The scale of the problem is sobering. Roughly 1,128 million hectares of land worldwide are damaged by salt, and in India about 6.727 million hectares, some 2.1 percent of the country’s total land area, are affected. The situation is especially acute in Punjab, where approximately half of the state’s 5.036 million hectares are estimated to suffer from salinization, driven by over-irrigation, waterlogging and poor drainage in districts such as Muktsar, Fazilka, Faridkot, Ferozepur, Mansa and Sangrur. For a crop like pea, the second most important food legume globally and a staple of Indian diets, salt stress strikes at the very first step of the life cycle: germination. Excess sodium and chloride ions disrupt the water potential gradient that seeds rely on to imbibe water, impair the enzymes needed to break dormancy, and trigger a cascade of reactive oxygen species that batter young cells.

The research team, led by Gagandeep Kaur and Rahul Kumar, designed a two-pronged experiment to test whether combining bio-stimulants could do what single treatments had not. In the laboratory, seeds of two pea varieties, Arkel and Punjab-89, were grown under 100 millimolar sodium chloride stress with five treatments: a distilled-water control, salt alone, salt plus Rhizobium, salt plus seaweed extract, and salt plus both. In the field, during the 2023 to 2024 rabi season at the university’s experimental farm, the same varieties received either no treatment, the recommended NPK fertilizer dose, or that dose supplemented with Rhizobium, seaweed extract, or both. Rhizobium culture was applied to seeds at 25 grams per kilogram, while the seaweed extract was sprayed at 3 milliliters per liter, in the lab at two-day intervals for twenty days and in the field at thirty and sixty days after sowing.

The laboratory results were striking. Salt alone slashed germination to 63.8 percent with a germination rate of just 1.50, but the combined treatment lifted germination to 97.2 percent and the rate to 4.00, effectively erasing most of the salt penalty. Seedlings treated with both bio-stimulants grew shoots of 21.8 centimeters and roots of 8.5 centimeters, compared with 15.9 and 4.2 centimeters under salt alone. Fresh weight nearly doubled, rising from 0.66 grams to 1.36 grams, and dry weight climbed from 0.09 to 0.19 grams. Relative water content rebounded from 70.8 percent to 96.8 percent, a sign that the treated seedlings were holding onto water far more effectively than their salt-stressed counterparts.

Beneath the visible recovery lay a deeper biochemical story. Salt stress devastated the photosynthetic machinery: chlorophyll a, chlorophyll b, total chlorophyll and carotenoids all collapsed under sodium chloride, dropping to 18.87, 12.96, 32.07 and 6.13 micrograms per gram fresh weight respectively. The combined treatment restored them to 53.41, 32.87, 78.03 and 18.88 micrograms per gram, levels approaching those of unstressed plants. At the same time, the molecular signatures of damage receded. Hydrogen peroxide, superoxide anion, malondialdehyde, the classic marker of lipid peroxidation, and free proline, an osmoprotectant that accumulates when plants are struggling, all fell significantly under the combined treatment, indicating that the bio-stimulants were not merely masking stress but actively reducing the oxidative assault on cellular membranes.

The antioxidant system told an equally interesting tale. Salt stress normally forces plants to ramp up defensive enzymes such as superoxide dismutase, catalase, guaiacol peroxidase, glutathione reductase and ascorbate peroxidase to detoxify the flood of reactive oxygen species. In this study, the combined bio-stimulant treatment significantly lowered the activity of these enzymes relative to salt-stressed controls, which the authors interpret as evidence that the treatment had reduced the underlying oxidative burden rather than simply boosting the cleanup crew. Non-enzymatic antioxidants moved in the opposite, protective direction: total phenolic content rose from 0.39 to 0.72 milligrams per gram, total flavonoids from 2.40 to 7.22 milligrams per gram, and ascorbic acid from 2.88 to 10.27 milligrams per gram when the combined treatment was applied under salt. Protein content, which salt stress depressed to 7.17 milligrams, recovered to 17.49 milligrams under the dual treatment.

