse study, Response, soil, applications

The researchers tested five nitrogen rates—0, 80, 160, 240 and 320 kg N ha−1—alongside three foliar treatments: a control, glycine betaine and zeatin. These combinations were evaluated in six barley varieties: Ramata, Placidia, Nonius, Sultan, Kıral-97 and Altıkat. The factorial field design examined the individual and combined effects of nitrogen fertilization and biostimulant treatment on growth, yield formation and agronomic nitrogen use efficiency.

Nonius recorded the highest grain yield among the six varieties, at 6.33 t ha−1, while Altıkat produced the lowest, at 5.17 t ha−1. Nitrogen rate produced a different result for total yield than for efficiency. Grain yield at 240 kg N ha−1 was reported as 116.71% higher than the unfertilized control, and the researchers identified this rate as providing the best overall balance for yield contribution.

By contrast, 80 kg N ha−1 was optimal for both agronomic nitrogen use efficiency and partial factor productivity of nitrogen. The comparison shows that the nitrogen rate associated with the highest yield response was not the same as the rate associated with the strongest efficiency measures. The full experimental range also included 320 kg N ha−1, but the abstract does not report its yield percentage or efficiency values relative to the other rates.

The findings support the tested combination of foliar biostimulants and nitrogen management as an approach for improving barley productivity and agronomic nitrogen use efficiency under rainfed field conditions, with zeatin producing the larger average grain-yield increase. Their scope remains bounded by the two-year experiment, six varieties and five nitrogen rates, and the supplied results do not establish whether the same treatment effects would occur in other environments or production systems. The research also does not show that one nitrogen rate should replace the others: 240 kg N ha−1 was associated with the strongest reported overall yield contribution, whereas 80 kg N ha−1 gave the best reported values for the two nitrogen-efficiency measures.

Within this experimental framework, the clearest result is that adding glycine betaine or zeatin improved overall measured agronomic performance, while the balance between total yield and nitrogen-use efficiency depended on the nitrogen application rate.

Subject of Research: Effects of foliar biostimulants and nitrogen rates on rainfed barley yield and agronomic nitrogen use efficiency

Article Title: Synergistic effect of biostimulants and nitrogen fertilization on crop performance of barley (Hordeum vulgare L.) under rainfed conditions

Article References: ÖZTÜRK AY, E., AKAY, H., SEZER, İ., & AY, A. (2026). Synergistic effect of biostimulants and nitrogen fertilization on crop performance of barley (Hordeum vulgare L.) under rainfed conditions. BMC Plant Biology. https://doi.org/10.1186/s12870-026-09911-x

Image Credits: AI Generated

DOI: 10.1186/s12870-026-09911-x

Keywords: barley, rainfed agriculture, biostimulants, glycine betaine, zeatin, nitrogen fertilization, grain yield, nitrogen-use efficiency, crop performance, field experiment, Synergistic, effect

Biostimulants occupy a curious regulatory and scientific niche. Unlike fertilizers, they are not defined primarily by the nutrients they deliver, and unlike pesticides, they do not kill pests directly. Instead, as the review emphasizes, they regulate plant metabolism. The authors stress that plant-derived extracts almost never act through a single active constituent. A typical extract is a dense biochemical cocktail containing phytohormone-like compounds, antioxidants, osmoprotectants, phenolics, oligosaccharides, fatty acids, proteins and peptides. This compositional complexity is not a nuisance to be purified away; it is the point. Multiple molecules converge on multiple signaling pathways simultaneously, producing effects that no isolated compound could replicate.

The mechanistic core of the review centers on hormone signaling. Extracts modulate the major stress hormones of plants, including abscisic acid, salicylic acid, jasmonic acid and ethylene, which together orchestrate everything from stomatal closure during drought to the activation of pathogen defenses. Transcriptomic studies cited in the review show that treatment with extracts such as those from Ascophyllum nodosum, a brown seaweed long used in commercial biostimulant products, upregulates stress-responsive genes in crops ranging from Arabidopsis to soybean and tomato. In effect, the extracts behave like a training signal, priming the plant’s own defense machinery so that when real stress arrives, the response is faster and stronger.

Beyond hormones, the review catalogues a suite of physiological adjustments that extracts induce. Treated plants accumulate more osmolytes, small compatible solutes such as proline and glycinebetaine that help cells retain water and maintain turgor under drought or salt stress. Antioxidant defenses are strengthened, allowing plants to neutralize the reactive oxygen species that spike when photosynthesis is disrupted. Ionic homeostasis is restored, helping roots exclude sodium or compartmentalize it away from sensitive metabolic machinery. Perhaps most intriguingly, the review highlights evidence that extracts regulate water transport through aquaporins, the membrane channels that control the flow of water across plant cells, offering a direct physical route to improved drought tolerance.

The review also draws attention to the rhizosphere, the teeming microbial zone around plant roots. Extracts influence rhizosphere interactions and microbiome dynamics, according to the authors, thereby improving nutrient acquisition and systemic resilience. Studies combining seaweed extracts with plant growth-promoting rhizobacteria in wheat, rice, onion and cucumber report synergistic effects on growth and yield that neither partner achieves alone. This reframes biostimulants not merely as foliar tonics but as ecosystem engineers that reshape the underground communities on which crop nutrition depends, a perspective increasingly central to soil health science.

Case studies across stress types give the review its agronomic weight. Under drought, moringa leaf extract has improved rice yield and grain quality through enhanced antioxidant activity, while seaweed extract has bolstered sugarcane drought resistance by modulating root architecture and soil properties. Under salinity, extracts from Ascophyllum, willow, licorice root and grape seed have each improved photosynthetic stability and ion balance in crops such as tomato, maize, pea and faba bean. Heat stress studies in wheat and maize report that moringa and sorghum water extracts preserve photosynthetic pigments, while cold stress trials in barley and tomato show brown seaweed extracts triggering cold-acclimation gene expression. Biotic stress studies add another layer, with laminarin from brown algae eliciting grapevine defenses against downy mildew and botrytis, and seaweed extracts reducing fungal disease on carrot foliage.

Application strategy emerges as a critical variable. The review distinguishes between foliar sprays, seed priming and soil drenching, noting that dose, timing and method can determine whether an extract helps or does nothing at all. Seed priming with moringa leaf extract has reduced chilling injury in spring maize and improved rice seedling establishment under water deficit, while foliar application has induced terminal heat tolerance in quinoa. Processing matters too: the review notes that extraction methods, from mechanical disruption to enzyme-assisted techniques, shape which phytochemicals survive into the final product, and that even storage temperature can alter cytokinin and auxin concentrations in seaweed concentrates.

The most forward-looking section concerns nanotechnology. Plant-mediated nanoparticles and nano-formulations, the authors report, improve the stability, delivery efficiency and bioavailability of bioactive phytochemicals. Examples span the emerging literature: Sargassum-synthesized zinc oxide nanoparticles inducing salt tolerance in maize, neem-mediated silver nanoparticles improving drought-stressed soybean growth, Spirulina-derived carbon dots used for seed nanopriming in rice, and nano-encapsulated biostimulants enhancing photosynthetic efficiency in heat-stressed peppers. Nano-encapsulation can also protect volatile or easily degraded compounds, such as essential oils, from rapid environmental loss. The authors caution, implicitly, that nanoparticle-plant interactions, including uptake, transport and potential toxicity, remain active areas of investigation, and that environmental implications must be weighed alongside agronomic gains.

What emerges from the synthesis is a picture of plant-derived biostimulants as systems-level interventions rather than simple inputs. A single seaweed extract may simultaneously adjust hormone signaling, boost antioxidant capacity, alter root growth, feed beneficial microbes and prime defense genes, all without introducing novel genetic material or synthetic chemistry. For farmers facing increasingly erratic rainfall, salinizing soils and heat waves, this profile is attractive precisely because it works with the plant’s existing physiology rather than overriding it. The review’s case studies consistently report improvements in photosynthetic stability, stress tolerance and yield under optimized application strategies, suggesting that the gap between laboratory promise and field performance is narrowing.

