Search Results (1,802)

The removal of nitrogen and phosphorus from wastewater with low organic carbon content requires the addition of an external carbon source. The objective of this study was to assess the influence of hydraulic retention time (HRT) on the efficiency of external carbon source utilization and on nitrogen and phosphorus removal in a Rotating Electro-Biological Disc Contactor (REBDC). The energy demand was evaluated based on energy consumption (E) and current efficiency (CE). Hydroponic tomato wastewater was treated in the REBDC at a constant current density of 2.5 A/m². Sodium acetate was used as the carbon source. Two C/N ratios were tested, 2.0 and 3.0, under HRT conditions of 24 h and 48 h. For both C/N ratios, extending the HRT resulted in decreased nitrogen removal efficiency. At HRT = 48 h and C/N = 3.0, the nitrogen concentration in the effluent was more than three times lower compared with C/N = 2.0. The highest phosphorus removal efficiency was achieved at C/N = 3.0 and HRT = 48 h (98.8%). Increasing the HRT led to reduced TOC utilization for both C/N ratios. As a consequence of extended HRT, lower CE values and higher E values were observed, indicating increased energy demand for nutrient removal. Full article

Hypersaline waters contaminated with crude oil represent a major obstacle for phytoremediation, as few plant species tolerate both high salinity and hydrocarbon toxicity. In this study, the halophyte Halocnemum strobilaceum (Pallas) M. Bieb. was grown hydroponically in hypersaline solutions (50 and 80 g L⁻¹ NaCl) containing crude oil (600 mg L⁻¹). The plant was inoculated with endophytic bacteria isolated in a previous step from its root and selected for salt tolerance and hydrocarbon-degrading potential. The plant behaviour was assessed through growth and photosynthetic performance, while the degradation of hydrocarbons (C < 12 and C > 12) was monitored over time. At 50 g L⁻¹ NaCl, crude oil reduced the plant growth by 60%, but inoculation with endophytic bacteria mitigated this decline, demonstrating their positive influence under combined salt and hydrocarbon stress. At 80 g L⁻¹ NaCl, neither plant biomass nor chlorophyll fluorescence was significantly affected by crude oil, with or without bacterial inoculation, consistent with the strong intrinsic salt tolerance of H. strobilaceum, which likely buffered additional stress inputs. Metagenomic analyses revealed distinct root-associated microbial communities under different treatments, suggesting synergistic plant–microbe interactions that enhanced photosynthetic efficiency and metabolic stability. The presence of endophytes accelerated the degradation of aliphatic hydrocarbons (C10–C40) at both salinity levels. These findings highlight the potential of endophytic bacteria to enhance resilience in H. strobilaceum and its phytoremediation capacity, offering a promising nature-based approach for the sustainable treatment of highly saline, crude oil-contaminated industrial waters. Full article

Clonal propagation of rust-resistant sugar pine (Pinus lambertiana Dougl.) is currently limited by extreme rooting recalcitrance and highly variable donor responses to nursery management. This study identified seed zone-specific nutritional sensitivities and evaluated rooting success; we hypothesized that northern seed sources would exhibit greater sensitivity to high nutrient loads and that stable microclimates would outperform high-intensity rooting systems. In Study 1, seedlings from five United States Department of Agriculture seed zones were grown for 27 weeks in five nutrient solutions (tap-water control, modified Hoagland, Foliage-Pro^®, Andrejow, and FloraNova^®) spanning 0.72–3.00 dS m⁻¹. The nutrient-rich Foliage-Pro^® and FloraNova^® solutions defined the upper end of the nutrient-intensity range and revealed strong seed zone contrasts: northern zones (526, 550) showed marked sensitivity, with survival declining from 70 to 100% in the control to 15–40% under the highest-EC formulations, whereas southern zones (992, 993) maintained high survival (≥75%) across all treatments and exhibited increased branching (up to 3.7 branches plant⁻¹) under higher-nutrient solutions. In Study 2, stem cuttings were rooted in three environments (non-mist, hydroponic, and aeroponic) and four hormone treatments (control, Clonex^®, Dip’n Grow^®, and IBA + Ethrel). Rooting occurred exclusively in the non-mist propagator; untreated controls achieved 65% success and outperformed all hormone treatments (0–10%). These results demonstrate that P. lambertiana propagation depends on seed zone-specific donor nutrition and stable, hormone-independent rooting environments. Full article

