This study focused on caryopsis development in a paleotropical woody bamboo, Melocalamus gaoligongshanensis , which produces a fleshy, bacoid type fruit. By integrating morphological dissection, paraffin sectioning, histochemical staining and untargeted metabolomic analysis, we characterised its developmental features as the caryopsis undergoes a transformation from a soft and globular form to a hard, triangular-pyramidal shape with prominent surface wrinkles. Cellular differentiation within the pericarp is pronounced, featuring a single-layered exocarp with a thickened cuticle, lignified mesocarp cells and a marked asymmetry in cell layer number and vascular bundle distribution between the ventral and dorsal sides of the endocarp and seed coat. Histochemical evidence confirms that the mature seed is exalbuminous and exhibits a post-maturation pattern. Metabolomic analysis of mature caryopsis reveals that amino acids and their derivatives dominate its metabolic profile. These findings clarify the structural specialisation of the fleshy bacoid caryopsis, offering new insights into caryopsis diversity in woody bamboos. Given the scarcity of such reproductive material in woody bamboos, this study also establishes a basis for future research on seed germination and germplasm conservation in this ecologically significant category of caryopsis.
Seed coating improves agricultural handling and germination, but obscures visual identification and complicates quality control and regulatory compliance. Conventional de-coating is destructive, time-intensive and raises concerns about reliability and analyst safety. To compensate for these limitations, we introduce PelletRayTion , a non-destructive, automated alternative for contaminants detection in pelleted seeds using high-throughput tomography and unsupervised machine learning. Our fully unsupervised pipeline for contamination detection using β-VAE was trained exclusively on pure tomography data. This approach was evaluated on Beta vulgaris and Cichorium endivia , artificially contaminated with three other species, and reciprocally Cichorium endivia or Beta vulgaris . Our models reached sufficient generalisation with a data size of 800 volumes (64×64×64) for Beta vulgaris and 700 (64×64×64) for Cichorium endivia , using latent space dimensionality of 512 and 256, respectively. Across 1–50% contamination, they achieved balanced accuracy of 98.45 ± 0.95% ( Beta vulgaris ) and 97.47 ± 0.95% ( Cichorium endivia ), with 0% false negatives and low false alerts (3.10% – 5.06%). In conclusion, these results demonstrate that PelletRayTion provides a rapid, safe, and highly accurate alternative to conventional pelleted seed testing. This approach eliminated the need for massive annotated datasets while maintaining strong performance across different species and contaminants. It holds a significant potential for routine testing, biosecurity and regulatory workflows.
The lengthening frost-free period in the Midwestern United States has led to earlier planting of summer annual crops like soybean and maize. Early planting poses risks of cold temperatures and precipitation, which could affect water uptake patterns and cause imbibitional chilling. This study investigated how moistened rolled paper towel temperature during imbibition (1.7-15.5°C), as opposed to full submersion of seeds, affected seed water uptake in commercial soybean cultivars and maize hybrids. Seeds were imbibed for up to 48 hours at temperatures ranging from 1.7-15.5°C. The rate of water uptake in soybeans was lowest at 1.7°C and was greatest above 12.8°C, but the rate of water uptake was unaffected by temperature in maize. Future work should examine how other media types (e. g., solid matrix materials) could influence water uptake dynamics with varied temperature to more closely emulate water uptake in soil after planting. Additional studies should also consider how water temperature (and rate of uptake) during imbibition influences the physiological processes of seed germination and seedling development.
This study investigated the seed dormancy and germination characteristics of Codonopsis javanica subsp. javanica , a species native to subtropical evergreen broad-leaved forests in China. We measured the embryoseed (E:S) length ratio in freshly dispersed seeds and in seeds at the stage of seed coat split before radicle emergence. We also examined the effects of light conditions (light vs. dark) and dry after-ripening (DAR) treatment on seed germination under five constant temperatures (5, 10, 15, 20 and 25°C) and two alternating temperature regimes (15/5 and 25/15°C). Our results showed that C. javanica subsp. javanica seeds possess underdeveloped embryos that grow internally prior to germination, with the E:S ratio increasing by 33%. Fresh seeds germinated well (> 95%) only under relatively high temperatures (20, 25 and 25/15°C) in light, whereas germination was strongly inhibited at lower temperatures and in dark. Six months of DAR effectively broke seed dormancy, significantly increasing the germination rate (GR) and the final germination percentage (FGP) at low temperatures in light, as well as significantly improving FGP at high temperatures in dark. Following dormancy release, the temperature range for germination expanded from high to low temperatures, and the light requirement for germination at high temperatures was significantly reduced. We conclude that freshly dispersed seeds of C. javanica subsp. javanica exhibit non-deep simple morphophysiological dormancy. These findings provide an effective and low-cost method for propagating this species for medicinal purposes, thereby contributing to the conservation of wild populations.
