The responses of pepper plants to nitrogen form and dissolved oxygen concentration of nutrient solution in hydroponics.

BACKGROUND: The presence of oxygen in the growth medium is absolutely essential for root development and the overall metabolic processes of plants. When plants do not have an adequate oxygen supply for respiration, they can experience a condition known as hypoxia. In order to investigate the impact of different nitrogen forms and varying oxygen levels in nutrient solutions on the growth, photosynthesis, and chlorophyll fluorescence parameters of bell pepper plants, a comprehensive study was conducted. The experiment was designed as a factorial experiment, considering two main factors: nitrogen forms (calcium nitrate and ammonium sulfate) with a fixed nitrogen concentration of 5 mM, and the oxygen levels of the nutrient solutions (ranging from 1.8 ± 0.2 to 5.3 ± 0.2 mg. L-1). RESULTS: The study examined the effects of nitrogen (NH4+ and NO3-) application on various parameters of vegetative growth. The results demonstrated that the use of ammonium (NH4+) led to a reduction in the most measured parameters, including the fresh and dry mass of both the root and shoot, at low O2 concentrations of 1.8 ± 0.2; 2.6 ± 0.2 and 3.8 ± 0.2 mg. L-1. However, an interesting observation was made regarding the impact of oxygen levels on root growth in plants grown with nitrate (NO3-). Specifically, the highest levels of oxygen significantly increased root growth in NO3--fed plants. Additionally, the application of NH4+ resulted in an increase in chlorophyll concentration in the leaves, particularly when combined with high oxygen levels in the nutrient solution. On the other hand, leaves of plants fed with NO3- exhibited higher photosynthetic rate (A), intrinsic water use efficiency (iWUE), and instantaneous carboxylation efficiency (A/Ci) compared to those fed with NH4+. Furthermore, it was found that NO3--fed plants displayed the highest instantaneous carboxylation efficiency at oxygen levels of 3.8 and 5.3 mg. L-1, while the lowest efficiency was observed at oxygen levels of 1.8 and 2.6 mg. L-1. In contrast, NH4+-grown plants exhibited a higher maximal quantum yield of PSII photochemistry (Fv/Fm), as well as increased variable fluorescence (Fv) and maximum fluorescence (Fm), compared to NO3--grown plants. Interestingly, the NO3--fed plants showed an increase in Fv/Fm, Fv, and Fm with the elevation of oxygen concentration in the nutrient solution up to 5.3 mg. L-1. CONCLUSION: This study showed that, the growth and photosynthesis parameters in bell pepper plants are sensitive to oxygen stress in floating hydroponic culture. Therefore, the oxygen level in the nutrient solution must not be lower than 3.8 and 5.3 mg. L-1 in NH4+ and NO3- -supplied culture media or nutrient solutions, respectively.

Assessing environmental sustainability by combining product service systems and life cycle perspective: A case study of hydroponic urban farming models in India.

Hydroponics technology offers an environmentally sustainable alternative to conventional farming for urban food needs. It attracts technologists, non-farmers, retailers, restaurants, and consumers. However, the environmental impact of hydroponics-based urban farming models is yet to be quantified. This study assesses the environmental impact of hydroponics-based urban farming models and makes suggestions to improve their adoption. The methodology involves the use of the Product-Service Systems perspective to categorise the hydroponics-based urban farming models and the Life Cycle Assessment (LCA) method to quantify their environmental impact from a cradle-to-gate perspective. The analysis focuses on the lettuce crop in the state of Tamil Nadu, India. The results from the study suggest that that greenhouse farming (BM1) is more environmentally sustainable than indoor farming (BM2), Cabinet selling and remote monitoring (BM3), and conventional farming. It outperforms other models in terms of GHG emissions, Human Toxicity, and fossil fuels per unit of product, with BM3 having high environmental impacts.

Nano-elicitation and hydroponics: a synergism to enhance plant productivity and secondary metabolism.

