Scientists in Brazil have demonstrated that a combination of three non-destructive imaging techniques, visible-spectrum (RGB) photography, X-ray radiography, and three-dimensional magnetic resonance imaging (MRI), can detect and characterize hidden damage in soybean seeds that conventional quality tests frequently miss. The study, published in Smart Agricultural Technology, comes at a critical moment: Brazil is the world’s largest soybean producer and exporter, with an estimated harvest of 166 million tons for the 2024/2025 growing season, and seed quality is increasingly under threat from the very climate extremes that help drive the country’s agricultural productivity.

The research, led by Rafael Mateus Alves and colleagues at institutions including the Seed Technology Center of Embrapa Soybean and the University of São Paulo, was funded by the São Paulo Research Foundation (FAPESP). Its central premise is deceptively simple: because seed quality is largely determined in the field, before harvest even begins, researchers and seed companies need tools that can look inside a seed without killing it. Destructive assays such as the tetrazolium viability test, which stains metabolically active tissue red, are the industry standard, but they end the life of the sample. That is a particular problem for breeding programs, where each seed represents a unique genetic combination that must survive analysis if it is to be planted.

The seed itself is a small miracle of engineering. A protective coat, derived from the ovule integuments and marked by a scar called the hilum, regulates water uptake and shields the embryo within. The embryo contains the plumule, which gives rise to the plant’s first true leaves; the apical meristem, precursor of the aerial plant; and the hypocotyl–radicle axis, which breaks through the soil and forms the primary root. Flanking this axis are the cotyledons, storage organs packed with macromolecules that are metabolized and shipped to the growing axis during germination. Damage to any of these structures, from insects, fungi, drought, heat, or rough handling during harvest, can silently reduce a seed lot’s vigor, the capacity for rapid, uniform germination that underpins successful crop establishment.

To interrogate this architecture non-invasively, the team assembled ten representative seeds from production fields, commercial lots, and storage samples, each embodying a distinct damage category: stink bug injury, purple seed stain caused by fungi, green seeds from incomplete maturation, wrinkled seeds from heat and drought stress, weathering-related coat ruptures, severe structural failure, mechanical harvest damage, and internal galleries bored by the cigarette beetle (Lasioderma serricorne) during storage. Every seed was imaged sequentially with each of the three modalities and then subjected to the tetrazolium test as a qualitative reference standard.

The technical pipeline was meticulously standardized. For visible-light imaging, seeds were mounted on acetate sheets and photographed with a Leica DMLB microscope equipped with a DFC 310FX digital camera, oriented in four standardized positions with the hilum consistently to the right. X-ray radiographs were acquired on a Faxitron MX-20 DC-12 system operating at 34 kilovolts, with a nine-second exposure and an object-to-source distance of 11.4 centimeters; uniform contrast settings were applied to all images to make damaged tissues directly comparable. The MRI work used a horizontal 2 Tesla superconducting magnet coupled to a Bruker Avance III spectrometer operating at 85.24 megahertz for proton nuclei. Before scanning, seeds were conditioned to raise their moisture content from roughly 8–10 percent (wet basis) by incubation on moistened germination paper for three hours at 25 °C, a step that ensured sufficient hydrogen signal for imaging. A three-dimensional FLASH pulse sequence, with a 3-millisecond echo time and 75-millisecond repetition time, collected data on a 128×128×128 matrix over a 12.8-millimeter field of view, yielding isotropic voxels of 100 micrometers per side. Datasets were zero-padded to 256³ before Fourier transformation and rendered in three dimensions using ImageJ with the 3Dscript plugin.

The resulting image galleries are striking. On seeds punctured by stink bugs, the dominant pest of Brazilian soybean fields, RGB images revealed darkened patches on the cotyledons and near the plumule, the visible legacy of insect feeding that lacerates tissue and injects yeasts that degrade it from within. X-ray images flagged zones of reduced radiation absorption in the same darkened regions, while MRI cross-sections exposed the depth of tissue destruction with unusual clarity, precisely because degraded tissue no longer absorbs water and therefore produces no magnetic resonance signal. The tetrazolium test confirmed that these zones lacked respiratory activity, meaning they were metabolically dead.