Genebanks support long-term germplasm conservation and ensure availability of viable seeds to users. The improved seed viability equation enables prediction of longevity by combining species-specific moisture content constants ( C W , K E ) with universal temperature constants ( C H = 0.0329; C Q = 0.000478). While the number of genebank collections of jute mallow ( Corchorus capsularis and C. olitorius ) has significantly increased in recent years, such constants are lacking to support management. To derive C W and K E and predict longevity, seeds of both species were equilibrated to five moisture content levels (7.5-12.2%) and subjected to experimental storage at 60°C for 25 or 35 days for C. olitorius and C. capsularis , respectively. The viability constants were then estimated as C W = 6.80 and K E = 10.78 for C. capsularis and C W = 6.21 and K E = 10.06 for C. olitorius . The validation of the derived constants indicated good agreement between predicted and observed viability at high viability levels in both species, with increasing divergence as seeds deteriorated. The predicted seed longevity under genebank conditions indicated that C. capsularis seeds live longer than C. olitorius . The derived constants provide a practical tool for genebanks to optimise germplasm regeneration cycles and minimise the risk of genetic erosion.
Seed pelleting improves the sowing precision and handling of small-seeded crops, but its effectiveness depends on the coating formulation and architecture. This study evaluated the influence of mineral fillers and coating structures on the physical properties, germination, and early seedling performance of pelleted rapeseed ( Brassica napus ) seeds. Monolayer pellets prepared with eucalyptus fibre, talc, vermiculite or diatomaceous earth were compared to bilayer pellets incorporating a bentonite outer layer. The addition of bentonite markedly increased pellet mass and compressive strength, with strength increasing from approximately 4 N in monolayer pellets to over 11 N in bilayer formulations, improving mechanical integrity but reducing impact resistance. Germination and seedling responses were formulation dependent. Under agar conditions, porous fillers, particularly diatomaceous earth and vermiculite–bentonite bilayers, maintained stable germination and enhanced early growth, whereas denser coatings delayed physiological processes. Under soil conditions, several bentonite- containing formulations maintained emergence comparable to uncoated seeds while promoting greater root elongation (> 8 cm versus 6–7 cm in controls). Overall, pelleted seed performance was governed primarily by the coating formulation rather than the pelleting process itself, providing a practical strategy to balance mechanical robustness with physiological accessibility to improve sowability and early crop establishment.
The dry root bark of Dictamnus dasycarpus (Rutaceae) is a common traditional Chinese medicine (TCM), known as Dictamni cortex. This TCM is primarily used in dermatology and the plant is mostly artificially cultivated. However, its seeds exhibit intrinsic physiological dormancy, making germination challenging and hindering rapid seedling production and breeding. A proposed method to address this issue entails treatment of Dictamnus dasycarpus seeds with 50 mg L -1 GA 3 , in conjunction with low-temperature stratification. This method resulted in improved germination compared to seeds merely soaked in distilled water. GA 3 accelerates the utilisation of storage substances in seeds, enhances enzyme activity and promotes the accumulation of endogenous GA 3 . Metabolomic analysis revealed that dormancy release is critically associated with sugar metabolism, the TCA cycle, phenylpropanoid biosynthesis and flavonoid biosynthesis pathways. Embryos mobilise lipids and accumulate amino acids, nucleotides and vitamins to initiate germination. In summary, GA 3 breaks dormancy by modulating hormones, refining lipid metabolism and accumulating key metabolites like malic acid and nucleotides. These findings provide a theoretical framework for the optimal utilisation of Dictamnus dasycarpus medicinal resources.