MAIN CONCLUSION: This review has explored the importance of using a synergistic approach of nano-elicitation and hydroponics to improve plant growth and metabolite production. Furthermore, it emphasizes the significance of green nanotechnology and eco-friendly practices while utilizing this approach to promote the development of a sustainable agriculture system. Nano-elicitation stimulates metabolic processes in plants using nanoparticles (NPs) as elicitors. The stimulation of these biochemical processes can enhance plant yield and productivity, along with the production of secondary metabolites. Nanoparticles have garnered the attention of scientific community because of their unique characteristics, such as incredibly small size and large surface-to-volume ratio, which make them effective elicitors. Hydroponic systems, which optimize growing conditions to increase plant production, are typically used to study the effect of elicitors. By integrating these two approaches, the qualitative and quantitative output of plants can be increased while employing minimal resources. As the global demand for high-quality crops and bioactive compounds surges, embracing this synergistic approach alongside sustainable farming practices can pave the way for resilient agricultural systems, ensuring food security and fostering an eco-friendly environment.

Measuring Bacterial Colonization on Arabidopsis thaliana Roots in Hydroponic Condition.

Measuring bacterial colonization on Arabidopsis thaliana root is one of the most frequent experiments in plant-microbe interaction studies. A standardized method for measuring bacterial colonization in the rhizosphere is necessary to improve reproducibility. We first cultured sterile A.thaliana in hydroponic conditions and then inoculated the bacterial cells in the rhizosphere at a final concentration of OD600 of 0.01. At 2 days post-inoculation, the root tissue was harvested and washed three times in sterile water to remove the uncolonized bacterial cells. The roots were then weighed, and the bacterial cells colonized on the root were collected by vortex. The cell suspension was diluted in a gradient with a phosphate-buffered saline (PBS) buffer, followed by plating onto a Luria-Bertani (LB) agar medium. The plates were incubated at 37 °C for 10 h, and then, the single colonies on LB plates were counted and normalized to indicate the bacterial cells colonized on roots. This method is used to detect bacterial colonization in the rhizosphere in mono-interaction conditions, with good reproducibility.

Exploring Trachyspermum ammi and Foeniculum vulgare in Hydroponic System and Compare its Chemical Constituents with Soil-Based Method: A Prospective in Agriculture.

BACKGROUND: The forthcoming problems will be of food, and soil due to environmental alteration, growing populations, pollution, and exhaustion of natural resources among other factors. Hydroponic farming has the capacity to alleviate the intimidation of these con-cerned issues in the agricultural system. Hydroponics is recommended as an alternative way to enhance product yield compared to conventional agriculture. OBJECTIVE: The present study aimed to determine the different growth parameters and constituents of soil-grown and hydroponically grown Trachyspermum ammi and Foeniculum vulgare for the first time, which could be a patentable in future. METHODS: In this study, extraction was carried out by maceration method using methanol as a solvent whereas, growth parameters were performed by the leaves number, plant height, and leaf area. Chlorophyll content was also performed in both sources. Further, a comparison of chemical constituents from different sources was analyzed by GC-MS. RESULTS: The bioactive components in hydroponically grown T. ammi were found more as compared to soil-grown T. ammi. The GC-MS analysis revealed the presence of various compounds in the methanolic extract of plant materials. CONCLUSION: Hence, hydroponics could be an alternative in agriculture and this system is now accepted globally. This method provides diverse perspectives for farmers to harvest high-yield, better quality, and enhanced bioactive compounds.

Cyanobacteria Based Nanoformulation of Biogenic CuO Nanoparticles for Plant Growth Promotion of Rice Under Hydroponics Conditions.