Out in the field, the pattern held and translated into harvest. The combined treatment of NPK fertilizer with both Rhizobium and seaweed extract produced the tallest plants at 82.27 centimeters, the most branches at 16.83 per plant and the most leaves at 70.50 per plant. It also accelerated phenology, with seedlings emerging in 6.50 days and first flowering arriving at 36.33 days, both significantly earlier than untreated controls. Yield attributes followed suit: pod length reached 8.41 centimeters, pod weight 6.84 grams, shelling percentage 35.06 percent and seeds per pod 10.55, all significantly above the control. Most importantly for farmers, the combined treatment delivered 18.17 pods per plant, 78.78 grams of pod yield per plant and 80.53 quintals per hectare, the highest of any treatment tested.

Quality improved alongside quantity. Pods from the combined treatment contained the highest levels of chlorophyll a, chlorophyll b, total chlorophyll and carotenoids, along with total soluble solids of 15.98 degrees Brix and ascorbic acid of 24.94 milligrams, all significantly above untreated plants. Between the two varieties, Punjab-89 consistently outperformed Arkel in both controlled and field settings, recording higher protein content under salt stress, greater photosynthetic pigments, taller plants and heavier yields, although Arkel claimed the longest roots and widest pods in certain interactions. The variety-by-treatment interactions were statistically significant across nearly every parameter measured, underscoring that genotype and management must be considered together rather than in isolation.

The mechanisms behind the synergy are plausible and complementary. Rhizobium inoculation helps legumes fix atmospheric nitrogen, synthesize compatible solutes and induce abscisic acid production, which tightens stomata and curbs water loss under salt stress. The bacteria also bind to roots, reduce ethylene levels and stimulate root hair development through phytohormone production, while binding sodium in the rhizosphere. Seaweed extract, meanwhile, supplies magnesium, calcium and iron that support key metabolic processes, along with osmoprotectants such as betaines and proline, antioxidants, and plant growth regulators including cytokinins and auxins that promote cell division, chloroplast development and floral initiation. Together, the two inputs address different halves of the salt-stress problem: the microbe fortifies the root zone and nitrogen economy, while the algal extract bolsters foliar physiology and antioxidant capacity.

The authors are careful to note the limits of their work. The study spanned a single growing season at a single location, and the laboratory salt stress was imposed with a uniform sodium chloride solution that cannot fully replicate the chemical heterogeneity of naturally saline soils. They call for multi-year, multi-location trials across diverse cultivars, soil types and salinity levels, along with optimization of application rates and timing, and deeper investigation of ion homeostasis, antioxidant regulation and stress-responsive gene expression. Still, the core message is compelling: a combination of a soil bacterium and a seaweed extract, both already commercially available, can protect germination, restore photosynthetic pigments, dampen oxidative damage and lift yields in one of the world’s most important legumes. As salinity creeps across irrigated valleys from Punjab to Pakistan to Australia, such biological partnerships may prove to be among the most practical tools farmers have for keeping salt-stressed land in production.

Subject of Research: Combined Rhizobium and seaweed extract bio-stimulants mitigating salt stress in pea (Pisum sativum L.)

Article Title: Insight into in-vitro biochemical amelioration by bio-stimulants under salt stress in pea (Pisum sativum L.) and impact on growth, yield and quality in-situ

Article References: Kaur, G., Thakur, T., Singh, N., Maurya, V., Reddy, A. H., Johar, V., Sharma, A., & Kumar, R. (2026). Insight into in-vitro biochemical amelioration by bio-stimulants under salt stress in pea (Pisum sativum L.) and impact on growth, yield and quality in-situ. Discover Plants, 3(1), Article 401. https://doi.org/10.1007/s44372-026-00870-z

Image Credits: AI Generated

DOI: 10.1007/s44372-026-00870-z

Keywords: pea, salt stress, bio-stimulants, Rhizobium leguminosarum, seaweed extract, Ascophyllum nodosum, soil salinity, antioxidant enzymes, germination, crop yield, plant physiology, sustainable agriculture

The study, conducted by scientists at the State University of Ponta Grossa and the Federal University of Santa Catarina and published in the journal Blue Biotechnology, tested two commercially available mineral fertilizers enriched with hydrolyzed extracts of the red seaweed Kappaphycus alvarezii and the brown seaweed Ascophyllum nodosum. One product, designated FR and intended for seed treatment, contained 3.0 percent total nitrogen, 10.0 percent P2O5, cobalt, molybdenum, boron, zinc and nickel alongside the algal extracts. The second, designated FG and used as a foliar spray, contained 2.0 percent nitrogen, 2.0 percent P2O5, boron, zinc, sulfur, manganese, magnesium and nickel with the same seaweed extracts.

