Search Results (820)

Dry direct seeding (DDS) is a water-saving and high-efficiency rice cultivation system. However, drought stress during DDS severely constrains seedling establishment. This study used the conventional rice variety Zhonghua 11 (ZH11) and the drought-tolerant hybrid Hanyou 73 to investigate the effects of exogenous silicon (Si) on seed germination and seedling growth under drought stress, and to explore the underlying mechanisms of Si-enhanced drought tolerance. Drought stress was imposed using PEG-6000 simulation and pot experiments with different soil relative water contents (60%, 45%, 25%, and 10%). Si treatment significantly alleviated simulated drought inhibition of seed germination, increasing germination percentage and index, improving seedling growth in both varieties. Under simulated DDS conditions, Si significantly improved plant height, biomass, and root development, while maintaining higher net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration, transpiration rate, and chlorophyll content. Meanwhile, Si reduced oxidative damage by promoting proline accumulation, enhancing peroxidase (POD) and catalase (CAT) activities in both leaves and roots, reducing malondialdehyde (MDA) accumulation, and upregulating the expression of key drought-responsive genes (SNAC1, DREB1A, SKIPa, P5CS2). Furthermore, Si upregulated the expression of genes involved in abscisic acid (ABA) (ABA1, ABA2, MHZ5, ABI3) and jasmonic acid (JA) (AOS2, AOS3, JAR1, JAR2, MYC2, COI1a) biosynthesis and signaling. Compared with the wild-type, the ABA signaling mutant abi3 and the JA signaling mutant myc2 exhibited significantly attenuated improvement of plant growth by Si treatment. Collectively, Si enhances antioxidant capacity and osmotic adjustment, maintains photosynthetic function, and is associated with the activation of ABA and JA signaling pathways, which together alleviate the inhibition of rice seedling establishment under DDS-associated drought stress. Our findings provide a theoretical basis for the application of Si fertilizer in DDS rice production. Full article

The development of sustainable and efficient plant growth substrates is crucial for modern agriculture. This study assessed the potential of plant pellets formulated from various lignocellulosic residues, either with or without bamboo biochar (BB-char) and arbuscular mycorrhizal fungi (AMF), to support seed germination and early seedling growth. Four types of residues, including coconut coir (CO), corn cob (CC), leaves from the genus Dipterocarpus (DL), and teak leaves (TL), were combined with soil and paper waste to produce eight pellet formulations, with commercial peat pellets serving as a control. Chemical analyses revealed significant variation among the pellet types, with pH values ranging from 6.40 to 7.65, electrical conductivity (EC) from 3.64 to 11.62 mS cm⁻¹, and differences in organic matter, carbon, and nutrient contents [nitrogen (N), phosphorus (P), potassium (K)], reflecting the influence of residue type and the addition of BB-char and AMF. Phytotoxicity screening using aqueous extracts demonstrated species-specific responses, with cucumber exhibiting high tolerance across treatments, whereas chili seeds were more sensitive. Final germination percentage (FGP) and seedling growth assays in greenhouse conditions showed that pellets derived from CC and CO, particularly when combined with BB-char and AMF (T6 and T7), enhanced shoot and root development in carrot, chili, cucumber, and tomato, approaching the performance of commercial peat pellets. In contrast, DL- and TL-based pellets resulted in lower germination and growth. These findings indicate that both the physicochemical properties of lignocellulosic wastes and the combination of BB-char and AMF are important factors influencing pellet efficacy, highlighting the potential of CC- and CO-based pellets as sustainable peat alternatives for early-stage plant cultivation. Full article