Carrot as a cool season vegetable crop is sensitive to abiotic stresses during field emergence. This study highlights the importance of nutripriming in reducing the detrimental effects of abiotic stresses on carrot seed germination dynamics and seedling growth through decreased lipid peroxidation and enhanced antioxidant enzymes activities. Carrot seeds were exposed to potassium phosphate (0.5% KH 2 PO 4 ) or to hydropriming with distilled water for 24 hours. The nutriprimed, hydroprimed and non-primed seeds were exposed to incremental salinity (0, 3, 9.6, 20.6 and 35 dS m -1 ), water potential (0, -0.15, -0.3 MPa) and temperature (10, 20 and 30°C) in completely randomised design (CRD) factorial experiments. Nutripriming enhanced the germination dynamics and reduced mean germination and 50% germination time under all stress conditions compared to control. Seed nutripriming increased the vigour index and seedling fresh and dry weights with substantial increases in antioxidant levels of catalase, superoxide-dismutase, peroxidase and ascorbate-peroxidase under 35 dS m -1 , -0.15 MPa and 30°C stress conditions. We conclude that nutripriming carrot seeds with 0.5% potassium phosphate significantly ( p ≤ 0.0.5) impacted germination ability, associated with enhanced antioxidant capacity through reduced lipid peroxidation (MDA) and oxidative stress (H 2 O 2 ) under salinity, drought and temperature stresses.
Population-based threshold (PBT) models provide powerful frameworks for quantifying temperature and water potential effects on seed germination. The evolution and scopes of these models were comprehensively assessed by bibliometric analysis of 624 scientific publications from 1980 to 2024. With 78% of the articles published after 2002, the growing utility of these models is emphasised. Key contributors and influential institutions were identified, led by the USA, Iran and the UK, with Professor K. J. Bradford as a central figure in the collaboration network. The conceptual structure of the field is organised into four thematic clusters: physiological responses to water and temperature stress, thermal and ecological drivers, weed seed bank dynamics and management, and predictive modeling of seedling emergence. The study documents the thematic evolution of PBT models from foundational mathematical constructs to interdisciplinary tools now applied in climate change studies, plant breeding, phenology and integrated crop models. Despite discussions on statistical assumptions, the biological interpretability of model parameters remains a key strength. Future research could also use these models at any level of biological organisation—from molecules and cells to tissues and organisms that exhibit population-based sensitivity variations—and make the behaviours of these complex organisations interpretable.
Northern Wild Rice (NWR; Zizania palustris ) is an ecologically important, annual, aquatic species native to North America that is also cultivated in irrigated paddies. NWR seeds are desiccation-sensitive and commonly stored submerged in water, where viability can rapidly decline post-dormancy break. During this short time period, microbial growth can be rampant. However, little is known about the impact of microbial communities on NWR seeds in storage. In this study, we evaluated the efficacy of four antimicrobial treatments at reducing microbial growth in submerged NWR seed storage, quantified by the culturable microbiome, and the impact on seed germination after the storage period. While the treatments did not impact seed germination significantly, we identified shifts in the microbial communities between the control and antimicrobial treatments. In general, fungi were more predominantly found in the control, while bacteria were more predominantly found in treatments, suggesting that bleach and H 2 O 2 reduced the recovery of culturable fungi. Proteobacteria, Pseudomonas and Sphingomonas , were major constituents of the NWR seed microbiome as were genera with species known to be pathogenic to NWR including Fusarium and Xanthomonas . Overall, this study provides a first look at the NWR seed microbiome during submerged storage and a foundation for future studies to evaluate the effect of microbial communities on NWR seed viability during submerged storage.
Seed dormancy caused by a water-impermeable seed coat limits the germination of Albizia julibrissin , an important agroforestry species. This study tested non-thermal plasma (NTP) as an eco-friendly method to break physical dormancy and improve early growth. Seeds were treated with corona-discharge NTP for 1.25–40 minutes and evaluated for surface changes, wettability, water uptake, germination and seedling performance. Scanning electron microscopy (SEM) showed progressive surface cleaning and microstructural modification with longer exposure, while energy-dispersive spectrometry (EDS) detected no changes in elemental composition. NTP significantly reduced water contact angle and increased imbibition, indicating enhanced hydrophilicity. Germination increased from nearly 10% in control seeds to nearly 90% after 40 minutes, accompanied by a notably faster germination. Seedling length, biomass and vigour indices improved significantly at longer treatments (20–40 minutes), whereas short exposures had no significant effect. Overall, NTP effectively alleviates physical dormancy in A. julibrissin through non-destructive surface activation, improving water uptake, accelerating germination and enhancing early seedling growth. The results highlight NTP as a promising sustainable technology for seed treatment in agroforestry and ecological restoration.
