Hydroponic Solution Research Articles

Agronomic characteristics and chemical composition of hydroponic maize fodder as influenced by animal waste solutions

The growing of plants hydroponically is a soilless form of growing in modern day agriculture. It helps to make feed available for animals throughout the season since it is not affected by what is faced by field grown crops. The use of animal waste, that is, their faeces, in the growth of forage was compared with commercial hydroponics solutions as a way of looking for a reduction in the cost incurred in the purchase of commercial hydroponics solutions. The study evaluated the use of organic nutrient solutions (ONS) alongside a standard/commercial nutrient solution in growing crops hydroponically on the growth, dry matter yield, water use efficiency, and chemical composition of hydroponic maize fodder. The ONS used were formulated from the dried faeces of cattle, poultry, rabbits, and swine. The prepared organic nutrient solutions with the control were used in growing the maize seeds for 10 days, and growth, yield, and chemical composition were determined. Results show the highest (196 g) dry matter yield for maize hydroponic fodder irrigated with poultry ONS. Similarly, maize irrigated with poultry ONS was significantly (P < 0.05) higher in CP content, while it was not significantly different from maize irrigated with cattle, swine, and commercial solutions. A lower water use efficiency value (0.19 kg DM/m3) was recorded for maize irrigated with cattle ONS. According to the study, irrigating maize with different organic nutrient solutions produced maize fodder with a higher yield and a similar chemical composition as the commercial nutrient solution.

Stable Isotope Analyses Reveal Impact of Fe and Zn on Cd Uptake and Translocation by Theobroma cacao.

High concentrations of toxic cadmium (Cd) in soils are problematic as the element accumulates in food crops such as rice and cacao. A mitigation strategy to minimise Cd accumulation is to enhance the competitive uptake of plant-essential metals. Theobroma cacao seedlings were grown hydroponically with added Cd. Eight different treatments were used, which included/excluded hydroponic or foliar zinc (Zn) and/or iron (Fe) for the final growth period. Analyses of Cd concentrations and natural stable isotope compositions by multiple collector ICP-MS were conducted. Cadmium uptake and translocation decreased when Fe was removed from the hydroponic solutions, while the application of foliar Zn-EDTA may enhance Cd translocation. No significant differences in isotope fractionation during uptake were found between treatments. Data from all treatments fit a single Cd isotope fractionation model associated with sequestration (seq) of isotopically light Cd in roots and unidirectional mobilisation (mob) of isotopically heavier Cd to the leaves (ε114Cdseq-mob = -0.13‱). This result is in excellent agreement with data from an investigation of 19 genetically diverse cacao clones. The different Cd dynamics exhibited by the clones and seen in response to different Fe availability may be linked to similar physiological processes, such as the regulation of specific transporter proteins.

Removal of Chromium (III) and Reduction in Toxicity in a Primary Tannery Effluent Using Two Floating Macrophytes.

Trivalent chromium (Cr(III)) is a contaminant with toxic activity. Its presence in waters and soils is usually related to industrial activities such as tanneries. The aim of this study was to compare the removal of Cr(III) in hydroponic solutions and tannery effluents using two floating macrophytes: Salvinia auriculata and Eichhornia crassipes. First, to determine the chromium removal capacity in solution and the bioaccumulation factor (BAF) in tissues of each plant, experiments were set up with contaminated solutions with Cr(III) concentrations of 2, 5, 10, 20, and 40 mg/L. Subsequently, both plant species were exposed to a primary tannery effluent contaminated with 12 mg/L of Cr(III) in order to study the removal capacity of organic and inorganic matter, as well as the acute toxicity in the water flea (Daphnia magna) and genotoxicity in zebrafish (Danio rerio). Tests carried out on nutrient solutions revealed that both plants have a high capacity for removing Cr(III) in solution. The BAF in tissues was higher in E. crassipes compared to S. auriculata. In the experiments with a tannery effluent, both species presented low nutrient and organic matter removal efficiency, but they showed good Cr(III) removal capacity, with average reduction values of 57% for S. auriculata and 54% for E. crassipes after 72 h of exposure. E. crassipes contributed most to the reduction in acute toxicity in D. magna, while S. auriculata did not show a similar effect. However, both plant species managed to reduce the genotoxicity marker in D. rerio when compared with the initial effluent and the control.

