Search Results (1,451)

Cucumis sativus L., a salt-sensitive horticultural crop, is severely affected by soil salinity, which disrupts photosynthetic efficiency and metabolic homeostasis. This study quantified the effects of Plant Growth-Promoting Rhizobacteria (PGPR)—Pseudomonas paralactis, Bacillus cereus, Sinorhizobium meliloti, and Acinetobacter radioresistens—on key enzymatic indicators of cucumber seedlings exposed to 0, 50, 100, and 150 mM NaCl. PGPR inoculation significantly enhanced bacterial stress-mitigation and hormonal pathways, with ACC-deaminase activity increasing by up to 78.8% (A. radioresistens, 150 mM NaCl) and nitrilase activity by 50.5% (S. meliloti, 50 mM NaCl). Auxin-related pathways were strongly induced, as reflected by increases of up to 51.1% in the IAM pathway (P. paralactis) and 42.9% in the IPA pathway (A. radioresistens). In plant tissues, key metabolic enzymes exhibited high stability under salinity, with ProDH and NDPK activities increasing by up to 4.5% and 2.35%, respectively, while RuBisCO activity remained unaffected across treatments. These results demonstrate that PGPR function as effective bioestimulants by coordinating hormonal regulation and metabolic resilience, providing a sustainable biotechnological strategy to enhance cucumber tolerance to salinity stress. Full article

Topography regulates vegetation functioning by controlling water redistribution, microclimate, and solar exposure. In Mediterranean ecosystems, where water availability constitutes a fundamental limiting factor, vegetation functioning is also influenced by environmental drivers such as temperature, climatic seasonality, drought recurrence, and soil properties that interact with terrain heterogeneity. Understanding how these elements operate at the micro-scale is essential for interpreting the spatial variability of photosynthetic vigor and canopy water condition. This study evaluates the relationships between the topographic metrics Topographic Position Index (TPI), Terrain Ruggedness Index (TRI), and Diurnal Anisotropic Heat Index (DAH) and two spectral proxies of vegetation condition, the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Moisture Index (NDMI), in Los Nogales Nature Sanctuary (central Chile). Multitemporal Sentinel-2 time series (2017–2025) were analyzed using Generalized Additive Models (GAMs) with Gaussian distribution and cubic splines to detect non-linear topographic responses. All topographic predictors were statistically significant (p < 0.001). NDVI and NDMI values were higher in concave and less rugged areas, decreasing toward convex and thermally exposed slopes. NDMI exhibited greater sensitivity to topographic position and thermal anisotropy, indicating the strong dependence of vegetation water condition on topographically driven water redistribution. These results highlight the role of terrain in modulating vegetation vigor and moisture in Mediterranean ecosystems. Full article

African vegetation responses to extreme drought represent a key challenge for global change research and sustainable water–land resource management. Satellite remote sensing provides long-term observations of vegetation dynamics, yet conventional analyses focus on vegetation structural, greenness, or productivity changes, lacking of understanding on physiological adaptation. This study applies a multi-model framework integrating high-temporal-resolution (4-day) and multi-spectral satellite data with machine learning to disentangle structural and physiological responses across Central and Western Africa. Three key indicators were used: evapotranspiration (ET), relative solar-induced chlorophyll fluorescence (SIF_rel), and the ratio of midday to midnight vegetation optical depth (VOD_ratio), which respectively, represent water flux, photosynthetic activity, and water regulation. A random forest model, combined with SHapley Additive exPlanations (SHAP) analysis, was used to separate vegetation anomaly signals and identify key climatic controls. The results reveal pronounced differences in vegetation responses between arid and humid climatic regions. In arid regions, near-infrared reflectance of vegetation (NIRv) and solar-induced chlorophyll fluorescence (SIF) exhibited clear negative anomalies and significant pre-drought declines, accompanied by marked changes in vegetation optical depth (VOD), indicating canopy structural damage and reduced photosynthetic activity. In contrast, trend analysis revealed that although SIF and NIRv in humid regions showed relatively strong responses during the pre-drought phase, they did not exhibit significant trends after the drought peak, and changes in VOD were comparatively small, suggesting that higher water availability partially buffered the prolonged impacts of drought on vegetation structure and function. Process analysis showed that three months before and after drought peaks, physiological indicators exhibited strong anomalies that closely tracked drought duration. SIF_rel, ET signals peaked earlier than water-content anomalies (VOD_ratio), suggesting a two-phase regulation strategy: early stomatal closure followed by delayed deep-root water uptake. Physiological anomalies accounted for over 88% of total vegetation anomalies during drought peaks, highlighting their dominant role in early-stage drought response. Precipitation and temperature emerged as primary drivers, explaining 76.8% of photosynthetic variation, 60.3% of ET variation, and 53.9% of water-content variation in the development. The recovery is influenced by the duration of drought and the regrowth of vegetation. By explicitly decoupling physiological and structural vegetation responses, this study provides refined, process-based insights into African ecosystem adaptation to water stress. These findings contribute to more accurate drought monitoring, water availability assessment, and climate adaptation strategies, directly supporting sustainable water and land management goals. Full article

