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

With the rising pressures on food security, GREENBOX technology was developed as an avenue for fresh leafy vegetable crop production in urban settings. GREENBOX units were designed to be thermally insulated and climate controlled, with an artificial lighting source that utilized soilless cultivation techniques. Previous studies conducted on GREENBOX technology used the Nutrient Film Technique (NFT);however, various hydroponic methods exist, such as the Deep-Water Culture (DWC) method being the most used. The APS Laboratory for Sustainable Food at Florida Gulf Coast University (FGCU) compared the crop growth performance between DWC and NFT systems using GREENBOX technology. The following study monitored environmental conditions and compared productivity and biomass data of Rex Butterhead Lettuce crops between DWC and NFT systems. We assembled two GREENBOX units using commercially available materials and the standard nutrient solution for fertigation. The crops grown in DWC and NFT were in a 4 × 6 configuration. The DWC and NFT systems were used to grow Lettuce Lactuca sativa “Rex Butterhead” over 30 days to full bloom from prepared plugs grown for 14 days. We collected environmental data including Photosynthetic Photon Flux Density (PPFD, μmol/m2∙s), Daily Light Integral (DLI, mol/ m2∙d), temperature (˚C), relative humidity (%), and Vapor Pressure Deficit (VPD, kPa). We collected lettuce crop growth data, which included wet weight (g), dry weight (g), leaf area (cm2), and chlorophyll concentration (μmol/m2). We derived data, including the Specific Leaf Area (SLA, cm2/g) and biomass productivity (kg/m2), from previously collected data. We used descriptive statistics to present the collected data. A paired t-test was performed to understand the differences in biomass and productivity parameters between the DWC and NFT-grown lettuce crops. Both the DWC and NFT-grown crops could grow lettuce crops to harvest weight at full bloom. Observed data demonstrated that the biomass parameters and productivity did not differ significantly between the two hydroponics techniques. Therefore, we believe both hydroponic methods may be similar in growth performance and may be used in future iterations of GREENBOX design and prove suitable for fresh vegetable crop production in urban settings.

The Comparative Performance of Soil-Based Systems with Hydroponics

Conventional soil-based agriculture is resource-intensive, utilizing large amounts of land and water, thereby placing a strain on Earth’s natural resources. Soil-based agricultural techniques create environmental issues such as soil degradation, deforestation, and groundwater pollution from the mass implementation of fertilizers and pesticides. Agricultural crop production using hydroponics has shown promise to be less resource intensive and provide a faster turnaround in crop production. Soilless cultivation using hydroponics promises to relieve some pressure on Earth’s ecosystems and resources by utilizing lesser land and water footprint. The APS Laboratory for Sustainable Food at Florida Gulf Coast University (FGCU) compared the growth of Lettuce Lactuca sativa “Rex Butterhead” crop grown using soil and soilless methods to analyze the growth performance in each setting. Crops grown in the soil-based medium were raised in the FGCU Food Forest, used a mix of soil and potting mix, watered regularly, and followed standard Integrated Pest Management (IPM) practices. Crops grown hydroponically were grown in a thermally insulated grow tent with an artificial lighting source, ventilation, environmental controls, and the Deep-Water Culture (DWC) method. Lettuce plugs were grown for 15 days in controlled environments until two leaves after the cotyledons had developed and were ready for transplant. Plugs were transplanted into a 4 × 6 matrix at the FGCU Food Forest and the DWC growth system. Crops were grown to full bloom and ready for harvest in the soil (60 days) and soilless (30 days) based setups. We collected crop growth data, including wet weight (g), dry weight (g), leaf area (cm2), and chlorophyll concentration (μmol/m2). From the collected data, we derived the Specific Leaf Area (SLA, cm2/g) and biomass productivity (kg/m2). Descriptive statistics were used to describe the collected and derived data. We investigated the slopes of regression lines for each growth curve which derived the differences in biomass and productivity parameters between lettuce grown using soil and hydroponics. Both growing methods can grow lettuce crops to full bloom and to adequate harvest weight. The biomass parameters and productivity differ significantly between the growing methods. The lettuce crops grown using hydroponics increase in wet weight statistically and significantly faster than those grown in soil (p < 0.0001). Therefore, we determined that a hydroponic method of crop production may provide better crop output and biomass indicators measured than soil-based growth.