Bioaccumulation of Microcystin-LR and Induced Physio-Biochemical Changes in Rice (Oryza sativa L.) at Vegetative Stage under Hydroponic Culture Conditions.

Irrigation with water containing a variety of microcystins (MCs) may pose a potential threat to the normal growth of agricultural plants. To investigate the phytotoxicity of MC-LR at environmental concentrations on rice (Oryza sativa L.), the characteristics of uptake and accumulation in plant tissues, as well as a series of key physio-biochemical process changes in leaves of rice seedlings, were measured at concentrations of 0.10, 1.0, 10.0, and 50.0 μg·L-1 in hydroponic nutrient solutions for 7, 15, 20, and 34 days. Results showed that MC-LR could be detected in rice leaves and roots in exposure groups; however, a significant accumulation trend of MC-LR in plants (BCF > 1) was only found in the 0.10 μg·L-1 group. The time-course study revealed a biphasic response of O2•- levels in rice leaves to the exposure of MC-LR, which could be attributed to the combined effects of the antioxidant system and detoxification reaction in rice. Exposure to 1.0-50.0 μg·L-1 MC-LR resulted in significant depletion of GSH and MDA contents in rice leaves at later exposure times (15-34 days). Low MC-LR concentrations promoted nitric oxide synthase (NOS) activity, whereas high concentrations inhibited NOS activity during the later exposure times. The reduced sucrose synthase (SS) activities in rice exposed to MC-LR for 34 days indicated a decrease in the carbon accumulation ability of plants, and therefore may be directly related to the inhibition of plant growth under MC exposure. These findings indicate that the normal physiological status would be disrupted in terrestrial plants, even under exposure to low concentrations of MC-LR.

Strong Invasive Mechanism of Wedelia trilobata via Growth and Physiological Traits under Nitrogen Stress Condition

Nitrogen (N) is one of the most crucial elements for plant growth. However, a deficiency of N affects plant growth and development. Wedelia trilobata is a notorious invasive plant species that exhibits superior tolerance to adapt to environmental stresses. Yet, research on the growth and antioxidant defensive system of invasive Wedelia under low N stress, which could contribute to understanding invasion mechanisms, is still limited. Therefore, this study aims to investigate and compare the tolerance capability of invasive and native Wedelia under low and normal N conditions. Native and invasive Wedelia species were grown in normal and low-N conditions using a hydroponic nutrient solution for 8 weeks to assess the photosynthetic parameters, antioxidant activity, and localization of reactive oxygen species (ROS). The growth and biomass of W. trilobata were significantly (p < 0.05) higher than W. chinensis under low N. The leaves of W. trilobata resulted in a significant increase in chlorophyll a, chlorophyll b, and total chlorophyll content by 40.2, 56.2, and 46%, respectively, compared with W. chinensis. W. trilobata significantly enhanced antioxidant defense systems through catalase, peroxidase, and superoxide dismutase by 18.6%, 20%, and 36.3%, respectively, providing a positive response to oxidative stress caused by low N. The PCA analysis showed that W. trilobata was 95.3% correlated with physiological traits by Dim1 (79.1%) and Dim2 (16.3%). This study provides positive feedback on W. trilobata with respect to its comprehensive invasion mechanism to improve agricultural systems via eco-friendly approaches in N deficit conditions, thereby contributing to the reclamation of barren land.