Tobacco (Nicotiana tabacum L.) is an economically important crop in China. The risk of cadmium (Cd) pollution is increasing, making the mitigation of Cd stress critical for the safe production of tobacco. Silicon (Si) has been demonstrated to enhance plant growth under heavy metal stress. To elucidate the physiological and biochemical mechanisms by which Si alleviates Cd stress in tobacco, this study conducted a hydroponic experiment with three replicates using tobacco variety Yunyan 87 and employed one-way analysis of variance (ANOVA) for statistical analysis. The effects of Si on tobacco growth and the antioxidant defense system under Cd stress were investigated. The results showed that Cd stress significantly inhibited tobacco growth, increased Cd accumulation, and induced oxidative damage. Si treatment alleviated Cd stress in tobacco, increased biomass, reduced Cd concentration in different plant organs, and decreased the Cd translocation factor and bioconcentration factor. Meanwhile, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in tobacco roots and leaves were significantly enhanced, while the activities of ascorbate peroxidase (APX) and glutathione reductase (GR) were also elevated. The accumulation of ascorbic acid (AsA) and glutathione (GSH) increased, and malondialdehyde (MDA) concentration decreased. Overall, these results demonstrate that Si mitigates Cd stress in tobacco by limiting Cd accumulation and transport and by coordinately activating both enzymatic and non-enzymatic antioxidant systems. Full article

Selenium nanoparticles (SeNPs) synthesized through green routes have emerged as promising nanobiostimulants in sustainable agriculture due to their ability to enhance plant growth and antioxidant defense. The aim of this study was to evaluate the biostimulant effect of SeNPs on Capsicum annuum at two stages of crop development to characterize the response to SeNP exposure and identify concentration-dependent effects and application methods. Physiological indicators, including growth, photosynthetic pigment content, and antioxidant activity, were evaluated. Different concentrations of SeNPs were tested during germination, and dosage and two types of application were compared during the vegetative phase in a hydroponic experiment. SeNPs at concentrations of 1.25, 2.5, 5, 10, 20, 40, and 80 µM were applied to chili seeds for 20 days. The plants were exposed to SeNPs concentrations ranging from 1.25 to 80 µM, applied through the roots and leaves. Germination parameters were not significantly affected except for the seed vigor index, which increased at all concentrations, particularly at 20 µM. Low to moderate doses (1.25–20 µM) acted as biostimulants, enhancing plant height, root length, biomass accumulation, photosynthetic pigment content, and phenolic and flavonoid compound synthesis. Conversely, high doses (80 µM) induced phytotoxic effects, especially via root exposure, reflected by growth inhibition, and reduced chlorophyll content. Foliar application demonstrated a systemic biostimulant response, improving root growth and photosynthetic activity without toxicity symptoms. Antioxidant assays (DPPH and ABTS) revealed dose-dependent modulation of redox balance, suggesting adaptive responses to SeNP-induced oxidative conditions. These findings highlight the potential of SeNPs as biostimulants that improve physiological performance in chili plants, while emphasizing the importance of an optimal dosing and application method for sustainable nanotechnology-based crop management. Full article

Aquaponics (AP) is the combination of aquaculture and hydroponic systems, developed based on waste to wealth theory. This study compared the plant growth and overall productivity of an aquaponic system (AP) with a controlled hydroponic system (HP) to assess the AP system’s performance and identification of the performance-limiting factors. This comparative study spanned over a 35-day period, supported by batch tests for the nutrient accumulation rate in plants and the NH₄⁺-N excretion rate by fish as a baseline for the system design. HP performed better in terms of plant growth, showing a mean plant fresh weight (g) of 165.6 ± 3.01 while AP showed 147.0 ± 4.6. Nutrient accumulation was better in HP for K and P; however, Ca²⁺, Mg²⁺, and Fe accumulation was higher in AP plants. The AP system supported a better fish growth of 31.95 ± 3.21% (FCR 1.29 ± 0.1, SGR 0.79 ± 0.06, and PER 2.24 ± 0.18) and a moderate plant biomass production. Further system design modifications and integrations are required to optimize the nutrient availability and sustainability of the AP systems. Full article

