Deep Water Culture Research Articles

Effect of Fluid Mechanics System in Growth of Vegetable Crops using Hydroponics Technique Compared to Conventional System

Hydroponic techniques have major advancements in the recent years compared to Conventional Systems. The flow pattern of fluid used in hydroponic system in a cultivation container affects the growth of plants. Vegetables such as Strawberry, Basil, Cauliflower, Tomato, Spinach and Radish saplings were grown in soil and soilless methods to compare the growth, yield and nutritional value. As for the conventional system, the plants were grown in soil and for hydroponic system Nutrient Film Technique, Deep Water Culture and Wick Systems were used to cultivate plants. On the completion of the growth of the plants, the samples were analysed in laboratory for biochemical analyses. The total yield of Strawberry was 46.5% and tomato with 42.05% in Hydroponics system compared to soil system, whereas in Biochemical analysis Cauliflower gave 10.02% higher results. Chlorophyll content in Basil was observed to be 0.15mg/g and Spinach with 0.04 mg/g which was different from other corresponding results. The commercially harvested root of radish showed a total growth of 22.4 cm in the hydroponic system. The root and shoot lengths had significantly better results in Hydroponic system. Nutritionally, there were not many differences in few aspects whereas the hydroponically grown plants had better qualitative results. It was evident by the obtained results that, the hydroponically grown plants had better results when compared to the plants that were grown conventionally and the fluid flow patterns could also affect the productivity in the hydroponics system.

Automated Hydroponics System

Abstract: The purpose of this study was to control the factors that are responsible for plants growth in hydroponics systems and automate them to reduce the human effort with less space and electricity. In this paper we used a combination of two methods: Deep water culture and Nutrient film technique for the system. In this method plants will have continuous nutrient supply. We used a linear regression method to control EC and pH of the system and the microcontroller will send signals to the system to adjust them to desired value with the help of dozers by taking average EC and pH values.

Growth, Flowering, and Fruit Production of Strawberry ‘Albion’ in Response to Photoperiod and Photosynthetic Photon Flux Density of Sole-Source Lighting

Beyond producing leafy greens, there is a growing interest in strawberry production on indoor vertical farms. Considering that sole-source lighting is one of the most important components for successful indoor crop production, we investigated how photosynthetic photon flux density (PPFD) and the photoperiod of sole-source lighting affected plant growth, flowering, and fruit production in strawberry 'Albion.' Bare-rooted strawberry plants were grown in deep water culture hydroponics inside an indoor vertical farm at 21 °C under white + blue + red light-emitting diodes at a PPFD of 200, 300, or 450 µmol∙m-2∙s-1 with a 12-h or 16-h photoperiod. Under both photoperiods, increasing PPFD from 200 to 450 µmol∙m-2∙s-1 linearly increased crown diameter by 18-64%, shoot fresh and dry mass by 38-80%, and root fresh and dry mass by 19-48%. Under a PPFD ≥ 300 µmol∙m-2∙s-1, root fresh and dry biomass increased by 95-108% and 41-44%, respectively, with an increasing photoperiod from 12 to 16 h. In addition, increasing the photoperiod from 12 to 16 h accelerated flowering by 17-21 days under a PPFD ≥ 300 µmol∙m-2∙s-1 and first fruit harvest by 17 days at a PPFD of 450 µmol∙m-2∙s-1. Regardless of PPFD, strawberry fruit production (g·m-2·month-1) increased by 372-989% under a 16-h photoperiod in comparison to under a 12-h photoperiod. In contrast, there was little effect of PPFD on fruit production. Our results suggest that increasing the PPFD or photoperiod can increase strawberry plant growth, but increasing the photoperiod can have a dominant effect on increasing early fruit production in strawberry 'Albion'.