Synthesizing nanoparticles through a green synthesis approach is common nowadays. Cyanobacteria have attained great importance in the field of biosynthesis of nanoparticles as there is no use of toxic chemicals as reducing or capping agents for the synthesis of metal oxide nanoparticles. Micronutrient-based nano-formulations have become a topic of great interest in recent times due to their various advantageous properties and applications in agriculture. The current study aims to exploit the potential cyanobacterial strains isolated from different locations such as freshwater and soil ecosystems. The potential cyanobacterial isolates were screened based on their multiple plant growth promoting (PGP) attributes such as Indol acetic acid (IAA) production, siderophores, and phosphate solubilization. After the screening of cyanobacteria based on multiple PGP activities, the cyanobacterial strain was identified at the species level as Pseudanabaena foetida RJ1, based on microscopy and molecular characterization using 16S rRNA gene sequencing. The cyanobacterial biomass extract and cell-free extracts are utilized for the synthesis of CuO micronutrient Nanoparticles (NPs). The cyanobacterial strain Pseudanabaena foetida RJ1 possesses plant growth-promoting (PGP) attributes that provide reduction and capping for CuO NPs. The synthesized NPs were characterized and subjected to make a nano-formulation, utilizing the cyanobacteria-mediated CuO NPs along with low-cost zeolite as an adsorbent. The application of cyanobacterial biomass extract and cell-free extract provided an excellent comparative aspect in terms of micronutrient NP synthesis. The NPs in the form of formulations were applied to germinated paddy seeds (Pusa Basmati -1509) with varying concentrations (5, 10, 15 mg/l). Effects of cyanobacteria based CuO NPs on hydroponically grown paddy crops were analyzed. The application of nano-formulations has shown a significant increase in plant growth promotion in rice plants under hydroponics conditions. There is no such type of comparative investigation reported earlier, and NPs of micronutrients can be utilized as a new economic nanofertilizer and can be applied to plants for their growth promotion.

Comparative uptake, translocation and metabolism of phenamacril in crops under hydroponic and soil cultivation conditions.

Many studies investigate the plant uptake and metabolism of xenobiotics by hydroponic experiments, however, plants grown in different conditions (hydroponic vs. soil) may result in different behaviors. To explore the potential differences, a comparative study on the uptake, translocation and metabolism of the fungicide phenamacril in crops (wheat/rice) under hydroponic and soil cultivation conditions was conducted. During 7-14 days of exposure, the translocation factors (TFs) of phenamacril were greatly overestimated in hydroponic-wheat (3.6-5.2) than those in soil-wheat systems (1.1-2.0), with up to 3.3 times of difference between the two cultivation systems, implying it should be cautious to extrapolate the results obtained from hydroponic to field conditions. M-144 was formed in soil pore water (19.1-29.9 µg/L) in soil-wheat systems but not in the hydroponic solution in hydroponics; M-232 was only formed in wheat shoots (89.7-103.0 µg/kg) under soil cultivation conditions, however, it was detected in hydroponic solution (20.1-21.2 µg/L), wheat roots (146.8-166.0 µg/kg), and shoots (239.2-348.1 µg/kg) under hydroponic conditions. The root concentration factors (RCFs) and TFs of phenamacril in rice were up to 2.4 and 3.6 times higher than that in wheat for 28 days of the hydroponic exposure, respectively. These results highlighted that cultivation conditions and plant species could influence the fate of pesticides in crops, which should be considered to better assess the potential accumulation and transformation of pesticides in crops.

Development of a method for the simultaneous determination of ionic nutrients in hydroponic solutions using cation-/anion-exchange chromatography with a neutral eluent.

Nutrient availability in hydroponic solutions must be accurately monitored to maintain crop productivity; however, few cost-effective, accurate, real-time, and long-term monitoring technologies have been developed. In this study, we describe the development and application of cation-/anion-exchange chromatography with a neutral eluent (20-mmol/L sodium formate, pH 7.87) for the simultaneous separation (within 50 min) of ionic nutrients, including K+, NH4+, NO2-, NO3-, and phosphate ion, in a hydroponic fertilizer solution. Using the neutral eluent avoided degradation of the separation column during precipitation of metal ion species, such as hydroxides, with an alkaline eluent and oxidation of NO2- to NO3- with an acidic eluent. The suitability of the current method for monitoring ionic components in a hydroponic fertilizer solution was confirmed. Based on our data, we propose a controlled fertilizer strategy to optimize fertilizer consumption and reduce the chemical load of drained fertilizer solutions.

Biocontrol potential of endophytic Pseudomonas strain IALR1619 against two Pythium species in cucumber and hydroponic lettuce.