Alongside these commercial formulations, the researchers prepared aqueous extracts from a blend of three microalgae species grown in their own laboratory: the cyanobacterium Arthrospira platensis, the green microalga Tetradesmus obliquus, and the marine diatom Chaetoceros muelleri. Cultures were grown to the stationary phase in tailored media, harvested by centrifugation, frozen at minus 80 degrees Celsius, lyophilized, and then macerated in deionized water with the pH adjusted to 5.5. The team used 2.5 milligrams of dry biomass from each species per treatment batch, delivering the blend either as a seed coating or as a foliar spray in 150 liters of solution per hectare.

The field experiment took place during the 2023 winter growing season at the Capão da Onça School Farm in Ponta Grossa, Paraná, at roughly 1,002 meters above sea level on a sandy Dystrophic Haplic Cambisol managed under no-till for fifteen years. The researchers employed a randomized block design with four replications in a 3 by 3 factorial arrangement: three seed treatments crossed with three foliar treatments produced 36 experimental units. The barley cultivar Imperatriz was sown at a target density of 2.5 million plants per hectare with base fertilization of 200 kilograms per hectare of 10-20-20 N-P-K and a topdressing of 120 kilograms per hectare of nitrogen at tillering. Foliar applications occurred at 24, 45, 65 and 87 days after sowing, and the 140-day crop cycle was assessed for plant stand, height, stem diameter, tillers, grains per ear, ear length, 100-grain weight and final yield.

The headline result was striking. Seed treatment with the commercial FR product combined with foliar application of the commercial FG product increased barley yield by 49.73 percent, equivalent to 784.24 kilograms per hectare, while the same seed treatment paired with the blended microalgae spray raised yield by 50.53 percent, or 788.84 kilograms per hectare, both compared with untreated controls. Even FR seed treatment alone, when followed by either foliar option, delivered yield gains of roughly 32 percent, translating to approximately 583 to 584 extra kilograms per hectare, or about 9.7 sixty-kilogram sacks.

The physiological story behind these numbers is intricate. FR seed treatment increased the number of tillers per plant by 19.37 percent and plant height by 8.47 percent, likely because the seaweed extracts supply auxin-like, gibberellin-like and cytokinin-like compounds that drive cell division and elongation, while the product’s 10 percent phosphorus content fuels ATP-dependent growth. However, the same treatment shortened ear length by 10.80 percent and reduced 100-grain weight by 5.43 percent. The authors suggest the surge in tillering, and the resulting yield, may partly reflect a compensatory response: unusually heavy early rainfall cut the initial plant stand by 43.13 percent below the intended population, and the sparser crop responded with more tillers and taller plants.

Intriguingly, foliar application alone produced no significant effect on any growth or yield parameter. The researchers attribute this to the formidable physicochemical barriers that dissolved molecules must cross, from the leaf cuticle through the apoplast, before reaching the protoplast of leaf cells. Molecules in the extracts, they note, may simply fail to reach their targets in sufficient concentrations, which helps explain why earlier studies using other growth stimulants reported positive foliar responses in spring barley. The yield benefits in this trial emerged only when the treatments were stacked: the foliar products acted synergistically with FR seed treatment rather than additively, mitigating the seed treatment’s negative effects on ear traits.

The economics look promising on paper. In March 2025 the combined cost of FR and FG was about 14.56 US dollars per hectare, while the extra grain harvested with both products was worth roughly 165 dollars at prevailing prices for a sixty-kilogram sack, a gross gain of about 150 dollars per hectare before labor, fuel and machinery costs. The authors caution, however, that a rigorous economic analysis accounting for all operational expenses remains necessary, and they stress that the FR dose used was based on the manufacturer’s wheat recommendation, since no barley-specific label exists.