Pea cultivation has witnessed significant growth in international trade in recent years, leading to increased export volumes worldwide. However, seed germination and early seedling growth often exhibit low uniformity, resulting in heterogeneous seedling sizes, which limit agronomic management and affect overall performance. As a result, this study aimed to assess the effects of gibberellin (GA) doses on the germination of the ‘Santa Isabel’ pea variety, one of Colombia’s most commonly cultivated varieties. A completely randomized design was employed with five treatments (0, 50, 100, 150, or 200 mg L⁻¹). The application of 200 mg L⁻¹ GA significantly enhanced germination percentage, germination potential, and germination speed index by 66.4%, 64.9%, and 71.5%, respectively, compared to the control. Furthermore, it increased the vigor index. The GA application reduced the mean germination time to 6.48 days, while the control exhibited 8.98 days. GA treatment increased seedling height to 5.3 cm, compared with 3.0 cm in the control. The variation coefficient in germinated seedling height increased as germination progressed and stabilized towards the end. Although GA did not affect the total fresh mass of the seedling, it did influence the proportion of mass allocated to each organ. Notably, there was a decrease in the amount of photoassimilates transferred from the seed to the leaves and stipules, accompanied by an increase in dry and fresh mass in the stems. The control treatment exhibited the highest fresh and dry leaf mass values compared with the GA-treated treatments. Full article

This study aimed to characterize corn (CS), wolf fruit (WF), and butterfly lily (BL) starches; to develop bioactive coatings from pure starches and their binary and ternary blends; and to evaluate the synergistic effects of these formulations on the physiological quality of common bean seeds. Films were prepared by thermocompression (80 °C, 6 min, 3 t) of film-forming solutions obtained via microwave processing and formulated using a simplex-centroid mixture design. The starches were characterized in terms of amylose content, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry, Rapid Visco Analyser, while the films were evaluated for thickness, water solubility, and water vapor permeability. The film-forming solutions were applied as coatings, and seed physiological quality was assessed through germination, first count, seedling length, and dry mass. BL exhibited higher gelatinization temperatures and produced films with adequate thickness and moderate permeability, indicating greater structural stability. The CS:BL blend produced films with balanced hydration, promoting rapid and uniform water uptake. Coatings based on BL and CS:BL showed the highest germination percentages, whereas CS:WF resulted in lower physiological performance. These results demonstrate that film properties directly influence seed vigor and germination. BL, alone or blended with CS, represents a promising starch-based material for seed coating, promoting high physiological quality and environmentally friendly characteristics. Full article

Since the status of C. jambhiri is “rare” and C. aurantifolia is endowed with folk medicinal properties, our study aimed at producing true-to-type seedlings for further conservation by using PGRs, ferrous sulfate, and casein hydrolysate in MS medium to induce in vitro germination and “callus” formation from seeds of C. jambhiri Lush. It also focused on evaluation of suitable species and the best type of explant for organogenesis. The present study was undertaken to develop an efficient micropropagation protocol for C. jambhiri Lush. and C. aurantifolia. The frequency of callus induction increased to its maximum when 2.0 mg/L 2,4-D and 1.0 mg/L picloram were added individually. The calli derived from 2,4-D exhibited maximum regeneration potentiality. In addition, sucrose (30 g/L), dextrose (60 g/L), and coconut water (10 mL/L and 15 mL/L) also enhanced callus induction. Regarding heavy metals, 100 ppm of Fe₂SO₄ exhibited maximum germination percentage (84.33%) from seeds of C. jambhiri Lush. However, maximum callus induction (50.00%) was induced from the seeds of C. aurantifolia incubated in Fe₂SO₄ (400 ppm). The maximum number of shoots per callus was produced (5.13) with the addition of 200 mg/L casein hydrolysate in the callus-induction medium. Pearson correlation analysis revealed a positive and significant association of the number of plantlets/calluses with shoot length and regeneration percentage, respectively. It was phenotypically observed that the tissue culture traits performed better from explants derived from C. jambhiri Lush. than C. aurantifolia when subjected to varying concentrations of PGRs, carbon sources, organic adjuvants, and heavy metals, respectively. Full article

Seed vigor is an important indicator for evaluating the physiological quality of seeds and directly affects germination rate, seedling emergence uniformity, and field establishment capacity. However, conventional vigor evaluation methods are often destructive, labor-intensive, and time-consuming. In this study, a nondestructive method for soybean seed vigor classification was developed by combining hyperspectral imaging with machine learning. A total of 6000 soybean seeds from four cultivars were subjected to artificial aging treatment to obtain samples with different vigor levels, and seed vigor classes were determined based on germination percentage, germination energy, and germination index. After spectral calibration, the effective spectral ranges of 401.0–1000.9 nm and 1003.7–2450.79 nm were retained for analysis. Four preprocessing methods, namely multiplicative scatter correction (MSC), standard normal variate transformation (SNV), Savitzky–Golay smoothing (SG), and Savitzky–Golay second-derivative preprocessing (D2), were applied to reduce noise and improve spectral quality. This was followed by dimensionality reduction using principal component analysis (PCA) and minimum noise fraction (MNF), and classification using random forest (RF), extreme gradient boosting (XGBoost), and support vector classifier (SVC) models. The best overall features were extracted using the method of SNV combined with PCA. On the independent test set, the highest classification performance was obtained, with accuracy, recall, and F1-score values of 93.33%, 93.33%, and 93.37%, respectively, using the SVC model. These results indicate that hyperspectral imaging combined with machine learning can provide rapid and nondestructive technical support for soybean seed vigor evaluation. Full article