Irrigation Sources with Chlorine Drinking Water Standard Limits Cause Phytotoxicity on ‘Rex’ Lettuce Grown in Hydroponic Systems

Chlorine is a disinfectant commonly used to treat water. The United States Environmental Protection Agency (USEPA) has set a standard limit of up to 4 mg·L−1 chlorine for drinking water. The objective of this project was to identify chlorine phytotoxicity thresholds on ‘Rex’ lettuce (Lactuca sativa) when the water source contained chlorine levels within the USEPA standard limits. The nutrient solution to grow lettuce was prepared with reverse osmosis–treated water treated with 0, 0.5, 1, 1.5, 2, and 4 mg·L−1 chlorine and then fertilizers were added. Lettuce plants were grown in a deep-water culture hydroponic system. Visual toxicity symptoms on leaves, relative leaf greenness, and fresh and dry biomass were measured. Our results indicate that irrigation water sources with ≥1 mg·L−1 chlorine used to prepare nutrient solutions can cause phytotoxicity in lettuce plants in just 3 days. Compared with the untreated control, lettuce shoot biomass was lower by 30%, 55%, 66%, 83%, and 92% at 0.5, 1, 1.5, 2, and 4 mg·L−1 of chlorine, respectively. Water sources with ≥ 1 mg·L−1 chlorine can cause significant marketable yield reduction in lettuce grown in deep-water culture.

Optimization of an Indoor DWC Hydroponic Lettuce Production System to Generate a Low N and P Content Wastewater

Hydroponic production raises economic and environmental issues related to the treatment, recovery or disposal of hydroponic wastewater, which can be rich in eutrophication-related nutrients, nitrogen (N) and phosphorus (P). Little focus has been put on the influence of the growth conditions on the N and P content in hydroponic wastewater, which is of uttermost importance when it is intended to reuse the wastewater for irrigation or other purposes with reduced impact on the environment. This study aimed to optimize an indoor non-recirculating deep-water culture (DWC) hydroponic system for lettuce (Lactuca sativa L. var. crispa) production, in terms of daily light integral (DLI) and volume of nutrient solution (NS) per plant, to maximize both the biomass production and the N and P removal, allowing for the wastewater to meet the criteria established for reusing in irrigation and minimizing the eutrophication impacts. A small-scale DWC hydroponic system with a fluorescent light fixture was built to study lettuce growth indoors for 35 days after transplanting (DAT). A first experiment was conducted under 14, 20 or 23 mol m−2 d−1 DLI and with 1.5 or 2 L of NS per plant. A pronounced inner leaf tip burn was observed, regardless of the volume of NS solution used, related to the unventilated conditions under high radiation. Total biomass was similar in all treatments and N and P removal was higher than 95% and 94%, respectively, at 35 DAT. Lettuces grown in 2 L of NS per plant exhibited higher average biomass. A second experiment was performed under 8, 10 or 12 mol m−2 d−1 DLI and with 2 or 3 L of NS per plant, making it possible to achieve healthy biomass at 35 DAT with higher water and light-use efficiency when compared to the first experiment. A DLI of 10 or 12 mol m−2 d−1 with 2 L of NS per plant and a DLI of 12 mol m−2 d−1 with 3 L of NS per plant made it possible to achieve both the best total biomass production and the highest N and P removal from water. Under those conditions, hydroponic wastewater complied with N and P criteria for reuse in irrigation, showing potential to be used as an alternative resource for agriculture and to minimize negative impacts on the environment.

Agronomic Performance and Phytochemical Profile of Lettuce Grown in Anaerobic Dairy Digestate

Anaerobic liquid dairy digestate is a by-product of dairy waste anaerobic digestion from dairy operations and is associated with environmental risks if not handled properly, particularly nutrient leaching losses, water contaminations, and greenhouse gas emissions. We tested the applications of anerobic digestate (AD) as a biofertilizer and water source in greenhouse vegetable production to integrate food production and industry waste management for sustainable environments. We used a deep water culture system to assess the effects of AD effluent alone, inorganic nutrient solution (NS), and a combination of AD and NS on the growth, yield, and phytonutrient profile and heavy metal contamination assessment of hydroponically produced lettuce. Lettuce produced in AD had a lower leaf area, total chlorophyll content, and fresh biomass; however, it displayed significantly higher chicoric acid (200%), chlorogenic acid (67%), luteolin (800%), quercetin-3-O-β-d-glucuronide (378%), quercetin-3-glucoside (200%), quercetin-3-O-(6″-O-malonyl)-β-D-glucoside (1077%), folate (248%), pantothenic acid (200%), total phenolics (111%), total antioxidants (44%), and soluble sugars (253%) compared to control (inorganic feed). The AD-produced lettuce also showed significantly lower heavy metal bioaccumulation risks associated with the human consumption. Based on various results, we may conclude that AD utilization in hydroponics can offer a sustainable solution to harvest a better lettuce yield, higher phytonutrients, and environmental benefits.

