Solution Electrical Conductivity Research Articles

Intelligent Rapid Asexual Propagation Technology—A Novel Aeroponics Propagation Approach

Various rapid propagation strategies have been discovered, which has facilitated large-scale plant reproduction and cultivar development. These methods, in many plant species, are used to rapidly generate large quantities (900 mini-tubers/m2) of high-quality propagule (free from contamination) at a relatively low cost in a small space. They are also used for plant preservation. This review article aims to provide potential applications for regeneration and clonal propagation. Plant propagation using advanced agrotechnology, such as aeroponics, is becoming increasingly popular among academics and industrialists. The advancement of asexual aeroponic propagation has been achieved through advancements in monitoring and control systems using IoT and smart sensor technology. New sensor technology systems have gained substantial interest in agriculture in recent years. It is used in agriculture to precisely arrange various operations and objectives while harnessing limited resources with minimal human intervention. Modern intelligent technologies and control systems simplify sensor data collection, making it more efficient than manual data collection, which can be slow and prone to errors. Specific ambient variables like temperature, humidity, light intensity, stock solution concentrations (nutrient water), EC (electrical conductivity), pH values, CO2 content, and atomization parameters (frequency and interval) are collected more effectively through these systems. The use of intelligent technologies provides complete control over the system. When combined with IoT, it aids in boosting crop quality and yield while also lowering production costs and providing data directly to tablets and smartphones in aeroponic propagation systems. It can potentially increase the system’s productivity and usefulness compared to the older manual monitoring and operating methods.

Physiological Responses of Different Aged Rice Seeds to Osmopriming with PEG 6000

The objective of this research was to compare the quality of different aged rice seed after priming. The rice seeds were deteriorated by accelerated aging method at 44 °C and relative humidity 100 %, in different periods for 0 (without accelerated aging), 1, 2, 3, and 4 days. Then, the germination of rice seeds of different ages were induced by soaking in 30% of PEG 6000 solution at room temperature for 24 hours. After that, the rice seeds were dried in a hot air oven at 35 °C for 10 hours until the moisture content was close to the initial moisture. Finally, these treated rice seeds were examined for the seed quality of various characteristics such as seed germination rate (planted in the laboratory and field conditions), germination index, speed of germination, and electrical conductivity of solution used for soaking seeds. The results showed that the electrical conductivity of all different aged seeds decreased after priming. For the field of germination and germination uniformity, it was found that the seeds with different rates of deterioration showed different responses to the priming. Aged seeds with germination rates of 12 and 33 percent germination were able to induce germination rate by 27 and 48 percent, respectively, while aged seeds with higher deterioration rate had a decreased response.

Synthesis of a Hybrid Membrane of Polysulfone with Zinc Oxide for Cleaning Textile Effluents.

This study aimed to investigate the influence of the ZnO concentration on the structure of a membrane for effluent filtration, varying this concentration from 0% to 3%. To analyze the results, X-ray diffraction tests, Fourier-transform infrared spectroscopy, apparent porosity, atomic force microscopy, and scanning electron microscopy were used, all of which were employed for the characterization of the produced membranes. The solution simulating the effluent was analyzed before and after the filtration process to assess the filtration results. The conducted tests reported results for filtered solution flow, turbidity, pH, dissolved oxygen, and electrical conductivity. All these results indicated that the membrane with the best performance in terms of cleanliness and the amount of filtered effluent was the one produced with a 13% hybrid polysulfone loaded with 1% ZnO in its structure.

