Search Results (258)

Large-scale wireless sensor networks with electric field energy harvesters (EFEHs) offer self-powered, eco-friendly, and scalable crop monitoring in hydroponic greenhouses. However, their practical adoption is limited by the low power density of current EFEHs, which restricts the reliable operation of external sensors. To address this challenge, this work presents a noninvasive EFEH assembled with hydroponic leafy vegetables that harvests electric field energy and estimates plant functional traits directly from the electrical response. The device operates through electrostatic induction produced by an external alternating electric field, which induces surface charge redistribution on the leaf. These charges are conducted through an external load, generating an AC voltage whose amplitude depends on the dielectric properties of the leaf. A low-voltage prototype was designed, built, and evaluated under controlled electric field conditions. Two representative species, Beta vulgaris (chard) and Lactuca sativa (lettuce), were electrically characterized by measuring the open-circuit voltage (VOC) and short-circuit current (ISC) of EFEHs. Three regression models were developed to determine the relationship between foliar moisture content (FMC) and fresh mass with electrical parameters. Empirical results disclose that the plant functional traits are critical predictors of the electrical output of EFEHs, achieving coefficients of determination of $R^2=0.697$ and $R^2=0.794$ for each species, respectively. These findings demonstrate that EFEHs can serve as self-powered, noninvasive indicators of plant physiological state in living leafy vegetable crops. Full article

Enhancing bioactive compounds with antioxidant activities has always been a pursuit of growers in the hydroponic production of lettuce in greenhouses with artificial lighting. Light-Emitting Diode (LED) lighting represents an effective lighting strategy that promotes the accumulation of bioactive compounds in lettuce by reducing dark periods under unfavorable meteorological conditions and extending the photosynthetic duration. In this study, the accumulation of bioactive compounds and their antioxidant activities, using lettuce-adapted growth technologies such as elevated oxygen concentration and elevated oxygen combined with LED red-blue light, were investigated. These technologies were compared to the control, which consisted of the natural oxygen concentration, in a controlled hydroponic system, for the two lettuce cultivars, Carmesi and Lugano. Our results demonstrate that lettuce grown under elevated oxygen combined with LED lighting exhibited increases of up to 48% in total phenolic content and up to 87% in total flavonoid content, depending on cultivar and growing season, compared to control growth technology. The highest antioxidant capacity was recorded under the EOC+LED growth technology, as confirmed by DPPH, FRAP, and CUPRAC assays. This study proposes an effective growth strategy for hydroponic lettuce cultivation that enhances bioactive compound accumulation and provides theoretical and technical guidance for energy-efficient greenhouse production. Full article

Hydrogen water, characterized by a high concentration of unionized hydrogen molecules, is being presented as a new alternative in agriculture. This study focused on the application of hydrogen water to leaves and its effects on crop yield and quality, especially on leaf lettuce, through foliar fertilization (twice a week at 25 L per 330 m²) experiments with hydrogen water with dissolved hydrogen of more than 300 ppb and control water with dissolved hydrogen close to 0 ppb. The experimental group that received foliar fertilization showed significant advantages over the control group in leaf thickness and stem thickness characteristics that affected post-harvest distribution quality. Area growth rate analysis revealed a consistently higher average area growth rate (up to 0.86%) in the group treated with hydrogen water compared to the control group (0.1%). The results of an independent-sample t-test of spectral indices showed that the experimental group showed a significance level above the critical value (p < 0.05) compared to the control group in the analysis results of NDVI in soil cultivation and NDRE in hydroponic cultivation. Although other spectral indices did not show differences between the experimental and control groups at the significance level, the average of all samples was higher in the experimental group than in the control group. Overall, the findings suggest that foliar application of hydrogen water positively influences the growth of lettuce crops, as evidenced by comprehensive trait, area growth rate, and spectral index analyses. These results underscore the novelty of hydrogen water as an efficient foliar treatment that enhances crop performance with minimal system changes. Its potential to improve yield quality while reducing chemical input demands suggests clear economic and environmental benefits. Full article