The increasing demand for sustainable food production has intensified interest in controlled-environment agriculture and soilless cultivation systems. This study evaluated the performance of local chicory (Cichorium intybus L., cultivar “Otrantina”) grown for 45 days in soil, hydroponics, and decoupled aquaponics under two different environments: a fully controlled growth chamber and a naturally variable greenhouse. Morphological, anatomical, biochemical, and physiological traits were analyzed to assess the combined influence of growth environment and cultivation system on plant development and nutritional quality. Across all parameters, the growth environment emerged as the main driver of plant performance. Greenhouse-grown plants exhibited greater leaf expansion, enhanced mesophyll and vascular development, and higher fresh and dry biomass than those cultivated in the growth chamber. Within each environment, hydroponics consistently supported vigorous growth, whereas aquaponics produced smaller leaves and pronounced root elongation, likely reflecting nutrient and pH instability in the decoupled system. Biochemical analyses revealed system-specific adaptive responses. Soilless cultivation promoted higher lipid accumulation and, under growth chamber conditions, increased protein content. Aquaponically grown plants, particularly in the greenhouse, accumulated elevated levels of soluble sugars and phenolic antioxidants, consistent with stress-related metabolic activation. In contrast, soil-grown plants displayed the highest flavonoid concentrations, suggesting a prominent role of rhizosphere–microbiome interactions in modulating secondary metabolism. Overall, these results indicate that, under the tested conditions, environmental control exerts a stronger influence than cultivation systems on chicory growth and metabolism. Hydroponics proved to be the most efficient system for biomass production, whereas aquaponics requires improved nutrient management to ensure stable growth and quality. The distinct metabolic profiles associated with each cultivation system highlight opportunities to tailor chicory nutraceutical traits within sustainable controlled-environment agriculture. Full article

Brackish aquaponics is expected to be a promising approach to sustainable food production, integrating saline water resources with simultaneous co-cultivation of fish and halophytes. The present study investigated the effects of three feeding ratios (FR1.5: 1.5%, FR3: 3%, and FR6: 6% b.w/d) on the growth performance of European sea bass (Dicentrarchus labrax) and glasswort (Salicornia europaea) co-cultured in three autonomous one-loop recirculation aquaponic systems (180 L each) at 20 ppt salinity over 78 days. Each system comprised three fish-rearing tanks connected to a two-stage sump filter and a nutrient film technique (NFT) hydroponic subsystem. Sea bass fed at FR3 achieved significantly higher weight gain, specific growth rate, and feed conversion efficiency than FR1.5. At FR6, feed consumption nearly doubled compared to FR3 (3.79 vs. 1.91 g), yet the feed conversion ratio increased from 0.79 to 1.65, and protein efficiency ratio declined from 3.80 to 1.91, indicating overfeeding effects. Regarding glasswort, FR6 produced significantly higher chlorophyll a content and plant biomass, whereas FR1.5 showed superior ammonia removal efficiency. Overall, FR3 provided the best balance between fish growth, plant yield, and water quality maintenance. These findings highlight the critical role of feeding management in brackish aquaponics in order to optimize nutrient coupling between fish and halophyte production. Full article

Controlled Environment Agriculture (CEA) has become a key driver of vertical farming (VF), offering innovative solutions for the sustainable production of ornamental plants in urban environments with limited arable land. This review examines recent advances in VF technologies and their applications in foliage and flowering ornamental plant production. The literature indicates that precise environmental control, including optimized LED lighting spectra, hydroponic and aeroponic nutrient delivery, and automated climate regulation, can significantly enhance plant growth, morphological characteristics, color intensity, and overall market quality of ornamental species. In addition, VF systems demonstrate substantial reductions in water consumption, pesticide use, and land requirements compared with conventional cultivation methods. However, several challenges remain, including high-energy demand, economic feasibility, and the need for crop-specific environmental optimization for different ornamental species. This review synthesizes current research on VF systems, highlights the integration of emerging technologies such as the Internet of Things (IoT), artificial intelligence (AI), and data-driven management tools, and evaluates their potential to improve production efficiency and sustainability in ornamental horticulture. Overall, vertical farming represents a promising approach for high-quality ornamental plant production, although further research is required to optimize energy efficiency and cultivation protocols for diverse ornamental crops. Full article

