The research was carried out at the Federal University of Piauí’s Professora Cinobelina Elvas Campus in Bom Jesus, Brazil, using a commercial seed lot of U. brizantha cv. MG-5 from the 2022/2023 crop year. The team, led by Tiago de Oliveira Sousa and Thalesram Izidoro Pinotti, began by characterizing the seed lot’s baseline quality. A tetrazolium viability test, which stains living tissue red and reveals whether embryos are metabolically active, showed that 86 percent of the seeds were alive and met the minimum standards required for commercialization. Yet when the seeds were actually germinated under ideal laboratory conditions, only 55 percent produced normal seedlings, and the first germination count on day seven was a mere 27 percent. That gap between viability and germination is the signature of dormancy, and it is precisely the problem the researchers set out to solve.

Dormancy in Urochloa species is widely attributed to physical barriers. The seeds are wrapped in glumes, lemmas, and paleas, the same bracts that enclose grass florets, and these structures, together with a rigid seed coat, can restrict water absorption and oxygen diffusion, both essential triggers for germination. Uneven inflorescence emergence, asynchronous flowering within racemes, a low proportion of fertile seeds, and natural seed shattering further complicate matters, meaning commercial seed lots can vary widely in quality. Under Brazilian regulations, seed lots of this species must reach at least 60 percent germination to be sold commercially, so lots that fall short represent both an agronomic and an economic liability.

To tackle the physical barrier, the researchers manually removed the glumes, lemmas, and paleas from half of the seeds, a process called scarification. Crucially, the procedure did not touch the seed coat itself, which in Urochloa is known for its rigidity and impermeability, so there was no risk of damaging the embryo. The effect was dramatic. Scarification raised the germination speed index by 73.7 percent, from 5.90 to 10.25, lifted the first germination count from 43 to 66 percent, and increased final germination from 50 to 69 percent, a gain of 19 percentage points. Scarified seedlings also grew longer and accumulated more biomass, with significantly higher root fresh mass, total fresh mass, root dry mass, total dry mass, and total seedling length than their non-scarified counterparts. The likely mechanism is straightforward: removing the coverings accelerates imbibition, the initial uptake of water that kick-starts the metabolic machinery of germination.

The second intervention was biochemical. The team prepared three crude extracts and tested them as seed treatments alongside distilled water and a commercial mineral fertilizer-based product. Two of the extracts came from Trichoderma orientale, a fungus isolated from the ecotone between the Caatinga and Cerrado biomes in Piauí, grown by solid-state fermentation on two agro-industrial residues: orange peel and maize cobs. The third extract was made from leaves of Pereskia aculeata, a plant better known in Brazil as ora-pro-nóbis, a traditional vegetable prized for its unusually high protein content. Using waste materials as fermentation substrates is both economically and environmentally attractive; maize cobs alone account for roughly 18 kilograms of residue for every 100 kilograms of grain harvested, so converting them into value-added products adds revenue and reduces waste.

Biochemical analysis revealed striking differences among the extracts. The orange-peel extract showed the highest proteolytic activity at 200 units per milliliter, far exceeding values previously reported for fungi such as Aspergillus niger, Aspergillus brasiliensis, and various Fusarium strains. The maize-cob extract reached 75.07 units per milliliter, while the Pereskia extract managed only 27.83. However, when activity was normalized to protein content, the two fungal extracts were statistically indistinguishable, at 588.24 and 625.58 units per milligram, both far above the plant extract’s 55.43. The Pereskia extract instead boasted the highest protein concentration, 0.502 milligrams per milliliter, consistent with leaves that contain 23 percent protein on a dry-matter basis. The substrate clearly mattered: orange peel, rich in pectin, cellulose, and easily metabolized sugars, appears to stimulate abundant protease secretion, while maize cobs, dominated by holocellulose and lignin, seem to favor the selective production of a smaller amount of highly efficient enzyme.

When the extracts were applied by soaking seeds for one hour, every treatment outperformed the water control. The germination speed index rose from 5.82 in the control to between 8.30 and 9.42 across the treated groups, with no significant differences among the treatments themselves. First germination counts climbed from 40 percent to between 56 and 62 percent, and final germination increased from 44 percent to between 61 and 67 percent. Notably, all treated seeds cleared the 60 percent germination threshold required for commercial sale, which the untreated lot failed to meet. The commercial fertilizer product and the crude extracts performed comparably on these germination metrics, suggesting that inexpensive, residue-derived extracts could match a conventional product where germination is concerned.

