Search Results (562)

Hydroponic (HP) and aquaponic (AQ) systems are widely known in greenhouse production; however, the combined effects of nutrient delivery system and substrate physical structure on crop performance and root-zone microbiomes remain insufficiently understood. Substrate physical properties influence water retention and aeration, which can affect root-associated microorganisms, plant growth, and yield. This study evaluated cucumber (Cucumis sativus L.) growth, yield, nutrient dynamics, physiological stress responses, and bacterial community composition under HP and AQ systems using bamboo-derived biochar substrates and coconut coir as a control. Vegetative growth was enhanced under AQ, with the greatest plant elongation (1102 ± 40.1 cm) and stem diameter (15.1 ± 1.0 mm) observed in biochar-grown plants. Total yield was consistently higher under AQ than HP, with the highest yield recorded in the coarse biochar treatment (28.6 kg m⁻²). Aquaponic systems were associated with greater nutrient availability under the conditions evaluated during mid to late season production, including nitrate concentrations of up to 226 mg L⁻¹. Physiological stress monitoring indicated lower stress exposure under aquaponic conditions in plants grown in medium and coarse biochar substrates across both systems, with 78 to 81% of the growing season classified within low to balanced stress conditions. Bacterial community composition was primarily shaped by cultivation system, which explained 19.3% of the observed variation, whereas substrate treatment did not significantly alter overall bacterial community structure. Overall, cultivation system was the dominant factor associated with variation in cucumber performance and root-zone bacterial communities, while biochar substrates supported improved plant growth, yield, and reduced physiological stress. Full article

Perfluoroalkyl carboxylic acids (PFCAs) are persistent contaminants increasingly subjected to regulatory restrictions. To date, their effects on terrestrial plants remain poorly investigated. To address these knowledge gaps, a comparative assessment was conducted to identify the most sensitive plant species and the most responsive early-growth endpoints. Five PFCAs were selected according to their carbon-chain length (from 3 to 8 C-atoms). Seven plant species were exposed to a wide range of concentrations (from 0.01 up to 100 µg kg⁻¹). Germination and root elongation were evaluated as developmental endpoints to assess both acute and sublethal effects. Across species, germination exhibited weak responses, whereas root elongation appeared to be the most sensitive screening parameter, displaying divergent species-specific patterns. Notably, Sinapis alba and Cucumis sativus emerged as the most responsive species, although they exhibited opposite responses. While mustard exhibited low-dose root stimulation, cucumber showed root inhibition. Interestingly, species within the same family (Brassicaceae and Cucurbitaceae) showed contrasting sensitivity, suggesting that PFCA phytotoxicity is species-specific rather than driven by taxonomic relatedness. This divergent pattern may be linked to distinct morpho-physiological traits, supporting their use as suitable model organisms for phytotoxicity screening of PFCAs. Full article

Application of microbial biostimulants can reduce the need for applying mineral fertilisers, particularly those with limited availability or high environmental impact, like phosphate fertilisers. A consortium of bacterial strains able of solubilizing phosphorous (P) was applied together with reduced P fertilization (60% of standard dose) carried out with either a complex fertilizer (CF) or simple P fertilizer (SF) and compared to standard fertilization rates. Trials with field grown cucumber plants were carried out for four years. The application of the microbial inoculum with reduced dose of both fertilizers did not negatively impact on plant physiological parameters and on yield. The evaluation of the inoculation impact on soil microbial activity, carried out on plants grown in rhizoboxes, showed that the aforementioned inoculation, combined with reduced doses of both fertilizers, significantly increased microbial activity in the rhizosphere compared to fertilizers applied at full doses without inoculation. The results suggest that the integration of microbial biostimulants to a reduced mineral fertilization is a strategy that can be applied also in the long term, leading to a significant reduction in the use of mineral fertilizers and a positive economic and environmental impact. Full article

The present study explored the dynamic effects of foliar biostimulants on cucumber (Cucumis sativus var. Centauro) accumulated yield curves using a novel statistical approach: Functional Data Analysis (FDA). Four treatments were tested: T1 (control, water), T2 (seaweed extract with N, K, B, Zn), T3 (high Mg, B, Zn), and T4 (T2 + T3). Yield was measured over four harvest cuts. FDA modelled cumulative yield as continuous functions. Functional principal component analysis identified one major mode of variation, revealing an accelerated yield response between the second and third cuts, especially for T4. A functional generalized regression detected significant treatment effects (p = 0.029), which were not detected by a traditional repeated-measures ANOVA (p = 0.074). The results showed that FDA captures subtle, time-dependent growth dynamics missed by conventional methods. The combination treatment (T4) maximized yield via early-phase acceleration, highlighting a synergistic biostimulant effect. FDA provided a superior analytical framework for understanding continuous crop responses to biostimulants. Full article