The authors close with a research agenda that reads like a roadmap for the next decade of the field. Future progress, they argue, will require integrating multi-omics approaches, combining transcriptomics, metabolomics and proteomics to resolve exactly which molecules in a complex extract drive which responses, alongside microbiome profiling to track how extracts reshape root communities over time, and precision nanotechnology to deliver the right bioactive to the right tissue at the right moment. If that integration succeeds, the humble plant extract, long dismissed as folk agronomy, could become a cornerstone of sustainable agriculture, helping crops weather a climate that is growing less forgiving by the season.

Subject of Research: Mechanisms of plant-derived biostimulants in enhancing crop stress tolerance and sustainable agriculture

Article Title: Mechanistic insights into plant-derived biostimulants for sustainable agriculture and stress tolerance

Article References: Mishra, A., Bhatt, U., & Soni, V. (2026). Mechanistic insights into plant-derived biostimulants for sustainable agriculture and stress tolerance. Plant Biosystems, 160(6), Article 295. https://doi.org/10.1007/s44473-026-00314-2

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00314-2

Keywords: biostimulants, plant extracts, seaweed extracts, abiotic stress, drought tolerance, salinity stress, phytohormones, antioxidants, nanotechnology, soil microbiome, sustainable agriculture, moringa oleifera

The choice of wheat as the experimental subject reflects both its global importance and its well-documented sensitivity to salinity during early development. Wheat is among the most widely cultivated cereals on Earth, and in many irrigated production systems—particularly in arid and semi-arid regions of Central and Western Asia, North Africa, and Australia—the water available to farmers carries substantial dissolved salt loads. Seedling establishment is a particularly vulnerable window, because young plants have limited root systems, thin cuticles, and immature antioxidant machinery. A seedling that survives early salt exposure with reduced vigor often carries that penalty through to tillering and grain fill, which is why interventions aimed specifically at the seedling stage can have disproportionate agronomic value even when the plants eventually recover.

The two cultivars examined in the study, Chamran and Mehregan, are bread wheat varieties bred for the contrasting but overlapping challenges of Iranian and regional production environments. Including two genotypes rather than one matters scientifically because salt responses in wheat are strongly genotype-dependent: varieties differ in their capacity to exclude sodium at the root, to compartmentalize it in vacuoles, and to maintain photosynthetic activity under osmotic strain. When a treatment effect appears in both cultivars, as the fresh-weight benefit of the combined formulation did at every salinity level tested, it suggests a mechanism that operates broadly rather than one contingent on a particular genetic background. At the same time, the magnitude of the benefit differed between the two lines, with Mehregan showing a larger relative gain at the highest salt concentration, a reminder that biostimulant performance cannot be assumed to transfer uniformly across germplasm.

The severity of the salt treatments deserves attention when interpreting the results. Irrigating with 150 millimolar sodium chloride already imposes stress well beyond what most productive wheat fields experience; 300 millimolar approaches the limits of what wheat seedlings can tolerate at all. These concentrations were chosen to create a steep stress gradient in which protective effects could be detected unambiguously, not to mimic field conditions directly. The fact that plant height, fresh weight, and dry weight all declined substantially at the highest concentration in both cultivars confirms that the stress was genuinely severe. Against that backdrop, even modest absolute differences in biomass between sprayed and unsprayed plants represent meaningful biological protection, and the roughly thirty-five percent fresh-weight advantage of the combined treatment over the unsprayed control in Chamran at 300 millimolar sodium chloride is notable.

Chitosan itself has a long history as a plant-protective agent, and its mechanism of action is worth unpacking. Derived by deacetylation of chitin from crustacean shells or fungal cell walls, chitosan is a positively charged polysaccharide that can interact with negatively charged components of plant cell surfaces. It is recognized by plants as a microbe-associated molecular pattern, triggering innate immune signaling pathways that overlap with those activated during abiotic stress. Spraying chitosan on leaves has been reported to induce stomatal closure, stimulate the phenylpropanoid pathway, and prime antioxidant enzymes, effects that collectively harden plants against subsequent stress. The polymer also forms films, which is why it is used commercially as an edible coating for fruit; on a leaf, that film-forming behavior may both retain moisture and slow the diffusion of dissolved solutes.

Selenium occupies an unusual position in plant biology. It is not considered an essential element for higher plants, yet at low concentrations it reliably alleviates oxidative stress in many species. The reason lies in its chemistry: selenite taken up by leaf tissue can be assimilated into selenocysteine and ultimately into selenium-containing forms that bolster the glutathione peroxidase system, an alternative route for decomposing lipid peroxides that complements the ascorbate-glutathione cycle. Selenium supplementation has also been shown to enhance the activity of catalase and superoxide dismutase and to slow chlorophyll degradation under stress. The dose window is narrow, however, because selenium becomes toxic to plants at concentrations only modestly above those that are beneficial, which makes delivery method and formulation critical variables in any field application.

The formulation strategy used in the study—ionotropic gelation with tripolyphosphate—is a standard technique for assembling chitosan into small cross-linked particles. When a tripolyphosphate solution is added to an acidic chitosan solution, the multivalent anion bridges the cationic polymer chains, condensing them into discrete nanoparticles. Incorporating sodium selenite into this process entraps or associates the selenium species within the particle matrix rather than leaving it as a free salt on the leaf surface. The practical rationale is that a particle-associated active ingredient may adhere better to the waxy cuticle, release its payload more gradually, and suffer less from rapid wash-off or photodegradation than a simple aqueous spray. The authors were careful, however, to note that the physicochemical properties of their specific formulation—particle size, surface charge, selenium loading efficiency, and release kinetics—were not characterized in this work, leaving an important gap between the concept and a fully validated delivery system.

The confocal microscopy experiment using fluorescein isothiocyanate-labeled chitosan provides some of the most visually direct evidence in the paper. Fluorescence was strongest in the epidermal layer and weaker in the underlying mesophyll, indicating that the polymer associates readily with the outer leaf tissues but penetrates only partially into the interior. This pattern is consistent with what is known about foliar uptake in general: the cuticle is a formidable hydrophobic barrier, and most solutes enter through stomata, trichomes, or specialized epidermal cells rather than diffusing across the cutin matrix. The authors are appropriately cautious in their interpretation, emphasizing that detecting the labeled chitosan demonstrates association with the leaf but does not prove that selenium, or the intact formulation, was internalized. Tracking the selenium itself would require a different analytical approach, such as isotope labeling or elemental imaging.

The gene expression data add a molecular dimension to the physiological observations. The genes examined span several functional categories that map directly onto the known components of salt stress. TaAPX and TaCAT encode ascorbate peroxidase and catalase, the two central enzymes of hydrogen peroxide detoxification. TaNHX1 encodes a vacuolar sodium-proton antiporter that sequesters sodium ions inside vacuoles, removing them from the cytoplasm where they would interfere with enzymatic function. TaHKT9-7D belongs to the high-affinity potassium transporter family, whose members participate in sodium retrieval and potassium-sodium balance in both roots and leaves. TaP5CS catalyzes the rate-limiting step in proline biosynthesis, and Ta4CL3-6B encodes a 4-coumarate ligase acting early in the phenylpropanoid pathway, which supplies lignin precursors and a wide range of protective secondary metabolites. TaPXPAO is involved in polyamine catabolism, a process that both generates hydrogen peroxide and participates in stress signaling.

The pattern of expression changes tells a coherent story. In unsprayed plants, salt exposure actually decreased the transcript levels of most of these genes, a somewhat counterintuitive result that may reflect stress-imposed suppression of transcription or a failure of the seedlings to mount a full defensive response at the severe concentrations used. The single gene that rose, TaP5CS, aligns with the accumulation of proline, the classic osmoprotectant whose synthesis plants upregulate under water stress. In contrast, the selenium-containing treatments at the highest salt level elevated TaCAT, TaNHX1, and Ta4CL3-6B in both cultivars, suggesting activation of antioxidant defense, sodium compartmentalization, and phenylpropanoid metabolism respectively. The combined formulation additionally influenced the polyamine catabolism gene, hinting at a broader reprogramming of stress metabolism when the two biostimulants act together.