Selected Beneficial Microbes Alleviate Salinity Stress in Hydroponic Lettuce and Pak Choi

Hydroponics is widely used in greenhouse and vertical farming production because these facilities can precisely control environmental conditions such as lighting, temperature, and vapor pressure deficit. However, the fertilizer solutions have a short life span, and they often do not have adequate microbial populations to enhance plant growth. Previous studies have shown the potential of beneficial microbes to promote plant production and alleviate abiotic and biotic stressors in the field, and studies on their use in controlled environments such as greenhouses and vertical farms are limited in the literature. In this study, we selected several plant growth promoting microbes (PGPMs) and tested their effects on alleviating salinity stress in ‘Rex’ lettuce (Lactuca sativa) and ‘Red Pac’ pak choi (Brassica chinensis) grown in deep water culture hydroponics. Our goal was to use one stressor, salinity, that induces profound symptoms in plant morphology. A three-cycle study was conducted using five PGPMs [Bacillus, Glomus, Lactobacillus, Trichoderma, and Bacillus/Pseudomonas/Trichoderma (B/P/T) mix] and two salinity levels [no salinity and salinity treatment, with 120 mM, 40 mM, and 80 mM sodium chloride (NaCl) solution used for the first, second, and third cycles, respectively]. We measured the effects of PGPMs and salinity on plant growth and quality and the solution pH and electrical conductivity (EC). Salinity stress decreased lettuce and pak choi leaf area and shoot fresh weight and increased plant leaf chlorophyll and anthocyanin contents with increased solution EC. Under high-salinity stress (120 mM NaCl), the addition of Trichoderma reduced pak choi leaf area and fresh weight but increased solution pH, whereas under low salinity stress (40 mM NaCl), Trichoderma increased pak choi leaf chlorophyll content. Under moderate-salinity stress (80 mM NaCl) condition, the addition of Glomus sp. increased lettuce fresh weight and leaf area, and B/P/T mix increased pak choi leaf area. In conclusion, using the selected PGPMs in low to moderate-salinity stress could increase lettuce and pak choi growth and quality parameters. These results have some practical applications in the future when more saline water is used for production.

Morphological and Physiological Responses of Two Penstemon Species to Saline Water Irrigation

Penstemon, with more than 250 species native to North America, holds significant aesthetic and ecological value in Utah, supporting diverse pollinators. Despite their significance, the survival of penstemon is threatened by challenges such as habitat loss, climate change, and Utah’s naturally high soil salinity. To address these challenges and understand their adaptability, this study evaluated the salt tolerance of two penstemon species [Penstemon davidsonii (Davidson’s penstemon) and Penstemon heterophyllus (foothill penstemon)] under controlled greenhouse conditions. The aim was to develop baseline information for nursery production and landscape use that utilize reclaimed water for irrigation. Plants were irrigated weekly with a nutrient solution at an electrical conductivity (EC) of 1.0 dS·m−1 as control or a saline solution at an EC of 2.5, 5.0, 7.5, or 10.0 dS·m−1 for 8 weeks. Half of the plants were harvested after four irrigation events, and the remaining plants were harvested after eight irrigation events. At harvest, visual rating (0 = dead and 5 = excellent without foliage salt damage), plant width, number of shoots, leaf area, shoot dry weight, leaf greenness [Soil Plant Analysis Development (SPAD)], stomatal conductance, and canopy temperature were collected to assess the impact of salinity stress. In both species, salt damage was dependent on the salinity levels and length of exposure. After four irrigation events, both species exhibited foliage damage that increased in severity with rising EC. The most severe damage was observed in plants receiving saline solution at an EC of 10.0 dS·m−1. After eight irrigation events, P. davidsonii exposed to a saline solution with an EC of 10.0 dS·m−1 received a visual rating of 0, whereas P. heterophyllus had a visual rating of 0.4. Both species exhibited salinity-induced effects, with variations observed in the specific parameters and the degree of response. Penstemon davidsonii exhibited significant salinity stress, as indicated by reduced leaf area, shoot dry weight, SPAD reading, and stomatal conductance with increasing EC of the saline solution. In addition, in both species, at both harvests, canopy temperatures increased either linearly or quadratically by 8% to 36% as the EC levels of the saline solution increased. These results indicate that P. davidsonii was more sensitive to salinity stress than P. heterophyllus.