Effects of Excessive Application of P and Zn Fertilizer on Growth and Yield of Maize under Hydroponic Conditions

Background: Phosphate is an essential nutrient but can be toxic to plants when phosphate accumulates in plants at high levels. The objective of the study was to find effects of excessive application of P and Zn fertilizer on growth and yield of maize under hydroponic conditions. Methods: Research of Experiment studied from August to December 2019 at the greenhouse of the Agriculture and Aquaculture School at Tra Vinh University. The study aimed to determine the effect of high phosphate application on growth, biomass, symptoms of poisoning, phosphate and zinc absorption in maize and vegetables grown in hydroponic solution. Result: Experimental results showed the symptoms of phosphate poisoning on maize when grown in Hoagland nutrient solution (2.0 mM P) with an additional phosphorus content of 0.1 mM P, 1.0 mM P, 3.0 mM P in the treatment with or without the addition of Zn. However, the poisoning symptoms have been yet clearly expressed when Zn was not added. Therefore, plants may exhibit phosphorus toxicity, reducing Zn absorption when the phosphorus concentration in solution was increased by more than 1%P2O5. It is necessary to continue investigating plants’ responses to phosphate fertilizers.

An Innovative Co-Cultivation of Microalgae and Actinomycete-Inoculated Lettuce in a Hydroponic Deep-Water Culture System for the Sustainable Development of a Food–Agriculture–Energy Nexus

In recent years, researchers have turned their attention to the co-cultivation of microalgae and plants as a means to enhance the growth of hydroponically cultivated plants while concurrently producing microalgal biomass. However, the techniques used require precise calibration based on plant growth responses and their interactions with the environment and cultivation conditions. This study initially focused on examining the impact of hydroponic nutrient concentrations on the growth of the microalga Chlorella sp. AARL G049. The findings revealed that hydroponic nutrient solutions with electrical conductivities (EC) of 450 µS/cm and 900 µS/cm elicited a positive response in microalgae growth, resulting in high-quality biomass characterized by an elevated lipid content and favorable properties for renewable biodiesel. The biomass also exhibited high levels of polyunsaturated fatty acids (PUFAs), indicating excellent nutritional indices. The microalgae culture and microalgae-free culture, along with inoculation-free lettuce (Lactuca sativa L. var. longifolia) and lettuce that was inoculated with plant growth actinobacteria, specifically the actinomycete Streptomyces thermocarboxydus S3, were subsequently integrated into a hydroponic deep-water culture system. The results indicated that several growth parameters of lettuce cultivated in treatments incorporating microalgae experienced a reduction of approximately 50% compared to treatments without microalgae, and lowering EC levels in the nutrient solution from 900 µS/cm to 450 µS/cm resulted in a similar approximately 50% reduction in lettuce growth. Nevertheless, the adverse impacts of microalgae and nutrient stress were alleviated through the inoculation with actinomycetes. Even though the co-cultivation system leads to reduced lettuce growth, the system enables the production of high-value microalgal biomass with exceptional biodiesel fuel properties, including superior oxidative stability (>13 h), a commendable cetane number (>62), and a high heating value (>40 MJ/kg). This biomass, with its potential as a renewable biodiesel feedstock, has the capacity to augment the overall profitability of the process. Hence, the co-cultivation of microalgae and actinomycete-inoculated lettuce appears to be a viable approach not only for hydroponic lettuce cultivation but also for the generation of microalgal biomass with potential applications in renewable energy.

Enhanced vegetable production in hydroponic systems using decontamination of closed circulating fluid

While plant microorganisms can promote plants by producing natural antibiotics, they can also be vectors for disease transmission. Contamination from plant management practices and the surrounding environment can adversely affect plants, leading to infections and hindered growth due to microbial competition for nutrients. The recirculation of nutrient-rich fluids can facilitate the transport of microorganisms between vegetables in the hydroponic production system. This issue can be addressed through the application of the decontamination method in the hydroponic liquid. Ultraviolet light (UV-C) has been employed for microbiology, and its effects on lettuce were evaluated in this study. This study aims to assess the effectiveness of a decontamination system using UV-C in hydroponic solutions during nutrient recirculation in hydroponics. We evaluated the time required for lettuce plants to reach their maximum height, as well as their pigment content, phenolic compounds, antioxidant capacity, and micro and macronutrient levels. The evaluation was conducted under two photoperiods (18 and 20 hours) in lettuce samples exposed to UV-C in the hydroponic fluid, with control groups not exposed to UV-C. The application of the UV-C decontamination system in hydroponic circulation water containing nutrients accelerated plant growth while maintaining nutritional values equal to or higher than those in the control groups without such a system. The results of microorganism control highlight the potential application of this technique for enhancing and expediting vegetable production. This approach reduces production time and enhances nutrient absorption and the content of certain compounds and minerals.