The authors are explicit that these expression changes are correlative: no enzyme activities, metabolite quantities, or ion contents were measured to confirm that the transcriptional shifts translated into functional differences. This is a standard and honest limitation of RT-qPCR surveys, and it defines the agenda for follow-up work. Measuring catalase activity, tissue sodium and potassium concentrations, proline levels alongside TaP5CS expression, and phenylpropanoid end products would connect the molecular signals to the growth outcomes. Similarly, the weak correlation between growth traits and pigment contents, with correlation coefficients not exceeding 0.30, indicates that the fresh-weight benefit of the treatment cannot be explained simply by preserved chlorophyll; other processes, such as osmotic adjustment, membrane stability, or ion homeostasis, are likely contributing.

The proline data illustrate this point nicely. Proline rose with increasing salinity in the selenium-treated and combined-treatment plants, consistent with induced TaP5CS expression, and proline serves multiple roles beyond osmotic adjustment: it scavenges reactive oxygen species directly, stabilizes proteins and membranes, and buffers cellular redox state. A treatment that enhances proline accumulation under salt stress therefore plausibly contributes to the observed biomass protection through mechanisms invisible to chlorophyll measurements. Disentangling how much of the growth benefit flows through osmotic protection versus antioxidant reinforcement versus ion management will require the kind of integrative physiological follow-up the authors themselves call for.

From an applied perspective, the study sits within a growing literature on biostimulants as complements to conventional breeding and soil management for salinity adaptation. Breeding for salt tolerance in wheat has proven slow because tolerance is controlled by many genes of modest effect and is strongly environment-dependent. Foliar interventions offer a complementary route: they can be applied reactively when salinity is known to be a problem, combined with existing agronomic practice, and adjusted by dose and timing. The caveats the authors raise—uncharacterized formulation physics, seedling-stage results only, controlled-environment conditions, and no field validation—are the standard hurdles between a promising greenhouse result and a usable product, and their candor about them strengthens rather than weakens the study’s contribution. The work was supported by Hungarian national research funding through the Thematic Excellence Program and the NRDI Fund, and the article is published open access under a Creative Commons license, making the full dataset and methods available to any research group wishing to build on these findings.

Subject of Research: Foliar chitosan–selenite biostimulant effects on wheat seedlings under salt stress

Article Title: Foliar chitosan–selenite formulation improves wheat seedling growth under NaCl irrigation

Article References: Gholizadeh, F., Fábián, A., Sohail, H., Majláth, I., & Janda, T. (2026). Foliar chitosan–selenite formulation improves wheat seedling growth under NaCl irrigation. BMC Plant Biology. https://doi.org/10.1186/s12870-026-10095-7

Image Credits: AI Generated

DOI: 10.1186/s12870-026-10095-7

Keywords: wheat, salinity stress, chitosan, selenium, foliar application, biostimulants, gene expression, antioxidant defense, proline, confocal microscopy, plant physiology, NaCl

The physiological damage heat and drought inflict on fruit crops is both intricate and economically brutal. Supra-optimal temperatures impair photosynthesis by reducing Rubisco activation and destabilizing thylakoid membranes, with net photosynthesis declining above roughly 35 °C in many species as respiratory carbon loss rises. Water deficit independently reduces stomatal conductance, curtails carbon allocation to fruit sinks, and forces osmotic adjustment in vegetative tissue at the expense of fruit expansion. Where the two stresses coincide, drought-induced stomatal closure limits transpirational cooling, amplifying tissue temperature while heat-driven evaporative demand deepens the drought signal—a feedback that promotes xylem embolism and compounds carbon limitations. The result is a cascade of disorders: fruit cracking when drought-stressed fruit rehydrate rapidly after irrigation or rainfall, sunburn and necrosis when apple surface temperatures exceed 52 ± 1 °C, and transcriptional suppression of anthocyanin biosynthesis when heat activates MdHSF3b and MdHSF4a in apple or microRNA858 targets AaMYBC1 in kiwifruit.

Against this backdrop, microbial interventions offer some of the most promising nature-based tools. Plant growth-promoting rhizobacteria (PGPR) support tolerance through phytohormone modulation, mitigation of oxidative damage, and remodeling of root architecture under heat and osmotic stress. Azospirillum species fix nitrogen and produce auxin that increases lateral root and root hair density, improving water and nutrient capture under drought. Bacillus subtilis secretes lipopeptides with antimicrobial and signaling functions and, in select strains, ACC deaminase activity that lowers stress-induced ethylene accumulation. Pseudomonas fluorescens contributes siderophore-mediated iron sequestration and volatile organic compound production triggering induced systemic resistance. Grapevine inoculated with Burkholderia phytofirmans strain PsJN shows enhanced cold tolerance associated with elevated proline, soluble sugars, and trehalose. PGPR inoculation has improved photosynthetic rate, water-use efficiency, and root growth in grapevine and citrus under drought and salinity, and enhanced antioxidant activity and fruit quality in strawberry and banana under heat and water-deficit stress.

Arbuscular mycorrhizal fungi (AMF) form obligate symbioses with most terrestrial plant roots, conferring benefits for phosphorus acquisition and abiotic stress mitigation. Colonization stimulates osmoprotectant biosynthesis—proline and reduced glutathione—and antioxidant enzymes including POD, SOD, and CAT, limiting ROS-mediated damage. In citrus and papaya, Glomus species colonization sustains photosynthetic performance and chlorophyll retention under thermal stress, with root colonization commonly exceeding 40–60%, chlorophyll increases of 15–30% relative to non-mycorrhizal controls, and comparable reductions in malondialdehyde under heat stress. Phosphorus uptake in mycorrhizal seedlings frequently increases several-fold under low-phosphorus conditions, reflecting extraradical hyphal access beyond the root depletion zone. Yet translation to open-field systems remains considerably less reliable: spatial heterogeneity in soil texture, pH, and phosphorus availability modifies establishment, competition from indigenous AMF communities reduces colonization by introduced inoculants, and commercial inocula frequently fail to maintain stable colonization beyond one or two seasons.

Synthetic microbial communities (SynComs) represent the current frontier, combining strains to achieve functions and stability unattainable with single inoculants. Rational assembly draws on resource ratio theory—pairing nitrogen fixers with phosphate solubilizers rather than competing strains—and the maximum power principle, favoring combinations that optimize metabolic cross-feeding. Multi-kingdom co-inoculations, such as Azospirillum brasilense paired with phosphate-solubilizing bacteria or bacterial-AMF combinations, have improved yield and stress resilience in wheat and pomegranate. Biosafety-compliant consortia applied to rough lemon (Citrus jambhiri) rootstock have produced measurable developmental improvements. But colonization stability remains the primary bottleneck limiting translation to commercial use, and regulatory acceptability constrains taxon selection, excluding strains with toxigenic potential or documented pathogenicity regardless of nutrient-mobilizing activity.

Non-microbial biostimulants occupy a parallel track with differentiated evidence bases. Seaweed extracts derived mainly from Ascophyllum nodosum and Durvillaea potatorum consistently induce antioxidant enzymes, regulate stomatal conductance, and preserve chlorophyll fluorescence under stress across greenhouse and field studies in perennial fruit crops, stabilizing membrane lipids under heat stress in strawberry and grape. Humic substances act through soil conditioning and plasma-membrane H⁺-ATPase stimulation driving root proliferation, translating into consistent field outcomes in apricot, pomegranate, and mango nursery grafts—the strongest and most consistent evidence base among non-microbial biostimulants. Protein hydrolysates supply assimilable nitrogen and signalling peptides that upregulate carbon-nitrogen metabolism, with particular value in accelerating metabolic recovery after acute heat or drought stress. Free amino acids such as proline and GABA act faster via osmoprotection, ROS scavenging, and stomatal regulation, but effects are transient, requiring frequent reapplication. Chitosan elicits defence responses and enhances antioxidant capacity, though efficacy is highly formulation-dependent. Silicon reinforces vascular tissue through phytolith deposition, improving fruit firmness and aiding osmotic adjustment, while engineered nanomaterials remain the least mature category with poorly understood environmental fate.