Reduced fertigation input sustains yield and physiological performance for improved economic returns and cleaner production of greenhouse eggplant

Greenhouse horticulture, a sustainable alternative to conventional horticulture, maximises resource use and return for vegetable production. This study evaluated the impact of varying nutrient solution electrical conductivity (EC) levels (EC 1.8, 2.8, and 3.8) on eggplant cultivars (Solanum melongena L. cv. Lydia, and Tracey) performance and economic viability in high-tech glasshouses. We found that morphological traits such as plant height and leaf number were consistent across EC levels, while fruit weight, length, and width are significantly higher at the lowest EC (1.8). Photosynthetic rates increased significantly with rising EC levels, while other gas exchange parameters such as stomatal conductance, intrinsic water use efficiency, and vapour pressure deficit were similar for all EC levels tested. Yield analysis revealed a negative correlation between eggplant yield and increasing EC levels, with optimal yields in both eggplant varieties (0.81 and 1.14 kg m−2 week−1 in Lydia and Tracey, respectively) achieved at the lowest EC. Economic analysis highlighted that lower EC levels lead to lower operational costs and higher net profit values (NPV). Sensitivity analysis underscored the importance of wholesale price and crop yield in determining NPV, with lower EC levels offering a shorter payback period of approximately 6 years in Australia and China and higher economic returns. The study highlights the significance of optimizing EC levels for achieving more resource-sustainable and profitable eggplant production in greenhouses.

Exploring the potential of stable isotope methods for identifying the origin of CO2 in the carbonation process of cementitious materials within the carbon capture and storage environment

This study investigates the potential of stable isotope (δ13C) methods for exploring the carbonation process of cementitious materials, including well cement paste, portlandite (CH), and calcium silicate hydrate (C–S–H). Through comprehensive chemical and isotopic characterization, along with extensive data analysis, several key conclusions emerge. Firstly, the pH of the solution, as well as the solubility and pH characteristics of mineral phases (CH and C–S–H), are identified as influential factors impacting the kinetics, thermodynamics, and distribution of carbon isotopes (12C and 13C) during the reaction process. Secondly, the study uncovered that higher final pH values correlated with a DIC pool enriched with 13C and a higher εDIC-CO2 isotopic enrichment factor (10.7–12.6 ‰). Furthermore, higher levels of DIC content, solution electrical conductivity, and lower pH lead to higher δ13C–CaCO3 and greater εCaCO3-DIC isotope fractionation (−12.9 to −7.5 ‰). These conditions favor the formation of carbonate minerals with higher isotopic signature (δ13C–CaCO3), thus better preserving the δ13C-DIC isotope ratio. It was identified that the carbonate mineral (δ13C–CaCO3) formed through the carbonation of cementitious materials (class G cement, CH, and C–S–H) appears to preserve the isotopic signature of the δ13C–CO2 source. In conclusion, stable isotope methods could be a valuable tool for assessing and monitoring the cement carbonation process in Carbon Capture and Storage (CCS) wells, particularly when it is crucial to distinguish between injected and endogenous CO2.

Reduced Growth in Eustoma under High Nutrient and Phytotoxic Organic Acid Concentrations and Recovery through Hot Water Conditioning of Continuously Cropped Soil

Stunted vegetative growth and delayed or absent flowering are commonly observed in eustoma (Eustoma grandiflorum) when cultivated continuously in the same greenhouse soil. These effects are likely caused by the excessive accumulation of soluble salts and/or phytotoxic organic acids in the soil. This study aimed to clarify the mechanism of continuous cropping obstacles and formulate prevention measures of eustoma. Seedlings of eustoma ‘Croma III White’ were grown hydroponically with 0%, 25%, 50%, 75%, 100% (full), 125%, 150%, 175%, or 200% strength of Johnson’s solution. Plant height, leaf area, and shoot dry weight increased steadily as solution strength increased from 25% to 125% [solution electrical conductivity (EC) of 2.4 dS⋅m−1] and then gradually decreased as solution strength further increased from 125% to 200% (solution EC of 3.8 dS⋅m−1). When grown hydroponically in 200% strength Johnson’s solution, plant height, leaf area, and root length increased with increasing equimolar mixtures of organic acids, including maleic acid, benzoic acid, malic acid, and hydroxybenzoic acid, up to 1.2 to 1.6 mM and decreased thereafter. Node number and the percentage of flower bud visibility declined beyond 1.6 mM organic acid mixtures. Plants with 2.0 and 2.4 mM organic acid mixtures had the lowest net photosynthetic rate, stomatal conductance, transpiration, and intercellular carbon dioxide concentration. Plants had normal growth and produced flower buds when the continuously cropped soil was preconditioned with 100 °C reverse-osmosis water before planting.