Large reservoir construction generates vast drawdown zones characterized by novel hydrological regimes that impose unprecedented selective pressures. While annual plants serve as pioneer colonists during secondary succession in these ecosystems, the mechanisms allowing their seeds to persist through prolonged anti-seasonal flooding remain poorly understood. We investigated how seed germination responses to extreme submergence are influenced by dormancy traits and phylogenetic history. We conducted a field experiment on 44 common annual plant species in the Three Gorges Reservoir drawdown zone. Seeds were subjected to maximum submergence depths of 0 m (control), 5 m, 10 m, 15 m, and 20 m, along the reservoir’s hydrological gradient. Post-submergence germination percentages were measured and analyzed using linear and Bayesian phylogenetic mixed-effects models, with seed dormancy status, seed type, season, and species’ phylogenetic relationships as explanatory variables. Submergence significantly reduced overall seed germination (p < 0.001), but more than 75% of species retained germination capacity even after 20 m of submergence. Germination percentage distributions shifted from near-normal to bimodal with increasing depth. Although the regression of squared PIC values against phylogenetic branch lengths showed a significant relationship, phylogenetic signal for germination percentages was weak and non-significant across all depths (Pagel’s λ < 0.101, Blomberg’s K < 0.228, p > 0.05). Bayesian models revealed that dormancy season significantly interacted with submergence depth (Estimate = −1.41, 95% CrI [−2.16, −0.67]). Seeds dormant during autumn-winter maintained stable germination percentages across depths, while germination of spring-summer dormant seeds declined significantly with increasing depth. Our findings demonstrate that annual plant seeds possess widespread, species-specific tolerance to extreme submergence. This tolerance is primarily driven by environmental filtering rather than phylogenetic history. The seasonality of dormancy is a crucial adaptive mechanism, enabling seeds, particularly those dormant in autumn-winter, to withstand the harsh conditions of the Three Gorges Reservoir drawdown zone. This study provides a functional trait-based framework for selecting suitable species for the ecological restoration of reservoir drawdown zones globally. Full article