Actinidia arguta is a nationally protected wild plant in China whose seeds exhibit deep dormancy, severely limiting seed propagation and germplasm improvement. To elucidate the molecular mechanisms underlying seed dormancy release, seed germination percentage and endogenous hormone changes were analysed following cold stratification for 0 (CK), 7, 14, 28, 42, 56 and 70 days, as well as 28 days combined with gibberellin treatment (CS28GA). Transcriptome sequencing was used to identify key regulatory genes associated with dormancy breaking. Seed germination was initiated after 28 days of cold stratification (CS28) and the germination percentage exceeded 60% after 42 days cold stratification (CS42). During dormancy release, GA levels increased, whereas abscisic acid levels declined. Transcriptome sequencing generated 159.7 million clean reads, comparative analyses identified 4,860 and 5,147 DEGs in CK-vs-CS28GA and CK-vs-CS42 comparisons, respectively. KEGG enrichment analysis indicated that these DEGs were mainly involved in secondary metabolite biosynthesis, while GO enrichment in cellular components, metabolic processes and catalytic activity, WGCNA identified 14 co-expression modules and 19 key hormone-related genes. 11 ABA biosynthesis genes were downregulated after cold stratification, while six GA-signaling genes and two GA-related genes were upregulated. Collectively, these genes form a regulatory network governing seed dormancy and germination in A. arguta.
This study investigated seed dormancy and germination ecology in two perennial alpine herbs endemic to the Qinghai-Xizang Plateau (QXP), Incarvillea forrestii and I. compacta. We determined how gibberellic acid (GA(3)), dry after-ripening (DAR) and cold-wet stratification (CS) treatments affect seed germination at three alternating (5/1, 15/5 and 25/15 degrees C) temperatures under light and dark conditions. Seeds of both species possessed a fully-developed embryo and water-permeable seed coats. Freshly dispersed seeds germinated only at higher temperatures (ca. 90% at 25/15 degrees C in light), with germination strongly inhibited at lower temperatures and under dark conditions. GA(3) significantly increased the germination of fresh seeds in both species at 15/5 and 25/15 degrees C, though no promotive effect was observed at 5/1 degrees C. DAR and CS for six months effectively released dormancy, significantly increasing germination percentage and/or reducing mean germination time (MGT) in both light and dark conditions, especially at lower temperature (15/5 degrees C). Dormancy-breaking treatments widened the temperature range for germination from high to low, and also significantly reduced the light requirement for germination. Thus, mature seeds of the two Incarvillea species have (conditional) Type-2 non-deep physiological dormancy. Nondormant seeds germinated rapidly at spring temperature (15/5 degrees C) in both light and dark, enabling immediate germination after snowmelt at the start of the short growing season. The study provides critical insights into the ecological adaptation and diversification of Incarvillea species in the QXP region.
Mining tailings are generally infertile, structurally poor and biologically inactive, limiting plant establishment. This study assessed the use of tailings, sewage sludge, and irrigation dam sediment as substrates for germination and early growth of Vachellia caven and Baccharis linearis, two native Chilean species with potential for phytostabilisation. Greenhouse trials included five treatments combining sediment (S) and sludge (SL) in ratios from 100:0 to 0:100, plus an additional treatment with 5% tailings. V. caven reached its highest germination (80%) and survival (66%) in 100% sediment, while the 50% S-50% SL treatment produced the lowest performance (22% and 12%, respectively). Sludge-rich mixtures increased biomass but reduced aeration and drainage, generating slender seedlings (SI > 10). B. linearis performed best in 100% sediment (8.4% germination, 6.1% survival) and showed very low establishment in sludge-only substrates. Its sensitivity to organic and saline loads limited its potential in high-sludge media. Adding 5% tailings did not significantly affect germination or growth in either species. Results indicate contrasting species-specific responses: V. caven showed greater tolerance to sludge and tailings, maintaining growth in mixed substrates, whereas B. linearis was restricted to sediment-dominated media. These findings highlight the importance of substrate composition for effective phytostabilisation strategies.
To investigate and enhance the quality of seed pelleting, a mineral powder coating loaded with a binder solution was applied to the surface of hybrid wheat seeds. Response Surface Methodology (RSM) was applied at each of three processing steps (wrapping, granulation and pilling) to optimise critical parameters, while Discrete Element Methodology (DEM) was used to investigate the mechanism influencing processing quality. The pelleting success rate reached 100%, powder utilisation rate was 98.7%, particle strength was 48.2 N and disintegration time was seven hours under the best process parameters, which included a machine speed of 2400 rpm at all stages, a powder feeding rate of 150, 180 and 210 g minute-1 and a water flow rate of 30, 35 and 45 mL minute-1. Simulation results revealed that machine speed regulates the interaction forces between seeds, powder and pellets within the drum; excessive speeds led to coating breakage, while insufficient speeds reduced particle contact, producing irregular pellets. The powder feeding rate was critical for balancing the water to powder ratio; overly high speeds caused powder loss, whereas low speeds resulted in an incomplete coating. The proposed three-stage variable frequency technique provides a robust theoretical foundation for enhancing seed pelleting quality and granulation efficiency.