The use of fungicides to manage disease has led to multiple environmental externalities, including resistance development, pollution, and non-target mortality. Growers have limited options as legacy chemistry is withdrawn from the market. Moreover, fungicides are generally labeled for traditional soil-based production, and not for liquid culture systems. Biocontrol agents for disease management are a more sustainable and environmentally friendly alternative to conventional agroprotectants. Pythium ultimum is a soil borne oomycete plant pathogen with a broad taxonomic host range exceeding 300 plants. Cucumber seedlings exposed to P. ultimum 1 day after a protective inoculation with bacterial endophyte accession IALR1619 (Pseudomonas sp.) recorded 59% survival; with the control assessed at 18%. When the pathogen was added 5 days post endophyte inoculation, 74% of the seedlings treated survived, compared to 36% of the control, indicating a longer-term effect of IALR1619. Under hydroponic conditions, IALR1619 treated leaf type lettuce cv. 'Cristabel' and Romaine cv. 'Red Rosie' showed 29% and 42% higher shoot fresh weight compared to their controls, respectively. Similar results with less growth decline were observed for a repeat experiment with IALR1619. Additionally, an experiment on hydroponic lettuce in pots with perlite was carried out with a mixture of P. ultimum and P. dissotocum after IALR1619 inoculation. The endophyte treated 'Cristabel' showed fresh weight gain, but the second cultivar 'Pensacola' yielded no increase. In summary, the endophyte IALR1619 provided short term as well as medium-term protection against Pythium blight in cucumber seedlings and may be used as an alternative to conventional fungicides in a greenhouse setting. This study also demonstrated the potential of ALR1619 as a biocontrol agent against Pythium blight in hydroponic lettuce.

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.

Life cycle assessment on marine aquaponic production of shrimp, red orache, minutina and okahajiki.

Aquaponics is an integrated food production system that intensively produces a diverse array of seafood and specialty crops in one closed-loop system, which is a potential solution to global challenges of food security. While current aquaponics systems are commonly operated with freshwater, marine aquaponics is an emerging opportunity to grow saltwater animals and plants. Although marine aquaponics can reduce the dependence on freshwater for food production, its environmental sustainability has not been systematically studied. This paper presents the first life cycle assessment (LCA) on a marine aquaponic production system growing shrimp and three halophytes. The system assessed covered from shrimp larvae nursery to grow-out. The effects of salinity, carbon/nitrogen (C/N) ratio and shrimp-to-plant stocking density ratio of aquaponics on its midpoint and endpoint environmental impacts were evaluated using a functional unit based on the economic value of the four products. Electricity use for aquaponic operation was the environmental hotspot, contributing ∼90 % to all the midpoint impacts. The system produced higher environmental impacts when operated at higher salinity, but lower C/N ratio and stocking density. Replacing fossil fuel with wind power for electricity generation can decrease the environmental impacts by 95-99 %. Variation in the shrimp price can change the impacts by up to 62 %. This study provides a useful tool to help marine aquaponic farmers improve their production from an environmental perspective, and can serve as groundwork for further assessing more marine aquaponic systems with different animal-plant combinations.

Response of leaf photosynthesis, chlorophyll content and yield of hydroponic tomatoes to different water salinity levels.