Comparison of Energy-use Efficiency for Lettuce Plantation under Nutrient Film Technique and Deep-Water Culture Hydroponic Systems

Energy conservation opportunities in closed plant production systems have been widely discussed, however, a comparison of energy-use efficiency (EUE) for different types of hydroponic systems is lacking. This paper compares the EUE of two different hydroponic systems, namely nutrient film technique (NFT) and deep-water culture (DWC), within an aquaponics facility. The energy is monitored in a controlled environment using artificial lighting and its impact on the growth dynamics of the crops is measured, in this case, on a leafy green crop (Lactuca Sativa L. ‘Little Gem’). Offering better efficiency and reliability, light-emitting diode (LED) irradiation is used with a photosynthetic photon flux (PPF) of 140 µmol·s−1 and a photoperiod of 12-hours. The seeds are then placed in growth chambers, kept at an ambient temperature of 18°C for 21 days. These seedlings are then transplanted in rockwool cubes, followed by placement in NFT or DWC systems in equal numbers. Both systems are illuminated with LED irradiation having a PPF of 200 µmol·s−1. Continuous irradiation with a photoperiod of 16-hours is provided to both systems for 5 weeks. Crop growth parameters, such as leaf count and plant height, are measured in both systems resulting in similar numbers obtained, however, shoot fresh weight, leaf area, and root length are significantly different. Furthermore, the NFT system exhibited an EUE of 31.3 g. kWh−1 and outperformed the DWC system with an EUE of 24.53 g. kWh−1; indicating higher growth and better energy savings associated with NFT systems. These results suggest that NFT systems has a higher potential to offer better energy-use efficiency for producing crops in plant factories and aquaponics facilities.

Prevention of Phytotoxic Effects of Regenerative In Situ Electrochemical Hypochlorination in Recirculating Hydroponic Systems

Recirculating nutrient solutions were treated using dimensionally stable anode (DSA)-based regenerative in situ electrochemical hypochlorination (RisEHc) in a deep water culture hydroponic lettuce (Lactuca sativa) production system. Phytotoxic effects were noted and attributed to the formation of chloramines in treated nutrient solutions containing ammonium. The presence of chloramines resulted in a decrease in overhead biomass by 53% using 2.27 mA/cm2 and 83% with 4.55 mA/cm2. Adding ultraviolet light as a tertiary treatment stage allowed the photodecomposition of chloramines, which prevented phytotoxicity in crops and caused no significant differences in growth between treatments. Furthermore, using a nitrate-based fertilizer also served to prevent phytotoxic effects in crops and showed no significant differences in growth between the control and 4.55 mA/cm2. In addition, it was found that the electrochemical flow cell (EFC) treatment resulted in a 13% increase in shoot biomass using 2.27 mA/cm2. The study demonstrated that phytotoxic effects can be prevented with the use of regenerative in situ hypochlorination through proper management and monitoring techniques in recirculating hydroponic systems.