Reciprocal modulation of responses to nitrate starvation and hypoxia in roots and leaves of Arabidopsis thaliana

ABSTRACT The flooding of agricultural land leads to hypoxia and nitrate leaching. While understanding the plant’s response to these conditions is essential for crop improvement, the effect of extended nitrate limitation on subsequent hypoxia has not been studied in an organ-specific manner. We cultivated Arabidopsis thaliana without nitrate for 1 week before inducing hypoxia by bubbling the hydroponic solution with nitrogen gas for 16 h. In the roots, the transcripts of two transcription factor genes (HRA1, HRE2) and three genes involved in fermentation (SUS4, PDC1, ADH1) were ~10- to 100-fold upregulated by simultaneous hypoxia and nitrate starvation compared to the control condition (replete nitrate and oxygen). In contrast, this hypoxic upregulation was ~5 to 10 times stronger when nitrate was available. The phytoglobin genes PGB1 and PGB2, involved in nitric oxide (NO) scavenging, were massively downregulated by nitrate starvation (~1000-fold and 105-fold, respectively), but only under ambient oxygen levels; this was reflected in a 2.5-fold increase in NO concentration. In the leaves, HRA1, SUS4, and RAP2.3 were upregulated ~20-fold by hypoxia under nitrate starvation, whereas this upregulation was virtually absent in the presence of nitrate. Our results highlight that the plant’s responses to nitrate starvation and hypoxia can influence each other.

Automated Drift Compensation System for Electrical Conductivity and pH Probes in Hydroponic Systems

Highlights Used one- and two-point normalization to compensate for drifts in EC and pH probes in hydroponic systems. Developed automated sensor drift compensation systems for hydroponic systems. Evaluated the compensation systems for open- and closed-hydroponics. Application of the normalization methods increased the accuracy of the EC and pH measurements. Abstract. In hydroponic systems, the nutrient solutions are dispensed based on pH and electrical conductivity (EC) to ensure that the nutrient components in the solution are optimal for crop growth. However, the pH and EC probes may exhibit signal drifts when immersed in the solution for a considerable period, which deteriorate the measurement accuracy and the nutrient and water use efficiency. Notably, the existing hydroponic systems require manual calibration of the pH and EC probes and do not provide any information regarding their accuracy. Consequently, faults in the probes are challenging to detect. In this study, two types of automated drift compensation systems for EC and pH probes, based on one- and two-point normalization, were developed to accurately monitor changes in the pH and EC values in hydroponic solutions and enhance sensor management. The proposed framework can provide information regarding the drifts of the pH and EC probes through automated normalization solution measurements. The effectiveness of the developed system in scenarios involving plant growth with open and closed hydroponics was evaluated through comparison with a standard method involving sampling and laboratory analysis. The results indicated that the one-point normalization strategy had a simple structure and was effective in compensating drifted offsets of sensors. A two-point normalization strategy could effectively predict the sensor drifts as well as variations in the sensitivities, which could be used in the compensation processes. Application of the one-point normalization-based system increased the accuracy of the EC and pH measurements, with root mean square errors decreasing from 50 to 28.5 µS·cm-1 and 0.43 to 0.17 pH in the open hydroponic systems and from 68.7 to 38.3 µS·cm-1 and 0.15 to 0.11 pH in the closed systems, respectively. The two-point normalization-based system decreased the RMSEs from 44.6 to 33.4 µS·cm-1 and 0.55 to 0.20 pH for the EC and pH measurements, respectively. In addition, the decreased slope and coefficient of determination in the linear regression according to the system application proved the system can compensate for the drifts of the EC and pH probes. The proposed system provided accurate EC and pH measurements and sensor status information, promoting more efficient nutrient use and sensor maintenance. Keywords: Automation, Compensation, Drift, EC, Hydroponics, pH.

