Nutrient Solution Research Articles

Smart Nutrient Solution Temperature Control System for Oversummering Lettuce Cultivation Based on Adaptive Dung Beetle Optimizer-Fuzzy PID

The summer cultivation of lettuce in greenhouses frequently encounters heat stress challenges. In hydroponic systems, cooling the nutrient solution to reduce root zone temperature is an effective strategy to alleviate heat stress. To address the issue of temperature control instability in hydroponic nutrient solutions under high-temperature conditions, this study developed a nutrient solution temperature control system based on an adaptive DBO-fuzzy PID controller. Firstly, the system integrates high-precision sensor networks and air-source heat pump units, forming the hardware foundation. Simultaneously, a fuzzy PID controller optimized by the Dung Beetle Optimizer (DBO) algorithm was designed for this system, enabling real-time adjustment of quantization and scaling factors in the fuzzy controller. Simulation results showed that the DBO-Fuzzy PID achieved a settling time of 35.23 s, overshoot of 2.18%, and steady-state error of 0.009 °C. The DBO-Fuzzy PID controller exhibited faster and more stable disturbance rejection compared to traditional PID and fuzzy PID control, demonstrating enhanced stability and robustness. System performance tests in the summer greenhouse demonstrated that with a setpoint of 22 °C, the DBO-Fuzzy PID optimized nutrient solution temperature control system maintained an average temperature of 21.98 °C, closer to the target value and exhibiting better adaptability to high-temperature environments compared to traditional PID control. Cultivation experiments confirmed the system’s effectiveness in mitigating heat stress and maintaining optimal nutrient solution temperature for lettuce growth. The results can provide a theoretical basis and practical reference for precise and stable temperature control in hydroponic nutrient solutions.

Estimating Leaf Nitrogen Concentration of Grain Sorghum, Corn, and Forage Sorghum with Hyperspectral Data and Vegetation Indices from a Spectroradiometer

ABSTRACT Nitrogen deficiency in plants is often done by visual scoring, but this process is labor-intensive and time-consuming. Spectroradiometers have been identified as a promising alternative because they can give information about plants’ stress in the shortest time. Therefore, this study was carried out to identify the regions of the electromagnetic spectrum (EMS) that are related to leaf N and to determine how well we can use vegetation indices to estimate leaf nitrogen concentration (LNC). Conducted in a controlled greenhouse in Stillwater, Oklahoma, from August to October 2021, the experiment involved three bioenergy crops (grain sorghum, corn, and forage sorghum) and four nitrogen levels (20%, 50%, 75%, and 100% of Hoagland’s nutrient solution). The crops were grown in a split-plot design with computer-controlled drip irrigation. The results showed that corn and grain sorghum treated with 100% nitrogen had the highest physiological growth, while forage sorghum responded best at 75%. Hyperspectral reflectance data were used to estimate LNC in the bioenergy crops studied, with vegetation indices effectively estimating LNC. Among the indices tested, the TCARI performed best, with an R2 of 0.72. Multiple linear regression (MLR) improved the estimation accuracy further, achieving an R2 of 0.77. These findings demonstrate that leaf spectral reflectance and VIs can provide a fast, cost-effective way to monitor nitrogen status in bioenergy crops during the growing season. The study highlights the potential of hyperspectral reflectance to aid in precision agriculture by enabling rapid, in-season adjustments to nitrogen application, thereby improving crop management and productivity.

Protective effects of melatonin on cadmium subcellular distribution, biochemical, and anatomical alterations in Malva parviflora roots.