A Comparative Study on the Leaf Characteristics and Root Vigor of Bowl Lotus under Hydroponics and Soil Culture

[Objective] The experiment aimed to study the growth characteristics of hydroponic bowl lotus. [Method] The lotus variety Hongxia was chosen as the experimental material. Two treatments, hydroponics and soil culture were set to measure their photosynthetic indices, chlorophyll content and root vigor, and to observe their leaf tissue structure and stomatal characteristics. [Result] The findings indicated that there are no differences in the leaf physiological indices between bowl lotus under hydroponics and soil culture, while the leaf stomata of hydroponic bowl lotus is bigger and its amount is larger than that of soil-culture bowl lotus. At the same time, the ratio of the palisade tissue thickness to spongy tissue thickness is small,and its leaf tissue structure is loose. The root vigor of hydroponic bowl lotus reached its summit earlier, then began to drop. Whereas, the root activity of soil-culture lotus sustained increasing, with vigorous growth. [Conclusion] Therefore, it indicated that hydroponic bowl lotus can adapt to the aquatic-culture environment well and quickly, meanwhile, it also enters into its aging period quickly and its growth cycle gets shorter.

Growth Responses of Wheat Cultivars to Rock Phosphate in Hydroponics

Screening cultivars to grow under conditions of low phosphorus (P) availability and utilize P efficiently from compounds of low solubility in soils may be beneficial to overcome poor plant growth in P-deficient soils. The growth behavior and P utilization efficiency of seven wheat cultivars grown in hydroponics were studied, using rock phosphate as P source. The wheat cultivars grown for 30 days were significantly different in biomass accumulation, P uptake and P utilization efficiency. The dry matter production of all the cultivars was significantly correlated with P uptake, which in turn correlated to the drop in the root medium pH. The ranking of wheat cultivars on the basis of dry matter yield, P uptake and P utilization efficiency was Zamindar 80 > Yecora > C 271 > WL 711 > Barani 83 > PARI 73 > Rohtas. The cultivar Zamindar 80 appeared to possess the best growth potential in P-deficient soils.

Response of Lettuce to the Coupling Electrical Conductivity and Circulation Rate of the Nutrient Solution in Hydroponics

The coupling effect of nutrient solution EC （electrical conductivity） levels and CR （circulation rate） on the morphology and quality, in hydroponically grown lettuce was assessed. Lettuce was grown at 5 treatments fi＇om High EC ＆ Low CR to Low EC ＆ High CR. The environmental parameters were controlled in a 20 m^2 plant factory during the hydroponic cultivation with the following values： irradiated by blue and red light-emitting diode lighting with PPFD （photosynthetic photon flux density） value of 150 mol·m^-2·s^-1 for 16 hours per day; Temperature was maintained at 22.0 ℃ during the photoperiod and 16.0 ℃ in dark cycle. The results demonstrate that growing lettuce can be adopted using nutrient solution with lower EC levels and higher CR. The results also indicate that the effect of bi-directional coupled EC and CR resulted in expansion of root length but reducing the root biomass. Nitrate content was significantly reduced.

Evaluation and Enhanced Use of Light Emitting Diodes for Hydroponics

Hydroponic farming is a viable and economical farming method,which can produce safe and healthy greens and vegetables conveniently and at a relatively low cost.It is essential to provide supplemental lighting for crops grown in greenhouses to meet the daily light requirement,Daily Light Integral(DLI).The present paper investigates how effectively and efficiently LEDs can be used as a light source in hydroponics.It is important for a hydroponic grower to assess the requirement of photo synthetically active radiation(PAR)or the Photosynthetic Photon Flux Density(PPFD),in a greenhouse,and adjust the quality and quantity of supplemental lighting accordingly.A Quantum sensor(or PAR sensor)can measure PAR more accurately than a digital light meter,which measures the light intensity or illuminance in the SI unit Lux,but a PAR sensor is relatively expensive and normally not affordable by an ordinary farmer.Therefore,based on the present investigation and experimental results,a very simple way to convert light intensity measured with a Lux meter into PAR is proposed,using a simple conversion factor(41.75 according to the present work).This allows a small-scale hydroponic farmer to use a simple and inexpensive technique to assess the day to day DLI values of PAR in a greenhouse accurately using just an inexpensive light meter.The present paper also proposes a more efficient way of using LED light panels in a hydroponic system.By moving the LED light panels closer to the crop,LED light source can use a fewer number of LEDs to produce the same required daily light requirement and can increase the efficiency of the power usage to more than 80%.Specifically,the present work has determined that it is important to design more efficient vertically movable LED light panels with capabilities of switching individual LEDs on and off,for the use in greenhouses.This allows a user to control the number of LEDs that can be lit at a particular time,as required.By doing so it is possible to increase the efficiency of a LED lighting system by reducing its cost of the electricity usage.