ПОЛУЧЕНИЕ НАНОВОЛОКНИСТЫХ МАТЕРИАЛОВ НА ОСНОВЕ АЦЕТАТА ЦЕЛЛЮЛОЗЫ И ПОЛИЭТИЛЕНГЛИКОЛЯ

This article discusses the production of nanofiber nonwoven polymer materials based on cellulose acetate and polyethylene glycol by electrospinning. The influence of the properties of the spinning solution (dynamic viscosity, pH and electrical conductivity) on the production of nanoparticles and polymer nanofibers was shown. Based on the experiments conducted, it was shown that with a ratio of cellulose acetate: polyethylene glycol equal to 1:1, high-quality fibers with an average diameter of 439-448 nm are formed.

Effect of Nutrient Solution Concentration on Growth, Yield, and Fruit Quality of Tomato Grown Hydroponically in Single-Truss Production System

Abstract The single-truss production system for tomatoes (Solanum lycopersicum L.) is a relatively new developed cultivation technology that guarantees high yields and high-quality fruit throughout the annual cycle. In this study, we examined the impact of electrical conductivity (EC) of nutrient solutions on the growth, yield, and fruit quality of tomatoes grown in a single-truss system in a hydroponic culture. Plants were supplied with nutrient solution at the following EC values: 0.8, 1.0, 1.2, and 1.4 mS·cm−1 in the spring and summer cycles, and at 1.0, 1.2, 1.4, and 1.6 mS·cm−1 in the winter cycle. In the spring cycle, the EC of the nutrient solution increased in all treatments, particularly after pinching the main stem. Increased EC values of nutrient solutions were also recorded at the 1.2 and 1.4 EC in the summer cycle and the 1.4 and 1.6 EC in the winter cycle. The leaf number per plant did not differ between treatments in all production cycles. The largest leaf area was found at the 1.2 and 1.4 EC in the spring cycle and the 1.0 and 1.2 EC during the summer. During the winter cycle, no differences in leaf area between treatments were observed. In spring, plants at the 1.2 and 1.4 EC had the highest yields and largest fruits, while during the summer, plants at the 1.0 and 1.2 EC produced the most fruit. In winter, the highest yield was found at the 1.4 EC. The soluble solids concentration (SSC) of fruit was increased at the 1.4 EC both in the spring and summer cycles, while in the winter cycle, there was no difference between the treatments. Only fruit at the 1.4 EC in the summer cycle had an increased acidity. The findings indicate that under greenhouse conditions, tomato cultivation in a single-truss system can be successful if the plants are supplied with a nutrient solution at an EC value of 1.2–1.4 mS·cm−1.

Responses of yield, fruit quality and water relations of sweet pepper in Mediterranean greenhouses to increasing salinity