Grassland fire is one of the major disasters threatening regional ecological security. Its occurrence, development, and spread are closely related to the spatial distribution and coverage of surface vegetation and snow cover across grassland areas. As the primary combustible fuel source, higher vegetation coverage increases fuel load and continuity, thereby directly determining grassland fire danger levels and accelerating fire spread velocity. In contrast, snow cover imposes an indirect regulatory effect on the spatiotemporal pattern of fire danger factors: it lowers surface temperature, raises near-surface humidity, and restricts the germination and growth of herbaceous vegetation in cold seasons, which effectively reduces available combustible materials and weakens regional fire hazard conditions. Therefore, accurately obtaining the coverage status of vegetation (direct combustible fuel factor) and snow cover (indirect fire-regulating factor) in complex grassland scenarios is the essential premise for reliable grassland fire danger monitoring, early warning, disaster prevention and control, and regional ecological management. Aiming at the practical problems in complex grassland scenarios (such as undulating terrain, uneven vegetation growth, large differences in snow depth, and complex lighting conditions), including difficulty in extracting vegetation and snow-covered areas, blurred and confusing boundaries, and low accuracy in coverage calculation, which seriously restrict the technical bottleneck of precise monitoring of grassland fire danger factors, this study takes near-ground images collected by grassland fire danger factor monitoring stations as the core data source, and proposes an improved UNet image segmentation model combined with image segmentation technology and deep learning methods to realize precise extraction of vegetation and snow-covered areas and efficient calculation of coverage in complex scenarios. To improve the model’s feature extraction ability, boundary localization accuracy, and reduce model parameters and computational overhead, the CBAM-ASPP (Convolutional Block Attention Module—Atrous Spatial Pyramid Pooling) module is integrated at the end of the encoding path. The attention mechanism is used to enhance the weight of key features, and the multi-scale receptive field of atrous spatial pyramid pooling is utilized to strengthen the model’s ability to fuse features of vegetation and snow areas of different scales. The residual attention mechanism is introduced in the upsampling stage to effectively alleviate the gradient disappearance problem, improve the model’s ability to accurately locate the boundaries of vegetation and snow areas, and reduce segmentation errors. In the training process, a dynamically weighted hybrid loss function is adopted to dynamically adjust the weights according to the segmentation difficulty of different types of samples during training, optimize the model training effect, and improve the segmentation accuracy and generalization ability. Experiments were conducted using near-ground images of typical complex grassland scenarios as the dataset, and the performance of the proposed model was verified through comparative experiments. The results show that in the vegetation segmentation task, the mean Intersection over Union (mIoU) of the model reaches 84.70%, and the accuracy rate is 91.28%, which are 1.48 and 1.58 percentage points higher than those of the standard UNet model, respectively. In the snow segmentation task, the mIoU of the model reaches 92.74%, and the accuracy rate is 94.19%, which are 2.39 and 2.36 percentage points higher than those of the standard UNet model, respectively. At the same time, the number of parameters of the model is reduced by 12.85% compared with the standard UNet. Also, its comprehensive performance is significantly better than that of mainstream image segmentation models such as FCN, SegNet, and DeepLabv3+. Based on the standardized time-series data retrieved by the optimized segmentation model, this study further constructs a Grassland Fire Risk Index (GFRI) using the Analytic Hierarchy Process (AHP). Pearson correlation verification confirms that the GFRI has an extremely significant positive correlation with historical fire frequency, accurately capturing the seasonal dynamic rhythm of regional grassland fire occurrence. This integrated framework of intelligent segmentation and fire risk quantification provides a reliable technical solution for grassland fire factor monitoring, dynamic fire risk assessment, early warning systems, and refined regional ecological management. Full article

Microalgae-based biostimulants are gaining increasing interest worldwide for promoting sustainable agriculture. The environmental risks associated with synthetic agrochemicals can be mitigated by using microalgae to enhance crop yield and quality. Cumin (Cuminum cyminum L.) is an herbaceous plant and ranks among the most popular seed spices worldwide. It is characterized by a low germination rate and poor seedling establishment, which negatively impact overall crop yield. To address these challenges, the present study investigates the potential of Chlorococcum sp. aqueous extract as a sustainable and cost-effective solution to overcome cumin seed dormancy and enhance germination. Results showed that Chlorococcum sp. exhibits a notably rapid growth rate (0.45 day⁻¹) and high biomass productivity (1.51 g/L/day). Additionally, the biochemical composition of the extract revealed a high concentration of bioactive compounds, including polyphenols (63.46%), flavonoids (29.36%), and Indole-3-acetic acid (5.38%), which make it an eco-friendly biostimulant for agricultural applications. Regarding germination, a single seed treatment with doses of 0.5 g/L and 1 g/L was efficient in achieving final germination percentages of 100% and 96.66%, respectively, and significantly increased the seedling vigor index and photosynthetic pigment content. Furthermore, these concentrations stimulated the synthesis and accumulation of key primary metabolites, including proteins and polysaccharides, while increasing phenolic and flavonoid levels compared to the control, suggesting enhanced growth and improved antioxidant defenses against environmental stressors. Overall, these findings highlight that Chlorococcum sp. aqueous extract serves as an innovative biological approach to overcoming cumin seed dormancy and enhancing germination, offering an alternative and sustainable solution to conventional synthetic fertilizers. Full article