Treatment and utilization of septic tank effluent using vertical-flow constructed wetlands and vegetable hydroponics

Vertical flow constructed wetlands is a typical ecological sanitation system for sewage treatment. The removal rates for COD, BOD 5, SS, TN, and TP were 60%, 80%, 74%, 49% and 79%, respectively, when septic tank effluent was treated by vertical flow filter. So the concentration of COD and BOD\-5 in the treated effluent could meet the quality standard for irrigation water. After that the treated effluent was used for hydroponic cultivation of water spinach and romaine lettuce, the removal efficiencies of the whole system for COD, BOD\-5, SS, TN and TP were 71 4%, 97 5%, 96 9%, 86 3%, and 87 4%, respectively. And it could meet the integrated wastewater discharge standard for secondary biological treatment plant. It was found that using treated effluent for hydroponic cultivation of vegetables could reduce the nitrate content in vegetables. The removal rates for total bacteria and coliform index by using vertical flow bed system with cinder substrate were 80%—90% and 85%—96%, respectively.

The Function of Roots of Tea Plant (<i>Camellia sinensis</i>) Cultured by a Novel Form of Hydroponics and Soil Acidification

A novel form of hydroponic culture was employed to explore the physiological function of roots of a tea plant (Camellia sinensis). The pH of the nutrient solution with an actively growing tea plant decreased during cultivation. Furthermore, no oxalic acid, tartaric acid, malic acid or citric acid, all possible factors in acidification, was detected in the nutrient solution of a growing plant. A proton pump inhibitor suppressed the acidification of the solution. Soil acidification might have been accelerated with a proton released from ammoniacal nitrogen preferentially for the growth, suggesting the specific mechanism of tea plant as a functional food.

Development of a Cylindrical Hydroponics System for Vertical Farming

The study aimed to develop a vertical crop cultivation system for leafy plants based on cylindrical hydroponics and light emitting diode （LED） technology. Investigations were conducted on growing lettuce （Lactuca sativa cv. ＂Rex＂, ＂Nanda＂ and ＂Canasta＂） indoors in a rotary system and Chinese cabbage （Brassica chinensis） in a multi-tier cylindrical hydroponics system under red and blue （RB） LED lightings. Light intensity from different light sources have an influence on the yield and growth behaviour of indoor lettuce. Photosynthetically active radiation （PAR） levels at 63 μmol/m2·s produced low fresh weights （FW） and leaf areas of lettuce ＂Rex＂ and ＂Nanda＂ were grown under rotating conditions. The effect was, however, different on the better developed ＂Canasta＂. Stem etiolation was a common occurrence under such influence. Chlorosis was not observed on all plant types grown under the LEDs. Cultivating Chinese cabbage plants （FW： 28 g/plant） in cylindrical units stacked vertically above another, increased planting density by 47% when compared to the rotary system,

Characteristics of <i>Morus alba</i>L. Cultured by In-Room Hydroponics

Morus alba L., (cv Ichinose) was cultivated by in-room hydroponics. The flavor and texture of leaves were markedly improved enough to be edible. When the contents of 1-deoxynojirimycin (DNJ) and polyphenols were measured in the hydroponic cultivar, DNJ increased in the leaf compared to the field grown M. alba. However, polyphenols, in contrast, decreased compared to the field cultivar. HPLC profiling revealed marked difference in leaf components between hydroponic and field cultivars indicating relative contents of lipophilic polyphenols were increased. The polyphenols contents, especially, lipophilic polyphenols in the root were remarkably high compared to So-Haku-Hi (Sang Bai Pi in Chinese). The anti-obesity effect of the hydroponically grown Morus was further studied in rats by feeding high-fat, high-sucrose (HFHS) diet with and without supplementation of dried leaf and root powders for 15 weeks. As the result, both the leaf and root from the hydroponic cultivar showed potential anti-obesity and anti-hyperlipidemic functions through amelioration of insulin resistance. Differential effects of leaf and root powders indicated that besides DNJ, the lipophilic polyphenols may play a crucial role in the anti-diabetic function of hydroponically grown Morus alba L. The hydroponics will provide an alternate way to cultivate a novel resource of Morus for developing functional foods and medicines.