Plants use various mechanisms to cope with cadmium (Cd) stress. Melatonin's impact on the root response to Cd stress, which is the first organ to detect its presence, has been less studied. This study aims to investigate the effects of melatonin pretreatment on the root strategies of Malva parviflora in response to Cd stress, focusing on the mechanisms of heavy metal tolerance. The plants, 42days post-germination, were subjected to a 48-h pretreatment with 50μM melatonin in a complete nutrient solution under controlled growth conditions. Following pretreatment, plants were exposed to a nutrient solution containing 50μM Cd for 8days. Comparative analyses were conducted on root length, weight, anatomical features, Cd content, Cd subcellular distribution, nutrient absorption, glutathione, and lignin. Melatonin pretreatment significantly enhanced root length and weight under Cd stress. It also increased the xylem and phloem area in the roots and promoted the absorption and translocation of essential nutrients such as Fe, Zn, Ca, and Mg to the shoots. Additionally, there was a marked increase in glutathione content and Cd proportion in the cell wall and organelle fractions in melatonin-pretreated roots. Notably, melatonin reduced overall plant Cd content and its translocation from roots to shoots, while decreasing root lignin content. This study demonstrates that melatonin plays an important role in managing Cd toxicity by improving morphological, anatomical, and biochemical characteristics of roots under Cd stress. The findings suggest that melatonin pretreatment can effectively alter Cd subcellular distribution, thereby mitigating its harmful effects in plants.

Alginate Oligosaccharide Promoted the Nutrient Uptake and Growth of Cucumber Seedlings Under Suboptimal Temperature Conditions

Due to its sensitivity to cold temperatures, cucumber growth is substantially constrained by suboptimal temperature stress in northern China’s off-season production systems. Suboptimal temperatures severely repress the nutrient absorption, growth, and yield formation of vegetables in solar greenhouses during winter and early spring in China. Alginate oligosaccharides (AOSs) are anionic acidic polysaccharides derived from brown algae, known for promoting plant growth and alleviating abiotic stress. In this study, we aimed to investigate the effects of different nutrient solution concentrations combined with AOS on the growth and nutrient uptake of cucumber seedlings under suboptimal temperatures (15/8 °C, day/night). Potted ‘Jinchun 4’ cucumber seedlings grown in coconut coir were treated with 0.5×, 1.0×, or 1.5× strength of Hoagland solution alone (N0.5, N1, N1.5), or with 30 mg·L−1 AOS (A0.5, A1, A1.5). The results showed that the growth attributes and nitrogen (N) accumulation of cucumber plants of N1 and N1.5 were significantly higher than those of N0.5. Additionally, plants of A0.5 exhibited significantly higher plant height, chlorophyll a content, root surface area, root volume, root vitality, N metabolism enzyme (NR, GDH, GS) activities, and N accumulation, than those under N0.5, N1, or N1.5. Moreover, compared to A0.5, the net photosynthetic rate, total root length, root surface area, root N content, leaf nitrate reductase activity, root glutamate dehydrogenase activity, and N accumulation of A1 and A1.5 were significantly higher than those of A0.5. Correlation analysis revealed strong linkages between root morphology traits and tissue N content. In summary, under suboptimal temperature conditions, the application of AOS improved cucumber seedlings’ nutrient absorption and growth more efficiently than merely raising nutrient levels, as it enhanced root surface area, root vitality, and N metabolic enzyme activities.

Optimizing Hydroponic Nutrient Solutions for Enhanced Growth, Root Biomass and Essential Oil Yield in the Endemic Medicinal Herb (Plectranthus vettiveroides)