Wood vinegar (WV), a by-product of biomass pyrolysis rich in organic acids and phenolic compounds, has gained increasing attention as a sustainable input for crop production, mainly through foliar application. However, its high content of volatile organic compounds (VOCs) suggests that WV may (also) interact with plants through the gaseous phase, a pathway that has so far been overlooked. This study tested the hypothesis that WV can modulate plant physiological performance, metabolic status, and nutrient accumulation not only via direct foliar contact but also through exposure to WV-derived VOCs. Lettuce (Lactuca sativa L.) was used as a model crop and grown under controlled environmental conditions. Plants were subjected to weekly treatments consisting of either foliar spraying with a 0.2% (v/v) WV solution or exposure to VOCs released from the same solution in a sealed chamber, without direct contact between the liquid and plant tissues, and were compared with untreated controls. Notably, plants exposed exclusively to WV-derived VOCs showed responses similar to those observed following foliar application. Both treatments significantly increased fresh weight, the content of chlorophyll, total polyphenols and the accumulation of key macro- and micronutrients, including Ca, K, P, S, and Zn. For both treatments, the efficiency of photosystem II remained stable, indicating the absence of photochemical stress, while stomatal conductance, transpiration rate, intercellular CO₂ concentration, and net photosynthetic rate were markedly reduced, suggesting a regulated stomatal response. Physiological, biochemical, and mineral parameters were assessed using non-destructive optical techniques, gas exchange measurements, spectrophotometric assays, and X-ray fluorescence analysis. These findings indicate that exposure to the volatile fraction released from WV under the exposure conditions adopted in this study can elicit biostimulant-like responses comparable to those observed after foliar application. Full article

Climate change is intensifying the simultaneous occurrence of biotic and abiotic stresses in fruit crops, but yet the molecular mechanisms underlying plant responses remain poorly understood. The physiological and transcriptomic responses of two sweet cherry (Prunus avium L.) cultivars, Santina and Bing, grafted onto Gisela 12, were investigated under single and combined stresses imposed by Pseudomonas syringae pv. syringae and water deficit. Although biomass, gas exchange, and hormone accumulation showed only minor changes, combined stress triggered distinct cultivar-dependent transcriptional reprogramming. The cultivar Bing exhibited a pronounced response with 4261 differentially expressed genes (DEGs), characterized by strong repression of photosynthetic processes and activation of defense- and hormone-related pathways. In contrast, the cultivar Santina showed a moderate response with 674 DEGs, primarily reinforcing structural and secondary metabolism. Cultivar-specific modulation of abscisic acid sensitivity was associated with the contrasting regulation of WRKY40 and Sin3-like repressors, despite comparable ABA levels. Strikingly, both cultivars upregulated the GIGANTEA gene, underscoring its role as a central regulatory hub linking circadian rhythm, stomatal function, and hormonal crosstalk under dual stress. Collectively, these results reveal non-additive, genotype-specific transcriptional strategies in sweet cherry trees, providing insights into stress integration in fruit trees and identifying regulatory genes that may inform breeding and management strategies for resilience under climate change. Full article