Reproductive barriers severely limit interspecific hybridization success among Hydrangea macrophylla, H. paniculata, and H. arborescens, thereby restricting the combination of ornamental traits and cold hardiness. We evaluated cross-compatibility, pollen tube growth, and embryo development in both direct and reciprocal crosses involving H. macrophylla with H. paniculata and H. arborescens. Both species pairs exhibited pronounced unilateral incompatibilities. When H. macrophylla served as the maternal parent, the percentages of seedling emergence were higher, whereas reciprocal crosses produced >84% ovary swelling but resulted in almost no seedlings. Fluorescence microscopy revealed mild prezygotic barriers in direct crosses but strong inhibition of pollen germination and pollen tube growth in reciprocal crosses. Paraffin section observations showed that postzygotic barriers were the primary cause of hybrid failure, with endosperm-type abortion predominating in direct crosses and embryo-type or complete abortion in reciprocal crosses. Consistent with these abortion patterns, direct crosses maintained higher proportions of normal embryos, whereas reciprocal crosses dropped below 10% at the globular stage and approached 0% at later stages. These findings support the use of timely embryo rescue for direct crosses and targeted mitigation of prezygotic barriers in reciprocal crosses to improve Hydrangea interspecific hybridization efficiency. Full article

Urbanization reduces biodiversity and affects plant–insect interactions, creating a need for more functional green spaces. Urban meadows with native species are a promising option, but their use is still limited due to a variety of reasons concerning the utilization framework of suitable plant species. The present study aimed to develop seed germination protocols for 26 native Mediterranean herbaceous species originating from northeastern Greece selected to support the establishment of species-rich and self-sustaining urban meadows. To the above end, seed germination experiments were conducted ex situ under controlled environment conditions using seeds collected from the wild for each species. Seed viability was assessed using the tetrazolium (TTZ) test to determine the maximum germination potential in each case. Freshly collected seeds were stored under ambient conditions for approximately 3 months (after-ripening) prior to germination testing, which was followed by cold stratification as a pretreatment for dormancy release. The results showed high embryo viability in all species and indicated that most taxa exhibited either no dormancy or relatively shallow physiological dormancy. Germination tests revealed that 14 of the 26 species presented high germination percentages in the control treatment, which suggests that after-ripening contributed to dormancy release in a significant portion of the seed lot. However, it remains unclear whether freshly collected seeds require an initial after-ripening period before responding to cold stratification. Furthermore, cold stratification significantly enhanced germination in 12 species confirming its effectiveness as a simple and practical method for dormancy release. In addition to the seed germination results, the selected species present a wide range of functional and esthetic characteristics, including variation in plant height, flowering phenology and flower and leaf color. These traits are important for both ecological performance and visual quality in urban environments. The combination of extended flowering periods and color diversity suggests the potential for continuous floral resource availability, which can support diverse pollinator communities and, indirectly, urban fauna such as insectivorous birds. The results indicate that the studied species are suitable for biodiversity-oriented urban plantings. Their relatively shallow dormancy and ease of propagation, coupled with their functional and aesthetic traits, support their use in the development of resilient and self-sustaining urban meadows. Full article

Seed pre-treatment is imperative for breaking the seed dormancy of some perennial species. The addition of soil amendments might be helpful in supporting seed germination and growth by available essential plant nutrients. This research investigated the effects of different pre-treatment and soil amendments on the germination, growth, and physiological performance of radhachura (Caesalpinia pulcherrima L.), an important ornamental and multipurpose woody shrub. Four pre-treatments and five soil amendments were applied in a CRD (Completely Randomized Design) arrangement to evaluate their individual and combined impacts under controlled nursery conditions. The ANOVA result revealed that seed germination indices of radhachura were mostly influenced by soil amendment rather than the seed pre-treatment. Among the soil amendments, vermicompost had a more profound impact on germination speed, Timson’s index and peak value, which had a similar effect to NPK application. Soil organic amendments positively affected growth, with vermicompost exerting the greatest influence on multiple germination traits that may support the early growth of radhachura, while biochar and compost maximized certain root and plant-length traits. Pearson correlations and PCA (first seven PCs explaining 76.2% variation) revealed the strong integration of late biomass, plant length, and root development, identifying vermicompost as key enhancers of multivariate vigor in radhachura seedlings. It might be concluded that C. pulcherrima L. species germination and growth was mostly influenced by soil amendment rather than seed pre-treatment. The study highlights that integrated nursery practices combining appropriate pre-treatment and soil amendments can enhance the germination success of radhachura. Full article