Plectranthus vettiveroides is a valuable medicinal and aromatic plant native to the Western Ghats, known for its essential oil extracted from roots. Its natural populations are vanishing due to habitat distraction. The present study explores hydroponic cultivation as a sustainable alternative and it was conducted at the Saraswathy Thangavelu Extension Centre, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Puthenthope, Thiruvananthapuram, Kerala, India, between January 2023 and May 2023. Apical shoot cuttings of P. vettiveroides with ~15cm length having four nodes with apical buds and a minimum of two fully expanded juvenile leaves were harvested from 75-day-old field-grown plants and they were hydroponically grown for 70 days in six different nutrient solutions—Hoagland, Cooper, Hewitt, Steiner, Knoop, and a control with distilled water—under ambient greenhouse conditions. Among the tested media, Hoagland solution supported the most vigorous shoot growth, including increased leaf number and branching. Cooper medium showed a notable effect on pigment synthesis, yielding the highest levels of chlorophyll and carotenoids. Early and enhanced root formation was observed in Hoagland and Hewitt media, although prolonged exposure to static conditions led to excessive root elongation and tip browning. Overall, morphological assessments indicated that plants grown in nutrient-rich media exhibited superior growth and biomass accumulation compared to the control. Additionally, a strong positive correlation was observed between root biomass, photosynthetic pigment concentration, and essential oil yield, emphasizing the role of nutrient availability in regulating key physiological traits. Hydroponic cultivation with optimized nutrient media significantly enhances the growth and essential oil production. This method offers a sustainable strategy for large-scale production of root biomass and essential oils, contributing to the conservation of wild populations.

Cold Plasma Treatment of Sweet Basil Seeds and Nutrient Water in Hydroponics: Impact on Growth and Quality.

This study investigated the combined effect of two plasma treatments during hydroponic growing of sweet basil plants. Air-based cold plasma was applied to basil seeds using a Plasmajet. Also, plasma-activated water (PAW) was produced by using a submerged gliding arc plasmatron system followed by mixing the PAW with a nutrient solution (NS) to make plasma-activated NS (PANS). Basil plants from untreated and plasma-treated seeds were grown hydroponically using NS and PANS in a greenhouse in an ebb-and-flow system. Basil plants were harvested after 21 days and analyzed for their dry tissue mass, growth parameters (plant height, number of branches and nodes, root length, and leaf index), quality (color, texture), and microbiology (total plate count). The combination of plasma treatment of seeds followed by growing the plants using PANS (treated group) resulted in higher plant height, longer root length, greater number of branches, bigger leaves, and higher zinc content in leaves in comparison to plants grown from untreated seeds and with NS (control group). Plasma treatment did not significantly affect moisture content, number of nodes, dry weight, wet weight, greenness, texture, aroma content, and sensory attributes of basil leaves. However, sensory results showed increased basil flavor, aroma, and bitterness in the tomato basil salad made with PANS-treated basil, compared to tomato basil salad made with NS-treated basil. This work revealed that the plasma treatment of the basil seeds combined with PANS could be effective to enhance the growth of sweet basil plants and increase the aroma and flavor of this culinary herb.

Different nitrate/ammonium relationships and light intensity and their effect on growth and nutritional content of hydroponic lettuce (Lactuca sativa L.)

Lettuce is the most consumed leafy crop worldwide and the high levels of nitrates in its leaves can be carcinogenic. The objective of this study was to evaluate the effect of different nitrate/ammonium ratios in the nutrient solution and two light intensities (200 and 400 μmol·m⁻²·s⁻¹) on the growth and nutrient concentration of lettuce plants under hydroponic conditions. Controlled environment chambers (light and temperature) and a floating root system were used with the application of Steiner's nutrient solution modified for each of the treatments. Treatments consisted of combinations of three nitrate/ammonium ratios (100/0, 75/25, and 50/50) and two LED light intensities. The variables evaluated were root volume, fresh and dry weight of the leaves, dry weight of the root, total dry weight and the mineral composition of the leaves. The experimental design was completely randomized with a 3 × 2 factorial arrangement with six repetitions. For the statistical analysis of the data, an analysis of variance and a comparison of means test were performed (Tukey, p≤0.05). The results showed that increasing the proportion of ammonium reduced the volume and dry weight of the root without affecting the fresh weight of the leaf. Increasing the light intensity increased the root volume and the fresh and dry weight of the leaves, while ammonium reduced the levels of potassium, calcium and nitrates in the leaves, especially when an intensity of 400 μmol·m⁻²·s⁻¹ was applied. These results suggest that optimizing nitrate/ammonium ratios and light conditions improves biomass production and nutritional quality of hydroponic lettuce.