Seedling development told a more nuanced story. The Pereskia aculeata extract produced the highest shoot dry mass and total dry mass of any treatment and, together with the maize-cob fungal extract, the greatest shoot length. Shoot fresh mass was higher in all three extract treatments than in either the water control or the commercial product. Root length, uniquely, depended on an interaction between treatment and scarification: among scarified seeds, the commercial product and the orange-peel fungal extract produced the longest roots, whereas among non-scarified seeds, the commercial product, the maize-cob extract, and the Pereskia extract led. Intriguingly, for the maize-cob and Pereskia treatments, root length did not differ between scarified and non-scarified seeds, implying that these extracts partially compensated for the physical constraint. Seedling vigor index I, which combines germination percentage with seedling length, rose by 47.7 to 59.5 percent under the treatments relative to the control, and scarification alone boosted it by 53.5 percent. Seedling water content, by contrast, was unaffected by any intervention, indicating that the treatments altered growth and biomass accumulation without disturbing tissue hydration.

Perhaps the most scientifically interesting result is what did not correlate. The extract with the highest proteolytic activity was not the one that produced the best seedlings, and the extract with the lowest activity delivered the greatest shoot growth and dry-mass accumulation. A Pearson correlation network built from the morphophysiological data showed that germination traits were tightly interconnected, with the germination speed index correlating at r = 0.99 with the first germination count and r = 0.97 with final germination, while vigor indices correlated strongly with both germination and seedling length. But germination speed was actually negatively correlated with some biomass traits, such as root dry mass, hinting at trade-offs in how seedlings allocate resources when they establish quickly. The authors conclude that seed responses reflect the integrated bioactivity of each crude extract, in which enzymes, proteins, peptides, amino acids, minerals, and soluble carbohydrates act jointly, rather than proteolysis alone. This functional dissociation opens the door to targeted fractionation and heat-inactivation experiments to identify which constituents actually drive the benefit.

The practical implications are considerable. Under laboratory conditions, a one-hour immersion in the extracts lifted final germination from 44 percent to as high as 68 percent, and scarification pushed it to 69 percent while improving seedling length and biomass. Together, the two approaches define complementary intervention points for seed technology: biochemical conditioning with bioactive crude extracts and physical removal of the structures that restrict water and oxygen uptake. The manual scarification used here serves as a proof of concept for developing scalable mechanical procedures, and the extract performance justifies further optimization of application rates, exposure times, formulation stability, and compatibility with seed storage. The authors caution that their results apply to the evaluated cultivar, seed lot, and controlled germination environment, and that validation across seed lots, storage periods, and field-emergence conditions will be needed before these treatments reach commercial protocols. Still, the vision is compelling: turning orange peels and maize cobs into fungal enzyme factories, and a protein-rich leafy vegetable into a seed treatment, to unlock the potential locked inside one of the tropics’ most important pasture grasses.

Subject of Research: Improving seed germination and early seedling development of Urochloa brizantha using scarification and biomolecule-rich fungal and plant extracts

Article Title: Fungal and plant extracts improve germination and early development of Urochloa brizantha

Article References: Sousa, T. D. O., Pinotti, T. I., Costa, T. B., de Sousa Mesquita, A., Gomes, S. O., Santos, A. M. G., & Nascimento, T. P. (2026). Fungal and plant extracts improve germination and early development of Urochloa brizantha. Discover Plants, 3(1), Article 439. https://doi.org/10.1007/s44372-026-00910-8

Image Credits: AI Generated

DOI: 10.1007/s44372-026-00910-8

Keywords: Urochloa brizantha, seed germination, seed dormancy, scarification, Trichoderma orientale, Pereskia aculeata, solid-state fermentation, proteolytic enzymes, agro-industrial residues, forage grass, seed treatment, seedling vigor

The research team germinated flax lines under four sodium chloride concentrations: zero as a control, then 50, 100, and 150 millimolar NaCl, spanning the range from mild field salinity to stress severe enough to cripple most seedlings. At each dose they measured a battery of germination and early seedling traits, from germination kinetics to seedling growth and vigor. The results confirmed a grim but predictable pattern: every measured trait declined as salt concentration rose, with inhibition growing in a concentration-dependent fashion. Germination is the most fragile moment in a plant’s life cycle, the window when the seed must rapidly hydrate, mobilize stored reserves, and push a radicle into soil that may be osmotically hostile, so it is precisely the right stage at which to hunt for tolerance genes.