The agricultural sector faces significant challenges related to climate change and population growth, which intensify pressure on natural resources and food security. Sustainable resource-efficient systems, alongside wastewater valorisation, are a promising solution. This study evaluated the reuse potential of aquaculture, urban, and swine farm wastewater in hydroponic cultivation. Trials with leafy vegetables and fruit crops were conducted in aquaponic systems containing two fish species (Koi carp and African catfish) and two small-scale hydroponic systems. Water quality, plant development, and environmental parameters were monitored. Results for the best performance scenarios within each cultivation system showed that in urban wastewater, strawberries yielded 183 ± 74 g/plant, exceeding yields in aquaponics (125 ± 60 g/plant). Lettuce performed better in swine farm wastewater (180 ± 39 g/plant) than in urban (65 ± 6 g/plant), with corresponding water-use efficiencies of 117 and 65 g/L. Aquaponics also supported stable yields, up to 108 ± 1 g/plant for lamb’s lettuce and 10,047 ± 8791 g of papaya fruit per plant. Nutrient recovery in hydroponic systems supplied with urban and swine farm wastewater reached up to 95% for N, P, and K. Overall, these systems demonstrated substantially lower water consumption compared with values commonly reported for conventional agriculture, underscoring their strong sustainability advantages. Full article

High-air temperature stress inhibits the growth of hydroponic lettuce. The practical application of conventional air cooling is constrained by high cost and moderate efficacy. However, root-zone cooling represents a more promising temperature regulation strategy for vegetable production, offering advantages such as ease of integration and lower cost. This study used lettuce (Spanish Green) as the plant material under four RZT treatments: T0 (control: 24.65~31.65 °C), T1 (24.5 °C), T2 (20.5 °C), and T3 (16.5 °C). Growth parameters and nutritional quality indicators under each treatment were systematically monitored, and a comprehensive evaluation was performed using the fuzzy membership function method. All cooling treatments (T1–T3) enhanced lettuce plant height, leaf area, and shoot dry weight. According to the fuzzy membership function analysis, the T1 treatment was found to exhibit the highest overall nutritional value. Although the T0 control group displayed the poorest growth performance, with a shoot dry weight 47.24% lower than that of T1, it accumulated significantly higher levels of P, Ca, and Zn. These findings demonstrate that regulating RZT to approximately 24.5 °C synergistically enhances both biomass and quality in lettuce, providing theoretical and practical support for optimizing hydroponic production in summer conditions. Full article

Root pruning has been proposed as a practical method to regulate growth and metabolite accumulation in horticultural crops, yet its physiological and metabolic consequences in hydroponically grown lettuce remain poorly understood. In this study, we examined the effects of root pruning, applied two days before harvest, on biomass production, oxidative stress responses, and metabolite accumulation in red leaf lettuce. Root pruning suppressed root growth and reduced root water content in a severity-dependent manner. Shoot fresh weight also declined, whereas shoot dry weight was significantly reduced only under severe pruning. Young leaves of pruned plants exhibited transient reddish coloration, which was most pronounced under severe pruning. Quantitative analyses revealed that anthocyanin content increased up to 4.5-fold compared with the control, while total phenolic content also rose significantly. These metabolic changes were accompanied by pronounced oxidative stress, as indicated by elevated hydrogen peroxide accumulation and enhanced lipid peroxidation. In addition, leaf nitrate concentration decreased significantly in both moderate and severe pruning treatments. Collectively, these findings demonstrate that root pruning acts as a controllable stressor that triggers oxidative stress signaling, enhances antioxidant metabolite accumulation, and reduces nitrate content, highlighting its potential as a pre-harvest strategy for improving the nutritional and functional quality of hydroponic lettuce. Full article