Alternative Growing Media Under the Same Fertigation Scheme Affected Mineral Accumulation and Physiological Parameters in Grapevine Cultivars

Under nursery conditions, various organic and inorganic growing media can be used for plant propagation. However, a common fertigation program may have varying effects on plant performance. This study evaluated alternative growing media under the same fertigation scheme in three indigenous Cypriot grapevine cultivars (Xynisteri, Maratheftiko, Giannoudi). Rooted cuttings were grown in pots containing soil, perlite, river sand, peat, and cocosoil. The plants were fertigated with a hydroponic nutrient solution with an electrical conductivity of 2.4 dS/m and a pH of 5.8. Xynisteri grown in peat and cocosoil accumulated minerals such as N and P while showing reduced levels of Na, total phenols, antioxidant capacity, and total flavonoids in the leaves. Additionally, plants exhibited low hydrogen peroxide and malondialdehyde (MDA) content, indicating a non-stressful growing environment. Maratheftiko cultivar accumulated N in perlite, K in cocosoil, and P in peat and cocosoil media. When grown in soil, Maratheftiko showed higher phenol content and increased antioxidant capacity, which is correlated with elevated oxidative stress (higher MDA). Giannoudi appeared to be more adapted to soil and/or cocosoil media, as evidenced by its lower MDA content, total phenols, total flavonoids, and antioxidant activity, compared to plants grown in perlite, sand, and peat. Chlorophyll and total carotenoid levels were increased in Giannoudi grown in soil. In conclusion, both growing media and fertigation practices should be tailored to optimize plant performance under nursery conditions.

Pest Management in Hydroponics Crop Production: Challenges and Solutions

Soilless cultivation, specifically hydroponic structures, is gaining attraction as a sustainable and green opportunity to conventional soil based agriculture. Hydroponic cultivation requires precise parameters adjustments inclusive of temperature, pH, water and nutrient formulations for optimized plant health and productiveness. However, these system have numerous challenges like pest and pathogen attack and further management, nutrient recycling and environmental impact. Therefore, present review discusses the comparative advantages and obstacles of open and closed hydroponic systems, highlighting the susceptibility of closed systems to pathogen spread and vehicle toxicity due to root exudates. The significance of IPM, plant health monitoring and the use of mycorrhizae in greenhouse hydroponic is emphasized in current study. Various strategies for managing the pathogens and toxic compounds in nutrient solutions are evaluated, which include activated carbon adsorption, electro-degradation, semiconductor photo-catalysis, ultraviolet irradiation, hydrogen peroxide treatment and filtration strategies. The article underscores the need for effective, sustainable and scalable treatment procedures tailored to closed hydroponic systems to make sure high productivity even as minimizing the environmental dangers. Moreover, it identifies the opportunities for scientific studies into optimizing the microbial health in substrates and enhancing the overall IPM implementation under controlled environments for sustainable crop production.

Development of a Permanent Magnet With High Uniformity and High Magnetic Field for Miniaturization of Nuclear Magnetic Resonance Measurement System

ABSTRACTWe developed a static magnetic field for miniaturization of the nuclear magnetic resonance (NMR) measurement system to measure nutrient solution in agricultural field. Instead of the large electromagnets used in our previous work, a permanent magnet was used to establish a static magnetic field. The design was based on the Halbach array, which allows the magnetic field to be concentrated on one side to increase the magnetic force. To avoid the problem of reducing the magnetic force of the magnets, the array magnets were optimized so that they could be composed of a combination of simple square prism magnets. Observation of the magnetic flux density of the fabricated permanent magnets showed that the magnetic flux density at the center was 0.946 T, and an error of less than 5 mT in magnetic flux density could be achieved. As a result, we succeeded in producing the permanent magnet. NMR measurements of water and air were performed using the produced magnets. When measuring water, a signal at 39.679 MHz was observed, which is the signal of hydrogen. In contrast, no signal was observed in air. Therefore, the NMR signal was successfully measured using the fabricated permanent magnet.