Organic Hydroponics Production

Hydroponic culture is a controlled systems use a soilless growing media,supply all of the plant’s nutrition in the plant’s solutions(water with dissolved fertilizers),result in higher yields of vegetables,flowers,herbs and others crops.Hydroponic systems derive in many various forms and types.Most traditional hydroponic systems are extremely specialized,controlled-environment production systems.Organic hydroponics is a system that is arranged based on organic agriculture of culture.Different approaches are used for controlling of plant pathogens such as physical,chemical,biological controls,biofertilizers,bioremediators and integrated pest management.All the required nutrients are supplied in controlled amounts,including organic crops.This article discuss the way for promoting organic hydroponics systems and to help the small-scale producer make decisions about follow this markets,production methods,and disease control.

Investigation on environment monitoring system for a combination of hydroponics and aquaculture in greenhouse

This work develops a distributed environmental monitoring system for the combination of hydroponics and aquaculture based on the internet of things technology,which mainly includes the information perception layer,the information transmission layer and the sys-tem architecture.The system has employed multiple sensors terminal to real-time acqui-sition,including air and water temperatures,dissolved oxygen etc.LoRa protocol is suitable for sending small data and the 4G was employed to collect data and send to the cloud plat-form.Java is used to develop background applications,to access cloud platforms and local data processing.Based on the collection and processing of environmental data and cloud service platform,the mobile application program client and remote login desktop have been developed.It has been implemented and tested in Tongzhou,Beijing for 3 months in 2020.The results showed the proposed monitoring system stability for overall operation and accuracy data transmission,which can support the actual hydroponics and aquacul-ture production management.After analysis of monitoring data collected from the devel-oped monitoring system,indoor air and water temperature have the obvious correlation with atmospheric pressure(0.7 and 0.9)and outdoor temperature(1.0 and 0.9),respectively.

The Assessment of Growth Performance of Brassica rapa var. chinensis ‘Li Ren Choi’, Spinacia oleracea ‘Auroch’, Eruca sativa ‘Astro’, and Brassica rapa var. japonica Using GREENBOX Technology

Obtaining nutritious food is becoming increasingly difficult due to the growing urban population and the degradation of soil, water, and air from mechanized and industrialized agricultural techniques. More than half the global population resides in urban areas, with not enough surrounding agricultural land to meet food requirements. Food traveling long distances, an average of 1020 miles, has resulted in increased food miles for the average food item in the United States of America, representing wasted resources. The novel GREENBOX technology was invented in response to increasing pressures on food security. Previous studies conducted on GREENBOX technology assessed the technical feasibility of utilizing Lettuce Lactuca sativa ‘Rex Butterhead’. We at the APS Laboratory for Sustainable Food at Florida Gulf Coast University assessed the technical feasibility of growing different leafy green vegetable crops. GREENBOX technology consists of thermally insulated climate-controlled enclosures, an artificial lighting source, a soilless cultivation method (hydroponics), and environmental control modules. We assembled two GREENBOX units to assess the environmental conditions and growth performance of Brassica rapa var. chinensis ‘Li Ren Choi’, Spinach Spinacia oleracea ‘Auroch’, Arugula Eruca sativa ‘Astro’, and Mizuna Brassica Brassica rapa var. japonica. Plugs were cultivated and then transplanted in a randomized manner to the nutrient film technique (NFT) channels, subsequently grown for 30 days to full bloom and ready for harvest. Fertigation was carried out using a standard concentration nutrient solution. Crops were arranged in twelve blocks of four species each. We collected environmental data including daily light integral (DLI, mol/m2∙d), temperature (˚C), relative humidity (%), and vapor pressure deficit (VPD, kPa). Collected biomass data included wet weight (g), dry weight (g), leaf area (cm2), and chlorophyll concentration (mg/cm2). We then derived the Specific Leaf Area (SLA, cm2/g). Descriptive statistics were utilized to understand the differences in biomass parameters between the four crops grown. We also compared the performance parameters of our crops with existing peer-reviewed literature and found it superior, if not comparable to commonly found industrial output. We determined that all crops grew to full bloom, demonstrating that GREENBOX technology may be used to grow a variety of different leafy green vegetable crops.