Seed germination represents a critical bottleneck for the establishment of halophytic crops under saline conditions. In Sarcocornia neei, a promising biosaline species, previous germination studies have focused almost exclusively on sodium chloride, despite the prevalence of sulfate-dominated salinity in many salt-affected environments. In this study, we evaluated the effects of salt type (NaCl vs. Na₂SO₄) and salinity level (0, 25, 50, 75 and 100% of sea water salinity) on seed germination of three natural populations from ecologically contrasting environments under controlled conditions. Germination percentage, rate and period and post-stress recovery were quantified. Seed germination responses were strongly site-dependent and differed markedly between salt types. Seeds from the inland saline population exhibited a euhalophytic germination pattern with low germination in distilled water and enhanced germination at moderate NaCl and Na₂SO₄ concentrations. In contrast, seeds from coastal populations showed the classical decline in germination with increasing salinity but displayed a high capacity for post-stress recovery, particularly under sulfate salinity. These results demonstrate that S. neei harbors substantial intraspecific variation in germination responses to both salt type and concentration, reflecting adaptation to local ionic environments. Our findings underscore the relevance of considering population-level variation when selecting plant material for biosaline agriculture and ecological restoration. Full article

Phytolacca acinosa Roxb., a perennial herb native to East Asia, is increasingly naturalizing in Europe, yet its reproductive ecology in the secondary range remains poorly understood. This study evaluated seed productivity across central and edge populations in the secondary range, fruit and seed morphometrics, and germination responses to cold storage, acid scarification (simulating bird endozoochory), and light exposure. Fruit production per raceme was influenced by an interaction between insolation and range position: reduced insolation increased fruit set in central populations but decreased it at the range edge. Raceme number per shoot was lower in spontaneous plants compared to cultivated ones. Fresh seeds exhibited strong dormancy with no germination without scarification. Acid scarification significantly enhanced germination, particularly with light exposure, reaching up to 55%. Cold storage did not increase germination percentage but accelerated germination of scarified seeds under light, reducing median germination time from 24 to 21 days. Compared to the congeneric P. americana, P. acinosa shows more stringent dormancy requirements. We conclude that P. acinosa retains deep seed dormancy in its secondary range and relies on bird-mediated endozoochory for both dispersal and dormancy release. At the northern range edge, reduced plant vigor and lower raceme numbers are partially offset by increased flower production per raceme, though fruit set remains constrained. The species does not exhibit the simplified germination requirements often associated with successful invaders; instead, its invasion success appears driven by a bet-hedging strategy combining persistent seed banks with specific dormancy-breaking cues. Full article

Seed aging is a critical biological process that leads to progressive loss of seed vigor, thereby constraining germplasm conservation and agricultural productivity. To elucidate the molecular mechanisms underlying this process in grass species, we performed transcriptomic analyses to characterize regulatory networks underlying seed aging in Elymus sibiricus, a dominant forage species on the Qinghai–Tibet Plateau. Seeds were subjected to artificial accelerated aging (45 °C, 80% relative humidity, 1–6 days), followed by physiological evaluation and RNA sequencing. Seed vigor and germination percentage declined markedly with aging, accompanied by extensive transcriptional reprogramming. Integrative analyses identified pyruvate metabolism, MAPK signaling, and peroxisome function as key processes associated with vigor loss during late-stage aging. WGCNA further revealed that genes encoding heat shock proteins and glutathione metabolism-related enzymes were co-localized within the same module, suggesting a possible synergistic role in preserving seed viability during aging. In addition, WRKY24, ARF9, and ARF19 were identified as candidate hub transcription factors. WRKY24 may contribute to aging by modulating antioxidant defense-related genes (e.g., TRX1 and NRPC1), while ARF9 and ARF19 may regulate ROS homeostasis through predicted downstream targets, including FQR1, PER2, MAO1B, ANN5, and MT2B. Together, these findings support a hypothetical regulatory model in which WRKY and ARF transcription factors coordinate redox homeostasis and hormone signaling to regulate seed longevity in E. sibiricus. This study provides a systems-level framework for understanding seed aging in perennial grasses and identifies potential genetic targets for improving seed storability, with implications for germplasm conservation and alpine grassland sustainability. Full article