Phytohormonal priming agents exploit the concept of stress memory: pretreatment with chemical or biological elicitors establishes an elevated defensive state via epigenetic and transcriptional memory, enabling faster and cheaper defense upon challenge. Melatonin elevates ascorbate-glutathione couples in apple and grape, sustains CO₂ assimilation under drought in apple, and downregulates chlorophyll catabolic genes to delay senescence in drought-stressed kiwifruit, grape, and loquat. Polyamines including putrescine, spermidine, and spermine regulate stomatal aperture through membrane permeability and guard cell potassium channels, with spermine at 1 mM more consistently improving drought tolerance in cherry tomato, apple, and citrus. Brassinosteroids act at nanomolar concentrations, stabilizing membranes and chloroplast ultrastructure under drought, salinity, and thermal stress, with ultra-low-dose (0.05 ppm) pre-stress application mitigating drought in apple orchards—one of the few field-tested brassinosteroid interventions. Paclobutrazol at 0.5 g per plant produces a field-validated antitranspirant effect in apple.

Antitranspirants converge on a single physiological objective—preserving plant water status under atmospheric or edaphic water deficit—yet differ markedly in where they intervene along the soil-plant-atmosphere continuum. Metabolic regulators such as abscisic acid, chitosan, and fulvic acid modify guard-cell ion fluxes and turgor regulation, acting fast and reversibly but remaining highly sensitive to concentration and application timing. Reflective particle films, predominantly refined kaolin or calcium carbonate, increase leaf surface albedo, reflecting incident infrared and ultraviolet radiation to reduce canopy heat load; while single-leaf interception of photosynthetically active radiation is reduced, whole-canopy carbon gain is often maintained or even enhanced through improved diffuse-light penetration into lower canopy strata. Film-forming polymers such as di-1-p-menthene derivatives polymerize on the leaf surface to obstruct transpirational efflux mechanically, persisting for a single seasonal application but suppressing carbon influx for as long as the film persists. Biogenic lipids and botanical waxes derived from agricultural by-products form biodegradable cuticle-like films that avoid the environmental persistence of synthetic polymers while achieving comparable reductions in stomatal conductance.

The deeper mechanistic insight emerging from the review is that these interventions do not act on independent targets. Reactive oxygen species, particularly hydrogen peroxide, function as signaling integrators rather than incidental toxins, existing in continuous cross-talk with reactive nitrogen species—principally nitric oxide—with the balance and spatial co-occurrence of the two determining whether a given signal is interpreted as protective priming or as damage. Redox homeostasis is maintained through a distributed network in which signaling specificity depends on the spatial localization of ROS/RNS production, the temporal dynamics of the signal, and threshold effects whereby the same molecule at different concentrations activates distinct downstream programs. This hub operates in tight integration with ABA signaling and MAPK cascades, translating redox signals into transcriptional and post-translational changes in antioxidant activity, osmolyte biosynthesis, and stomatal aperture. Single-cell and spatial transcriptomic profiling further reveals substantial cell-type specialization: guard cells, mesophyll, vascular tissue, epidermis, and root cell types each mount quantitatively and qualitatively distinct stress-signaling programs, such that bulk physiological measurements can average away biologically important localized responses.

Agroecological case studies ground these mechanisms in real-world systems. In the arid agroecosystems of Rajasthan, India, the Bishnoi community’s conservation of Prosopis cineraria (khejri), a keystone leguminous tree, sustains soil health via leaf litter deposition and symbiotic nitrogen fixation. Field trials at the Central Institute for Arid Horticulture in Bikaner intercropping aonla and ber with khejri found aonla yield highest under an aonla-khejri configuration at 46.2 kg per plant, with an aonla-khejri-cluster bean-ajowain rotation producing the greatest gains in soil organic carbon, available nitrogen and potassium, and microbial populations. Underutilized fruit crops such as baobab and dragon fruit are increasingly integrated into semi-arid agroecosystems of Rajasthan and Gujarat, sustaining productivity in degraded soils that constrain conventional cultivars while contributing to nutritional security through polyphenol, flavonoid, and carotenoid profiles. Integrated Soil Fertility Management synchronizes inorganic fertilizers, organic amendments, and microbial inoculants to jointly optimize soil’s physical, chemical, and biological dimensions, with biochar increasing soil porosity and cation exchange capacity while creating microhabitats for beneficial microbiota.

Crop-specific evidence illustrates both promise and persistent gaps. In mango, combined zinc oxide and silicon nanoparticles in salinity-stressed ‘Ewais’ significantly enhanced nutrient uptake and carbon assimilation, while foliar seaweed extract offers a sustainable alternative to synthetic potassium-based regulators in ‘Palmer’ under semi-arid conditions. In a two-season field-based regulated-deficit-irrigation trial on drought-sensitive ‘Keitt’ mango, foliar co-application of 24-epibrassinosteroid and hydrogen peroxide reduced physiological decline associated with water stress and improved fruit set, yield, and crop water productivity relative to either compound alone. In subtropical litchi, high thermal loads combined with low relative humidity accelerate epicuticular wax degradation and mesocarp desiccation, culminating in skin cracking and sunburn injury, while district-level analysis of Bihar’s climate record documents a consistent upward trend in maximum temperature, most pronounced since 1981. In temperate apple and stone fruits, inadequate chilling during warming winters causes erratic bud break and asynchronous flowering, while more frequent late spring frosts expose floral primordia to freezing stress via intracellular ice nucleation and irreversible membrane rupture.

The principal challenge emerging from the synthesis is the persistent gap between controlled-condition efficacy and commercial orchard performance. Microbial inoculants, biostimulants, and phytohormonal priming agents that appear highly effective in laboratory or greenhouse experiments often show weaker, inconsistent, or no benefit under field conditions—not because of a simple failure of biology, but because of interacting environmental, ecological, formulation, and management constraints largely minimized in controlled studies. Introduced microorganisms must compete with resident microbiota for niche availability and resources, and establishment is often transient or incomplete. Host genotype and cultivar specificity further constrain generalization, since the same product can elicit divergent responses across cultivars or rootstocks. Product performance is limited by formulation stability, carrier choice, storage conditions, and delivery logistics, with living inoculants particularly vulnerable to temperature fluctuation, desiccation, and UV exposure. Regulatory fragmentation and the absence of standardized strain characterization and quality-control protocols further hinder product consistency and multi-region commercialization.

Future progress requires predictive, systems-based research integrating multi-omics profiling, microbiome engineering, precision management, and improved delivery formulations to enable scalable, evidence-based climate-resilient fruit production. Integrating genomics, transcriptomics, proteomics, metabolomics, and microbiomics could improve identification of stress-resilience mechanisms and beneficial microbial functions beyond the scope of single-omics studies. Precision agriculture offers additional opportunities: remote and proximal sensing can characterize within-orchard variability and support targeted application of biological inputs, while AI-based decision-support systems may optimize intervention timing. Improved formulation and encapsulation technologies are needed to enhance product stability, shelf life, and delivery efficiency. Until rigorous multi-location, multi-season field validation under commercially realistic conditions is available, claims of practical readiness should remain proportionate to the available data. Nature-based interventions should be viewed as complementary components of climate-smart orchard management rather than standalone solutions, with integrated approaches generally providing more consistent improvements in stress tolerance, physiological performance, and fruit productivity than single-input interventions.