What elevates this study above a simple salt-bath experiment is its analytical machinery. Rather than ranking lines on a single trait, the researchers deployed a three-part quantitative framework. First, Principal Component Analysis compressed the correlated web of measured traits into a small number of independent axes that captured the bulk of the multi-trait variance, revealing which combinations of characteristics move together under stress. Second, they converted each trait’s performance into Fuzzy Membership Function values and integrated them into a single composite score, the D-value, which places every germplasm on a continuous tolerance scale from zero to one. Third, they fitted quadratic regressions of trait performance against salt concentration to estimate the IC50, the salt dose at which each trait falls to half of its unstressed value.

The IC50 analysis produced one of the study’s most striking findings. Among all the traits measured, the seedling vigor index showed the lowest IC50, meaning it collapsed at the mildest salt concentrations. That sensitivity is a gift in disguise: a trait that fails early is a trait that discriminates sharply, and the seedling vigor index thus emerges as the single most sensitive indicator of salt injury in young flax. Breeders screening large collections can watch this one metric and catch stress damage before other traits even register it. Meanwhile, the PCA results showed that as stress intensified, germination kinetics, the speed and rhythm of germination rather than its final percentage, became increasingly important in separating tolerant from sensitive lines, suggesting that rapid early mobilization of reserves is a hallmark of salt-resilient flax.

The integrated D-value framework then delivered the headline results, and they are more nuanced than a simple winner-takes-all ranking. Under mild stress at 50 millimolar NaCl, the line designated G-2 topped the tolerance table. At moderate stress of 100 millimolar, G-1 took the lead. And under severe stress at 150 millimolar, G-8 proved the strongest performer. This shifting hierarchy matters because it demonstrates that salt tolerance is not a single fixed property but a stress-level-dependent one: a line that thrives under the modest salinity of coastal paddies may falter under the brutal chemistry of degraded inland soils. For breeders, the lesson is that screening programs must match their test conditions to the salinity profile of their target production regions.

Two lines, however, earned consistent bragging rights. G-1 and G-8 both ranked among the tolerant germplasms at every salinity level tested, making them the most robust candidates for use as tolerant checks in future breeding work. At the other end of the spectrum, G-6 was consistently the most salt-sensitive line across all concentrations, with G-7 and G-4 also falling into the sensitive group at most doses. These sensitive lines are far from useless; as susceptible checks they provide the low anchor of any screening comparison, ensuring that a breeding program’s assays can actually distinguish the extremes of the tolerance spectrum rather than lumping everything into an undifferentiated middle.

Perhaps the most practically valuable output of the study is a single number: approximately 118.0 millimolar NaCl. By fitting quadratic regression curves to how trait discrimination changed with salt dose, the researchers identified this concentration as the optimal screening level, the sweet spot at which differences among germplasms are maximized. Below it, tolerant and sensitive lines look too similar to separate reliably; above it, stress becomes so punishing that even tolerant lines are crushed and the ranking loses resolution. A screening protocol calibrated to roughly 118 millimolar NaCl gives breeders the sharpest possible lens for sorting flax germplasm, saving time, greenhouse space, and seed in programs that may need to evaluate hundreds or thousands of accessions.

The broader significance of the work lies in its confirmation that flax harbors considerable genetic diversity for salt tolerance, diversity that has been sitting largely unexploited in germplasm collections. Flax is grown on millions of hectares for both fiber and oilseed, and its dual-purpose profile makes it an attractive crop for sustainable agriculture, but its salinity sensitivity has constrained expansion into marginal lands where salt accumulation is worst. Identifying tolerant donor lines like G-1 and G-8 gives breeders raw material to cross resilience into elite cultivars, and the study’s explicit recommendation of robust, tolerant, and sensitive checks provides a standardized toolkit so that results from different laboratories and breeding programs can be compared on common ground.