The researchers are careful to flag the limitations. Total rainfall over the 140-day cycle hit 1,064.2 millimeters, far above the 450-to-600-millimeter optimum for barley and likely suppressing both disease-free growth and treatment responses, particularly for foliar products. The 100-grain weight averaged 3.79 grams, well below the cultivar’s expected 4.54 grams, and soil conditions were suboptimal. The team therefore calls for multi-year, multi-site trials to confirm the results, alongside deeper investigation into the physiological mechanisms by which macroalgal and microalgal biocompounds—polysaccharides, polyphenols, amino acids, sterols, vitamins and phytohormone mimics—act on germination, tillering and grain filling.

Even with those caveats, the study stands as one of the first field demonstrations that marine macroalgae and freshwater-to-marine microalgae can work together as a coherent biofertilizer system in a temperate cereal crop. With barley demand steady and growers under pressure to cut synthetic inputs, the message from Paraná is that the ocean’s flora, harnessed as seed coatings and leaf sprays, may offer a genuinely scalable route to larger harvests—potentially half again as much grain from the same land, without a single extra kilogram of conventional nitrogen or phosphate.

Subject of Research: Field evaluation of seaweed-extract biofertilizers and blended microalgae extracts for enhancing barley crop growth and yield

Article Title: Seed treatment with seaweed extract biofertilizers and foliar application of blended microalgae extracts enhanced barley (Hordeum vulgare) crop yield

Article References: de Moraes, V. C., Ruivo, L. B., Lopes, R. G., Barboza, L. E., Matiello, R. R., Owatari, M. S., Derner, R. B., & Ohse, S. (2026). Seed treatment with seaweed extract biofertilizers and foliar application of blended microalgae extracts enhanced barley (Hordeum vulgare) crop yield. Blue Biotechnology, 3(1), Article 3. https://doi.org/10.1186/s44315-026-00055-z

Image Credits: AI Generated

DOI: 10.1186/s44315-026-00055-z

Keywords: barley, Hordeum vulgare, biofertilizers, biostimulants, seaweed extract, Kappaphycus alvarezii, Ascophyllum nodosum, microalgae, Arthrospira platensis, Tetradesmus obliquus, Chaetoceros muelleri, sustainable agriculture

Ulcerative colitis is a chronic inflammatory bowel disease in which the immune system attacks the lining of the colon, causing inflammation, ulceration, abdominal pain, diarrhea and, in some cases, rectal bleeding. Its development is influenced by genetic susceptibility, immune dysfunction and environmental factors, and the condition is becoming an increasing public-health concern worldwide. Although existing therapies can suppress inflammation and induce remission, many patients require long-term treatment, and some eventually lose responsiveness or experience significant side effects. Researchers have therefore been searching for compounds that can influence inflammation while also repairing the chemical damage that accompanies it. Oxidative stress is especially important in this process. When reactive oxygen species accumulate faster than cells can remove them, they damage proteins, lipids and DNA, weaken the intestinal barrier and amplify immune signaling. This creates a damaging feedback loop in which inflammation generates oxidative stress, and oxidative stress intensifies inflammation.

The new work focused on Caulerpa peltata, a green macroalga belonging to a genus known for producing chemically diverse natural products. The researchers prepared an ethanolic extract, referred to as CPEE, and first examined its phytochemical composition and antioxidant capacity. Their screening indicated that the extract contained high levels of flavonoids and tannins, two broad classes of plant and algal compounds often associated with the ability to neutralize reactive molecules or influence cellular signaling. Such screening does not identify a single active drug, however. An extract is a complex mixture, and its biological effects may arise from several compounds acting together, from one dominant molecule, or from chemical interactions that change how individual constituents are absorbed and metabolized. The team therefore combined chemical analysis with biological testing and computer-based modeling to build a more complete picture of how CPEE might work.

Before testing the extract in a disease model, the researchers investigated its safety at concentrations ranging from 1.25 to 100 micrograms per milliliter using zebrafish embryotoxicity assays. Zebrafish embryos are widely used in early toxicology because their development is rapid, their transparent bodies make morphological changes easy to observe, and many basic cellular pathways are conserved with other vertebrates. In this study, the reported screening identified concentrations considered safe for subsequent investigation. That result is an initial safety signal rather than proof of safety in humans: an exposure that does not disrupt zebrafish development may still behave differently in mammals, and an extract administered to the body can produce metabolites not present in a laboratory dish. Nevertheless, the zebrafish stage allowed the researchers to narrow the experimental range before moving to mice and to examine whether the seaweed preparation caused obvious developmental or biochemical abnormalities.