Subject of Research: Nature-based strategies for heat and drought resilience in fruit crops through genotype, environment, and management interactions

Article Title: Nature based strategies for heat and drought resilience in fruit crops through genotype environment and management interactions

Article References: Sharma, K. (2026). Nature based strategies for heat and drought resilience in fruit crops through genotype environment and management interactions. Discover Plants, 3(1), Article 469. https://doi.org/10.1007/s44372-026-00941-1

Image Credits: AI Generated

DOI: 10.1007/s44372-026-00941-1

Keywords: fruit crops, heat stress, drought resilience, microbial inoculants, biostimulants, phytohormonal priming, antitranspirants, G×E×M framework, climate-smart horticulture, arbuscular mycorrhizal fungi, SynComs, orchard management

The research team, drawn from the ESPOL Polytechnic University, the Federal University of Santa Maria, the Universidad Agraria del Ecuador, and the Universidad de Especialidades Espíritu Santo, framed the work against the realities of Ecuadorian cocoa farming. Cacao is one of the country’s leading non-oil agricultural exports, prized internationally for the distinctive flavor and aroma of its beans. In 2024, roughly 612,453 hectares were planted with cacao in Ecuador, producing 403,699 metric tons of dry cocoa beans. Yet the crop’s economics are dominated by smallholders: approximately 87 percent of production units cultivate fewer than five hectares, often with limited access to credit, technical assistance, and agricultural inputs. That combination constrains essential agronomic practices and keeps yields well below the crop’s genetic potential, creating an opening for low-cost interventions that could improve establishment without demanding heavy investment.

Biostimulants occupy a peculiar niche in this picture. Unlike conventional fertilizers, they are not primarily nutrient sources. As defined in the plant science literature, a biostimulant is a formulated product of biological origin that improves productivity through the emergent properties of its complex constituents, modulating processes such as cell division, root and shoot elongation, photosynthesis, nutrient uptake, and stress responses. Seaweed-derived products are among the oldest and most widely used categories, with liquid seaweed extracts dating back to the 1950s. Their bioactive repertoire is broad: polysaccharides, phenolic compounds, amino acids, minerals, vitamins, pigments, and hormone-like molecules that can influence respiration, photosynthesis, nucleic acid metabolism, and ion uptake. The authors caution, however, that biostimulants should complement rather than replace balanced plant nutrition and sound agronomic management.

The two seaweeds chosen for the study were not arbitrary. Ulva species are rich in ulvan, a water-soluble sulfated polysaccharide composed mainly of rhamnose, glucuronic acid, iduronic acid, and xylose, which can act as a bioactive elicitor of physiological and biochemical responses in plants. Previous work has shown dramatic effects in other species: a crude ulvan extract applied to Arabidopsis thaliana increased root length by 174 percent and total plant dry weight by 62 percent under specific experimental conditions. Acanthophora spicifera, a tropical red seaweed that grows along the Ecuadorian coast, contains its own suite of sulfated polysaccharides, phenolics, and pigments, and its extracts have modulated photosynthesis, hormonal signaling, and defense-related genes in tomato and sweet pepper while reducing bacterial and fungal disease severity. Notably, the researchers point out that no previous study had tested either species as a biostimulant for cacao seedlings.

Experimentally, the design was exhaustive. The red seaweed was collected from the intertidal zone at San Pedro, Santa Elena, and the green seaweed from Puerto El Morro in Guayas. Biomass was cleaned, frozen, and then extracted at a 1:10 biomass-to-solvent ratio using three media: pure water, 25 percent aqueous ethanol, and 50 percent aqueous ethanol, followed by maceration in darkness at 4 degrees Celsius and centrifugation. Each extract was diluted to 2.5, 5, or 7.5 percent by volume and sprayed weekly onto grafted CCN-51 cacao plantlets, with filtered water serving as the control. In total, 450 plants were assigned to treatments in a completely randomized design, each plant acting as its own experimental unit across repeated measurements of plant height, leaf number, leaf length, and chlorophyll content taken at 15-day intervals.

The statistical machinery matched the complexity of the design. Because the same plants were measured repeatedly, the team used linear mixed-effects models with plant-level random intercepts for chlorophyll and height, and a generalized model with a negative binomial error distribution for leaf counts, which showed substantial overdispersion. The analysis revealed a significant interaction between treatment-dose combination and time for the Chlorophyll Content Index, meaning the effect of each formulation was not constant across the season. No differences existed among treatments at baseline, but by Day 45 the low-dose Ulva 50 percent ethanol extract stood clearly apart, with several other low-to-moderate Ulva treatments also producing relatively high chlorophyll values in later evaluations. Differences emerging only after the third week suggest the algal compounds progressively influence chlorophyll synthesis, nitrogen metabolism, and photosynthetic efficiency rather than acting immediately.

Leaf number told a more complicated story. It varied significantly among treatments at intermediate time points, but by Day 45 four treatment combinations had suffered complete defoliation, a treatment-specific phytotoxic response after prolonged exposure. The affected combinations included Ulva extracts at both 25 and 50 percent ethanol and an Acanthophora 25 percent ethanol extract at the highest dose. Meanwhile, plant height and leaf length showed no significant differences among treatments at any point, indicating that the seaweed extracts acted primarily at a physiological level, on photosynthetic pigment and foliar dynamics, before any structural growth changes became visible. A principal component analysis reinforced this pattern: the first principal component, explaining 46.4 percent of variance, was driven mainly by chlorophyll content, and the Ulva ethanol treatments at low doses clustered toward the favorable pole.

What explains the potency of the dilute Ulva extract? The authors point to betaines and cytokinin-like compounds previously identified in Ulva species, which have long been associated with enhanced leaf chlorophyll. Cytokinins regulate chlorophyll biosynthesis and chloroplast function, and a recent measurement of the green alga Ulva intestinalis, collected near the study site, found high cytokinin concentrations specifically in 50 percent ethanol extracts, matching the extraction medium that performed best here. The dark side of the results, the defoliation at higher or prolonged exposures, illustrates the narrow therapeutic window of biostimulants: excessive concentrations may inhibit pigment accumulation through osmotic or metabolic overload. The effect also underscores why extraction chemistry matters, since solvent polarity determines which bioactive constituents are recovered from the algal biomass.

The Ecuadorian context gives the findings practical weight. Locally harvested seaweed could become a sustainable, homegrown input for smallholder nurseries, and the study was supported by the country’s REDD+ Early Movers program as part of a mariculture project designed to create incentives for mangrove conservation, tying cacao agriculture to coastal ecosystem stewardship. The researchers are careful about scope: the responses were dose- and time-dependent, height and leaf size were unaffected, and the phytotoxic defoliation shows that concentration and application frequency must be optimized before any agronomic deployment. Still, as the first documented report of increased chlorophyll content in cacao seedlings treated with Ulva extracts, the study opens a precise, chemically informed path toward helping one of the world’s most beloved crops take root.

Subject of Research: Seaweed-derived biostimulants and the early growth and physiology of cacao plantlets

Article Title: Enhancing growth and physiological performance of Theobroma cacao plantlets with biostimulant extracts from Acanthophora spicifera and Ulva sp

Article References: Chavez-Navarrete, T., Briones-Avilés, B., Villao, L., Santos-Ordóñez, E., Portalanza, D., & Bonilla, J. (2026). Enhancing growth and physiological performance of Theobroma cacao plantlets with biostimulant extracts from Acanthophora spicifera and Ulva sp. Frontiers in Agronomy, 8, Article 1957460. https://doi.org/10.3389/fagro.2026.1957460

Image Credits: AI Generated

DOI: 10.3389/fagro.2026.1957460

Keywords: biostimulants, seaweed, cacao, Theobroma cacao, Ulva, Acanthophora spicifera, chlorophyll, Ecuador, plant physiology, sustainable agriculture, Enhancing, growth

The research team, led by Mohamed S. Gawish of Damietta University together with colleagues from Tanta University, Al-Azhar University, the Horticulture Research Institute, and Kafrelshaikh University, focused on two of Egypt’s most widely used mango rootstocks: Sokkary and Gahrawy. These are the rootstocks onto which commercial mango scions are grafted, meaning their ability to cope with salt in the soil and irrigation water directly determines whether a young orchard thrives or fails. The scientists irrigated potted seedlings of both rootstocks with ordinary tap water or with seawater diluted to 1500 or 3000 parts per million, levels that mimic the saline irrigation water increasingly common in coastal and delta agriculture.