Study on the Activity of Herbal Extract to Kill Root-knot Nematode of Cucumber Seedlings Stage

Present mature plants hydroponic technology was used,combined with some excellent characteristics,such as growth conditions was easy to control and process of root growth was easy to continuously observe,the nematicidal activity of 5 kinds of Chinese herbs extracts and the compound solution of Avermectin,with strong contact toxicity effect indoor,was systematically studied and investigated the affection on the root-knot nematode parasitized on the cucumber seeding stage. It is found that under the premise of no influence on root growth of cucumber,extracts from Picrorhiza scrophulariiflora and Punica granatum showed strong prevention and nematicidal activity,and had the similar efficacy of Avermectin; while the extracts from Cibotium barometz,Aucklandia lappa Decne and Fructus cnidii showed low nematicidal activity and various degrees inhibition effect on plant growth.

Response of Over-summer Hydroponic Lettuce to Nutrient Solution Temperature Control

Temperature, as an important feature of hydroponic nutrient solution, is closely related to dissolved oxygen content of nutrient solution and growth status of plant roots. How to precisely adjust the temperature of nutrient solution is the key to obtain high quality and high yield of hydroponic vegetables over summer. With Lactuca sativa vat. crispa ＇Luosheng No.3＇ as the test material, the effect of chiller cooling technology on the temperature of nutrient solution, as well as on the yield and quality of Luosheng No.3, in over-summer hydroponic cultivation was studied. The results showed that the chiller cooling technology controlled the nutrient solution temperature in a reasonable range （（20 ± 1）℃） and promoted the growth and dry matter accumulation of Luosheng No.3, instead of affecting the quality. In short, the chiller cooling technology is applicable to the temperature regulation of nutrient solu- tion in hydroponics over summer.

Study on Optimization of Hydroponic Technology of Virus-free Potato Plantlets in Winter in Chengdu Plain

The effects of different heating measures on breeding virus-free potato plantlets with hydroponic technology were studied in this paper. The virus-free tube plantlets of potato （Favorita） were used as test material. A total of 3 treatments were designed, including traditional hydroponics （CK）, installing heaters （T1） and in- stalling heaters and thermal insulation device （T2）. The results showed in the Chengdu Plain in low-temperature winter, the installing of heaters and covering of thermal insulation device could maintain the hydroponic water temperature at 15-22 ~C. The potato seedlings grown in heaters and thermal insulation device-installed seedbed rooted 6.4 d earlier and emerged 13 d earlier compared to that in tradi- tional seedbed. The growth of potato seedlings grown in heaters and thermal insu- lation device-installed seedbed was more robust. Their root length, stem diameter, plant height, leaf number and fresh weight were all higher than that of traditional potato seedlings. The tuber number per plant in T1 group reached 1.7 and in T2 group reached 3.57 42 d after the cutting of hydroponic seedlings, while then the plantlets in CK group just turned into the aeroponics stage. Therefore, heating hy- droponics is conducive to advancing the cutting of virus-free seedlings and breeding robust water-cultured seedlings. Moreover, the fruiting of aeroponics seedlings is al- so advanced. The heating hydroponics plays an important role in actual production.

ALA Altered ABA Content of Winter Oilseed Rape(Brassica napus L.)Seedling

[Objective] The paper was to explore the impact of 5-aminolevunic acid（ALA）treatment on growth of winter oilseed rape（Brassica napus L.）seedlings and its mechanism.[Method] The effects of ALA on abscisic acid（ABA）contents in plant organs and xylem saps were investigated through hydroponic experiment.Four treatments including seed soaking with 0,25,50 and 75 mg/L ALA solutions（CK,A1,A2 and A3）for 6 h were set in the test.[Result] In addition to A3 treatment which made the dry weights of oilseed rape seedlings slightly decrease,after seed soaking with ALA,dry weights,net photosynthetic rate（Pn）,transpiration rate（Tr）and stomatal conductance（Gs）of plants significantly increased compared with control.ABA concentrations in plant shoots and xylem saps increased in different levels after seed soaking with ALA.[Conclusion] The increasing endogenous ABA contents might be an explanation for promotion effect of ALA application on the growth of winter oilseed rape seedling.