Physiological and transcriptomic analysis provides novel insight into growth in Kam sweet rice under different nitrogen supplies

AbstractKam Sweet Rice (KSR) is a rice cultivar cultivated for thousands of years in China. Proper and balanced use of nitrogen sources is essential for achieving optimal growth and yield in KSR. This study was carried out to find the most effective hydroponic nutrient solution for cultivating and promoting the growth of KSR. Different nitrogen treatments were applied to KSR cultivars GouDan (GD), GouHa (GH), HongHe (HH), LeiLongGang (LG), and ZaiBianXiaoXiangHe (ZH), resulting in noticeable changes in both growth and physiological traits. Our findings revealed that D3 treatment [1.2 mM NH4Cl + 2.4 mM NaNO3+ neutral amino acids (0.1 mM Ser + 0.2 mM Thr + 0.2 mM Gly + 0.2 mM Pro +0.3 mM Ala)] had a notable positive impact on the growth of GH and ZH which showed the best performance in terms of plant height, root length and fresh weight when compared to the control (CK). Through transcriptome analysis, we discovered that these treatments altered the expression levels of genes associated with carbon metabolism, photosynthesis, and nitrogen pathways within 40 days. Interestingly, by altering the growth and tillering in rice transgenic plants, we validated the role of amino acid transporter OsAAP13 identified in transcriptome profiling, underscoring its significance. Our results are helpful for large‐scale production of KSR with the key methods for controlling the growth of KSR. It is a valuable asset for future investigations aimed at unravelling the intricate mechanisms governing plant growth in the context of different nitrogen supplies.

Nutrient Solution Application of a Calcium-mobilizing Biostimulant Mitigates Tipburn without Decreasing Biomass of Greenhouse Hydroponic Lettuce

Lettuce tipburn is a physiological disorder characterized by marginal necrosis and curling of inner, younger leaves caused by localized calcium deficiency, especially in low evapotranspiration environments that restrict mass flow and thus calcium mobility. Severe tipburn negatively affects the marketability and quality of greenhouse-grown hydroponic lettuce. We aimed to assess the effectiveness of a chemical-based, calcium-mobilizing biostimulant for mitigating lettuce tipburn when applied in hydroponic nutrient solutions. Butterhead lettuce (Lactuca sativa ‘Rex’) was grown indoors under warm-white light-emitting diodes at a mean photosynthetic photon flux density of 300 μmol⋅m−2⋅s−1 for 11 days. Subsequently, we transplanted seedlings into deep-water-culture hydroponic trays in a greenhouse at an air temperature of 24.6 ± 1.2 °C, relative humidity of 76.2% ± 7.4%, and 20-hour photoperiod with supplemental lighting from high-pressure sodium lamps. The plants were grown in nutrient solutions with and without the biostimulant codenamed CC US-2105 at two concentrations (22 and 220 μL⋅L−1). Data were collected from plant samples at three harvests at 14, 21, and 28 days after transplant (DAT). At 14 DAT, there was no tipburn under any treatments. Compared with the control, the biostimulant at 22 μL⋅L−1 increased shoot dry mass by 31%. At 21 DAT, the biostimulant at 220 μL⋅L−1 eliminated tipburn, and the biostimulant increased shoot fresh weight by 28%, irrespective of the concentration. At 28 DAT, despite sufficient calcium in the whole plant and the remaining nutrient solution, severe tipburn still occurred in plants that did not receive the biostimulant (control). Compared with the control, the biostimulant at the higher concentration of 220 μL⋅L−1 decreased the tipburn rating by 88% and the number of leaves with tipburn by 85%, increased the plant diameter by 11%, increased the total leaf number by six, and accumulated higher levels of manganese and zinc. In contrast, these parameters remained unaffected at the lower biostimulant concentration of 22 μL⋅L−1. At 28 DAT, shoot biomass was unaffected by the biostimulant. In conclusion, the calcium-mobilizing biostimulant is an effective strategy to mitigate hydroponic lettuce tipburn without decreasing biomass accumulation in greenhouse conditions.