Soil mulching materials play an important role in regulating the greenhouse crop microclimate, as they influence light distribution, plant physiological activity, and crop yield. The aim of this study was to evaluate the effects of two plastic mulches (black polypropylene and white polyethylene mulch) on the microclimate, photosynthetic activity, crop development, yield, and fruit quality of sweet pepper (Capsicum annuum L.) grown under greenhouse conditions. The trial was developed during a spring–summer growing cycle in a single multispan greenhouse divided into two compartments (sectors) separated by a vertical polyethylene sheet. In the eastern sector of the greenhouse (control treatment), a black polypropylene agrotextile mulch with a thickness of 2500 μm was installed, while in the western sector, a white polyethylene plastic mulch (black on the inner side) with a thickness of 30 μm was used. The use of white polyethylene mulch resulted in slightly higher mean and maximum PAR inside the greenhouse by up to 3.7% compared with black polypropylene mulch, leading to slightly higher leaf-level PAR and net photosynthetic rate. Although no significant differences were observed in plant morphology or fruit quality parameters, marketable yield increased by 66% and total yield by 40% under white polyethylene mulch. Slight increases in internal air temperature were recorded without exceeding critical thresholds, while relative humidity remained largely unaffected. The use of reflective mulches may represent a promising low-cost and sustainable strategy to improve pepper yield and radiation-use efficiency in passively ventilated greenhouse systems under Mediterranean climatic conditions. Full article

The physiological mechanism of melatonin in alleviating combined saline-alkali stress in Fraxinus mandshurica remains unclear. This study aimed to determine the efficacy of exogenous melatonin in enhancing salt tolerance and elucidate the underlying mechanisms through integrated physiological and multi-omics analyses. Seedlings were subjected to 400 mmol L⁻¹ saline-alkali stress and treated with foliar melatonin. We quantified key growth indicators (height, diameter, dry biomass) and measured the activities of antioxidant enzymes (SOD, POD). Melatonin significantly alleviated growth inhibition, increasing biomass and height by 29% and 13%, respectively, while enhancing net photosynthetic rate and antioxidant capacity. To uncover the systemic regulation, conjoint analysis of transcriptome (RNA-seq) and metabolome data was performed. This integrated approach revealed that melatonin specifically activated common KEGG pathways pivotal for stress adaptation, including plant hormone signal transduction, phenylpropanoid biosynthesis, and starch and sucrose metabolism, with coordinated upregulation of associated genes and metabolites. Collectively, our integrated data demonstrate that melatonin enhances Fraxinus tolerance by synergistically improving photosynthesis and antioxidant defense, underpinned by a reconfigured molecular network. This study provides a theoretical basis for using melatonin as an eco-friendly biostimulant to improve woody plant resilience in saline-alkali soils. Full article

Light-emitting diode (LED) technology allows for precise spectral tailoring in controlled-environment agriculture, with red light (R; 600–700 nm) acting as a central regulator of plant photophysiology through phytochrome (PHY)-mediated control of photosynthesis, morphology, and metabolic adjustment. This review synthesizes the current knowledge of the benefits and limitations of monochromatic and multichromatic R-containing LED systems under both optimal and saline conditions. Monochromatic R light enhances chlorophyll biosynthesis, carbon assimilation, and biomass accumulation; however, its exclusive application can restrict stomatal regulation, photoprotection, and secondary metabolism due to the absence of blue (B)- and green (G)-light-dependent signaling pathways. In contrast, multichromatic spectra incorporating R—particularly R-B, R-far-red (R-FR), and R-centered multi-spectral combinations with white (W) or G wavelengths—provide broader physiological advantages. These include improved photosystem II efficiency, pigment stability, ion homeostasis, antioxidant defense, and metabolic quality, while also optimizing canopy light distribution and energy use efficiency. Under salinity stress, R-containing spectral combinations consistently outperform monochromatic R by enhancing osmotic adjustment, reducing oxidative damage, and maintaining photosynthetic integrity. Nevertheless, species-specific sensitivity, ratio-dependent responses, and potential risks such as excessive elongation under FR enrichment highlight the need for careful spectral optimization. Despite substantial progress, the mechanisms underlying the integration of PHY signaling with salinity-responsive networks remain insufficiently resolved. Advances in multi-omics approaches and dynamic spectral management will be critical for the development of R-based LED strategies that sustainably enhance crop performance and stress resilience in controlled environments. Full article