Effect of inoculation methods of Azospirillum brasilense on growth and yield of lettuce in the hydroponic system

Lettuce (Lactuca sativa L.) is one of the most popular and economically critically leafy vegetable crops in the world. Nevertheless, the existing studies offered information limited on the Azospirillum brasilense effects in this research system makes it necessary to verify the best method of inoculation for these bacteria. Currently, a variety of techniques for producing Lettuce have been investigated, including soilless aeroponic, hydroponic, and deep-water culture systems. Therefore, this study aimed to verify the beneficial effects of inoculation methods of A. brasilense on plant growth and nutrition of two lettuce cultivars grown in the hydroponic system. The study was conducted in a greenhouse with 30% shading at Vietnam National University of Forestry – Dong Nai campus, Trang Bom district, Dong Nai province. A randomized block design with three replicates in a 4 × 2 factorial scheme was used. Four A. brasilense inoculation methods (non-inoculated, foliar application, nutrient solution, and nutrient solution + foliar application) and two lettuce cultivars were evaluated. All inoculation methods improved plant height, shoot fresh and dry mass, fresh leaf yield, and accumulation of potassium, calcium, phosphorus, iron, manganese, and copper. Inoculation via nutrient solution + foliar application of A. brasilense is the most suitable for hydroponic lettuce GR-607 cultivation because it provides greater fresh leaf yield. All inoculation methods increased leaf yield in hydroponic lettuce.

The Comparative Performance of Nutrient-Film Technique and Deep-Water Culture Method of Hydroponics for GREENBOX Technology

The Comparative Performance of Nutrient-Film Technique and Deep-Water Culture Method of Hydroponics for GREENBOX Technology

EVALUATION OF Azospirillum brassilense DOSE RESPONSE ON GROWTH AND YIELD OF MINITUBERS FROM APICAL ROOTED CUTTINGS GROWN IN COCO-PEAT

Potato (Solanum tuberosum L.) is one of the most valuable crops in the world, ranked as the 4th most important food crops after rice, wheat and maize. Currently, a variety of techniques for producing potato minituber have been investigated, including soilless aeroponic, hydroponic and deep-water culture systems. However, minitubers potato production in the greenhouse from apical rooted cutting grown coco-peat under a photoperiod and nutritional - shock system is a new and creative idea. The use of diazotrophic bacteria such as Azospirillum brasilense demonstrates a positive effect on nitrogen availability, a primordial element for the development of this plant. Therefore, this study aimed to evaluate the growth and minitubers yield in a potato cultivar inoculated with A. brasilense at different doses. The experiments were conducted in controlled greenhouse on concrete raising beds with dimensions of 10 m x 1 m x 0.3 m. The study revealed that the concentration of A. brasilense at different doses significantly affected the height growth, leaves growth, leaves area growth, the average number of tubers plant-1, standard tuber and potato seed minituber yield. The treatment applied with A. brasilense at a concentration of 200 mL m-2 after planting gave the highest yield of potato minitubers (277.8 tubers m-2).

무동력 수경재배 장치의 상추 생육과 수확 후 포장에 따른 품질 특성

The research was aimed to improve pre-harvest methods to maintain marketability in postharvest leaf lettuce. In this study, the effect of hydroponics on the growth and post-harvest storage characteristics of ‘Chongchima’ lettuce grown in peat mass medium hydroponic system using a non-powered culture device or deep water culture (DWC) was evaluated. There was no difference in fresh weight, leaf number, SPAD, moisture content, and C/N ratio between peat moss growing medium hydroponic and DWC methods except plant height. It was found that lettuce cultivation by a nonpowered hydroponics method is easier than the existing DWC. The quality parameters, such as fresh weight loss, SPAD value, and general appearance of lettuce were investigated after harvest. There was no significant difference in fresh weight loss and general appearance during storage of lettuce by the hydroponics methods. However, with the increased storage time of SPAD, which is related to chlorophyll content, was slightly higher in peat moss medium hydroponic was than DWC. When crops such as lettuce are grown under favorable conditions without any agronomic abnormalities, it is suggested that post-harvest storage is not significantly affected by peat moss growing medium hydroponic and DWC.

Symbiotic association of microalgae and plants in a deep water culture system.