Tomato (Solanum lycopersicum L.) is an important vegetable crop that grows easily under controlled conditions, such as in greenhouses and hydroponics. To overcome freshwater scarcity, researchers are searching for alternatives to groundwater sources such as desalinated water (saline water) for irrigation. High salinity in irrigation water alters physiological functions and crop development, thereby reducing the yield. Best management practices and the use of grafted tomato plants on salt-tolerant rootstocks can alleviate salinity stress. The present study was conducted to address the impact of salinity stress on leaf transpiration (Tr), stomatal conductance (gs), photosynthesis (Pn), leaf chlorophyll content, proline content, and yield of hydroponically cultivated tomato plants. Saline (NaCl) water was used for the preparation of nutrient solution with three salinity levels, electrical conductivity (EC, dS m-1) of 2.5 (control), 6.0, and 9.5. Three commercial tomato cultivars (Valouro-RZ, Ghandora-F1, and Feisty-Red) were used. Both self-rooted plants and plants grafted onto Maxifort rootstocks were transplanted onto a perlite substrate. The recorded data revealed that all studied cultivars were critically affected by higher salinity (≈ 9.5 dS m-1) compared to low (≈ 2.5 dS m-1) and medium (≈ 6.0 dS m-1) salinity levels. The Variations in Tr, Pn, gs, chlorophyll content of leaf, and yield between medium and high salinity trials were reported at 3%, 5%, 9%, 5%, and 7.1%, respectively, whereas no significant differences were observed between low and medium salinities. However, at medium salinity levels, grafted plants performed better in photosynthesis than non-grafted plants. This is due to the accumulation of leaf proline, which maintains osmotic regulation and photosynthetic activity by preventing cell damage at medium salinities. Hence, this study confirmed the use of saline water for growing tomatoes under hydroponic conditions up to an EC of 6.0 dS m-1 including the EC of nutrient fertilizers.

Hydroponic materials improve organic micropollutant removal in vertical flow constructed wetlands treating wastewater.

Unconventional substrata like activated carbon or clay beads can enhance micropollutant removal in constructed wetlands. However, hydroponic materials widely used in horticulture have not yet been investigated for their potential to remove micropollutants. In addition, potential effect of plant species other than reeds on micropollutant removal has not been sufficiently investigated. Therefore, a nature-based, post-treatment technology called improved vertical flow constructed wetlands (CW) with hydroponic (H) materials (CWH) was designed by employing cocopeat and mineral with ornamental plant species syngonium and periwinkle. A mesocosm CWH system was tested in a climate-controlled greenhouse for 550 days for its potential to remove frequently found micropollutants in wastewater, namely sulfamethoxazole, trimethoprim, diclofenac, erythromycin, carbamazepine, pyrimethanil, tebuconazole, pymetrozine, atrazine and DEET from wastewater effluent. The main focus was to understand the contribution of sorption, microbial degradation and phytoremediation on the removal of those micropollutants. It was found that cocopeat showed a capacity for sorbing micropollutants, ranging between 80 and 99% of the compounds added while less than 10% sorption was observed for mineral wool. Additionally moderate to high biological removal (25-60 µg of compound/kg dry weight of substratum/day) for most of the studied compounds was observed in all the cocopeat biotic groups. Furthermore, it could be stated that plants appear not to be an important factor for micropollutant removal. The observed differences in removal between the cocopeat and mineral wool systems could be explained by the difference in physico-chemical properties of the substrata, where cocopeat has a higher water holding capacity, moisture content, nutrient and organic matter content, and a higher intraparticle porosity and surface area. This study revealed notable removal of persistent and mobile micropollutants in cocopeat CWH, namely carbamazepine (80-86%) and diclofenac (97-100%). These results demonstrate the potential beneficial use of hydroponic materials as substratum in more advanced constructed wetlands designed to remove micropollutants.

Nutrient supply systems and their effect on the performance of the Nile Tilapia (Oreochromis niloticus) and Lettuce (Lactuca sativa) plant integration system.

The main aim of this work is to study the effect of different nutrient supply systems and their effect on the performance of the Nile Tilapia (Oreochromis niloticus) and Lettuce (Lactuca sativa var. crispa) plant integration system. To achieve that, five treatments having different culture systems (T1: Aquaculture (control), T2: Hydroponics (standard requirement: N = 210, P = 31, K = 234, Mg = 48, Ca = 200, S = 64, Fe = 14, Mn = 0.5, Zn = 0.05, B = 0.5, Cu = 0.02 and Mo = 0.01 ppm), T3: Aquaponics without nutrients addition, T4: Aquaponics with supplementary nutrients (KNO3, 101 g L-1, KH2PO4, 136 g L-1, Ca(NO3)2, 236 g L-1, MgSO4, 246 g L-1, K2SO4, 115 g L-1 and chelates for trace elements) in water (EC is 800 ppm) and T5: Aquaponics with supplementary nutrients spray on plants) were carried out. The previous systems were operated at three flow rates, namely, 1.0, 1.5 and 2.0 L h-1 plant-1. The various water quality parameters, plant growth and fish growth were studied. The result indicated that the highest values of N, P, k, Ca and Mg consumption rate were found with T2 and 1.5 L h-1 plant-1 of flow rate. The root length, fresh and dry of shoot and root for lettuce plants grown in T2 system was better than those grown in different culture system (T3, T4 and T5). Different culture systems showed significant effect on fish growth in terms of weight gain, specific growth rate and feed efficiency ratio. Higher growth rate was observed in treatment T3 as compared to other treatments. The production costs ranged from 2820.5 to 4885.4 LE ($ = 30.92 LE) for all culture systems.