Banana Fusarium wilt represents a considerable threat to the sustainable development of the global banana industry. Nonetheless, the regulatory mechanisms through which different nitrogen forms (nitrate, ammonium) and concentrations (low, normal) affect the growth and photosynthetic functions of banana seedlings following Foc TR4 infection are not yet fully elucidated. This study employed these nitrogen treatments to assess seedling growth indicators, chlorophyll fluorescence parameters, and light response curves both prior to and following Foc TR4 infection. The findings indicated that, before infection, ammonium nitrogen significantly enhanced root growth and increased leaf relative chlorophyll content (SPAD) and non-photochemical quenching (NPQ) values, whereas low-nitrogen conditions promoted biomass allocation to roots but inhibited maximum photochemical quantum yield of photosystem II (Fv/Fm). Post-infection, critical photosynthetic parameters such as SPAD value and Fv/Fm were significantly elevated in the nitrate nitrogen treatment compared to the ammonium nitrogen treatment, with the normal-nitrogen treatment yielding the most favorable results. Furthermore, Foc TR4 infection significantly reduced the leaf electron transport rate (ETR) across all treatments. In summary, nitrogen is integral to the modulation of seedling growth and stress resistance, primarily through its regulation of leaf photosynthetic apparatus efficiency, photoprotection mechanisms, and biomass allocation. These findings offer significant insights for formulating nitrogen management strategies aimed at the sustainable prevention and control of banana Fusarium wilt. Full article

Crassulacean acid metabolism (CAM) is a specialized photosynthetic pathway that enhances water-use efficiency by temporally separating nocturnal CO₂ uptake from daytime decarboxylation and carbon fixation. To uncover the regulatory mechanisms coordinating these temporal dynamics, we generated high-resolution, 48 h time-course transcriptomes for the CAM model Kalanchoe fedtschenkoi under both 12 h/12 h light/dark (LD) cycles and continuous light (LL). A rhythmicity analysis revealed that diel light cues are the dominant driver of transcript oscillations: 16,810 genes (54.3% of annotated genes) exhibited rhythmic expression only under LD, whereas just 399 genes (1.3%) remained rhythmic under LL. A smaller set of 3009 genes (9.7%) oscillated in both conditions, indicating that the intrinsic circadian clock sustains rhythmicity for a limited subset of the transcriptome. A gene co-expression network analysis revealed extensive integration between circadian clock components, core CAM pathway enzymes, and stomatal regulators, defining regulatory modules that coordinate metabolic and physiological timing. Notably, key hub genes associated with post-translational and post-transcriptional regulation, including the E3 ubiquitin ligase HUB2 and several pentatricopeptide repeat (PPR) proteins, act as central nodes in CAM-associated networks. This discovery implicates epigenetic and organellar regulation as previously unrecognized critical tiers of control in CAM. Together, our results support a regulatory model in which CAM rhythmicity is governed by both external light/dark cues and the endogenous circadian clock through multi-level control spanning transcriptional and protein-level regulation. To support community exploration, we also provide an interactive eFP (electronic Fluorescent Pictograph) browser for visualizing time-resolved gene expression profiles. Full article