In this study, microalgae culture (Chlorella vulgaris) and mint seedlings (Mentha spp.) were combined in a hydroponic system to improve plant growth. Mint seedlings were grown both in microalgae-containing and in microalgae-free trial groups, and both groups were subjected to aerated and non-aerated conditions to show the effect of aeration and microalgae co-cultivation on the mint weight and height. The plant quality was also determined with color measurements of the mint leaves. The increase in the weight of the plants was the highest in microalgae-containing and aerated group (0.47 g) and the lowest in microalgae-free and non-aerated group (0.22 g). On the other hand, the variation in the plant height was not significant between the groups, the growth was lateral. The best quality mint leaves were also produced in microalgae-containing and aerated group. Our results have revealed the symbiotic life of the mint plant placed in the hydroponic system with microalgae and demonstrated improved mint growth and quality. This co-cultivation system is also potentially more environmentally friendly compared to growing microalgae and mint independently because of lower cost of aeration and mixing for microalgae cultivation, higher nutrient consumption efficiency, and reduced nutrient outflow.

The effect of different ammonium to nitrate ratios on antioxidant activity, morpho-physiological and phytochemical traits of Moldavian balm (Dracocephalum moldavica)

Improving yield and secondary metabolites production of medicinal plants through nutrition management recently has been considered. The present study was done to determine the effects of different ammonium (NH4+) to nitrate (NO3−) ratios (100:0, 75:25, 50:50, 25:75, 0:100) on morphophysiological, nutrient contents (N, P, K, Ca, and Mg), phenolic compounds (Total phenolics (TPC) and flavonoid (TFC) contents and individual phenolics including chlorogenic acid, rosmarinic acid, gallic acid, cinnamic acid, caffeic acid, rutin, p-Coumaric acid, apigenin, and quercetin by HPLC–DAD), essential oil composition (by GC and GC–MS), and antioxidant capacity (by DPPH and FRAP assays) of Moldavian balm (Dracocephalum moldavica L.) in deep water culture (DWC) system. The highest biomass and morphological traits values of D. moldavica observed in 0:100 ratio of NH4+:NO3−. Also, the highest TPC and TFC was earned in plants that supplied with 0:100 ratio of NH4+:NO3−. Using the 25:75 ratio of NH4+:NO3− caused the highest nutrient contents (N, Ca and Mg) in the leaves. p-Coumaric acid was detected as the major abundant phenolic compound in extracts and the application of 75:25 ratio of NH4+:NO3 resulted in the highest amounts of p-Coumaric acid, gallic acid, rosmarinic acid, caffeic acid, quercetin, and rutin. The highest antioxidant capacity by both FRAP and DPPH assays was obtained in 75:25 ratio of NH4+:NO3−. Also, the highest geranial and geranyl acetate, geraniol, and neral were obtained in 75:25, 25:75, and 50:50 ratios of NH4+:NO3−, respectively. Plants supplied with the 0:100 ratio of NH4+:NO3−, had the highest total carotenoids, while the highest chlorophyll a and b content gained with 75:25 ratio of NH4+:NO3−. These results suggest that the management of N source in nutrient recipe could contribute to enhance of morphophysiological traits, antioxidant activity and phytochemical compounds in Moldavian balm.

Influence of calcium macronutrient on tip burn occurrence in hydroponically cultivated lettuces

Tip burn in hydroponics lettuce is an undesirable phenomenon identified by necrotic breakdown of marginal tissue of leaves. A deep-water culture hydroponics system was designed to determine the effect of increasing nutritional calcium concentration and varying nutritional calcium sources in alleviating the tip burn development for the hydroponics growth of lettuce (Lactuca sativa). Lettuces was cultivated separately in an untreated fish wastewater (150mg/L) and four treated fish wastewaters with calcium addition by calcium hydroxide and calcium carbonate to concentrations of 250 and 350mg/L respectively. Increasing calcium concentration from 150 to 350mg/L demonstrated not only an increase in tip burn incidence by 33.33% (calcium carbonate) and 50% (calcium hydroxide), but a slower plant growth in comparison with lettuces cultivated at 150mg/L. Besides, lettuces treated by calcium carbonate has greater leaf calcium concentrations by 48.17% at constant calcium concentration, attributed to its high solubility to release more Ca2+ ions in fish wastewater for plant adsorption. Results suggest that the addition of calcium carbonate to fish wastewater for hydroponics cultivation is more suitable for reducing the tip burn occurrence and growth inhibition at concentrations up to 150mg/L.