The Reutilization of Hydroponic Nutrient Solutions and Disease Control by LED Irradiation

The Reutilization of Hydroponic Nutrient Solutions and Disease Control by LED Irradiation

Pengaruh Larutan Hara dan Pupuk Organik Cair Urin Kelinci terhadap Pertumbuhan Pakcoy (Brassica rapa L.) pada Teknik Hidroponik

The demand for pakcoy (Brassica rapa L.) a nutritious vegetable is increasing without being balanced due to the limited of agricultural land. The Wick system hydroponic cultivation technique can be a solution to increase pakcoy productivity. AB mix hydroponic nutrient solution is difficult to reach because it is expensive and has a negative impact on plants. It can be combined with rabbit urine LOF to provide essential nutrients for plants. This research aims to determine the effect of the combination of AB mix with LOF rabbit urine on the growth of pakcoy plants. The research design is CRD, 1 factor, 8 treatments, and 3 replications. Treatments include A1P0=AB mix 100% +0mL/L LOF rabbit urine, A1P1=AB mix 100% + 1mL/L LOF rabbit urine, A1P2=AB mix 100%+2mL/L LOF rabbit urine, A1P3=AB mix 100% +3 mL LOF rabbit urine, A2P0=AB mix 75%+0mL LOF rabbit urine, A2P1=AB mix 75%+1mL/L LOF rabbit urine, A2P2=AB mix 75%+2mL/L LOF rabbit urine, and A2P3=AB mix 75%+3mL/L L of rabbit urine.The addition of rabbit LOF gave the best results with AIP3 treatment on growth parameters, plant height, number of leaves, leaf area, fresh weight of shoots, and roots, dry weight of shoots and roots, respectively 27.41 ± 1.44 cm, 17.33 ± 0.95 pieces 632.89±228.20cm2, 61.88±13.42g, 1.648±0.374g, 3.132±0.614g, and 0.101±0.021g. The essential nutrient content of rabbit urine LOF increases the availability of internal nutrients which are influenced by metabolism, absorption capacity, water and sunlight.

Silicon-Selenium Interplay Imparts Cadmium Resistance in Wheat through an Up-Regulating Antioxidant System.

Cadmium (Cd), being a highly toxic heavy metal, significantly impacts plant growth and development by altering nutrient uptake and causing oxidative and structural damage, resulting in reduced yield. To combat Cd toxicity and accumulation in wheat, it was hypothesized that co-application of Selenium (Se) and Silicon (Si) can reduce the adverse effect of Cd and regulate Cd resistance while improving Se fortification in wheat. Therefore, this study evaluated the comparative effect of Se and Si on the growth and antioxidant defense systems of wheat plants grown in a hydroponic setup. Briefly, the plants were acclimatized to the hydroponic solution for 1 week and then exposed to 10 µmol Cd. Afterwards, the treatments, including 0.2 mmol Si and 1.5 µmol Se, were applied as a root and foliar application, respectively. Plants supplemented with both Se and Si showed improved biomass and other physiological growth attributes, and this response was associated with improved activity/contents of antioxidants, including glutathione (GSH) content, glutathione reductase (GR), ascorbate peroxidase (APX), and catalase (CAT), with related lowering of hydrogen peroxide, malondialdehyde content, and structural damages. Moreover, by Se + Si supplementation, a decrease in total S levels in plant tissues was observed, whereas an increase in total protein concentration and GSH indicated a different and novel mechanism of Cd tolerance and S homeostasis in the plant. It was observed that Si was more involved in significantly reducing Cd translocation by stabilizing Cd in the root and reducing its content in the soluble fraction in both the root and shoot. Whereas Se was found to play the main role in reducing the oxidative damage caused by Cd, and the effect was more profound in the shoot. In addition, this study also observed a positive correlation between Si and Se for relative uptake, which had not been reported earlier. Our findings show that the Se and Si doses together benefit growth regulation and nutrient uptake; additionally, their combinations support the Cd resistance mechanism in wheat through upregulation of the antioxidant system and control of Cd translocation and subcellular distribution, ultimately contributing to the nutritional quality of wheat produced. Thus, it is concluded that the co-application of Se and Si has improved the nutritional quality while reducing the Cd risk in wheat and therefore needs to be employed as a potential strategy to ensure food safety in a Cd-contaminated environment.