Increasing salinization of groundwater used for irrigation is a current and growing problem for vegetable production in greenhouses in the Mediterranean Basin. Vegetable growers in this system require clear information of crop response to salinity, particularly of threshold values. For sweet pepper in Mediterranean greenhouses, this work (i) evaluated the effect of increasing salinity on various parameters of crop yield, fruit quality and plant water relations, and (ii) determined threshold and slope values for the Maas and Hoffman (M&H) model. Sweet pepper was grown with nutrient solutions (ns) with electrical conductivities (EC) of 2.5 (T1), 3.5 (T2), 4.5 (T3), 5.5 (T4), 6.5 (T5) and 7.5 (T6) dS m−1. There were substantial and statistically significant reductions in total and marketable yield, dry matter production (DMP) and average fruit weight, with increasing salinity. In treatment T4 (ns of 5.5 dS m−1), the respective reductions for these parameters, compared to T1 (ns of 2.5 dS m−1), were 37%, 37%, 47%, 52% and 30%. Applying the M&H model, soil solution EC threshold (ECsst) values for total and marketable yield were 4.8 and 5.0 dS m−1. The respective slope values were − 8.0 and − 12.0%/dS m−1. The more rapid decline in marketable yield was influenced by a large increase in the incidence of blossom end rot (BER) with increasing salinity. In treatment T1, 25% of discarded fruit had BER which increased to 70% in T6. Average fruit size was affected by salinity, but fruit number was not. Most fruit quality parameters were unaffected by increasing salinity. However, fruits were more red and more yellow. Leaf water potential (ΨW), leaf osmotic potential (ΨO), stomatal conductance (gS) and leaf turgor potential (ΨP) followed the Maas and Hoffman model, with ΨW, ΨO and gS declining and ΨP increasing after the EC threshold value. The ECsst value for ΨW was 5.0 dS m−1, and for ΨO, gS and ΨP was 5.6–5.8 dS m−1. Considering all data, an ECsst value of 5.0 dS m−1 is suggested for sweet pepper grown in Mediterranean greenhouses.

Assessing Soil Dynamics and Improving Long-Standing Irrigation Management with Treated Wastewater: A Case Study on Citrus Trees in Palestine

Irrigation with Treated Wastewater (TWW) is a well-known agricultural practice in Palestine. The long-term use of irrigation with TWW, a source of water and nutrients, can affect plant development, soil, and groundwater quality. Consequently, the frequency and the intervals of irrigation events should be adequately scheduled, especially when nutrients (TWW-N) cannot be separated from the water. Achieving good water quality implies its immediate reuse in irrigated agriculture. In contrast, long-term soil and groundwater quality conservation is marked by the complex mechanisms that correlate the soil, water, plant, and atmosphere. Therefore, monitoring and modeling (MMA) are combined to retrieve the soil water and nitrate fluxes and identify a proper irrigation management plan in a case study in Beit Dajan-Palestine, where a schedule adapted to conventional water was applied to a 6-year-old citrus orchard continuously irrigated with TWW. Soil nitrogen concentration and water content data were collected from March to August 2021 to calibrate the Hydrus-1D model under the (1) farmer demand (F) scenario, where irrigation volumes are delivered according to the farmer experience, and to define an optimal irrigation management strategy with TWW according to the (2) model demand (M) scenario, based on the irrigation frequency. The latter respects the allowable thresholds of soil solution electrical conductivity, σe, assuming an average soil salinity profile and estimated leaf nitrogen concentrations tolerance as reference; 2021 was taken as a calibration year to retrieve water and nitrate fluxes for 2019 and 2020. In 2021, the measured soil electrical conductivity, σe, showed no salinity risk with an average value of 1.07 dS m−1 (low salinity < 2 dS m−1) but with a leaf nitrogen deficit. Although an acceptable level of available soil nitrogen was observed (ranging between 10 and 35 mg kg−1, whereas the standard value is 10–40 mg kg−1), critical concentrations were observed in the leaves (below 1%) in scenario (F) compared to scenario (M) (ranging between 1.7 and 1.9%). The latter also showed a decrease in nitrate leaching by 33% compared to the former. Overall, the comparison between the simulated and measured soil variables shows that the 1D-Hydrus model could follow the temporal variation in the monitored data, with some overestimation of the measured data during the simulation period. The simulations demonstrate that by modulating the salt tolerance threshold, the M scenario achieved better results in terms of root water and N uptake despite the stress inevitably experienced by citrus with long-term TWW irrigation. Moreover, the optimum threshold values used to assess the soil quality and citrus response under conventional water irrigation were inadequate for TWW practices. Therefore, MMA could be an alternative strategy to schedule proper TWW irrigation.