Physiological and biochemical characteristics of high and low Cd accumulating Brassica napus genotypes.

Phytoremediation is a widely used and cost-effective technique for in situ remediation of heavy metals. Brassica napus L. genotype with high Cd accumulation and strong Cd tolerance is an ideal candidate for phytoremediation. In this study, a hydroponic experiment was conducted to select a Brassica napus genotype with either high or low Cd accumulation from a panel of 55 genotypes. The physiological mechanisms governing Cd accumulation and Cd tolerance were then explored. BN400 and BN147 were identified as the high and low Cd accumulating genotypes, respectively. Additionally, BN400 exhibited greater tolerance to Cd stress compared to BN147. Root morphology analysis revealed that BN400 exhibited longer root length, smaller root surface area and root volume, and less root tips but bigger root diameter than BN147. Subcellular Cd distribution showed that the Cd concentrations in the cell wall and vacuole in shoot were significantly higher in BN400 than in BN147, whereas the opposite trend was observed in the roots.. Pectate/protein-integrated Cd was found to be the predominant form of Cd in both shoots and roots, with significantly higher levels in BN400 compared to BN147 in the shoot, but the opposite trend was observed in the roots. These results suggest that the long fine roots play a role in Cd accumulation. The high Cd accumulating genotype was able to retain Cd in leaf cell walls and vacuoles, and Cd was mainly present in the form of pectate/protein-integrated Cd, which contributes to its strong Cd tolerance. These findings have important implications for the screening and breeding of Brassica napus genotypes with high Cd accumulation for phytoremediation purposes.

Migration of phosphorus in pig manure during pyrolysis process and slow-release mechanism of biochar in hydroponic application.

Pyrolysis is an effective method for treating of livestock and poultry manure developed in recent years. It can completely decompose pathogens and antibiotics, stabilize heavy metals, and enrich phosphorus (P) in biochar. To elucidate the P migration mechanism under different pig manure pyrolysis temperatures, sequential fractionation, solution 31P nuclear magnetic resonance, X-ray photoelectron spectroscopy, X-ray diffraction, and K-edge X-ray absorption near-edge structure techniques were used to analyze the P species in pig manure biochar (PMB). The results indicated that most of the organic P in the pig manure was converted to inorganic P during pyrolysis. Moreover, the transformation to different P groups pathways was clarified. The phase transition from amorphous to crystalline calcium phosphate was promoted when the temperature was above 600 °C. The content of P extracted by hydrochloric acid, which was the long-term available P for plant uptake, increased significantly. PMB pyrolyzed at 600 °C can be used as a highly effective substitute for P source. It provides the necessary P species (e.g. water-soluble P.) and metal elements for the growth of water spinach plants, and which are slow-release comparing with the Hogland nutrient solution.

Environmental and health values, beliefs, norms and compatibility on intention to adopt hydroponic farming among unemployed youth.