Not every symptom tells the same story, however, and the multimodal approach proved especially powerful at distinguishing superficial from structural damage. Seeds with purple seed stain, caused by Cercospora fungi that secrete the toxin cercosporin, showed internal structures that appeared entirely normal in both X-ray and MRI. Yet the tetrazolium test produced an unusually intense red coloration at the stained coat, indicating that fungal activity had compromised the seed coat’s ability to regulate water uptake, allowing the staining solution to penetrate more deeply into the embryo. Similarly, green seeds, which retain chlorophyll because heat and drought interrupted maturation, showed no structural anomalies under X-ray or MRI, but their membranes proved unusually permeable to the tetrazolium solution, hinting at the physiological deterioration typical of immature tissue.

Where MRI truly distinguished itself was in detecting damage invisible to every other method. One seed that appeared flawless in visible light and radiographically normal in X-ray images revealed, in its three-dimensional MRI reconstruction, internal ruptures running through the central cotyledons, the likely consequence of rapid, uneven drying that forces differential cellular expansion and eventual tissue collapse. In mechanically damaged seeds, the X-ray images showed a crack in the hypocotyl–radicle axis that the camera could not see, but MRI went further, revealing the full extent of the fissure and the displacement of the axis relative to the cotyledons. The team also documented a dramatic structural failure nicknamed the “popcorn effect,” in which alternating wetting and rapid drying cycles tear the seed coat and force the cotyledons apart, a phenomenon increasingly reported in Brazilian seed lots as late-season weather grows more erratic.

To move beyond qualitative observation, the researchers extracted grayscale histograms from each X-ray image, normalizing pixel frequencies across the full 0–255 intensity range. Two statistical descriptors, mean gray level and Shannon entropy, were then compared across damage categories using one-way ANOVA followed by Tukey’s honest significance test. The analysis yielded clear separation: undamaged seeds showed the narrowest distributions with peaks at high grayscale values, while beetle-infested seeds and wrinkled seeds displayed the broadest distributions with heavy weight in the lower gray ranges, reflecting hollowed-out tissues and sparse, deformed structures. Mean gray level differed significantly across categories, peaking in undamaged seeds and bottoming out in wrinkled ones, while Shannon entropy, a measure of histogram complexity, was highest in beetle-damaged seeds and lowest in healthy ones. Because each damage category produced a characteristic radiographic fingerprint, the authors suggest these histogram metrics could support automated, quantitative screening in commercial seed laboratories.

Each modality, the authors stress, occupies a distinct niche. RGB imaging is fast, cheap, and ideal for surface screening but blind to anything beneath the coat. X-ray radiography, already a mainstay of seed testing labs, reveals internal voids, malformations, and cavities rapidly and non-destructively, though it cannot report on metabolic viability and demands careful standardization. MRI, with its superb soft-tissue contrast and genuine three-dimensional resolution, excels at detecting subtle physiological and structural alterations, latent mechanical injury, hydration-induced ruptures, and moisture redistribution, but its cost and acquisition time currently confine it to research settings. The tetrazolium test remains valuable as a reference but is destructive and subject to interpreter bias.

The authors argue the techniques should be viewed as complementary rather than competing, and they sketch a future in which RGB and X-ray screening handle high-throughput commercial quality control while MRI resolves ambiguous or high-stakes cases, such as breeding lines and seed physiology studies. Advances in imaging hardware, automation, and artificial intelligence-based analysis, they note, could eventually fuse these modalities into scalable phenotyping workflows. For now, the message is clear: in an era when a single season of heat, drought, and hungry insects can undermine an entire seed lot, the ability to see damage in all three dimensions, without sacrificing the seed itself, may prove as transformative for agriculture as it has been for medicine.

Researchers in Brazil have demonstrated that a hybrid advanced oxidation process can transform pharmaceutical-laden wastewater into an effluent that is dramatically safer for plants, earthworms, onion root cells, and beneficial microorganisms, offering a rigorous ecotoxicological case for reusing treated sewage in agriculture. The study, published in Environmental Science and Pollution Research, addresses a long-standing blind spot in water treatment: proving that a chemically “clean” effluent is also biologically compatible.