Crossbreeding Rootstocks Improve Nitrogen Efficiency of Grafted Watermelon by Inducing Leaf Physiological and Root Morphological Responses

This is the first hydroponic study that evaluated the role of the heterotic plant characters of crossbreeding progenies and accessions which were used as rootstock for watermelon (scion) to improve the nitrogen (N) efficiency of this crop by grafting. The target of the research was to evaluate if grafting could enhance the nitrogen efficiency of watermelon through examining the responses of heterotic plant characters of crossbreeding rootstocks in the shoot development at the agronomical stage, root developments at the morphological stage, and leaf growth at various physiological stages. A hydroponic experiment was conducted by using an aerated deep-water culture (DWC) system in a well-equipped growth chamber of Erciyes University’s Plant Physiology Laboratory located at Kayseri, Türkiye. A watermelon cultivar Crimson Tide (CT) was grafted onto watermelon cultivars of Calhoun Gray (CG), Charleston Gray (Cha. G), and accessions of PI 296341 and PI 271769, the crossbreed progenies of Calhoun Gray × PI 296341, Calhoun Gray × PI 271769, and Charleston Gray × PI 296341. Plants were grown in 8 L plastic containers filled continuously with aired stock nutrient solution under two nitrogen (N) doses (low dose N: 0.3 mM unit N, and high dose N: 3.0 mM unit N) in a completely randomized block design (RBD) which was replicated three times, for six weeks. The grafted plants usually showed a higher crop growth performance than the self-grafted control plants, illustrating that nitrogen efficiency was significantly enhanced with respect to rootstocks of crossbreed progenies under a low N dose and high N dose. The N efficiency of grafted watermelon (CT) was improved by the high manifestation of heterosis in some root morphological characters (vigor root development and active root mechanism) of some of the crossbreeding rootstocks (Calhoun Gray × PI 271769) particularly in low-N conditions. Additionally, some of the crossbreeding rootstocks (Charleston Gray × PI 296341) exhibited high heterosis, which led to improving the N efficiency of grafted watermelon (CT) by inducing leaf physiological responses under high N supply. This clearly indicated that heterosis plays a crucial role in exploiting the genetic diversity in the N efficiency of watermelon. Therefore, these heterotic plant traits may be vital for the selection and breeding of nitrogen-efficient rootstocks for both small-scale and large-scale commercial farming in the nearby future.

Using deep water culture as one of the important hydroponic systems for saving water, mineral fertilizers and improving the productivity of lettuce crop

Two experiments was carried out during for two successive seasons of 2020/2021 and 2021/2022 2021at the research farm of National Research Center (NRC) at Nubaryia Region, Al Buhayrah Governorate, Egypt., to Study of the performance of the deep water culture as one of the most important hydroponic systems in comparison with drip irrigation systems in open fields and under greenhouses on productivity, water productivity, fertilization productivity and some quality characteristics of lettuce. The experiment was arranged in a complete randomized block design with three replicates for each cultivar [two cultivars, CHE: CHEROKEE RZ (81-36) and AFI: AFICION RZ (81-82)] in each farming system [three farming systems, (Deep Water Culture (DWC) as hydroponic system, Drip Irrigation in Greenhouse (DIGH) with sandy soils, Drip Irrigation in Open Field (DIOF) with sandy soils)]. The study concluded that, by using the DWC, the vegetative growth characteristics were improved, productivity and water productivity increased, and the quality of the lettuce crop been improved.

Sensory Evaluation of Common Ice Plant (Mesembryanthemum crystallinum L.) in Response to Sodium Chloride Concentration in Hydroponic Nutrient Solution.