This study evaluated the effects of various LED spectra—white (W), red and blue (RB), W plus far-red (FR), and RB plus FR—on the growth, fruit quality, and phytochemical accumulation of greenhouse-grown hydroponic watermelon. Watermelons were cultivated with controlled temperature and humidity and subjected to four LED treatments at an equivalent PPFD of 200 ± 3 µmol·m⁻²·s⁻¹ and a 15 h light period for 43 days, with sunlight as a control. The photosynthetic rate and stomatal conductance were significantly higher in the RB LEDs than in all other treatments. Fv/Fm and PIABS exhibited time-dependent differences among treatments after 13:00, with all LED treatments showing higher values than the control, except for the Fv/Fm of RB LEDs. SPAD, chlorophyll, and carotenoid contents were the highest in the RB LEDs, and 40%, 30%, and 19% higher than those in the control group, respectively. Growth characteristics, such as plant height and node and leaf number, were highest in the control group and were significantly higher than the RB LEDs. Petiole length tended to increase in LEDs treated with FR. Sweetness was the highest in W LEDs. Therefore, supplemental LED lighting can potentially improve the production and fruit quality of greenhouse watermelons. Full article

Light quality is a crucial factor influencing plant growth and physiological quality in controlled-environment agriculture (CEA). This study examined how different LED light spectra affect the growth and internal quality of Ligularia stenocephala cultivated in a plant factory. The plants were grown under five types of LED light: monochromatic red, monochromatic blue, a combination of blue and red, white LEDs, and quantum dot (QD) LEDs. We evaluated various growth parameters, biomass accumulation, chlorophyll indices, and antioxidant capacity. Monochromatic red LEDs promoted rapid early growth and stem elongation but led to lower chlorophyll accumulation and antioxidant capacity. In contrast, monochromatic blue LEDs increased chlorophyll content, leaf thickness, dry matter accumulation, and antioxidant capacity, although they limited leaf expansion and shoot biomass. Composite-spectrum LEDs displayed distinct trade-offs between growth and quality parameters. QD LEDs maximized shoot biomass accumulation while maintaining moderate internal quality, whereas Blue+Red LEDs provided a balanced combination of significant biomass and enhanced phytochemical content. Principal component analysis indicated a fundamental trade-off between quality-related (PC1: 57.6%) and growth-related (PC2: 22.7%) parameters, showing that no single LED spectrum could optimize all cultivation factors simultaneously. Therefore, LED selection should align strategically with specific cultivation goals: use QD LEDs for volume-based production, Blue+Red LEDs for balanced premium markets, and blue LEDs for specialty functional vegetables. These findings underscore the importance of context-dependent lighting optimization strategies in plant factory systems and offer a framework for selecting the most effective LED spectra to enhance crop performance in CEA. Full article

Sustainable agricultural techniques can ensure food security around the world. Hydrogel based soilless culture is an ecological and efficient alternative compared to conventional agriculture. Here, a multi-component hydrogel (pectin, Kelcogel, and chitosan/Se hydrogel, PKCH) was prepared by synthesizing natural biomolecules to cultivate dandelion for stimulate dandelion growth and improve nutritional value. The germination percentage of dandelion on PKCH (88.89%), was significantly higher than that in traditional hydroponics and pure Kelcogel (p < 0.05). Compared with hydroponics, the long-term dandelion cultivation experiments demonstrated that the PKCH cultivation mode enhanced root vitality, further increasing the growth and yield of dandelions (shoot length: 18.36 ± 0.30 cm, root length: 9.28 ± 0.21 cm, main root diameter: 0.94 ± 0.02 cm). The hydrogel substrate was associated with improved nutrient solubilization and sustained release, which may be linked to the accumulation of low-molecular-weight organic acids in the rhizosphere. Exogenous Se was effectively assimilated and transported to the above-ground parts of dandelion, which stimulated the photosynthetic efficiency and nutritional accumulation of dandelion. The polysaccharide content of dandelion reached 69.40 ± 0.13% (expressed as glucose-equivalent total sugars), which demonstrated the potential antioxidant properties and medicinal value. Technical economic analysis revealed the cost-effectiveness of PKCH synthesis and application. This study enriches the application of hydrogels in dandelion cultivation and provides an alternative approach for cultivating dandelion in soilless environments and medicinal crop production techniques. Full article