Lettuce (Lactuca sativa), pak choi (Brassica rapa), and basil (Ocimum basilicum) were grown in hydroponic NFT systems under four nitrate levels (80–180 mg L⁻¹ N). We measured natural microbial contamination by plating nutrient-solution samples and leaf washes to obtain colony-forming unit (CFU) counts of bacteria and fungi. Separately, postharvest leaves were artificially inoculated with Botrytis cinerea and stored at 22 °C or 4 °C for 7 days to assess gray mold. In lettuce, high N (180 mg L⁻¹) markedly increased culturable microbial loads in both solution and leaves, whereas pak choi microbial counts remained low at all N levels. Basil showed a non-linear response: CFU counts peaked at moderate N (120 mg L⁻¹) and were lower at both deficit and excess N. At 22 °C, gray mold severity in pak choi increased with N; leaves fertilized at N150–180 suffered about 1.5–2 times greater lesion area than those at N80. By contrast, lettuce exhibited the worst decay under N deficiency: N80 leaves developed the largest lesions by 4–7 DPI, while moderate N (120–150 mg L⁻¹) minimized disease progression. Basil was highly susceptible under warm storage: all N levels reached near-total decay by 7 days, though N120 delayed early infection slightly. Refrigeration (4 °C) greatly suppressed lesion development in lettuce and pak choi, although high-N pak choi still showed ~20–30% more infected area than low-N after 7 days. Basil, however, suffered chilling injury at 4 °C, and all refrigerated basil leaves decayed severely (regardless of N). These results indicate crop-specific nutrient and storage strategies: avoid excessive N in pak choi, maintain balanced N in lettuce, and handle basil with non-chilling methods to reduce postharvest gray mold. Full article

Graphene oxide (GO) was prepared by a waterless synthesis route to generate GO sheets, which were then applied to coat calcined oyster shell with fertilizer (OSF) pellets, resulting in the creation of an OSF-GO particle. The GO sheets (ID/IG = 0.86) were characterized by Raman spectroscopy, which showed that the GO-coated OSF pellet features a compact coating approximately 13.68 μm thick. SEM and AFM analyses revealed that the GO sheets displayed a monolayer configuration with a crinkled topography (about 0.91 nm). The EDS analysis confirmed that the core was primarily composed of Ca, K, P, O, N, and C elements. The hydroponic experiment results showed that a GO concentration of 80 mg/L significantly enhanced plant height, stem thickness, and root length in loose-leaf lettuce, while higher concentrations induced oxidative stress. In pot experiments, the OSF-GO composite effectively raised the soil pH from 5.38 to 6.41 and improved nutrient availability. OSF-GO composite functions effectively as both a soil conditioner and slow-release fertilizer (SRF), simultaneously remediating degraded soils and optimizing nutrient delivery. Full article

The fungal genus Trichoderma is highly valued in agriculture for its versatile roles, mainly as a biocontrol agent against plant pathogens. Recently, its use as a natural biofertilizer has gained attention, as Trichoderma spp. promotes crop growth and improves yield by enhancing the rhizosphere environment and activating plant defences. Globally, over 250 Trichoderma-based products dominate 60–90% of the market, but their efficacy can decline during transportation and storage. Additionally, concerns about their impact on native soil biodiversity have led to interest in using locally adapted, native strains. The novel native strain of Trichoderma sp. STP8 (formerly T. koningiopsis agg. STP8) previously showed strong antagonism against Sclerotinia sclerotiorum and promoted lettuce growth in greenhouse conditions. This study evaluated Trichoderma sp. STP8’s effectiveness in field-grown lettuce, revealing yield increases of 16.6% to 30.5%. The most significant gains occurred when Trichoderma sp. STP8 was applied before head formation, 26 days after planting. That was in one treatment with two applications (at seedling planting and after 26 days) and another with three applications (at sowing, at seedling planting, and after 26 days). These results demonstrate Trichoderma sp. STP8’s potential as a sustainable biocontrol and biofertilizer agent for lettuce, encouraging further research across different agricultural systems, including hydroponics and soil-less medium. Full article