Methodologically, the study also offers a template that extends well beyond flax. The combination of PCA for dimensionality reduction, fuzzy membership functions for multi-trait integration, and regression-based IC50 estimation for calibrating stress intensity is a portable framework applicable to any crop where germination-stage tolerance needs to be quantified across a stress gradient. It replaces the older, cruder practice of scoring survival at one arbitrary salt concentration with a continuous, statistically grounded tolerance metric that captures both the severity threshold and the shape of each line’s decline. As salinity spreads through over-irrigated and warming agricultural landscapes, such quantitative screening frameworks will become essential infrastructure for the crop improvement pipelines of the coming decades, and this flax study shows exactly how to build one.

For now, the immediate beneficiaries are flax breeders, who gain a ranked germplasm panel, a validated indicator trait in the seedling vigor index, and an evidence-backed screening dose of about 118 millimolar NaCl. The longer-term beneficiaries may be the salt-stressed farmlands themselves, where tolerant flax cultivars descended from lines like G-1 and G-8 could one day turn saline ground into productive fields of blue-flowered, oil-rich crops. The study, published open access in BMC Plant Biology, was supported by the Genetics and Agricultural Biotechnology Institute of Tabarestan at Sari Agricultural Sciences and Natural Resources University, and its data and analysis code are available in the article’s supplementary materials for researchers worldwide to build upon.

Subject of Research: Salt tolerance evaluation of flax germplasm during germination and early seedling growth under sodium chloride stress

Article Title: Comprehensive evaluation of salt tolerance in flax (Linum usitatissimum L.) germplasm based on a multi-trait approach during germination and early seedling growth

Article References: Hashempour, F., Najafi-Zarrini, H., Katalani, C., & Ranjbar, G. (2026). Comprehensive evaluation of salt tolerance in flax (Linum usitatissimum L.) germplasm based on a multi-trait approach during germination and early seedling growth. BMC Plant Biology. https://doi.org/10.1186/s12870-026-10048-0

Image Credits: AI Generated

DOI: 10.1186/s12870-026-10048-0

Keywords: flax, Linum usitatissimum, salt tolerance, salinity stress, germination, seedling vigor, germplasm screening, NaCl stress, principal component analysis, D-value, IC50, plant breeding

The study, led by Tayeb Muhammad and colleagues including Tao Yang, Juan Wang, Baike Wang, and corresponding author Qinghui Yu, focused on the earliest and most vulnerable phase of a crop plant’s life: germination and seedling establishment. This window is decisive for final yield, because seedlings that fail to establish vigor in their first days rarely recover. The researchers compared three groups of tomato seeds: untreated controls, seeds soaked in water alone (hydro-primed), and seeds primed in a melatonin solution. The primed and control seeds were then exposed to cadmium, a toxic heavy metal that accumulates in agricultural soils worldwide, and to polyethylene glycol, a laboratory-standard agent that mimics the osmotic stress plants experience during drought by restricting water availability.

Without protection, both stressors inflicted severe damage. Cadmium and osmotic stress significantly inhibited seed germination, stunted seedling growth, and reduced biomass accumulation. The mechanism behind this damage is well understood in plant physiology: both stresses trigger the overproduction of reactive oxygen species, including hydrogen peroxide, which attack cellular membranes and macromolecules. The team measured this oxidative assault directly, recording elevated hydrogen peroxide levels and increased lipid peroxidation, the destructive degradation of membrane fats that is tracked through malondialdehyde, a classic biomarker of oxidative injury. They also observed increased electrolyte leakage, a sign that cell membranes had lost their integrity and were allowing ions to escape from the cells.

One of the most scientifically interesting aspects of the work is the discovery that the two stressors behave in strikingly different ways within the plant. Cadmium stress primarily targeted the root system, which is unsurprising given that roots are the first point of contact for the metal in the soil solution and the main site of cadmium uptake. Osmotic stress imposed by polyethylene glycol, by contrast, had its strongest impact on shoot growth and above-ground physiological performance, reflecting the plant’s struggle to take up water and maintain turgor in its leaves. This differential targeting pattern matters for breeders and agronomists, because it suggests that no single trait or treatment can fully shield a seedling; a successful protective strategy must strengthen both root and shoot systems simultaneously, which is precisely what melatonin priming achieved.

Melatonin, chemically known as N-acetyl-5-methoxytryptamine, has emerged over the past decade as a master regulator of stress responses in plants, functioning alongside its better-known role as a circadian signal. In this study, melatonin priming significantly improved germination efficiency and seedling vigor under both stress conditions. Primed seedlings displayed enhanced root and shoot elongation, accumulated greater biomass, and maintained higher levels of chlorophyll, the photosynthetic pigment whose degradation is an early casualty of stress. The treatment also boosted proline accumulation, a compatible osmolyte that plants deploy to protect proteins and membranes while adjusting their internal water balance, an adaptation especially valuable under drought.