Bioaccumulation and Biotransformation of Triazole Pesticides in Rice (Oryza sativa L.): Quantitative Structure-Activity Relationship, Metabolic Pathways, and Toxicity Assessment.

Root uptake is a primary pathway for pesticides to enter the plants; however, their uptake mechanisms and biotransformation behaviors are still lacking. Herein, the root uptake and biotransformation behaviors of 21 triazole fungicides in rice plants (Oryza sativa L.) by hydroponic experiments were investigated. The uptake of triazoles in rice roots may directly and mainly originate from adsorption in the root surface, not directly dominated by nutrient solution. A QSAR model revealed that the molecular descriptors related to log Kow and molecular polarizability (e.g., ALogP and ATSC6p) were closely associated with the bioaccumulation of triazole fungicides. Twenty-six metabolites of six typical triazole pesticides were identified, and six among them were determined for the first time. The toxicity prediction by Ecological Structure Activity Relationships Predictive Model (ECOSAR) software indicated that biotransformation products (e.g., methylation products) may exhibit a higher toxicity. Therefore, the ecological risk posed by pesticide biotransformation products should be a concern, which needs further investigation.

Clinical application of percutaneous gastrostomy in children with dysphagia after traumatic brain injury: A single-center experience.

This study explores the clinical application value of percutaneous endoscopic gastrostomy (PEG) in children with dysphagia after brain injury. Children with dysphagia after brain injury were selected and randomly divided into a treatment group and a control group using a random number table method, with 42 cases in each group. The control group received nutritional support using indwelling nasogastric tube technology, while the treatment group received nutritional support using PEG technology. Both groups received the same tube feeding nutrient solution. At the same time, both groups of patients received comprehensive training methods including oral sensation training, oral exercise training, and physical therapy for swallowing dysfunction. Weight, total serum protein, serum albumin, and hemoglobin of the patients were measured 1 day before treatment and 28 days after treatment, respectively. The degree of dysphagia was evaluated by the water swallow test and the dysphagia disorders survey of each patient 1 day before treatment and 28 days after treatment, respectively. Adverse events such as gastrointestinal bleeding, aspiration pneumonia, and reflux esophagitis were recorded. After 28 days of treatment, both the control group and the PEG group showed an increase in body weight, total serum protein, serum albumin, and hemoglobin compared to before treatment (P < .05), and the PEG group showed a more significant increase than the control group (P < .05). At the same time, swallowing function improved more significantly in the PEG group (P < .05), and the incidence of adverse events was lower compared to the control group (P < .05). The comprehensive training method for swallowing disorders combined with enteral PEG nutrition has a definite effect on children with swallowing disorders after traumatic brain injury.

Optimizing Hydroponic Crop Production: A Multifaceted Approach to EC, pH and Nutrient Management

Hydroponics is the practice of growing crops without soil, which relies on careful calibration of pH, EC (electrical conductivity) and nutrient availability to promote plant growth and yield. In hydroponics, pH is an important factor governing how nutrient availability is affected. Ideal pH range for most of the crops is 5.5-6.5. pH is important to determine acidity and alkalinity of a solution and it further affects nutrient absorption. pH management is different in Deep water Culture, Nutrient Film Technique and System of Flooded tubes. Modern techniques like microcontroller and sensors are being used to monitor hydroponic solution. Optimum pH is important for nutrient uptake and proper nutrient ratio influence uptake of another nutrient.EC or dissolved amounts of salts, measures the concentration of nutrients available for the plants. There are various nutrient recipes for the crops that are being added to the system in dosage of gram/litre. Higher EC can be managed by diluting the solution. Falling EC levels can be adjusted by adding the nutrient solution. An increase in EC value can be beneficial for the fruit quality but may result in yield reduction. Real time sensors are used nowadays for monitoring of EC and pH. In hydroponics there is less contamination, low water consumption, higher yield and no need of herbicides or pesticides but initial cost is high and regular monitoring is important.