This study presents an Internet of Things (IoT)-assisted semi-open hydroponic system for cultivating Andrographis paniculata under tropical conditions, aiming to enhance biomass productivity, andrographolide (AG) yield, and production efficiency. IoT-assisted hydroponics, non-IoT hydroponics, and soil-based cultivation were compared in 10 m² greenhouses. The IoT system enabled real-time monitoring and adaptive regulation of temperature, relative humidity, light intensity, nutrient solution pH, and electrical conductivity (EC). IoT-assisted hydroponics achieved earlier harvest (≈90 days) and the highest fresh biomass yield (0.409 ± 0.014 kg m⁻²) while maintaining per-plant productivity (15.74 ± 0.54 g plant⁻¹) comparable to soil-based cultivation. Andrographolide concentration reached 25.58 ± 3.36 mg g⁻¹ DW (2.56% w/w), meeting pharmacopeial requirements. Owing to stable environmental regulation and tolerance to high planting density, the IoT system produced the highest areal AG productivity (209.5 mg m⁻²), representing a four- to tenfold increase over the other systems. Despite higher operational costs, IoT-assisted hydroponics achieved the lowest AG unit cost (≈6.77 USD g⁻¹). While most previous studies emphasize tissue-level AG concentration, system-level productivity and cost efficiency under realistic cultivation conditions remain insufficiently explored. Overall, IoT-enabled semi-open hydroponics provides a scalable and economically viable approach for medicinal plant production, bridging the gap between open-field cultivation and fully controlled plant factory systems. Full article

Silicon (Si) serves as a beneficial element that enhances plant resistance to both abiotic and biotic stresses. Although its positive effects have been widely investigated, the molecular mechanisms by which silicon improves stress tolerance in rice (Oryza sativa L.) remain unclear. Here, we show that Si displayed an optimal improved effect at concentrations of 2–4 mM in hydroponic system, and Si enhanced rice tolerance to drought and blast disease by maintaining reactive oxygen species (ROS) homeostasis and reducing root cell damage. In addition, Si at 4 mM upregulated the ABA biosynthesis gene OsNCED3, stress- and ABA-responsive genes OsDREB2A and OsLEA5, as well as the catalase gene OsCatB, while suppressing the drought-responsive negative regulator OsWRKY5, thereby enhancing drought tolerance through an ABA-dependent signaling pathway. Si at 4 mM enhanced resistance to rice blast by activating defense-related genes OsPBZ1, OsPR10a, OsPR5 and OsWRKY45 while simultaneously boosting ROS-scavenging capacity. Collectively, our results demonstrate that Si enhances rice tolerance to drought and blast disease through the coordinated modulation of ABA signaling, ROS homeostasis, and stress-related gene expression. Full article

Light quality is a critical regulatory factor for the growth and nutritional quality of hydroponic lettuce (Lactuca sativa L.), and red–blue combined light serves as a key artificial light source for protected horticulture. This study aimed to investigate the effects of different red–blue (R:B) light ratios on the growth, photosynthetic pigment content, nutritional quality, antioxidant capacity, and mineral nutrient content and accumulation of hydroponic lettuce. Lettuce was cultivated under four R:B light treatments (CK: pure red light, 100:0; T1: 90:10; T2: 80:20; and T3: 60:40) with a uniform photosynthetic photon flux density of 350 µmol m⁻²s⁻¹ and a 12 h photoperiod. The results showed that all red–blue combined light treatments significantly improved the above physiological and nutritional indices compared with monochromatic red light (CK), with the fresh weight increased by 0.73 to 0.78 times and different R:B ratios inducing distinct tissue-specific and element-specific responses in lettuce. Specifically, T3 (60:40) exhibited the highest root dry weight (0.57 ± 0.02 g plant⁻¹), inhibited excessive leaf elongation to form a compact plant architecture, and its chlorophyll a and b contents increased significantly by 1.6 and 2.25 times compared with CK, respectively. Furthermore, T3 markedly enhanced the accumulation of soluble sugar (0.36 times higher), soluble protein (1.16 times higher), and vitamin C (4.09 times higher), reduced the nitrate content to 0.58 times that of CK, and showed the highest antioxidant capacity (polyphenol content and DPPH free radical scavenging rate), with antioxidant traits positively correlated with the blue light proportion. In contrast, T2 (80:20) effectively promoted plant biomass accumulation and exhibited the most balanced mineral nutrient profile, with significant increases in nitrogen, calcium, and magnesium accumulation, and it also upregulated chlorophyll synthesis to enhance carbon assimilation. T1 (90:10) had moderate regulatory effects on both lettuce growth and nutritional quality and was favorable for potassium accumulation in lettuce tissues. These findings clarify the differential regulatory mechanisms of red–blue light ratios on hydroponic lettuce and provide a theoretical basis for the precise configuration of LED lighting in greenhouse lettuce production. Lettuce producers can select specific R:B ratios according to actual cultivation demands, and the regulatory effects of such light ratios on red leaf lettuce varieties merit further exploration. Full article