The damage from salt was swift and measurable. Salinity significantly reduced plant height, stem diameter, leaf area, and chlorophyll content, while also lowering the crucial potassium-to-sodium ratio in leaf tissue. That ratio matters because potassium fuels enzyme activity and stomatal function, whereas sodium accumulates to toxic levels, disrupting membranes and starving plants of the nutrients they need. Under the harshest treatment, 3000 ppm seawater, untreated seedlings of both rootstocks managed to reach only 24 to 25 centimeters in height—stunted specimens of what healthy mango nursery stock should be.

Beneath the visible stunting, the researchers documented the molecular fingerprints of salt stress. Levels of malondialdehyde, a marker of lipid peroxidation in cell membranes, climbed as salt concentrations rose, as did hydrogen peroxide, a reactive oxygen species that damages proteins and DNA. In response, the seedlings ramped up their antioxidant enzyme systems, the plant equivalent of an emergency repair crew. These biochemical indicators confirmed that the seedlings were under genuine oxidative siege, not merely growing slowly, and gave the team a quantitative baseline against which to judge the biostimulant treatments.

Then came the rescue. When the researchers sprayed the seedlings with glycine betaine or algae extract, the results were striking. At 3000 ppm seawater, glycine betaine application on Gahrawy seedlings and algae extract application on Sokkary seedlings restored plant height to 42.25 and 40.00 centimeters respectively—nearly doubling the height of untreated salt-stressed plants. Glycine betaine, a small quaternary ammonium compound that plants naturally accumulate under stress, works as an osmolyte, helping cells retain water and stabilize proteins and membranes even when external salt concentrations would otherwise pull moisture out of tissues.

The two rootstocks, however, told different stories. Gahrawy proved to be the intrinsically tougher customer, retaining more potassium in its leaves at 2.174 percent, producing more of its own endogenous glycine betaine at 2.91 micromoles per gram of dry weight, and showing stronger baseline antioxidant capacity, measured as 40.23 percent DPPH radical scavenging. Sokkary, by contrast, was more salt-sensitive on its own but responded far more vigorously to biostimulant applications, particularly glycine betaine under severe salinity. This genotype-by-treatment interaction is the study’s central insight: there is no universal fix, and matching the biostimulant to the rootstock is what unlocks the full benefit.

The numbers behind glycine betaine’s performance are compelling. In Gahrawy seedlings irrigated with 1500 ppm seawater, glycine betaine treatment pushed plant height to 50.0 centimeters, and at the severe 3000 ppm level it reduced leaf sodium accumulation by up to 51 percent. That sodium exclusion is critical, because limiting how much salt enters and accumulates in leaves is one of the primary mechanisms by which plants tolerate saline conditions. The treatment also improved osmotic adjustment, ion homeostasis, and chlorophyll stability, meaning treated plants could keep photosynthesizing under conditions that would normally bleach their leaves and shut down carbon fixation.

Algae extract worked through a complementary route. Rather than primarily boosting osmotic protection, the seaweed-derived spray enhanced antioxidant activity, reaching 53.0 percent DPPH scavenging in treated plants, while promoting leaf expansion and vascular development. Seaweed extracts are known to contain a cocktail of bioactive compounds, including cytokinins, betaines, polysaccharides, and micronutrients, which can stimulate growth and prime plant defense systems. The anatomical analyses in this study added a structural dimension: treated plants developed improved vascular tissue organization, suggesting that the extract helped seedlings maintain the plumbing needed to transport water and nutrients even as salt threatened to disrupt it.

Perhaps most intriguingly, the team’s microscopic examination of leaf and stem anatomy revealed genotype-specific structural adaptations associated with salinity tolerance. Differences in tissue organization between Sokkary and Gahrawy help explain why the two rootstocks respond differently to both salt and the biostimulants. Such anatomical evidence is often missing from biostimulant studies, which tend to stop at biochemical measurements, but it provides a mechanistic bridge between what happens at the cellular level and what a grower sees in the nursery bed. The fact that structural adaptations differed between genotypes reinforces the conclusion that salt tolerance in mango is a multi-layered trait, woven from ion regulation, antioxidant chemistry, and physical architecture all at once.

For mango growers and nursery operators in Egypt and across the salinity-prone tropics, the practical implications are immediate. Foliar sprays of glycine betaine or algae extract are inexpensive, easy to apply, and compatible with existing nursery routines, making them far more accessible than genetic engineering or expensive soil remediation. The study suggests a simple decision rule: pair Gahrawy rootstock with glycine betaine and lean on its inherent salt tolerance, or choose Sokkary and boost it with algae extract or glycine betaine when salinity is unavoidable. As climate change pushes seawater further inland and freshwater for irrigation grows scarcer, such sustainable, genotype-matched biostimulant strategies may become essential tools for keeping mango orchards—and the livelihoods that depend on them—alive in salty ground.

Subject of Research: Effects of glycine betaine and algae extract on salinity tolerance of two mango rootstocks

Article Title: Genotype performance, biochemical and anatomical response of two mango rootstocks to glycine betaine and algae extract under salinity stress

Article References: Gawish, M. S., Abo-Ogiala, A. M., Abdel-Aziz, E. A., Ahmed, E.-E. A., El-Enien, M. S. A., & Salama, A.-M. (2026). Genotype performance, biochemical and anatomical response of two mango rootstocks to glycine betaine and algae extract under salinity stress. BMC Plant Biology, 26(1), Article 1661. https://doi.org/10.1186/s12870-026-09893-w

Image Credits: AI Generated

DOI: 10.1186/s12870-026-09893-w

Keywords: mango rootstocks, salinity stress, glycine betaine, algae extract, antioxidant enzymes, oxidative stress, Sokkary, Gahrawy, plant physiology, biostimulants, climate resilience, BMC Plant Biology

The scale of the improvements is what makes the findings remarkable. Compared with conventional fertilization, the fully enriched biochar treatment raised soil organic carbon by 109 percent and cation exchange capacity by 68 percent, while cutting soil bulk density by 19 percent. Those three numbers describe a soil that stores more carbon, holds and exchanges more nutrients, and is physically less compacted — a combination that directly benefits roots, which must push through dense soil to reach water and nutrients. In semi-arid regions where drought degrades soil structure year after year, reversing all three trends at once with a single amendment is an unusual outcome.

Below ground, the effects were even more dramatic. Root surface area increased 2.8-fold under the enriched treatment, and fine roots — those thinner than half a millimeter — made up 71 percent of total root length. This shift in root architecture matters enormously for drought adaptation. Fine roots are the workhorses of water and nutrient uptake, exploring soil pores that thicker roots cannot penetrate. A root system dominated by fine roots can exploit a much larger volume of soil for the same carbon investment, effectively giving the vine a larger and more efficient foraging network precisely when water is scarce. The researchers attribute this architectural shift partly to the biostimulant components, particularly brassinosteroid, a plant hormone known to regulate root development, and partly to the improved physical conditions created by the biochar itself.

The physiological evidence of drought relief was equally clear. Leaf relative water content — a direct measure of how well-hydrated the foliage is — climbed from 68.5 percent to 88.2 percent under the fully enriched treatment. Meanwhile, two classic biochemical stress markers moved sharply in the right direction: proline, an amino acid that accumulates when plants are water-stressed, fell by 67 percent, and malondialdehyde, a byproduct of oxidative damage to cell membranes, dropped by 62 percent. In plain terms, the vines were no longer desperately conserving water or repairing membrane damage. They were functioning as well-hydrated, low-stress plants despite receiving no irrigation at all.

These physiological gains translated into photosynthetic performance and nutrient uptake. The enriched treatment improved photosynthetic efficiency and increased the uptake of essential nutrients, consistent with the combined action of the amendment’s components. The arbuscular mycorrhizal fungus Rhizophagus irregularis extends the root’s effective reach through fungal hyphae that access phosphorus and other nutrients beyond the depletion zone around roots. The bacteria Azospirillum brasilense and Pseudomonas fluorescens contribute nitrogen fixation, hormone production, and general growth promotion. Biochar serves as an ideal carrier for these organisms, offering a porous, carbon-rich habitat that protects microbial inoculants from the harsh conditions of semi-arid soil — a role that has attracted growing attention in recent years as researchers seek reliable ways to keep beneficial microbes alive long enough to colonize plant roots.