In searching of optimum electrospray ionization using both spray image and electric current measurement

Electrospray image and spray electric current measurement were used to experimentally characterize the optimum operating condition of the electrospray ionization process under different operating conditions, including electrospray flow rate (Q), solution electric conductivity (k) and the organic solvent content in the sample solution (Ro). It was first observed that a special cone-jet mode electrospray with extremely high stability could be obtained when the electrospray voltage was operated in a specific range (the optimum voltage range). In this mode, the spray current remains independent of spray voltage and the angle of electrospray (the optimum spray angle) was much larger than the ones in other modes of electrospray. The experimental results also showed that the optimum voltage range was dependent on multiple factors. The average value of the optimum voltage range (the optimum voltage) increased slightly as Q was increased and decreased significantly as Ro was increased. In addition, the optimum voltage would increase initially with the increase of k and become essentially independent of k at a sufficiently high solution electric conductivity. In contrast to a rather complicated parametric dependence of the optimum voltage range, the optimum spray angle was found to only depend on Q. It would increase initially as the increase of Q and remain to be constant when Q was higher than a specific value. The experimental results in this study allow one to maintain an optimum electrospray ionization under different operating conditions as required by the actual method of mass spectrometry analysis.

Nutrient Solution Electrical Conductivity Affects Yield and Growth of Sub-Irrigated Tomatoes

Sub-irrigation of greenhouse crops has the potential to increase water and nutrient use efficiency; however, fertilizer salts that are not absorbed by the plants tend to accumulate in the substrate and eventually raise the substrate’s electrical conductivity (EC). The objective of this study was to determine the optimum EC of the nutrient solution in sub-irrigated tomatoes to allow maximum yield. Total fruit yield was higher in sub-irrigated plants with solutions at 2.0 dS m−1 (5105 g per plant), and it was comparable to that obtained for drip-irrigated plants (4903 g per plant); however, the yield of fruits from the second truss was 37% higher in sub-irrigated than in drip-irrigated plants when the EC was 2.0 dS m−1. In contrast, at the end of the growing season, the yield of plants sub-irrigated with nutrient solutions of 2.0 dS m−1 was the lowest, being surpassed by 37% by that of plants treated with 1.4 dS m−1. The dry weight of vegetative plant parts was reduced in sub-irrigated plants, suggesting a shift in dry mass partitioning. Our results show that with sub-irrigation, the growing season should be started using nutrient solutions with higher EC, but eventually, this EC should be decreased to maintain proper substrate EC and high yield.

Improving Production Yield and Nutritional Quality of Coastal Glehnia Using Developed Hydroponic Nutrient Solution in Controlled Environment Agriculture

This study was conducted to develop a nutrient solution for coastal glehnia, evaluate the performance of the newly developed nutrient solution, and determine an adequate electrical conductivity (EC) level for growth and bioactive compounds production in controlled environment agriculture (CEA). Coastal glehnia plants cultivated in Hoagland nutrient solution with EC 1, 2, 3, 4, and 5 dS·m−1 for 20 weeks had the same ratio of cations and anions in terms of macro essential elements. Based on the ratio, a new nutrient solution for coastal glehnia was developed. Subsequently, seedlings with two main leaves were grown in Hoagland nutrient solution (H1 and H2; EC 1 and 2 dS·m−1) or a newly developed nutrient solution (N1–5; EC 1–5 dS·m−1) for 23 weeks (about 6 months), and the leaves were harvested every 5 weeks. The N1 treatment resulted in significantly higher accumulated and average shoot fresh and dry weights than in the H1 and H2 treatments. In addition, the total phenolic content and antioxidant capacity per shoot were the highest under the N1 treatment. Individual bioactive compounds, such as xanthotoxin, bergapten, and imperatorin, levels per shoot with the N1 treatment were significantly higher than those with the H1 and H2 treatments. These results demonstrate that the newly developed nutrient solution of EC 1 dS·m−1 increases the biomass and bioactive compound levels of coastal glehnia and is suitable for cultivating coastal glehnia in CEA, such as vertical farms and greenhouses.