The increasing need to reduce agrochemicals has intensified the search for sustainable alternatives in crop production. Insect frass, a by-product of insect rearing, has recently emerged as a promising organic fertilizer. In the present study, the effects of Tenebrio molitor frass (TMF) on plant growth and productivity were evaluated in three vegetable crops, cucumber (cv. Aisopos), pepper (cv. Lamuyo), and lettuce (cv. Paris Island), under greenhouse conditions. Experimental plants were grown in pots under two substrate fertility levels (fertilized and non-fertilized peat, hereafter referred to as “rich” and “poor” soil) and received TMF at two rates (1% and 2% w/w), applied either once or twice. Plant height and weight, fruit number and weight, and total production per plant were recorded. TMF application, applied as a soil amendment, enhanced plant growth and yield of the treated plants compared to the control, although the magnitude and consistency of the response varied among crops, soil types, and measured parameters. A clear dose-dependent response was not observed, as the 2% rate did not consistently outperform the 1% rate. Likewise, splitting the same total amount of TMF into two applications did not significantly improve plant performance. The response to the TMF application varied among crops in terms of growth and yield parameters. Lettuce recorded the strongest response, while cucumber and pepper exhibited more moderate improvements. Notably, TMF significantly increased growth and productivity even at the lowest application rates under poor soil conditions. These findings demonstrate that TMF is a promising low-input organic fertilizer under the tested conditions and highlight the importance of optimizing application rate and strategy for sustainable vegetable production. Full article

This study examined the effectiveness of using biochar from the tanning industry as a silicon carrier to reduce trace element toxicity and improve plant nutrition in soil–plant systems. Silicon-enriched biochar was produced from chromium-free leather waste and applied in 21-day pot trials with cucumber. It contained 11.6 ± 2.3% SiO₂ and effectively served as a slow-release silicon carrier. Optimal plant growth and nutrient uptake were achieved with the application of 100% silicon without additional NPK fertilizers, demonstrating a strong positive correlation with essential trace elements such as copper and iron. Importantly, silicon fertilization significantly reduced the uptake of toxic metals such as Al, Cd, and Ti, underscoring the potential of silicon-enriched biochar for phytoremediation and sustainable crop production. Using silicon-enriched biochar from industrial leather waste thus provides a novel, sustainable strategy to improve soil fertility and plant health while repurposing waste. Future work should include long-term field trials and examine species-specific responses and management practices to scale up this approach for enhanced crop resilience. Full article

The toxicity of copper (Cu) severely affects the growth and physiological metabolism of plants. 2-(3,4-Dichlorophenoxy) triethylamine (DCPTA) is a plant growth regulator known to enhance plant tolerance to various abiotic stresses; however, its specific role in mitigating Cu toxicity via cell wall modulation and nitrogen metabolism remains unclear. “Zhongnong 26” (Cucumis sativus L.) seedlings were subjected to a randomized block design with four treatments: control (CK), 0.25 mg/L DCPTA, 50 μM Cu, and 50 μM Cu + 0.25 mg/L DCPTA, with three biological replicates per treatment. The results indicated that DCPTA application significantly alleviated Cu-induced growth inhibition. Specifically, DCPTA improved root system architecture by markedly increasing total root length (68.8%), surface area (68.7%), and the number and length of secondary lateral roots (69.6%, 173.2%). Furthermore, DCPTA enhanced the biosynthesis of cell wall polysaccharides—including pectin (24.3%), hemicellulose 1 (22.4%), hemicellulose 2 (23.7%) and cellulose (33.1%) in roots. Fourier Transform Infrared (FTIR) spectroscopy analysis revealed that DCPTA modified functional groups (e.g., –OH, –COOH) within the cell wall, enhancing their metal-chelating capacity. Consequently, DCPTA promoted the immobilization of Cu in the root cell wall fractions (particularly pectin and HC2) and shifted Cu into less toxic, pectate- and protein-bound forms, thereby reducing its translocation to leaves. Additionally, DCPTA restored the activities of key nitrogen metabolism enzymes in leaves and roots. Compared with Cu treatment alone, nitrate reductase (NR) activity increased by 77.7% and 90.6%, while glutamine synthetase (GS) activity remained stable, and glutamate synthase (GOGAT) activity increased by 10.3% and 71.3% in leaves and roots, respectively. In conclusion, DCPTA enhances copper sequestration in roots by coordinating the regulation of root structure and cell wall strengthening (with an increase in pectin and hemicellulose content). This is crucial for protecting the nitrogen metabolism within the cells (including the enzymes that drive the nitrate–ammonium reduction pathway) to maintain metabolic balance under Cu stress. Full article