Background/Objectives: Soil salinization and alkalization critically limit global agricultural production. This study aimed to investigate the differential response mechanisms of rapeseed (Brassica napus L.) varieties to saline and alkaline stresses at the seedling stage. Methods: Seedlings of a salt-tolerant variety, Huayouza 62 (H62), and a non-salt-tolerant variety, Xiangyou 15 (X15), were exposed to saline (NaCl:Na₂SO₄ = 1:1) and alkaline (Na₂CO₃:NaHCO₃ = 1:1) stresses. An integrated analysis combining physiology, biochemistry, transcriptomics, and metabolomics was conducted to systematically elucidate their differential stress responses. Results: (1) H62 maintained favorable photosynthetic and carbon–nitrogen homeostasis. Notably, under saline and alkaline stresses, the activity of glutamate dehydrogenase (GDH) in H62 showed a significant increasing trend, whereas it was inhibited in X15. (2) Alkaline stress triggered more differential genes than saline stress, with H62 exhibiting broader transcriptional up-regulation in carbon–nitrogen metabolism. (3) Metabolomic profiling showed that H62 accumulated more beneficial metabolites than X15 under both stresses, such as phenolic acids, amino acids, and their derivatives. (4) In multi-omics analysis, key genes in starch–sucrose and amino acid metabolism in H62 were up-regulated to accumulate osmolytes, enabling an efficient defense network. However, X15’s responses were disordered. Conclusions: H62 leverages robust transcriptional reprogramming to coordinate carbon–nitrogen metabolism, constituting a multidimensional defense network. This study provides potential physiological indicators, candidate genes, and metabolite markers associated with short-term saline–alkaline stress responses, laying a foundation for further exploration of stress response mechanisms. Full article

Salt stress is one of the main abiotic stresses that restrict crop production. Melatonin (MT), a signal molecule widely present in plants, plays an important role in regulating abiotic stress response. In this study, celery seedlings were used as experimental materials, and the control, salt stress, and exogenous MT treatment groups under salt stress were set up. Through phenotypic, physiological index determination, transcriptome sequencing, and expression analysis, the alleviation effects of MT on salt stress were comprehensively investigated. The results showed that exogenous MT treatment significantly reduced seedling growth inhibition caused by salt stress. Physiological measurements showed that MT significantly reduced malondialdehyde content, increased the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), promoted the accumulation of free proline and soluble protein, and increased photosynthetic parameters such as chlorophyll, ΦPSII, Fv/Fm, and ETR. Transcriptome analysis showed that MT regulates the expression of several genes associated with carbon metabolism, including β-amylase gene (AgBAM), sucrose-degrading enzyme genes (AgSUS, AgINV), and glucose synthesis-related genes (AgAG, AgEGLC, AgBGLU). The results of qRT-PCR verification were highly consistent with the transcriptome sequencing data, revealing that MT synergistically regulates starch and sucrose metabolic pathways, and effectively alleviates the damage of celery seedlings under salt stress at the molecular level. In summary, exogenous MT significantly improved the salt tolerance of celery by enhancing antioxidant capacity, maintaining photosynthetic function, promoting the accumulation of osmotic adjustment substances, and synergistically regulating carbon metabolism-related pathways. The concentration of 200 μM was identified as optimal, based on its most pronounced alleviating effects across the physiological parameters measured. This study provides an important theoretical basis for utilizing MT to enhance plant salt resistance. Full article