Common ice plant (Mesembryanthemum crystallinum L.) is a novel edible plant with a succulent and savory flavor. The plants display prominent epidermal bladder cells (EBCs) on the surface of the leaves that store water and sodium chloride (NaCl). The plants have high nutritional value and are adapted to saline soils. Previous research has determined the impact of NaCl on the growth and mineral content of ice plant, but as NaCl has an impact on a food’s sensory properties, an interesting question is whether saline growth media can affect the plant’s taste and texture, and if this alters consumers’ sensory response to ice plant. The objective of this study was to evaluate the sensory aspects of ice plant, as well as consumer liking in response to increasing NaCl concentration in hydroponic nutrient solution. Four-week-old seedlings of ice plant were transplanted into deep water culture (DWC) hydroponic systems and treated with five NaCl concentrations (0 M [control], 0.05 M, 0.10 M, 0.20 M, and 0.40 M NaCl). Eight-week-old plants (after four weeks of NaCl treatment) were harvested, and the middle leaves of each plant were sampled for consumer testing. A total of 115 participants evaluated various flavor, texture, and appearance aspects of ice plant and provided their liking ratings. The consumers were able to discriminate differences in salt intensity from the plants based on NaCl treatment in the hydroponic nutrient solution. Low NaCl concentrations (0.05–0.10 M) did not have obvious adverse effect on consumer liking, which aligns with the result of previous research that 0.05–0.10 M NaCl could largely stimulate the growth of ice plant. NaCl concentrations higher than 0.20 M are not recommended from both a production and consumer perspective. With increased NaCl level in plant samples, the consumers detected more saltiness, sourness, and fishiness, less green flavor, and similar levels of bitterness and sweetness. NaCl treatment had no effects on leaf appearance and texture, and the consumers’ overall liking was mainly determined by flavor. Overall, ice plant presents some unique attributes (salty and juicy) compared to other edible salad greens; however, consumer awareness of ice plant is very low, and purchase intent is relatively low as well. Consumers picture ice plant being used mainly in salads and in restaurants.

Effect of Nutrient Solution Cooling in Summer and Heating in Winter on the Performance of Baby Leafy Vegetables in Deep-Water Hydroponic Systems

Hydroponics has become a popular production technology for leafy greens in greenhouses. However, year-round production of cool-season leafy greens remains challenging due to costly heating and cooling during winter and summer seasons, depending on location. Therefore, the objective of this study is to investigate the effect of nutrient solution cooling and heating in deep-water hydroponic systems on the performance of several leafy green vegetables. Two experiments of nutrient solution cooling during the summer season and another two experiments of nutrient solution heating during the winter season were conducted in Texas, USA in 2020–2021. Lettuce (Lactuca sativa L.) ‘Bergams Green’ and ‘Red Mist’, Pak Choi (Brassica rapa subsp. chinensis) ‘Purple Magic’ and ‘White Stem’, and spinach (Spinacia oleracea L.) ‘Mandolin’ and ‘Seaside’ were grown in the summer experiments, and only the two lettuce cultivars were grown for the winter experiments. For both cooling and heating studies, six deep-water culture systems were used with two treatments: cooling (23 °C) vs. no cooling, and heating (22 °C) vs. no heating, with three replications in each experiment. In the nutrient solution cooling study, spinach was the most heat-sensitive species, and ‘Mandolin’ was more heat-tolerant than ‘Seaside,’ as evidenced by its lower mortality rate in both experiments. Lettuce and pak choi grew well and solution cooling increased shoot fresh weight in both lettuce cultivars and in ‘White Stem’ pak choi but not in ‘Purple Magic’ pak choi. Conversely, during the winter season, solution heating increased shoot fresh weight of both lettuce cultivars; however, ‘Red Mist’ was more responsive than ‘Bergams Green’ lettuce. These results indicate the potential to increase crop yield by controlling nutrient solution temperature throughout the year, depending on the season. Also, there were genotypic differences in both cooling and heating experiments, indicating that more research is needed to determine the species-dependent and even cultivar-dependent nutrient solution temperature control strategies to achieve optimum year-round production.

Novel strategy for effective utilization of anaerobic digestate as a nutrient medium for crop production in a recirculating deep water culture hydroponics system

Novel strategy for effective utilization of anaerobic digestate as a nutrient medium for crop production in a recirculating deep water culture hydroponics system