The potential of Trichoderma nordicum (Hypocreales, Ascomycota), a recently described species, for antagonism and use in the biocontrol of oomycete-caused plant diseases is unknown. Trichoderma is a well-known genus for containing microbial antagonists and biocontrol agents. The T. nordicum in this study was isolated from decomposing wood, and rpb2 and tef1 barcode sequencing demonstrated that the isolates were a match to the reference T. nordicum and T. nigricans strains. Since T. nordicum was described before T. nigricans, the isolates were assigned to T. nordicum, although taxonomic uncertainty between these species requires future clarification. In dual-culture confrontation assays, T. nordicum overgrew five economically important oomycete plant pathogens (Phytophthora capsici, P. sojae, Pythium aphanidermatum, P. myriotylum, and Globisporangium ultimum). The inability to recover viable P. aphanidermatum and P. capsici from the parts of the plate overgrown by T. nordicum, coupled with protease and endo-cellulase activities, correlates with T. nordicum having antagonistic abilities. Inoculation with T. nordicum preventively reduced the levels of cucumber seedling damping-off caused by P. aphanidermatum by up to 70%. The T. nordicum biocontrol effects against pepper blight caused by P. capsici were greater than 80%, compared to an autoclaved T. nordicum spore control. T. nordicum could also significantly promote the growth of pepper, with plant weight increased by up to 40%, compared to an autoclaved-spore control. In contrast, T. nordicum could not be used to control Pythium soft rot of ginger caused by P. myriotylum, even though P. myriotylum was overgrown by T. nordicum, suggesting host- or pathosystem-specific factors influence biocontrol efficacy. In summary, T. nordicum is a promising biocontrol agent for use in the control of pepper blight caused by P. capsici, and also has potential for use in the control of other oomycete-caused plant diseases in vegetable production systems. Full article

To enhance the benefits and ecological safety of tomato residue retention, this study evaluated the regulatory effects of conventional ambient temperature retention (CR) and solar high-temperature retention (TR) on the initial soil environment and rhizosphere microecology of subsequent crops (continuous tomato and rotational cucumber). The results showed that CR promoted the accumulation of humic acid and increased the contents of phenolic acids and small-molecule organic acids in the soil. TR also increased small-molecule organic acids but primarily enriched fulvic acid, accompanied by higher concentrations of phenolic acids. Regarding microecological responses, CR enriched potential plant-growth-promoting bacteria (Pseudomonas, Sphingomonas, Lysobacter) in the rhizosphere, but it also increased the relative abundance of the potential pathogen Fusarium. In contrast, TR promoted the colonization of heat-tolerant beneficial biocontrol microbes (Bacillus, Chaetomium, Mycothermus), with no Fusarium enrichment observed. Redundancy analysis and Mantel tests revealed that the changes in soil nutrients and organic acid fractions induced by residue retention were correlated with the succession of the rhizosphere microbial community and the reconstruction of the metabolic profile. This study demonstrates that TR can effectively mitigate the risk of pathogen enrichment associated with ambient temperature retention, constructing a potentially disease-suppressive initial microecological environment for subsequent crops. Full article