Rootstocks play a central role in modulating grapevine responses to water scarcity, yet their morpho-functional strategies remain highly genotype-dependent. This study compared three functionally contrasting rootstocks, 1103 Paulsen, 420 A, and M2, grafted with Vitis vinifera cv. Merlot, which differ in root system architecture, hydraulic efficiency, canopy development, and stomatal regulation, with the aim of elucidating their hydraulic, morphological, and physiological responses under controlled conditions. Plants were grown in containers and assessed for root system architecture, hydraulic conductance, gas exchange including transpiration rate, chlorophyll fluorescence, and biomass allocation. The results revealed three distinct adaptive strategies: 1103 P exhibited the highest structural root biomass and rootstock hydraulic conductivity, supporting elevated axial water transport, higher transpiration rates, and a larger canopy, consistent with an “active tolerance” strategy; 420 A showed balanced structural and absorptive root development, moderate hydraulic performance, and the highest transpiration rates, reflecting a flexible, opportunistic response to water availability. In contrast, M2 displayed markedly reduced structural root biomass but a high proportion of absorptive roots and the greatest scion hydraulic conductance combined with low stomatal conductance, reduced transpiration, and high intrinsic water use efficiency, which is indicative of a conservative, resource-efficient strategy. These findings demonstrate that the three rootstocks express fundamentally different drought response syndromes driven by coordinated variation in root morphology, hydraulic traits, canopy development, and stomatal behavior. The integration of hydraulic and morphological traits provides a robust framework for selecting rootstocks tailored to specific pedoclimatic and management contexts in water-limited environments. Full article

Mangrove forests provide essential climate regulation and coastal protection, yet fine-scale quantification of carbon dynamics remains limited in the Sundarbans due to spatial heterogeneity and tidal influences. This study estimated canopy structural and photosynthetic dynamics from 2019 to 2023 by integrating 10 m spatial high-resolution remote sensing with a light use efficiency (LUE) modeling framework. Leaf Area Index (LAI) was retrieved at 10 m resolution using the PROSAIL radiative transfer model applied to Sentinel-2 data to characterize the canopy structure of the mangrove forest. LUE-based Gross Primary Productivity (GPP) was estimated using Sentinel-2 vegetation and water indices and MODIS fPAR with station observatory temperature data. Annual carbon uptake showed clear interannual variation, ranging from 1881 to 2862 g C m⁻² yr⁻¹ between 2019 and 2023. GPP estimates were strongly correlated with MODIS-GPP (R² = 0.86, p < 0.001), demonstrating the method’s reliability for monitoring mangrove carbon sequestration. LUE-based Solar-induced Chlorophyll Fluorescence (SIF) was derived at 10 m resolution and compared with TROPOMI-SIF observations to assess correspondence (R² = 0.88, p < 0.001) with photosynthetic activity. LAI, GPP and SIF exhibited pronounced seasonal and interannual variability on photosynthetic activity, with higher values during the monsoon growing season and lower values during dry periods. Mean NDVI declined from 2019 to 2023 and modeled annual carbon uptake ranged from approximately 43 to 65 Mt CO₂ eq, with lower sequestration in 2022–2023 associated with climatic stress. Strong correlations among LAI, NDVI, GPP, and SIF indicated consistent coupling between photosynthetic activity and carbon uptake in the mangrove ecosystem. These results provide a fine-scale assessment of mangrove carbon dynamics relevant to conservation and climate-mitigation planning in tropical regions. Full article

Sorghum (Sorghum bicolor L.) is a vital crop for both grain production and forage, playing a critical role in ensuring global food security and sustainable livestock production. Drought stress represents one of the most severe abiotic constraints in sorghum cultivation, adversely affecting plant growth and development, and ultimately leading to significant reductions in yield and quality. Melatonin has emerged as a multifaceted plant growth regulator that enhances plant growth and confers tolerance to various abiotic stresses. It actively participates in regulating key physiological processes, including seed germination, seedling establishment, cellular development, and metabolic homeostasis. This review synthesizes current knowledge on the impacts of drought stress on sorghum growth and physiological metabolism, with a specific focus on the protective role of melatonin under water-deficit conditions. The underlying physiological and molecular mechanisms are comprehensively discussed, encompassing ion homeostasis, nutrient metabolism, reactive oxygen species (ROS) scavenging, photosynthetic efficiency, energy metabolism, phytohormone crosstalk, signal transduction, and associated gene expression. Finally, we outline future research directions to advance our understanding of melatonin-mediated drought tolerance in sorghum, providing insights for breeding drought-resilient varieties and developing high-yielding cultivation strategies. Full article