Inoculation and co-inoculation of lettuce and arugula hydroponically influence nitrogen metabolism, plant growth, nutrient acquisition and photosynthesis.

The objective of this study was to investigate the effects of single and combined inoculations of A. brasilense, B. subtilis and P. fluorescens on lettuce and arugula grown in a hydroponic system. The study was carried out in a greenhouse and was designed in randomized blocks with five replications. The treatments consisted of inoculation with A. brasilense, B. subtilis and P. fluorescens and co-inoculation with A. brasilense + B. subtilis, A. brasilense + P. fluorescens, B. subtilis + P. fluorescens and A. brasilense + B. subtilis + P. fluorescens via nutrient solution. An increase in the length and fresh mass of the shoot and leaf chlorophyll concentrations of arugula and lettuce was observed under co-inoculations of A. brasilense + P. fluorescens and B. subtilis + P. fluorescens. Greater length, fresh mass and volume of the lettuce root system were observed under the co-inoculations of A. brasilense + B. subtilis, A. brasilense + P. fluorescens and B. subtilis + P. fluorescens in arugula under the inoculations of A. brasilense and A. brasilense + P. fluorescens. Greater nitrate reductase activity was detected in leaves, and lower nitrate accumulation was detected in lettuce and arugula under inoculations with A. brasilense, P. fluorescens and B. subtilis + P. fluorescens. The greatest accumulation of N, P, K, Ca and Mg in the lettuce shoot was obtained under inoculation with P. fluorescens, A. brasilense + P. fluorescens and B. subtilis + P. fluorescens. Co-inoculation with A. brasilense + P. fluorescens and B. subtilis + P. fluorescens was the most efficient combination for increasing the growth, nutrient acquisition and functioning of nitrogen metabolism in arugula lettuce plants.

Production Performance of Lettuce (Lactuca sativa L. var. Lalique) Using Organic Nutrient Solution Under Hydroponic System

This study evaluated the production performance of lettuce (Lactuca sativa L. var. Lalique) using organic nutrient solutions in a non-circulating hydroponic (Kratky) system. The experiment was conducted in a polyhouse at Camiguin Polytechnic State College, using a Randomized Complete Block Design (RCBD) with seven treatments: SNAP (synthetic control), Water (negative control), Vermitea, VegeGrow, Ramils, Biovoltin, and Healthynest. Growth parameters, yield components, nutrient solution consumption, sensory attributes, and profitability were assessed. Results indicated that Ramils (T5) and Healthynest (T7) performed comparably to SNAP (T1) in plant height, leaf width, canopy diameter, root development, and yield while also exhibiting high sensory quality and marketability. In contrast, T3 (Vermitea), T4 (VegeGrow), and T2 (Water) showed suboptimal performance, reflecting variability in organic fertilizer efficacy. The findings suggest that select organic nutrient solutions can be a viable alternatives to synthetic fertilizers in hydroponic lettuce production. However, further refinement of organic formulations is needed to improve stability and nutrient bioavailability. Further research is needed to assess long-term agronomic, economic, and environmental impacts. This study contributes to sustainable agriculture by supporting the integration of organic fertilizers into hydroponic systems.

Optimum concentrations of potassium and zinc for better performance, nutritional, and biochemical quality of hydroponically cultivated Spinacia oleracea Cv. Virofly