Powdery mildew (PM) is a major fungal disease in cucumber (Cucumis sativus L.) cultivation. Grafting serves as an important agricultural practice for improving disease resistance and stress tolerance in scions. This study aimed to determine the effects of different pumpkin rootstocks on PM resistance in grafted cucumber plants. Susceptible ‘Xintai Mici’ cucumber scions were grafted onto 10 different pumpkin rootstock varieties, with self-grafted plants serving as the experimental control. Grafting significantly promoted plant biomass accumulation compared to the self-grafted control, and this enhancement was positively correlated with the rootstock’s root system size. However, grafted plant growth was still negatively affected by PM infection. Among the 10 rootstocks, seedlings grafted onto rootstock GP8 exhibited the lowest disease index, the slowest spore development, and the strongest PM resistance. While some resistant pumpkin rootstocks failed to confer significant PM resistance to their grafted cucumber scions, rootstock GP8 provided consistent PM resistance to its grafted plants. Furthermore, cucumber grafted onto rootstock GP8 showed a significantly enhanced net photosynthetic rate and increased antioxidant enzyme activities (superoxide dismutase, ascorbate peroxidase, and glutathione reductase). Concurrently, these plants accumulated lower levels of superoxide anions and exhibited the smallest increases in malondialdehyde content among all the grafted combinations. Additionally, during PM infection, the expression levels of salicylic acid biosynthesis-related genes (CsICS1 and CsPAL) and downstream disease resistance genes (CsPR1, CsPR5, and CsNPR1) were significantly higher in scions grafted onto rootstock GP8 compared to self-grafted cucumbers. These results suggest that the enhanced PM resistance in grafted cucumber is significantly influenced by the rootstock, potentially through the regulation of photosynthetic performance, reactive oxygen species metabolism, and the expression of genes associated with the salicylic acid signaling pathway in the scion. Full article

To elucidate the cooperative regulatory mechanisms underlying Paraburkholderia sp. GD17-mediated salt tolerance in cucumber plants. Hydroponically grown cucumber plants were inoculated with GD17 and subsequently subjected to NaCl treatment. Physiological, biochemical parameters, as well as gene expression profiles, were comprehensively analyzed. GD17 inoculation significantly improved plant growth, developmental performance, and salinity tolerance. Under salt stress, GD17-inoculated plants exhibited higher leaf nutrient contents compared to non-inoculated controls, particularly an elevated K⁺/Na⁺ ratio, which was closely associated with the upregulated expression of Na⁺ extrusion-related genes. A substantial increase in proline content and the corresponding biosynthesis-related gene expression indicated that enhanced osmoprotectant synthesis played a critical role in GD17-conferred salt tolerance. Phytohormone levels and their signaling-related gene expression were also significantly upregulated in GD17-inoculated plants under salt stress. Moreover, transcription factor gene expression was markedly increased in GD17-treated plants following salt exposure. GD17 inoculation alleviated salt-induced photosynthetic inhibition, as demonstrated by improved photosynthetic efficiency and reduced suppression of photosynthesis-related gene expression. Transcriptional profiling further revealed that starch degradation, photorespiration, and the pentose phosphate pathway were crucial for GD17-mediated salt tolerance. Reduced oxidative damage, driven by enhanced antioxidative activity, further contributed to the observed protective mechanisms. This study demonstrates that the application of Paraburkholderia sp. GD17 concurrently enhances cucumber growth and salinity tolerance, effectively resolving the trade-off between growth and defense. Multi-level analyses provided comprehensive mechanistic insights into these synergistic effects. Full article

Prickly cucumber (Echinocystis lobata), originating from eastern North America, exhibits a range of adaptations that enable it to effectively colonize temperate and humid forest environments, among others in Europe. This study examined the allelopathic effects of E. lobata as a factor influencing its competitive interactions with other plant species. Laboratory bioassays were conducted to evaluate the effects of aqueous extracts (2.5%, 5%, and 7.5%) obtained from different organs of E. lobata on the germination of grains or seeds and the early growth of seedlings of Festuca arundinacea Schreb. (monocotyledon) and Raphanus sativus L. var. sativus ‘China Rose’ (dicotyledon). Germination percentage, as well as root and shoot growth parameters, were analyzed. In addition, biochemical analyses of E. lobata organs (leaves, stalks, fruits) used in the experiment were performed. Analysis using a combined chromatographic and mass spectrometric technique identified 21 compounds, including secondary metabolites potentially associated with allelopathic activity. Petri dish assays revealed significant inhibition of the germination of grains and seeds and the growth of seedlings of both tested species, depending on the E. lobata organ and extract concentration. The strongest inhibitory effects were generally observed at concentrations of 5% and 7.5%. In conclusion, the biochemical analyses confirmed the clear primary allelopathic potential of E. lobata, which presumably may enhance its competitive ability. Full article