The protective effect extended deep into the plant’s biochemical defenses. Melatonin-primed seedlings showed markedly lower levels of electrolyte leakage, malondialdehyde, and hydrogen peroxide, indicating that the hormone had blunted the oxidative cascade at its source. The team traced this resilience to a strengthened enzymatic antioxidant system. Activities of four key antioxidant enzymes rose in primed seedlings: superoxide dismutase, which converts superoxide radicals into hydrogen peroxide; peroxidase and catalase, which break hydrogen peroxide down into water and oxygen; and ascorbate peroxidase, a central component of the ascorbate-glutathione cycle that detoxifies peroxide within chloroplasts and other compartments. Crucially, this enzymatic upregulation was mirrored at the molecular level, with increased transcript abundance of the genes encoding these enzymes, showing that melatonin primes the seedlings’ stress-response machinery at the level of gene expression rather than merely acting as a chemical antioxidant itself.

The researchers went further, profiling stress-responsive genes that coordinate the plant’s broader adaptive response. Primed seedlings showed upregulation of SlGST, a glutathione S-transferase involved in detoxifying reactive compounds and sequestering heavy metals; SlDREB, a transcription factor that switches on suites of genes during drought and other abiotic stresses; SlNHX1, a sodium/proton antiporter that contributes to ion homeostasis and vacuolar sequestration of toxic ions; and SlDHN, a dehydrin gene whose products stabilize proteins and membranes during dehydration. Together, these molecular signatures indicate that melatonin priming activates both the ROS-scavenging frontline and the downstream regulatory and protective networks that give seedlings lasting tolerance rather than a fleeting chemical shield.

The practical implications of the work are considerable. Cadmium contamination of agricultural soils is a global problem driven by industrial emissions, phosphate fertilizers, and wastewater irrigation, and drought is intensifying across many of the same regions. Tomato, one of the most widely grown and economically important horticultural crops, is particularly sensitive during establishment. Seed priming is attractive as a technology because it is inexpensive, requires no genetic modification, applies no chemical load to soil, and can be integrated into existing seed conditioning pipelines before sowing. Compared with hydro-priming, melatonin priming conferred a clear and consistent advantage, suggesting that the hormone acts as a genuine elicitor of stress memory rather than simply accelerating germination. The study builds on a growing body of evidence from wheat, maize, rice, rapeseed, and other crops showing that melatonin seed treatments can improve germination under salinity, drought, and heavy metal stress, and extends this evidence to the combined challenge of cadmium and osmotic stress in tomato specifically.

The authors, whose work was supported by the Research Fund for Young Tianchi Talent program of the Xinjiang Uyghur Autonomous Region, published their findings in Volume 160 of Plant Biosystems, article number 245, on 20 August 2026. As climate change expands the footprint of drought and legacy contamination continues to constrain arable land, strategies that harden crops at the very start of their lives are likely to attract growing attention. This study demonstrates that a molecule best known for regulating sleep can, at the scale of a seed, set a young tomato plant on a fundamentally more resilient developmental trajectory, strengthening antioxidant defenses, reprogramming stress-responsive gene expression, and preserving the growth and physiological functions on which a season’s harvest ultimately depends. Future work will need to confirm these benefits under field conditions, but the message from the laboratory is clear: what happens to a seed before it meets the soil may determine how well the plant survives what the soil has in store.

Subject of Research: Melatonin seed priming as a strategy to alleviate cadmium and drought stress in tomato seedlings

Article Title: Seed priming with melatonin alleviates cadmium and drought stress by regulating growth, physiological functions and defense mechanisms in tomato

Article References: Muhammad, T., Yang, T., Wang, J., Wang, B., & Yu, Q. (2026). Seed priming with melatonin alleviates cadmium and drought stress by regulating growth, physiological functions and defense mechanisms in tomato. Plant Biosystems, 160(5), Article 245. https://doi.org/10.1007/s44473-026-00261-y

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00261-y

Keywords: melatonin, seed priming, tomato, cadmium stress, drought stress, oxidative stress, antioxidant enzymes, reactive oxygen species, germination, seedling vigor, stress-responsive genes, plant stress physiology