A Graminaceae-derived protein hydrolysate and its fractions provide differential growth and modulate qualitative traits of lettuce grown under non-saline and mild salinity conditions

The modulation of plant secondary metabolism by the manipulation of nutrient solution (NS) electrical conductivity and biostimulant application has the potential to increase crop growth and the content of bioactive compounds, thus ameliorating the qualitative attributes of vegetables. A Graminaceae-derived protein hydrolysate (pH) and its molecular fractions PH1 (>10 kDa), PH2 (1 < x <10 kDa) and PH3 (<1 kDa) were applied on lettuce grown in a soilless system and irrigated with two levels of NaCl in the NS (0 and 30 mM). The different pH fractions provided distinct responses, with PH2 in saline conditions increasing lettuce fresh weight by 10.48%, and decreased Na, Cl, malate and citrate concentrations in the leaves by 37.24%, 15.45%,31.4% and 33.73% compared to control. Similar results were achieved by the fraction PH3. However, pH and its fractions PH2 and PH3 increased total flavonoids in salinity conditions, while pH and its fraction PH3 increased total phenolic acids in both saline and non-saline conditions. At the same time, all the 3 fractions of pH increased lutein in both conditions. Therefore, pH fractions should be casted, under tailored conditions, to achieve the desired growth and modulation of qualitative attributes. Nonetheless, omic approaches should be further recommended to support and clarify the mechanisms of these fractions.

Phenylalanine Losses in Neutralization Dialysis: Modeling and Experiment.

A non-steady state mathematical model of an amino acid (phenylalanine (Phe)) and mineral salt (NaCl) solution separation by neutralization dialysis (ND) carried out in a batch mode is proposed. The model takes into account the characteristics of membranes (thickness, ion-exchange capacity, and conductivity) and solutions (concentration, composition). As compared to previously developed models, the new one considers the local equilibrium of Phe protolysis reactions in solutions and membranes and the transport of all the phenylalanine forms (zwitterionic, positively and negatively charged) through membranes. A series of experiments on ND demineralization of the NaCl and Phe mixed solution was carried out. In order to minimize Phe losses, the solution pH in the desalination compartment was controlled by changing the concentrations of the solutions in the acid and alkali compartments of the ND cell. The validity of the model was verified by comparison of simulated and experimental time dependencies of solution electrical conductivity and pH, as well as the concentration of Na+, Cl- ions, and Phe species in the desalination compartment. Based on the simulation results, the role of Phe transport mechanisms in the losses of this amino acid during ND was discussed. In the experiments carried out, the demineralization rate reached 90%, accompanied by minimal Phe losses of about 16%. Modeling predicts a steep increase in Phe losses when the demineralization rate is higher than 95%. Nevertheless, simulations show that it is possible to achieve a highly demineralized solution (by 99.9%) with Phe losses amounting to 42%.

Effects of LED Red and Blue Spectra Irradiance Levels and Nutrient Solution EC on the Growth, Yield, and Phenolic Content of Lemon Basil (Ocimum citriodurum Vis.)