Greenhouse cultivation enables year-round vegetable production and high yields through precise environmental regulation. Yet, the same stable microclimate that promotes crop growth also favors the proliferation of pests and diseases. This review synthesizes current knowledge on how greenhouse climate variables govern pest and disease epidemiology in tomato, cucumber, and sweet pepper. Only greenhouse-based studies were included to ensure direct relevance to protected horticulture. Microclimatic stability determines infection probability, vector behavior, and host susceptibility. Warm, humid conditions promote fungal and bacterial pathogens, whereas dry, high vapor pressure deficit (VPD) environments favor mites and thrips and enhance virus transmission. Species-specific traits further modulate vulnerability. Tomato is dominated by virus–bacterium complexes and foliar/stem fungal diseases, cucumber by phytopathogenic fungi favored by high relative humidity (RH) and soilborne pathogens, and sweet pepper by virus–vector systems and long-cycle fungal infections. Temperature exerts the strongest influence, while RH and VPD jointly regulate surface moisture and vector activity. Light intensity and spectral composition also affect pest orientation and fungal sporulation. Integrating environmental sensing, biological control, and adaptive climate regulation offers a pathway toward preventive, climate-smart Integrated Pest Management (IPM). The review highlights the emerging role of climate-informed decision-support systems (DSSs) and the need for greenhouse-specific datasets to improve pest and disease forecasting. Full article

Microalgal and cyanobacterial biostimulants are increasingly recognized as sustainable tools for enhancing crop establishment and reducing dependence on synthetic agrochemicals. However, the strain-specific effects of many taxa on seed germination and early seedling development remain insufficiently characterized. This study evaluated the effects of seven microalgal and cyanobacterial suspensions on the germination kinetics and early seedling vigor of cucumber (Cucumis sativus L.). Several strains significantly accelerated germination and enhanced seedling performance relative to the control. Treatment with Coelastrella rubescens BCAC 301 S39, Scotinosphaera lemnae BCAC 113, Vischeria magna UTEX 2351, and Anabaena sp. IT4 significantly reduced mean germination time from 4.50 d to 2.23–2.29 d and advanced the time to 50% germination (T₅₀) from 4.0 to 2.0–2.1 d. These treatments also increased the germination index from 48.32 to 78.17–100.67 and enhanced seedling traits, including root length (32–53%), shoot length (≈29%), leaf length (17–21%), and fresh (30–43%) and dry biomasses (12–22%). Correlation analysis revealed strong positive associations between germination indices and seedling vigor parameters, indicating the faster germination promotes early growth. In conclusion, the results demonstrate that specific microalgal strains can function as effective seed-phase biostimulants, offering a sustainable strategy to enhance germination uniformity, early seedling establishment, and crop productivity. Full article

Root-knot nematodes (Meloidogyne incognita) are among the most destructive pests affecting cucumber production, causing significant reductions in plant growth and yield. This study investigated the efficacy of chitosan-based soil amendments, alone and in combination with hot or cold jojoba (Simmondsia chinensis) leaf extracts and leaf powder, in suppressing nematode infestation and enhancing cucumber vegetative growth under greenhouse conditions. Treatments were evaluated for their impact on nematode reproduction, including egg masses, eggs per egg mass, second-stage juveniles (J2s), female numbers, and gall formation, as well as on plant growth parameters such as height, leaf number, and fresh and dry biomass. Chitosan alone reduced egg masses, eggs per egg mass, and J2s by 43.83%, 56.35%, and 50.63%, respectively, while hot water extract reduced them by 44.10%, 54.18%, and 50.48%. Cold extract was less effective, with reductions of 31.36%, 48.29%, and 40.31%, whereas leaf powder alone caused reductions of 44.20%, 54.60%, and 45.00%. Combined applications exhibited higher efficacy: hot extract + chitosan reduced egg masses, eggs per egg mass, and J2s by 61.64%, 59.45%, and 55.57%, leaf powder + chitosan by 64.38%, 60.70%, and 60.71%, and the triple treatment (leaf powder + chitosan + hot extract) achieved the highest suppression, reducing egg masses, eggs per egg mass, and J2s by 75.90%, 74.66%, and 69.22%, respectively. All treatments significantly enhanced cucumber growth compared with the naturally infested control. The triple treatment increased plant height by 38.5%, leaf number by 42.1%, fresh shoot biomass by 46.3%, and dry shoot biomass by 44.8%. Single treatments also improved growth, though to a lesser extent, reflecting a synergistic effect of chitosan and jojoba-derived amendments. These findings demonstrate that integrating biopolymer-based amendments with plant-derived bioactive compounds can simultaneously suppress root-knot nematode populations and promote cucumber growth. This study provides a solid basis for developing sustainable and eco-friendly integrated pest management strategies that reduce reliance on chemical nematicides. Full article