The enrichment strategy is what distinguishes this work from most biochar studies. Plain biochar has been tested extensively in vineyards, with mixed results that often depend on soil type, pyrolysis conditions, and climate. Here, the researchers layered multiple functions onto the same carbon matrix. Chitosan, a biopolymer derived from crustacean shells, acts as a soil conditioner and elicitor of plant defense responses, and it can improve water retention in amended soils. Fulvic acid, a small-molecule component of humic substances, chelates nutrients and enhances their mobility toward roots. Brassinosteroid tunes hormonal signaling for stress tolerance and root growth. By loading all of these onto grapevine-pruning biochar — itself a clever piece of circular agriculture, since the feedstock comes from the same vineyards being treated — the team created what is essentially a slow-release, biologically active soil supplement.

The four-year duration of the experiment, running from 2022 to 2025, lends the results particular weight. Many biochar trials last a single season, which raises questions about whether initial flushes of improvement will persist once the amendment’s labile fractions are consumed. Multi-year data showing sustained gains in soil carbon, root architecture, water status, and yield suggest that the enriched biochar is not merely a short-lived fertilizer spike but a durable modification of the soil-plant system. The seven treatments evaluated across the trial also allowed the researchers to isolate the contribution of each enrichment component, and the fully enriched formulation consistently outperformed simpler combinations.

Yield is where the story becomes genuinely viral-worthy for the agricultural world: the fully enriched treatment produced a 114 percent increase in yield relative to conventional fertilization. Doubling the productivity of rain-fed vines, without irrigation, in a semi-arid climate, is the kind of result that could reshape how marginal vineyard regions approach water scarcity. And the economics held up. The benefit-to-cost ratio for the fully enriched treatment was 2.95 — the highest among all treatments — meaning that every unit of money spent on the amendment returned nearly three units of value. For growers operating on thin margins in drought-prone regions, that ratio may matter as much as the yield figure itself, because it demonstrates that the approach is not just scientifically interesting but commercially viable.

The broader context is a growing scientific consensus that single-tool solutions are insufficient for climate adaptation in agriculture. Reviews of biochar research have emphasized that its effects on soil and plants depend on mechanisms that vary widely — carbon sequestration, water retention, microbial habitat, nutrient exchange — and that combining biochar with complementary technologies often outperforms biochar alone. Similarly, meta-analyses of mycorrhizal fungi and plant growth-promoting bacteria show consistent benefits for drought tolerance and nutrient uptake, but field delivery of living inoculants remains a persistent challenge. The enriched-biochar approach addresses that challenge directly by using the biochar’s porous structure as a protective carrier, effectively solving two problems — soil conditioning and microbial survival — with one material.

For the wine and grape industries, which face intensifying drought pressure across the Mediterranean, the Middle East, and other warm-climate regions, the study points toward a practical pathway: recycle vineyard pruning waste into biochar, enrich it with chitosan, fulvic acid, brassinosteroid, and proven microbial strains, and return it to the soil. The result, according to the Iranian research team led by Mohammad Saeed Tadayon of the Agricultural Research, Education and Extension Organization, is a soil that holds more carbon and water, roots that forage more efficiently, leaves that stay hydrated under stress, and harvests that roughly double. As climate change tightens its grip on rain-fed agriculture worldwide, a treatment that turns vineyard waste into vineyard resilience — profitably — is exactly the kind of innovation the sector has been waiting for.

Subject of Research: Enriched biochar amendments for drought resilience and productivity in rain-fed grapevines

Article Title: Biochar enriched with chitosan and biostimulants improves root architecture, nutrient uptake, and drought adaptation of rain-fed grapevines

Article References: Tadayon, M. S., Mousavi, S. M., Hosseini, S. M., & Sadeghi, S. (2026). Biochar enriched with chitosan and biostimulants improves root architecture, nutrient uptake, and drought adaptation of rain-fed grapevines. Plant and Soil. https://doi.org/10.1007/s11104-026-09031-3

Image Credits: AI Generated

DOI: 10.1007/s11104-026-09031-3

Keywords: biochar, grapevine, drought resilience, chitosan, fulvic acid, brassinosteroid, mycorrhizal fungi, plant growth-promoting bacteria, root architecture, soil organic carbon, rain-fed viticulture, biostimulants

The research team focused on two formulations drawn from a commercial biostimulant platform: fulvic acid alone, designated BLG, and a mixture of fulvic acid with quillaja extract, designated BLGQ. Fulvic acid is a humic substance known for its ability to chelate nutrients and modulate plant metabolism, while quillaja extract, derived from the soapbark tree, is rich in saponins and is often included in biostimulant blends for its surfactant and signaling properties. By comparing these two treatments against untreated controls, the researchers could isolate not only what each formulation does, but what the quillaja component adds to the mixture. Leaf tissue was collected at two carefully chosen time points, three hours and twenty-seven hours after application, capturing what the authors describe as the early signaling phase and the later transcriptional and metabolic adjustment phase of the plant response.

The sequencing data showed that the earliest hours after treatment are anything but quiet. Within three hours, both formulations triggered rapid activation of genes involved in hormone signaling, ion transport, proteostasis, and transcription factor networks, the cellular machinery a plant needs to reprogram itself quickly in response to an external cue. What stood out most was the difference in amplitude: the quillaja-containing mixture, BLGQ, induced broader and stronger transcriptional changes than fulvic acid alone. This suggests that the saponin-rich extract acts as an amplifier of sorts, widening the set of genes that respond and pushing the early signaling cascade harder than the humic component can achieve on its own.

Among the most prominently upregulated genes in that early window were members of several major transcription factor families, including ERF, NAC, C2H2, WRKY, and MYB-related factors. These families are well known to science as master regulators of stress responses, growth, and developmental pathways in plants. ERF factors, for example, sit downstream of ethylene signaling and orchestrate responses to stress and senescence, while WRKY and NAC factors coordinate defenses against pathogens, drought, and other challenges. Their rapid mobilization within three hours indicates that the biostimulant treatments are perceived by maize not as passive nutrition but as genuine biological signals that engage the plant’s own regulatory architecture, priming pathways associated with both stress adaptation and growth promotion.

By twenty-seven hours, the picture had shifted in revealing ways. The fulvic acid treatment, BLG, predominantly reinforced broad metabolic, redox, and transcriptional regulatory networks, consistent with a formulation whose effects radiate outward into general adaptive processes: energy metabolism, oxidative balance, and wide-ranging gene regulation. The quillaja mixture, by contrast, emphasized signaling integration, vesicle trafficking, and secondary metabolism at the later time point. Vesicle trafficking, the cellular logistics system that moves proteins and signaling molecules between compartments, is an intriguing target for biostimulant action, as it underpins cell wall modification, hormone transport, and defense signaling. The secondary metabolism signal hints at the production of specialized compounds that may bolster the plant’s defensive and adaptive chemistry over longer timescales.

The transcription factor analysis added a further layer of nuance, showing that each formulation deploys its own regulatory strategy over time. Fulvic acid sustained the upregulation of MYB-related, NAC, GRAS, and ERF transcription factors across the response window, maintaining pressure on pathways tied to general adaptation. The quillaja mixture took a more surgical approach, selectively balancing upregulation and downregulation of NF-YB, HSF, and bZIP families. This push-and-pull pattern suggests a fine-tuning function, in which the mixture modulates heat shock responses, abiotic stress signaling, and specialized metabolic pathways with greater precision rather than simply turning them up. The authors interpret these contrasting patterns as evidence of stimulus- and time-specific strategies, meaning the plant’s response depends on both what is applied and when you look.