The objective of this study was to examine the relationships among environmental and health values, ecological worldview, perception of consequences, the ascription of responsibility, and personal norms in the context of the value-belief-norm (VBN) model and how compatibility influences the intentions and behaviors of Chinese youth regarding the use of hydroponic farming technology. The study employed a survey questionnaire to collect data from the target population. The sample size was determined through a power analysis to ensure sufficient statistical power for the analysis. A total of 727 potential respondents' responses were analyzed using SmartPLS (4.0) to perform structural equation modeling. The results confirmed that environmental, emotional, and health values significantly associated with individuals' ecological worldviews. There was an interconnection between ecological worldview, awareness of consequences, and ascription of responsibility, and all three significantly influenced personal norms. The key determinants of the intentions and behaviors to adopt hydroponic farming technology are personal norms and technology compatibility. Therefore, to promote and motivate the interest and intention to use hydroponics among unemployed youth, government agencies, and related companies should focus on providing technology-related and pro-environmental information and training. This is expected to increase the acceptance and awareness of hydroponics among this group, thus increasing the adoption rate of hydroponics.

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.

Polyethylene microplastic modulates lettuce root exudates and induces oxidative damage under prolonged hydroponic exposure.

Root exudates are pivotal in plant stress responses, however, the impact of microplastics (MPs) on their release and characteristics remains poorly understood. This study delves into the effects of 0.05 % and 0.1 % (w/w) additions of polyethylene (PE) MPs on the growth and physiological properties of lettuce (Lactuca sativa L.) following 28 days of exposure. The release characteristics of root exudates were assessed using UV-vis and 3D-EEM. The results indicated that PE increased leaf number but did not significantly affect other agronomic traits or pigment contents. Notably, 0.05 % PE increased the total root length and surface area compared to the 0.1 % addition, while a non-significant trend towards decreased root activity was observed with PE MPs. PE MPs with 0.1 % addition notably reduced the DOC concentration in root exudates by 37.5 %, while 0.05 % PE had no impact on DOC and DON concentrations. PE addition increased the SUVA254, SUVA260, and SUVA280 values of root exudates, with the most pronounced effect seen in the 0.05 % PE treatment. This suggests an increase of aromaticity and hydrophobic components induced by PE addition. Fluorescence Regional Integration (FRI) analysis of 3D-EEM revealed that aromatic proteins (region I and II) were dominant in root exudates, with a slight increase in fulvic acid-like substances (region III) under 0.1 % PE addition. Moreover, prolonged PE exposure induced ROS damage in lettuce leaves, evidenced by a significant increase in content and production rate of O2·-. The decrease in CAT and POD activities may account for the lettuce's response to environmental stress, potentially surpassing its tolerance threshold or undergoing adaptive regulation. These findings underscore the potential risk of prolonged exposure to PE MPs on lettuce growth.

Nutrient recovery from wastewater for hydroponic systems: A comparative analysis of fertilizer demand, recovery products, and supply potential of WWTPs.

Nutrient recovery from wastewater treatment plants (WWTPs) for hydroponic cultivation holds promise for closing the nutrient loop and meeting rising food demands. However, most studies focus on solid products for soil-based agriculture, thus raising questions about their suitability for hydroponics. In this study, we address these questions by performing the first in-depth assessment of the extent to which state-of-the-art nutrient recovery processes can generate useful products for hydroponic application. Our results indicate that less than 11.5% of the required nutrients for crops grown hydroponically can currently be recovered. Potassium nitrate (KNO3), calcium nitrate (Ca(NO3)2), and magnesium sulfate (MgSO4), constituting over 75% of the total nutrient demand for hydroponics, cannot be recovered in appropriate form due to their high solubility, hindering their separated recovery from wastewater. To overcome this challenge, we outline a novel nutrient recovery approach that emphasizes the generation of multi-nutrient concentrates specifically designed to meet the requirements of hydroponic cultivation. Based on a theoretical assessment of nutrient and contaminant flows in a typical municipal WWTP, utilizing a steady-state model, we estimated that this novel approach could potentially supply up to 56% of the nutrient requirements of hydroponic systems. Finally, we outline fundamental design requirements for nutrient recovery systems based on this new approach. Achieving these nutrient recovery potentials could be technically feasible through a combination of activated sludge processes for nitrification, membrane-based desalination processes, and selective removal of interfering NaCl. However, given the limited investigation into such treatment trains, further research is essential to explore viable system designs for effective nutrient recovery for hydroponics.