In order to evaluate micro and macronutrient balance in vegetable growth, a study on greenness, yield, nutritional value, as well as biochemical status in spinach, has been conducted in a greenhouse, utilising the different concentrations of zinc (Zn) and potassium (K) in the nutrient solution. So, three concentrations of Zn (0.22, 5, and 10 mg L− 1) and K (39, 78, and 117 mg L− 1) were applied to hydroponically grown spinach (Spinacia oleracea cv. Virofly) through a factorial experiment based on a randomized complete design with three replications. The results showed that along with increasing concentrations of Zn and K in a nutrient solution, chlorophyll index and plant performance were increased although Zn showed more influence than K. The maximum plant yield was observed at 117 mg L− 1 of K in combination with both concentrations of Zn (5 and 10 mg L− 1). Along with an increase in Zn and K concentrations, the amount of nutrients including Na, Fe, Cu, Ca, Mn, and Mg decreased compared to the control level of Zn and K in nutrient solution except for Zn and K, which increased due to the Zn and K, respectively. Increased levels of Zn and K caused to decrease in malondialdehyde (MDA) content by 51% and 34%, respectively. Hydrogen peroxide (H2O2) was decreased also by 29% and 14% at 10 and 117 mg L− 1 concentration of Zn and K while higher levels of Zn and K in the nutrient solution, increased protein content by 1.4 and 1.2 folded compared to the control plants. The maximum activity of superoxide dismutase (SOD) was recorded in spinach treated with 10 mg L− 1 of Zn in combination independent to the K concentrations. The activity of ascorbate peroxidase (APX) was also affected by Zn as it showed up to 2.1 folded increment at 10 mg L− 1 Zn compared to the 0.22 mg L− 1 concentration. In general, an increase in Zn and K concentration in the nutrient solution decreased the absorption of measured nutrients except for Zn and K in spinach leaves. The effect of increased levels of Zn was more obvious than that of potassium in qualitative and biochemical traits of spinach specially at 5 mg L− 1 concentration. These findings suggest that supplementing hydroponic nutrient solutions with 5 mg L− 1 Zn in combination with 78 mg L− 1 K can lead to the better quality and tolerance of the plant, offering a promising strategy to enhance crop productivity and nutritional value in hydroponically cultivated spinach.

Comparative performance of lettuce cultivars Batavia and Romain in nutrient film technique under hydroponics system

Due to the impact of climate change, modern agriculture faces growing challenges demanding innovative and sustainable solutions like soilless farming. Hydroponic systems, particularly the Nutrient Film Technique (NFT), have gained attention for their efficiency in water, nutrient and space management. Lettuce (Lactuca sativa L.) is a widely consumed leafy vegetable known for its health-promoting nutrients and bioactive compounds, making it a key candidate for hydroponic cultivation. The experiment was conducted at Centurion University of Technology and Management, Paralakhemundi, Odisha, India, using an A-frame vertical NFT system with four tiers designed to hold 64 mesh pots. After preparation of the nursery in pro-trays, lettuce seedlings of Batavia and Romain were transferred into the NFT channels and grown in a circulating nutrient solution with slightly acidic pH (5.5–6.5) and electrical conductivity (1.0–2.4 dS/m) throughout the crop cycle. The cultivar Romain exhibited superior growth characteristics, including increased leaf area, plant height, root length, and chlorophyll content. Conversely, Batavia displayed higher fresh leaf weight, indicating its potential for applications prioritizing fresh weight. Notably, Romain's leaves showed marginally higher nitrogen content, which correlated with its enhanced biomass and chlorophyll concentration.

Molybdenum supply increases 15N-nitrate uptake by maize.

Nitrogen (N) is widely used in maize (Zea mays L.) production. The supply of molybdenum (Mo) can increase the recovery of N by the plant due to the role of this micronutrient in the assimilation of nitrate through nitrate reductase (NR). We aimed to evaluate N metabolism and auxiliary measurements in maize as affected by combined N and Mo omission or supply under controlled conditions. Plants were grown for 28d in a nutrient solution without Mo and N, with Mo and N, and under the omission of Mo or N. The treatments with omission received nutrients with foliar application or via nutrient solution after 28d. Gas exchange, chlorophyll and anthocyanins indexes, and N accumulation were evaluated at 28, 35, and 44d after transplanting (DAT). The amino acid profile was altered due to Mo and N supply to the plants, as well as the uptake and accumulation of nitrate. The highest biomass production was quantified in the positive control, supplied by the nutrient solution and later by the absence of Mo, being the foliar application inferior to this treatment. Maize biomass, with the omission of N and Mo, was 31 % lower than the supply of both nutrients. Molybdenum favors nitrate uptake by maize, mainly when supplied through the nutrient solution.