The main animal experiment used BALB/c mice in which acute colitis was induced with dextran sodium sulfate, commonly abbreviated DSS. DSS damages the protective epithelial lining of the colon, allowing bacteria and inflammatory molecules to come into closer contact with tissue and provoking a reproducible inflammatory response. This model is not a replica of every feature of human ulcerative colitis, but it is widely used to study intestinal barrier failure, immune activation and oxidative injury. After colitis was induced, mice received CPEE at 100 milligrams per kilogram for seven days. Compared with untreated mice exposed to DSS, the treated animals showed reduced disease severity and less pathological damage, according to the study. The extract also helped maintain antioxidant enzyme activity, suggesting that its effects were not limited to suppressing visible inflammation but extended to the biochemical defenses that normally keep reactive oxygen species under control.

The molecular centerpiece of the findings was the Nrf2 pathway. Under resting conditions, the transcription factor Nrf2 is held in check by the protein Keap1, which helps direct Nrf2 toward degradation. When cells encounter oxidative or electrophilic stress, chemical changes in Keap1 can release Nrf2. The freed transcription factor moves into the nucleus, binds antioxidant response elements in DNA and increases production of protective proteins. Among the genes and enzymes associated with this response are heme oxygenase 1, or HO-1, and NAD(P)H quinone dehydrogenase 1, known as NQO1. HO-1 helps process heme and can generate products with cytoprotective effects, while NQO1 supports the reduction of reactive quinones and limits redox cycling. In the mouse colon, CPEE treatment improved expression of Nrf2, HO-1 and NQO1, linking the extract’s antioxidant effects to a defined cellular defense program rather than to nonspecific chemical scavenging alone.

The researchers also used liquid chromatography–mass spectrometry to characterize bioactive compounds in the extract and then applied molecular docking and molecular-dynamics simulations to predict how those compounds might interact with Keap1. Molecular docking estimates how a small molecule could fit into a protein’s binding pocket and calculates a predicted binding energy. Molecular dynamics goes further by simulating the movement of atoms over time, allowing researchers to ask whether a proposed interaction remains stable under changing molecular conditions. The computational analysis supported stable interactions between compounds identified in CPEE and Keap1. These results are mechanistically suggestive, but they do not demonstrate that the same compounds reach the relevant tissues at sufficient concentrations inside a living animal. Docking scores are hypotheses about binding, not measurements of drug action. Confirming the mechanism will require purification of individual molecules, biochemical binding assays, genetic tests of the Nrf2–Keap1 system and pharmacokinetic studies showing how the compounds are absorbed and distributed.

The study’s appeal lies in the way it connects marine biodiversity with a therapeutic problem that remains difficult to solve. Seaweeds of the Caulerpa genus have been investigated for antioxidant, anti-inflammatory and other biological activities, and related compounds such as caulerpin have shown protective effects in experimental models of colitis. The new results add C. peltata extract to that growing research landscape, while pointing specifically to Nrf2-related signaling as a potential explanation for its protective activity. Yet the distance between a promising mouse experiment and a clinically useful treatment is substantial. The researchers tested an acute DSS model over seven days, not the prolonged, relapsing disease experienced by many patients. The extract’s precise active ingredients, optimal dose, long-term toxicity, effects on the gut microbiome and interactions with standard medicines remain unresolved. The datasets generated in the work are available from the corresponding author upon reasonable request, creating an opportunity for independent analysis and follow-up studies.

For now, the findings suggest that Caulerpa peltata is best viewed not as an unproven dietary cure, but as a chemically rich source for drug discovery. If future experiments confirm that its compounds selectively activate protective antioxidant signaling without suppressing necessary immune functions, they could help inspire new treatments designed to protect the intestinal barrier while reducing inflammation. Such therapies might eventually take the form of purified molecules, standardized extracts or targeted delivery systems that release active compounds in the colon. Before any of those possibilities can be considered for patients, researchers will need to reproduce the results, identify the molecules responsible, establish rigorous manufacturing standards and test safety and efficacy in progressively more realistic models, followed by carefully controlled clinical trials. The seaweed’s promise is therefore real but preliminary: its most important contribution may be showing how an organism growing in the ocean can illuminate a molecular route toward treating disease in the gut.