Effect of Root-Zone Temperature on Growth and Quality of Hydroponically Grown Red Leaf Lettuce (Lactuca sativa L. cv. Red Wave)

Soil temperature influences crop growth and quality under field and greenhouse conditions;however, precise investigation using controlled cultivation systems is largely lacking. We investigated effects of root-zone temperatures on growth and components of hydroponically grown red leaf lettuce (Lactuca sativa L. cv. Red Wave) under a controlled cultivation system at 20&degC. Compared with ambient root-zone temperature exposure, a 7-day low temperature exposure reduced leaf area, stem size, fresh weight, and water content of lettuce. However, root-zone heating treatments produced no significant changes in growth parameters compared with ambient conditions. Leaves under low root-zone temperature contained higher anthocyanin, phenols, sugar, and nitrate concentrations than leaves under other temperatures. Root oxygen consumption declined with low temperature root exposure, but not with root heating. Leaves of plants under low rootzone temperature showed hydrogen peroxide production, accompanied by lipid peroxidation. Therefore, low temperature root treatment is suggested to induce oxidative stress responses in leaves, activating antioxidative secondary metabolic pathways.

Morphological and Physiological Responses of Weedy Red Rice (<i>Oryza sativa</i>L.) and Cultivated Rice (<i>O. sativa</i>) to N Supply

Red rice (Oryza sativa L.), a noxious weed in rice production, competes with cultivated rice for nutrients. Accumulation of more N in red rice than in cultivated rice may be due to a mechanism different from that of cultivated rice. To test this assumption, red rice and cultivated rice were grown in nutrient solution to compare their growth and physiological responses to N supply. Experimental design was a split-plot, where main plot factor was rice type (Stf-3, ‘Wells’);split-plot factor was N treatment [T1 (complete nutrient solution);T2 (–NH4NO3);T3 (+NH4NO3 for 24-h post-N deficiency);and T4 (+NH4NO3 for 48-h post-N deficiency)]. Nitrogen deficiency was defined as N sufficiency index (NSI) 4, Stf-3 showed higher increment in root length and surface area than Wells. Shoot tissue concentrations of N and total sugars were measured to determine physiological response in N-deficient and N-supplemented plants. Stf-3 had greater N and sucrose tissue concentrations at N-deficient conditions compared with Wells, implying a stress-adaptive molecular mechanism regulated by N and sucrose availability.

Light-Emitting Diodes (LEDs) for Miniature Hydroponic Lettuce

There is growing concern about food safety, environmental impact, and efficient energy usage in agricultural production systems. Producing lettuce under artificial lighting could be a solution addressing these concerns. Light-emitting diodes (LEDs) offer the advantages of a narrow light spectrum, low power consumption, and little heat production. The objective of this study was to determine the effects of different light sources on the growth of miniature “Tom Thumb” butterhead lettuce in a non-circulating hydroponic system. Lettuce seedlings, started in Oasis Horticubes, were transferred to net pots in containers with a hydroponic nutrient solution. The lettuce was grown in a lab under three light treatments—blue LEDs, red LEDs, and fluorescent lights. At the end of the study, fluorescent lights resulted in greater root dry weight than blue LEDs and red LEDs. Total plant dry weight under fluorescent lights was greater than under red LEDs. There were no significant differences in shoot dry weight and plant height among the treatments. Percent partitioning of dry weight to shoots was greatest with red LEDs, followed by blue LEDS, and fluorescent lights. Percent partitioning of dry weight to roots was greatest with fluorescent lights, followed by blue LEDS, and red LEDs. Leaf chlorophyll content was greater under blue LEDs and fluorescent lights than red LEDs. The pH of the nutrient solution of the blue LED and the fluorescent light treatments were greater than the red LED treatment. Electrical conductivity of the nutrient solution of the fluorescent light treatment was greater than the blue LED treatment and the red LED treatment. In conclusion, LEDs could provide an alternative lighting source for miniature lettuce production.