Data-driven empirical models, including those based on reaction kinetics, are well-regarded for their ability to make accurate predictions and uncover underlying relationships. While such models have been extensively employed for microbial communities, their use in agricultural populations remains comparatively limited. In this study, researchers analyzed data from hydroponic lettuce cultivation experiments observing nitrogen-, phosphorus-, and potassium-limited growth. Dynamic μ models, which incorporated nutrient-fueled growth and maturity-based rate decay, were adapted to accommodate a variable nutrient supply, as would be expected for nutrient recovery efforts using domestic wastewater. To test these models, researchers analyzed multiple approaches, differing variations in analyses, and other agricultural models against observed biomass measurements. The resulting Dynamic μ biomass models showed significantly less error than all other tested models, were validated against three variable nutrient treatments, and were evaluated against expected wastewater concentrations. Wastewater-cultivated lettuce was predicted to grow between 20 and 72% of fresh mass compared to lettuce grown under ideal nutrient concentrations, and models identified 41.7 days to maximize dry biomass, with a final harvest time of 44.0 days to maximize fresh biomass. Finally, this research demonstrates the application of agricultural modeling for profit estimation and informing decisions on supplemental nutrient use, providing guidance for nutrient recovery from wastewater. Full article

Maintaining optimal pH in hydroponic systems typically requires continuous pH adjustment, increasing both labor and production costs. In regions with alkaline water sources, this challenge is especially critical. Identifying lettuce cultivars tolerant to high pH conditions offers a cost-effective and sustainable alternative to frequent pH buffering. This study evaluated the impact of water pH on growth, water use efficiency (WUE), and nutrient use efficiency (NUE) of lettuce (Lactuca sativa L.) in deep water culture (DWC) hydroponics. A greenhouse experiment was conducted from June to July 2024 using a completely randomized design with four pH treatments: T1 (unbuffered control), T2 (pH 6.3), T3 (pH 7.0), and T4 (pH 8.3). Three lettuce cultivars—Tacitus (L1), Rex (L2), and Rutilai (L3)—were tested, with three replicates per treatment. Results showed that fresh yield was significantly affected by cultivar but not by pH treatment. Rex produced the highest yield, reaching 132 g/plant at pH 7.0, compared to 127 g/plant for Tacitus and 98 g/plant for Rutilai. WUE differed strongly among cultivars, with Rex achieving 68.7 g/L at pH 7.0, which is nearly double that of Rutilai (37.2 g/L). Nitrogen uptake was unaffected by treatment; however, nitrogen NUE differed significantly, with Rutilai recording 12.8 mg N/g fresh weight at pH 8.3, compared to 8.3 mg N/g fresh weight for Rex and 6.7 mg N/g fresh weight for Tacitus. Calcium uptake and NUE were significantly influenced by both pH and cultivar, ranging from 3.2 to 10.7 mg Ca/g fresh weight. These findings suggest that selecting pH-tolerant cultivars plays a more critical role than pH adjustment in determining yield and efficiency in hydroponic lettuce. Choosing pH-tolerant cultivars such as Rex can reduce dependence on chemical buffering, offering a cost-effective strategy for sustainable hydroponic lettuce production in regions with alkaline water sources. Full article

To meet global food demand, agricultural systems must enhance crop performance, productivity, and sustainability. Biostimulants have emerged as a promising strategy, particularly in vegetable production, due to their ability to enhance plant growth and resilience. This study characterized milk-derived protein hydrolysates (MPH) produced from expired milk and evaluated their potential as biostimulants for hydroponic cos lettuce. Hydrolysis of expired milk with hydrochloric acid achieved 94.55% hydrolysis and yielded 80.77% free amino acids. MPH was applied at volumes of 0, 1, 3, and 5 mL L⁻¹ in combination with Hoagland and Arnon nutrient solution. The 1 mL L⁻¹ (MPH1) treatment significantly increased shoot and root biomass and canopy size while reducing nitrate accumulation and enhancing total flavonoid and ascorbic acid content, as well as antioxidant capacity. HPLC analysis showed that MPH1 treatment promoted the accumulation of key metabolites, including vanillic acid, para-coumaric acid, salicylic acid, ferulic acid, gallic acid, syringic acid, quercetin, myricetin, and naringenin. MPH1 improved uptake of phosphorus, potassium, calcium, magnesium, and iron, contributing to mineral biofortification and nutritional quality. These results demonstrate that MPH at 1 mL L⁻¹ is an effective biostimulant, improving yield and quality while reducing nitrate levels in hydroponically grown cos lettuce, offering a sustainable solution for food waste valorization. Full article