Decision-tree-based ion-specific dosing algorithm for enhancing closed hydroponic efficiency and reducing carbon emissions.

The maintenance of ion balance in closed hydroponic solutions is essential to improve the crop quality and recycling efficiency of nutrient solutions. However, the absence of robust ion sensors for key ions such as P and Mg and the coupling of ions in fertilizer salts render it difficult to effectively manage ion-specific nutrient solutions. Although ion-specific dosing algorithms have been established, their effectiveness has been inadequately explored. In this study, a decision-tree-based dosing algorithm was developed to calculate the optimal volumes of individual nutrient stock solutions to be supplied for five major nutrient ions, i.e., NO3, K, Ca, P, and Mg, based on the concentrations of NO3, K, and Ca and remaining volume of the recycled nutrient solution. In the performance assessment based on five nutrient solution samples encompassing the typical concentration ranges for leafy vegetable cultivation, the ion-selective electrode array demonstrated feasible accuracies, with root mean square errors of 29.5, 10.1, and 6.1 mg·L-1 for NO3, K, and Ca, respectively. In a five-step replenishment test involving varying target concentrations and nutrient solution volumes, the system formulated nutrient solutions according to the specified targets, exhibiting average relative errors of 10.6 ± 8.0%, 7.9 ± 2.1%, 8.0 ± 11.0%, and 4.2 ± 3.7% for the Ca, K, and NO3 concentrations and volume of the nutrient solution, respectively. Furthermore, the decision tree method helped reduce the total fertilizer injections and carbon emissions by 12.8% and 20.6% in the stepwise test, respectively. The findings demonstrate that the decision-tree-based dosing algorithm not only enables more efficient reuse of nutrient solution compared to the existing simplex method but also confirms the potential for reducing carbon emissions, indicating the possibility of sustainable agricultural development.

Sustainable Water Management: Developing a Hydroponic-Watering System to Support Epiphytic Plant Growth

This study introduces an innovative hydroponic–epiphytic water system designed to address water conservation challenges in urban agriculture. The system involves repurposing water from a hydroponic setup to irrigate epiphytic plants, promoting sustainability and efficient water management. Expert opinions on the system's development and innovations were gathered using a structured evaluation based on key indicators. Notably, the mean scores were analyzed using an Inter-rater reliability assessment in order to determine the expert's opinion on the development and innovations of the hydroponic-epiphytic water system, and indicate strong acceptance in various aspects, including economic profitability, low initial cost, and compatibility with social values. However, identified areas for modification, such as time and effort savings and immediate benefits, offer valuable insights for refinement. The hydroponic–epiphytic system's components, meticulously detailed in the study, contribute to its structural integrity and water circulation efficiency. The chemical composition of the hydroponic solution, emphasizing nitrogen-rich urea, ensures precise nutrient delivery. The hydroponic growing medium, a blend of carbonized rice hull and coconut coir, provides an optimal environment for plant growth. The closed-loop water flow system minimizes wastage by recycling hydroponic water for epiphytic plants, aligning with sustainable gardening practices. In conclusion, the hydroponic–epiphytic water system proves effective in meeting its objectives of innovation and water conservation. Expert evaluations enhance its credibility, and the identified areas for improvement offer a roadmap for optimization. Recommendations include exploring alternative energy sources, conducting extended studies for long-term observations, and a more comprehensive expert opinion study. This study contributes to the advancement of urban-friendly, sustainable water management practices in agriculture.