Conventional wastewater treatment plants were never designed to strip out recalcitrant organic micropollutants such as pharmaceuticals, and trace amounts routinely slip through into receiving waters. Advanced oxidation processes (AOPs) attack these stubborn compounds by generating highly reactive free radicals that fragment contaminant molecules. But chemical degradation alone does not guarantee safety. As contaminants break down, they spawn transformation products (TPs) that can, in some cases, be as toxic as—or more toxic than—the parent compounds. The research team, led by Lucas Gustavo da Costa and Alam Gustavo Trovó of the Federal University of Uberlândia, together with collaborators at the Oswaldo Cruz Institute, set out to answer a deceptively simple question: does measurable chemical removal of micropollutants actually translate into reduced biological harm?

The centerpiece of their work is the H₂O₂/S₂O₈²⁻/UVC process, a hybrid system that combines hydrogen peroxide and persulfate with short-wave ultraviolet C radiation. UVC photons cleave both oxidants simultaneously, generating hydroxyl radicals (HO•) and sulfate radicals (SO₄•⁻) in the same reaction volume. This dual-radical strategy outperforms systems relying on either oxidant alone, or on peroxymonosulfate (HSO₅⁻), which is costlier and demands more energy for activation. The hybrid route also resists interference from inorganic species commonly found in real effluents, making it an economically attractive candidate for deployment at full-scale treatment plants. The process had already been chemically optimized in the team’s earlier work using multivariate mixture design and rotatable central composite design experiments; the new study is its first integrated biological stress test.

The experiments used real municipal effluent from a wastewater treatment plant in Uberlândia, Minas Gerais, sampled after the plant’s final tertiary treatment stage of coagulation-flocculation with ferric chloride and flotation. The effluent was enriched with three pharmaceuticals representing different therapeutic classes: colchicine (COL, an antimitotic agent), nitazoxanide (NTZ, an antiparasitic), and sulfamethoxazole (SMX, a widely detected antibiotic), each at 325 nmol L⁻¹—equivalent to 130, 100, and 82 micrograms per liter, respectively. That concentration was deliberately chosen as high enough for direct HPLC–DAD analysis without preconcentration, yet low enough to be environmentally representative. Treatment was carried out in an amber glass reactor irradiated by two 8-watt UVC mercury lamps emitting at 254 nm, with a measured irradiance of 4.9 W m⁻². Residual oxidants were neutralized with sodium thiosulfate before any biological testing, ensuring that observed effects could not be attributed to leftover peroxide chemistry.

The ecotoxicological battery spanned multiple trophic levels and levels of biological organization. Oxidative stress was assessed in the earthworm Eisenia andrei by measuring malondialdehyde (MDA), a marker of lipid peroxidation, and protein carbonylation, an irreversible oxidative modification of proteins. Phytotoxicity was evaluated using lettuce (Lactuca sativa) seeds and a growth index combining germination rate and root elongation. Cytotoxicity and genotoxicity were quantified in onion (Allium cepa) root meristems through the mitotic index and the frequency of chromosomal and nuclear aberrations—micronuclei, chromosome breaks, stickiness, bridges, and nuclear buds—across 5,000 cells per sample. Finally, growth inhibition was tested in two environmentally relevant microbes: Azospirillum brasilense, a plant growth-promoting bacterium used in soybean cultivation, and Saccharomyces cerevisiae, a yeast that persists in soils and fermentative niches.

The untreated enriched effluent told a worrying story. It exhibited substantial genotoxicity in onion cells—21%, approaching the 24% seen with the positive control, methyl methanesulfonate—and severe phytotoxicity, with lettuce growth indices far below the 80% threshold that signals absence of toxicity. Even the unspiked effluent itself suppressed lettuce growth, achieving a growth index of only 47%, evidence that bioactive compounds survive conventional treatment. In earthworms, individual aqueous solutions of NTZ and SMX raised MDA levels by 37.2% and 23.5% respectively, while the three-compound mixture increased lipid peroxidation by 38.0%, pointing to additive or synergistic oxidative stress mechanisms involving reactive oxygen species and Fenton-type chemistry within cells.