By 2030, the world’s population is projected to reach 8.5 billion, posing significant challenges for food production. Traditional agriculture, which requires large amounts of water, soil, and energy, can contribute to the depletion of natural resources and environmental degradation. In this context, organic hydroponic systems emerge as a sustainable alternative, allowing for more efficient, controlled, and resilient production in the face of climate change. In this research, the physical development of romaine lettuce and the physicochemical parameters of the crop water are evaluated as a function of the number of daily recirculations. The crop variables are measured with the help of an intelligent control system, which allows the real-time monitoring of the process variables. The methodological approach is mixed: quantitative, for the recording of physicochemical variables, and qualitative, for the physical analysis of the crop throughout the process, With the experiments conducted it was found that the treatment with four daily recirculations promoted the most significant physiological growth of the plants. Despite having a pH of approximately five and dissolved oxygen of 6 mg/L, this treatment maintained adequate levels of TDS (2050 ppm) and hardness (1000 ppm), favoring the development of the crop. The treatments with less recirculation presented lower growth values. These results suggest that increased recirculation can optimize yields in floating-root hydroponic systems, addressing global food challenges from an environmentally responsible perspective. Full article

This study evaluated the qualitative and quantitative performance of lettuce (cv. Romana) grown using different cultivation systems under Mediterranean greenhouse conditions equipped with photoluminescent glass panels. Five systems were compared: outdoor soil (PSO), indoor soil (PSI), aeroponic (A), hydroponic with inorganic nutrients (HSN), and hydroponic with organic nutrients (HSO). Morphological, physiological, and quality parameters were measured alongside solar irradiance and extended PAR. The results showed that aeroponics significantly outperformed other systems in fresh weight (52.7 g), photosynthetic pigments, and carotenoids, while HSO showed the lowest yield and quality. Although PSO had the highest antioxidant activity and phenolic content, it exhibited poor yield due to lower water use efficiency and light-induced stress. The PCA analysis highlighted distinct groupings among systems, with A linked to yield and pigment concentration, and PSO associated with antioxidant traits. Despite a 44.8% reduction in solar radiation inside the greenhouse, soilless systems—especially aeroponics—proved effective for maintaining high productivity and quality. These findings support the integration of soilless systems and photoluminescent technologies as sustainable strategies for high-efficiency lettuce production in controlled environments. Full article

Traditional soil cultivation of lettuce faces challenges; hydroponic technology offers solutions to improve lettuce production. However, the interrelationships among the root phenotype of lettuce, auxin synthesis and signal transduction, and nutrient solution flow, and their effects on hydroponic lettuce growth remain unclear. We investigated the effects of nutrient solution flow state on lettuce’s early growth, transcriptomic changes, and auxin-related gene expression. Growth indicators were measured 2, 4, and 6 days after transplanting. The shoot and root fresh weights, total root length, and root surface area were significantly higher under the flow treatment than under the non-flow condition. The shoot fresh weight increased by 29, 64, and 31%, respectively, at the three growth stages. A clear distinction was observed between the samples from different treatment groups. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways that were commonly enriched included “Plant hormone signal transduction (auxin)”. Moreover, the significantly enriched Gene Ontology (GO) terms varied across different time points, which vividly reflected the dynamic characteristics of the plant’s response. Genes related to auxin biosynthesis—such as AL3F1, YUC5, and AMI4G—exhibited higher expression levels under the flow treatment. Overall, these results indicate that nutrient solution flow can promote auxin synthesis and signal transduction in early roots of lettuce. Full article