Nutrient Solution Selection Modulates Growth Patterns and Leaf Elemental Accumulation in Alfalfa (Medicago sativa) Grown

While forage grasses in southern China exhibit yield and nutritional advantages, the impact of nutrient solutions on alfalfa (Medicago sativa BC4) growth and elemental accumulation remains understudied. We conducted a pot-based controlled substrate cultivation trial using a nitrogen-poor substrate to compare four treatments: MS, Hoagland, B5 nutrient solutions, and RO water (control). From the V1 to R1 stages, the plant height was monitored continuously, with leaf dimensions and soluble proteins (Bradford method) measured at R1. ICP-MS quantified macro elements (Na+, K+, and Mg2+) and microelements (Cu2+, Fe2+, Mn2+, and Zn2+). The growth rates followed the order: MS &gt; Hoagland &gt; RO water &gt; B5. Both the MS and Hoagland solutions significantly increased the leaf length at the R1 stage (p &lt; 0.001 vs control), with Hoagland showing the greatest leaf expansion. The soluble protein content decreased significantly in all groups (p &lt; 0.05) except MS-treated plants. An elemental analysis revealed treatment-specific accumulation patterns, most notably 1.17-fold higher Fe and 1.48-fold higher Mn in the MS group versus control (p &lt; 0.001). Magnesium levels showed no significant differences among treatments. These results demonstrate the MS nutrient solution’s superior efficacy in enhancing the alfalfa growth parameters (height and leaf size) while maintaining the soluble protein content and promoting Fe/Mn accumulation. The findings provide empirical evidence for optimizing alfalfa cultivation in a nitrogen-deficient soil-based mix substrate through nutrient solution selection.

Root-applied brassinosteroid and salicylic acid enhance thermotolerance and fruit quality in heat-stressed 'Kyoho' grapevines.

The increasingly severe global greenhouse effect has become an irreversible trend, significantly impacting viticulture regions through heat stress during various grape growth stages, especially under protected cultivation conditions where high temperatures frequently occur. Therefore, studying the impact of heat stress on grapevine growth and fruit quality across the entire growth and development period, along with effective mitigation measures, is crucial. In this study, three-year-old 'Kyoho' grapevines were used as experimental materials, with four treatment groups: a control group, a hightemperature group (heat stress, HT), a high-temperature + brassinolide group (BR), and a high-temperature + salicylic acid group (SA). During the flowering, young berry swelling, and veraison stages, BR and SA were applied via nutrient solutions every seven days. The results demonstrated that BR restored the maximum photosynthetic rate (Amax) to 96.14% of CK by the 18th day of flowering, significantly outperforming SA's recovery rate of 86.64%. Both treatments maintained light saturation points (1200 μmol•m⁻²•s⁻¹) and CO2 saturation thresholds equivalent to CK. The decline in PSII photochemical efficiency (Fv/Fm) was reduced from 18% in HT to 5-8% in BR/SA-treated groups, with BR showing minimal deviation (2.3%) from CK during veraison, effectively mitigating PSII photoinhibition caused by heat stress. Furthermore, both treatments reduced leaf malondialdehyde (MDA) content, minimizing membrane lipid peroxidation, while increasing soluble protein (SP) content to protect leaves. Under heat stress, BR notably improved the fruit set rate by 22.67% compared to HT (SA: 13%), promoted berry expansion, and enhanced the accumulation of sugars and anthocyanins in the fruit skin, with SA showing similar, though slightly less pronounced, effects. These findings provide valuable theoretical insights into the use of exogenous hormones in root nutrient solutions as a strategy to mitigate the adverse effects of heat stress in grape production.