The picture changed decisively after oxidation. Following 10 minutes of UVC-driven treatment—the point at which 80% chemical degradation had been achieved, matching the minimum removal target proposed in the European Union’s COM(2022)541 directive—genotoxicity fell to 10%, and after 20 minutes, corresponding to the limit of quantification for the parent compounds, it dropped further to 6%, a statistically significant reduction. The plant growth index climbed above 80%, crossing from toxic territory into biocompatibility. The mitotic index in onion cells remained statistically indistinguishable from the deionized-water control (around 39–40% versus 40%), demonstrating that the process generated no cytotoxic byproducts capable of arresting cell division. And crucially for agricultural applications, neither the treated effluent nor its transformation products inhibited growth of A. brasilense or S. cerevisiae.

The mechanistic details are instructive. In the untreated enriched effluent, micronuclei—membrane-bound DNA fragments expelled from the nucleus during flawed cell division—were among the most frequent aberrations, indicating clastogenic and aneugenic damage. Colchicine exposure predictably produced C-metaphase accumulation, a signature of its tubulin-binding, spindle-disrupting mechanism first described in Allium nearly a century ago. SMX depressed the mitotic index and induced chromosomal damage, consistent with prior findings in Vicia faba. NTZ, whose genotoxicity had never before been reported, produced chromosome breaks, stickiness, and nuclear buds. After oxidation, the overall aberration burden fell sharply, particularly micronuclei and stickiness, although a few bridges and polyploid cells persisted even at 20 minutes—a reminder that some transformation products or resistant residuals may linger.

The microbial results came with a subtlety. Reduced A. brasilense growth after treatment initially looked like a red flag, but the team attributes it to depletion of assimilable organic matter, which serves as radical scavenger during oxidation and as a nutrient source afterward—not to toxicity. The negative control likewise grew slowly. This distinction matters because AOPs are designed to mineralize organic carbon, and a nutrient-poorer medium should not be misread as a more toxic one. For S. cerevisiae, no inhibition occurred at any stage of treatment, although NTZ alone significantly depressed yeast optical density, reinforcing the compound’s cell-cycle interference potential even at nanomolar-scale exposures.

The study’s broader significance lies in its methodological stance. By adopting an “effect-driven approach,” the team evaluated the toxicity of whole reaction mixtures without needing to isolate and identify individual transformation products—an impractical task given that many degradation byproducts are not commercially available. Their findings align with a growing consensus that treatment efficacy must be judged not merely by parent-compound removal but by the nature and reactivity of the resulting transformation products. Biochemical biomarkers such as MDA and protein carbonylation detected sublethal disturbances that mortality-based endpoints would have missed entirely, providing early warnings of cellular distress at environmentally relevant concentrations.

One caveat deserves attention: while lipid peroxidation declined after treatment, protein carbonylation rose slightly—1.05-fold above control—suggesting some transformation products may still provoke protein oxidation even as lipid damage subsides. The authors flag this discrepancy and call for future identification of the specific TPs responsible, alongside expanded organism panels, longer-term exposure studies, and pilot-scale validation across different environmental matrices.

The regulatory context sharpens the urgency. The EU’s proposed urban wastewater treatment directive mandates at least 80% removal of specified organic micropollutants and microbiological control for agricultural reuse, yet it conspicuously omits eco-compatibility assessment of the treated water itself. This study supplies exactly that missing dimension, showing that a process satisfying the chemical benchmark also delivers measurable biological benefit—lower genotoxicity, restored plant growth, intact cell division, and unharmed beneficial microbes. As water scarcity intensifies globally and reuse becomes less optional, the Brazilian team’s integrated bioassay framework offers a template for ensuring that the water farmers irrigate with is not merely chemically compliant, but genuinely ecologically safe.

These new findings could help scientists adapt crops to dry environmental conditions in the future. Plants rely on sunlight to turn water and carbon dioxide into energy-rich sugars and oxygen through different forms of photosynthesis. Drought can make that process far more difficult. A research group led by Wolfram Weckwerth at the University of Vienna [...]

Around 1590 BCE — more than 800 years before Rome was founded, and before Tutankhamun was even born — a small number of people in what is now southeastern Poland started eating a cereal that had never grown in their fields. It wasn’t a local crop, and it didn’t belong to any plant known elsewhere […]