Taken together, the findings reframe how biostimulants should be understood at the molecular level. Rather than acting as generic tonics, these formulations appear to engage distinct, overlapping but separable regulatory programs. The fulvic acid response was associated with broader transcriptional changes in genes involved in general adaptive processes, while the quillaja-containing mixture was associated with more specific signaling and regulatory pathways. For growers and agronomists, this has practical implications: the choice between formulations, and the timing of their application, could be optimized based on which physiological outcome is desired, whether broad metabolic support or targeted signaling priming. For biostimulant developers, the study provides a mechanistic roadmap for designing products with defined molecular targets rather than relying on empirical field trial results alone.

The study also carries a methodological lesson that extends well beyond biostimulants. Had the researchers sampled only a single time point, they would have captured a misleadingly static snapshot and missed the fundamental shift in response character between three and twenty-seven hours. The early phase is dominated by rapid signaling and transcription factor activation, while the later phase reflects downstream metabolic and regulatory consolidation. The authors explicitly underline the importance of time-resolved analyses for understanding plant growth and stress adaptation, a point that applies equally to studies of fertilizers, elicitors, and stress treatments across crop science. Dynamic processes demand dynamic measurement, and this work demonstrates how RNA sequencing at multiple time points can expose the temporal architecture of a plant’s response to agricultural inputs.

Maize, as one of the world’s most important cereal crops and a staple grown across diverse and increasingly unpredictable climates, stands to benefit considerably from this kind of mechanistic insight. As agriculture confronts pressure to reduce synthetic inputs while maintaining yields under heat, drought, and disease stress, biostimulants are likely to play an expanding role, and understanding their molecular modes of action will be essential for credible, effective deployment. This transcriptomic study provides a foundation for that understanding, mapping the temporal layers of biostimulant action in a major crop and showing that the mixture of quillaja extract with fulvic acid is more than the sum of its parts. The next steps for the field will involve connecting these transcriptional signatures to measurable agronomic traits, but the study makes clear that the conversation between biostimulant and plant begins within hours and unfolds along distinct, formulation-specific paths that science is only now beginning to read.

Subject of Research: Temporal transcriptomic responses of maize to fulvic acid and quillaja extract biostimulants

Article Title: Temporal and stimulus-specific transcriptional responses of maize to a biostimulant mixture of quillaja extract and fulvic acid

Article References: Hesami, M., Rahbari, M., & Salzman, R. A. (2026). Temporal and stimulus-specific transcriptional responses of maize to a biostimulant mixture of quillaja extract and fulvic acid. PLOS One, 21(10), e0360081. https://doi.org/10.1371/journal.pone.0360081

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360081

Keywords: maize, biostimulants, fulvic acid, quillaja extract, transcriptomics, RNA sequencing, transcription factors, plant stress response, hormone signaling, secondary metabolism, time-resolved gene expression, PLOS One

The research team, led by Mujahid Farid of the University of Gujrat in Pakistan together with collaborators at universities in Saudi Arabia and Syria, set out to test whether a dual-route strategy could overcome the central weakness of phytoextraction: plants that accumulate large quantities of metals usually suffer severe growth penalties, while plants that grow well often accumulate too little metal to be useful for cleanup. Spinach, a fast-growing leafy vegetable with substantial biomass, sits squarely in the middle of this trade-off, which is precisely why the researchers chose it as their experimental system.

The experiments used real surgical industry wastewater rather than artificially prepared metal solutions, an important distinction because genuine effluents contain complex mixtures of contaminants that can interact in unpredictable ways. Plants were grown under two levels of contamination, 50 percent and 100 percent wastewater, and the untreated conditions proved harsh. At full-strength wastewater, plant height fell by 65.8 percent, biomass production collapsed, and the plants showed clear signs of oxidative damage as reactive oxygen species accumulated in their tissues.

That oxidative damage is the biochemical heart of heavy metal toxicity. Metals such as nickel, copper and lead interfere with electron transport chains and enzyme active sites, causing cells to overproduce reactive oxygen species. Left unchecked, these molecules attack membranes, degrade photosynthetic pigments and damage DNA. Plants normally defend themselves with an antioxidant arsenal, including the enzyme superoxide dismutase, which converts the superoxide radical into less harmful compounds. Under severe metal stress, however, this defense system is quickly overwhelmed.

The dual treatment changed that picture in striking fashion. When spinach plants received 10 millimolar malic acid in the rhizosphere together with foliar applications of Moringa oleifera leaf extract, the damage from full-strength wastewater was largely reversed. Plant height, which had dropped by nearly two-thirds, recovered by 42.8 percent. Root superoxide dismutase activity rose from 34.25 to 53.06 units per milligram of protein under the harshest conditions, indicating a substantially strengthened antioxidant front line. The treated plants also maintained their photosynthetic pigments, preserving the green machinery on which growth depends.

The two components of the treatment play complementary roles. Malic acid, a natural organic acid found in the rhizosphere of many plants, acts as a chelator. By binding metal ions in the soil solution, it increases their bioavailability, effectively unlocking metals that would otherwise remain locked to soil particles and unavailable for uptake. This is a well-known principle in assisted phytoextraction, but the study shows it operating under genuinely contaminated, multi-metal conditions rather than in simplified single-metal pot experiments.

Moringa leaf extract, by contrast, works from above. The extract of the moringa tree, often called the miracle tree, is rich in growth-promoting compounds including cytokinins, antioxidants, amino acids and vitamins. Sprayed onto foliage, it appears to bolster the plant’s internal defenses and support photosynthetic performance while the roots are busy absorbing an increased load of metals. The result is a rare combination: more metal taken up and a healthier plant at the same time.

The accumulation figures are the most eye-catching part of the study. Under 100 percent wastewater, treated plants accumulated 7046.67 micrograms of copper and 10510.69 micrograms of nickel in their roots, alongside significant increases in lead. These absolute accumulation values matter because phytoextraction is ultimately judged on the total mass of metal removed from a site, not merely on concentration measurements. A plant that concentrates metals modestly but produces abundant biomass can outperform a hyperaccumulator that barely grows, and the malic acid plus moringa strategy appears to push spinach toward that favorable balance.

The authors emphasize that this is the first report of simultaneous rhizosphere application of malic acid and foliar application of Moringa oleifera leaf extract tested against authentic multi-metal surgical wastewater in spinach. Previous work has generally examined these treatments separately, in isolation, or against synthetic contamination. Testing the combined approach under real-world effluent conditions gives the results practical weight, since industrial wastewater chemistry, with its mixture of metals and organic compounds, is far more challenging than any laboratory solution.

The implications extend in two directions. For environmental remediation, the study points toward a low-cost phytoextraction package: malic acid is inexpensive and biodegradable, and moringa leaf extract can be prepared from a widely grown tree, making the approach accessible in regions where synthetic chelators and sophisticated amendments are unaffordable. For agriculture, the work suggests that organic biostimulants can help crops tolerate contaminated irrigation water, a growing concern in areas where wastewater is routinely reused. The researchers caution, implicitly, that metal-enriched spinach is not for the dinner plate; the value here lies in cleanup and in understanding stress regulation. As wastewater reuse expands worldwide, strategies that let plants survive, grow and simultaneously pull metals out of the soil and water could become an important tool in the fight against insidious, long-lasting heavy metal pollution.

Subject of Research: Regulation of multi-metal stress responses and phytoextraction in spinach using malic acid and Moringa leaf extract

Article Title: Regulation of multi-metal stress responses in spinach by malic acid and Moringa leaf extract: implications for plant performance and phytoextraction

Article References: Farid, M., Farooq, F., Alghanem, S. M. S., Alhaithloul, H. A. A. S., Alotaibi, M. S., Munir, M., Hamoud, Y. A., & Shaghaleh, H. (2026). Regulation of multi-metal stress responses in spinach by malic acid and Moringa leaf extract: implications for plant performance and phytoextraction. BMC Plant Biology. https://doi.org/10.1186/s12870-026-10087-7

Image Credits: AI Generated

DOI: 10.1186/s12870-026-10087-7

Keywords: spinach, phytoextraction, heavy metals, malic acid, Moringa oleifera leaf extract, oxidative stress, antioxidant defense, industrial wastewater, nickel, copper, lead, biostimulants