Controlled deterioration (CD) methods are used to assess the vigour of seed samples when shorter tests such as electro-conductivity or radicle emergence tests are not relevant. The aim of this study was to demonstrate that results from a controlled deterioration method developed for tomato are correlated with results from greenhouse emergence trials. To develop the CD method, two seed moisture contents (25 and 30% +/- 0.5%) were compared over different durations (24, 48, 72 and 96 hours) at 47 degrees C using four samples of tomato (Solanum lycopersicum L.). A combination of time, temperature and seed moisture content was selected to maximise the germination capacity (GC) differences of these tomato seed samples and to assess vigour differences. Additional trials on six other samples established a significant relationship between one controlled deterioration combination and greenhouse emergence after 16 days (r = 0.88). In addition, a very good relationship was obtained with the selected CD method and the rate of usable tomato plants (r = 0.95).
A study was carried out to determine whether seed vigour tests including radicle emergence (RE), mean germination time (MGT) and accelerated ageing (AA) correlate with post-storage germination percentages (PSGP) and mean germination times (PSMGT) of spinach seed lots after one of year hermetic storage at 18 degrees C with 11.9 and 13.9% seed moisture. The RE test counted radicle emergence percentage (2 mm) after 48, 72, 96, 120 and 144 hours of germination, and mean germination was calculated by daily counts over 21 days at 20 degrees C. Accelerated ageing was conducted at 41 degrees C for 72 hours at 100% RH. Correlation analysis showed significantrelationships between both PSGP and PSMGT values after storage and initial MGT (r = 0.807-0.840, p < 0.001), RE (r = 0.681-0.932, p < 0.01-0.001) and AA (r = 0.690-0.890, p < 0.001). This indicates that these three seed vigour tests can predict the quality after storage of spinach seeds.
Understanding how storage conditions and seed traits impact the lifespan of seeds is important for the curation of banked seed collections. Storage temperature, seed moisture content and oxygen are factors known to influence seed longevity. Rapid ageing - storing seeds under high temperature and moisture conditions - is used to identify shorter- or longer-lived seeds in a shortened timeframe. Rapid ageing is conducted in either open or hermetic storage conditions; the former being commonly used for efficiently studying the longevity of large numbers of diverse species, for example to improve curation practices for seed banks conserving wild plant species. However, these open storage conditions differ from the hermetic environments typically used in seed banking, particularly in terms of oxygen availability. We investigated the longevity of seeds of 13 wild Australian plant species rapidly aged for up to 236 days at 45 degrees C and 60% RH under both open and hermetic conditions. We found differential responses to the storage conditions amongst species. Seeds of three species aged faster in open storage, four species aged faster in hermetic storage, while the remaining species showed similar ageing rates in both conditions. The methodology for rapid ageing of seeds should be considered if the purpose is to inform genebank management where seeds are commonly stored hermetically.
Estimating the viable lifespan of botanical seeds during storage is an important factor in managing seed germplasm collections. In this research, true potato seeds from 22 accessions (23 samples in total) of six wild potato species were used to estimate seed longevity in experimental storage, analyse the differences between species and determine if there is a pattern of longevity associated with the geographical origin of these species and accessions. An accelerated ageing method using controlled conditions (60% relative humidity, 45 degrees C) was used during storage, removing seeds at different times to test for viability. The emergence of a 3 mm-long radicle was used as a positive indicator of seed viability in a standard germination test. A seed survival curve was plotted and the time at which germination declined to 50% (p50) was determined. The p50 ranged between 23.6 days for accessions CIP 760355 and CIP 761977 (both Solanum raphanifolium), to 53.1 days for accession CIP 764506 (S. wittmackii), with an average of 36.7 days across all accessions. Based on our studies, the seeds of these 22 wild potato accessions appear to have intermediate seed longevity. Overall, these data can help prioritise and inform regeneration and conservation strategies of potato species held in long term conservation in genebank collections.