This research was conducted to study the effects of LED red and blue spectra irradiance levels and nutrient solution (electrical conductivity) and their interaction on the plant growth, yield, and phytochemical contents of lemon basil (Ocimum citriodorum Vis.) in a controlled environment. The controlled environment was equipped with red and blue spectra at a 4:1 ratio with irradiance levels of 80 and 160 µmol m−2 s−1 and irrigated with four different nutrient solution ECs at 1.0, 1.8, 2.6, and 3.4 mS cm−1, cultivated on a vertical structure. The temperature and relative humidity of the controlled environment and the pH of the nutrient solution were maintained at 26 and 18 °C day and night, 65 ± 5%, and pH 6, respectively. It was observed that plant height, canopy diameter, and the number of leaves of lemon basil had significantly increased under the irradiance levels of 160 µmol m−2 s−1 in combination with a nutrient solution EC of 2.6 mS cm−1. In addition, there was an interaction observed between the LED irradiance levels and the nutrient solution EC on the fresh weight of the stem and the dry weight of all the plant parts (leaves, stem, and roots). Lemon basil cultivated at 160 µmol m−2 s−1 and irrigated with 2.6 mS cm−1 was significantly higher in fresh stem weight and dry leaf, stem, and root weight at 17.36, 1.79, 1.82, and 0.22 g, respectively. The ascorbic acid of lemon basil was significantly higher under a treatment of 160 µmol m−2 s−1 irradiance level and an EC of 2.6 mS cm−1, and no interaction was observed. At the same time, there was an interaction observed between the LED irradiance level and the nutrient solution EC on the total phenolic content (TPC), total flavonoid content (TFC), and caftaric acid concentration of lemon basil. Lemon basil cultivated at 160 µmol m−2 s−1 and irrigated with 2.6 mS cm−1 was significantly higher in TPC, TFC, and caftaric acid concentration, with 1440.62 mg gallic acid equivalent to 100 g−1 DW, 1148.79 mg quercetin equivalent to 100 g−1 DW, and 2812.50 mg 100 g−1 DW, respectively. This result indicates that the irradiance levels of red and blue LED spectra at 160 µmol m−2 s−1 and irrigated with a nutrient solution EC of 2.6 mS cm−1 enhances the growth, yield production, and phenolic content of lemon basil in a controlled environment facility.

Study of the dextrose equivalent of maltodextrins in electrospinning using an ethanol/water mixture as the electrospinning solvent

Maltodextrin (MD) is a natural polymer ideal for electrospinning due to its non-toxicity, water solubility, and low viscosity. In this investigation, MD solutions, each containing a different dextrose equivalent (DE) value of 18, 10, and 4, were studied in an ethanol/water solvent system for the manufacture of fibers, and their rheological properties and electrospinnability were evaluated. The viscosity data from the solutions indicated that the entanglement concentration (Ce) was higher in the MD solution with the highest DE value, with a value of 40.02% (w/v). As the concentration of MD in the electrospinning solutions increased, the transition of the beads to a beads–fibers mixture and finally to fibers was observed, this behavior being more notable in MD18. To obtain well-formed MD fibers, the optimum concentrations of MD18 and MD10 were found to be 1.30 and 1.22 times the Ce, respectively. Smooth, continuous fibers without beads and diameters of 627.52 ± 146.12 nm and 748.20 ± 256.48 nm, respectively, were produced, while in the MD solution with DE 4, a cluster of short fibers with a diameter of 620.23 ± 167.09 nm was observed. The electrical conductivity significantly influenced the diameter of the fibers, and it was apparent that as the concentration of MD increased, the solution's electrical conductivity decreased. Electrospun MD fibers were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry. This study provides a means of producing MD fibers for use in food applications as vehicles for bioactive compounds.

Effects of amount, electric conductivity, and frequency of a nutrient solution on melon yield and flavor quality

This study aimed to obtain an irrigation strategy for high-quality melon production in a high electric conductivity (EC) value of irrigation areas. The experiment was conducted in Yan'an Shaanxi Province, China, from August 2020 to October 2020. The effects of different irrigation amounts (W), E (EC of a nutrient solution), and frequencies (F) of a nutrient solution on the yield and flavor quality of the oriental melon cultivar ‘Qingnong Cuibao’ cultivated in plastic bags were investigated. Random forest was used to analyze the aromatic substances of melon in the whole growth period and principal component analysis (PCA) was used to obtain the best treatment for melon yield and aromatic substances. Results showed that the main aromatic substances were ethyl acetate, ethyl butyrate, hexanal, octanal, and 2-nonenal during the growth period of melon. The melon fruit ripening stage was the main period of the accumulation of aromatic substances. The W, E and their interaction had substantial effects on the content of esters and yield (P < 0.05). The W had greater an effect on aromatic substances and yield than E and F. PCA showed that the optimal water and fertilizer strategy was to irrigate 1.68 L/plant nutrient solution with 3.53 mS/cm EC for 7 times one day. The results of this experiment could provide a reference for melon production in irrigation areas with a high E value.