Current perspective on nutrient solution management strategies to improve the nutrient and water use efficiency in hydroponic systems

Hydroponics, a soilless cultivation technique using nutrient solutions under controlled conditions, is used for growing vegetables, high-value crops, and flowers. It produces significantly higher yields compared to conventional agriculture despite its higher energy consumption. The success of a hydroponic system relies on the composition of the nutrient solution, which contains all the essential mineral elements necessary for optimal plant growth and high yield. This review delves into the discussion of enhancing nutrient solution management strategies across different hydroponic systems. The aim of this review is to discuss various techniques for monitoring nutrient solutions in order to improve nutrient use efficiency (NUE) and water use efficiency (WUE). The conventional approach of monitoring the hydroponic nutrient solution using electrical conductivity measurement may not provide precise information about ion concentrations, potentially resulting in poor yields or excessive fertilizer usage. To overcome these limitations, alternative management strategies have been developed to enable more accurate monitoring and efficient management. One such strategy is the nitrogen-based approach, where nitrogen concentration becomes the primary controlled element in the nutrient solution and leads to WUE and NUE development by prolonging nutrient solution recirculation. Furthermore, various methods have been devised to improve nutrient solution strategies. These include using ion-selective electrodes to measure individual ions in the hydroponic nutrient solution, using sensors to monitor substrate moisture content, estimating water requirements, and implementing programmed nutrient addition methods. In addition to introducing different management techniques to optimize hydroponic performance, this review provides a better understanding of hydroponic systems.

Reliable Multi-Path Communication for IoT Based Solar Automated Monitoring as Motivation Towards Multi-Farming Hydroponic

The current reliance on single-path communication presents limitations for effectively monitoring and controlling critical parameters that are essential for hydroponic success. This hampers the achievement of optimal plant growth and overall system performance in multi-farming hydroponic setups. The issue lies in the inherent vulnerabilities of single-path communication, which can result in data loss and transmission errors. Therefore, reliable multi-path communication is essential for Internet of Things (IoT)-based automated monitoring systems. The research aims to enhance monitoring and control capabilities in multi-farming hydroponic environments by integrating advanced communication technologies. Utilizing the ESP microcontroller in conjunction with the Painless Mesh library enables seamless communication among nodes, facilitating real-time data exchange and control. Additionally, app-based dashboard monitoring offers a user-friendly interface for remote monitoring. The findings demonstrate that reliable multi-path communication, combined with app-based dashboard monitoring, promotes optimal plant growth, efficient resource allocation, and sustainable multi-farming practices. In summary, this research contributes to a deliberate efficiency increase of 30% in pH level, 25% in humidity level, and 35% in temperature level. This paves the way for adopting efficient multi-farming hydroponic solutions that are based on resource-efficient energy usage.

Pharmacokinetics of the Recalcitrant Drug Lamotrigine: Identification and Distribution of Metabolites in Cucumber Plants.

Treated wastewater is an important source of water for irrigation. As a result, irrigated crops are chronically exposed to wastewater-derived pharmaceuticals, such as the anticonvulsant drug lamotrigine. Lamotrigine is known to be taken up by plants, but its plant-derived metabolites and their distribution in different plant organs are unknown. This study aimed to detect and identify metabolites of lamotrigine in cucumber plants grown for 35 days in a hydroponic solution by using LC-MS/MS (Orbitrap) analysis. Our data showed that 96% of the lamotrigine taken up was metabolized. Sixteen metabolites possessing a lamotrigine core structure were detected. Reference standards confirmed two; five were tentatively identified, and nine molecular formulas were assigned. The data suggest that lamotrigine is metabolized via N-carbamylation, N-glucosidation, N-alkylation, N-formylation, N-oxidation, and amidine hydrolysis. The metabolites LTG-N2-oxide, M284, M312, and M370 were most likely produced in the roots and were translocated to the leaves. Metabolites M272, M312, M314, M354, M368, M370, and M418 were dominant in leaves. Only a few metabolites were detected in the fruits. With an increasing exposure time, lamotrigine leaf concentrations decreased because of continuous metabolism. Our data showed that the metabolism of lamotrigine in a plant is fast and that a majority of metabolites are concentrated in the roots and leaves.