Nutrient Film Technique Research Articles

A STUDY ON HYDROPHONIC FARMING

Hydroponics technology is possibly the most intensive and a versatile method of growing crops production at present as it allows optimum utilization of nutrient solution, water and space, as well as a better control of climate and plant protection factors. Hydroponic technology can be an efficient mean for food production from extreme environmental ecosystems such as deserts, mountainous regions, or arctic communities. Furthermore, hydroponics production increases the quality of crops and its productivity, which results in higher competitiveness and economic income. Several types of hydroponics systems can be used to grow the crops. Commercially Nutrient Film Technique (NFT) has been used across a globe for successful production of the leafy as well as other exotic vegetables cultivation. Hydroponic systems use mineral nutrient solutions to feed the plants in water of using several non-soil growing media. Despite of having few disadvantages, Hydroponics technology provides variety of benefits when compared with conventional farming methods Hydroponic farming is an innovative soil-less cultivation method that has gained significant attention in recent years due to its potential for sustainable and efficient food production..

Effects of Root Zone Temperature of Hydroponic Lettuce Affects Plant Growth, Nutrient Uptake, and Vitamin A Content

Water temperature can affect plant growth and quality in hydroponic production. Lettuce ‘Antonet’, ‘Waldman’s Dark Green’, ‘Parris Island’, ‘Jericho’, and ‘Rex’ were grown using the nutrient film technique with chilled (water temperature set at 21.1 °C) or ambient water. Data were collected on plant growth, foliar nutrient content, and vitamin A content. ‘Jericho’ had the greatest shoot fresh weight but was only significantly different from ‘Antonet’, which had the lowest shoot fresh weight but the greatest vitamin A content. SPAD was greatest in ‘Paris Island’ and was significantly greater in chilled water over ambient for ‘Antonet’. Plants grown in ambient water had greater number of leaves and root dry weight, whereas SPAD was greatest with chilled water. Greater nutrient values were observed in ‘Rex’, ‘Jericho’, and ‘Waldman’s Dark Green’ in chilled water, whereas no nutrient differences were observed in ‘Antonet’ and ‘Parris Island’.

Multicriteria decision-making tool for investigating the feasibility of the green roof systems in Egypt

Urbanization in Egypt detracts from green spaces, reduces the per capita green ratio, and increases adverse effects such as heat islands, air pollution, and energy consumption. In addition, it affects social human comfort issues. In this context, building rooftops is a potential solution that could reduce the impact of green space scarcity. Such a solution has multiple evidence-based environmental, economic, and social benefits. Consequently, numerous governmental and private initiatives have spread the rooftop greening concept in Egypt. These initiatives have adopted several planting systems, such as soil-based, deep-water culture, and nutrient film technique systems. This manuscript examines these prevalent systems through environmental, economic and social lenses. This paper pioneers a user-centric tool to facilitate the system selection that aligns with individual needs. An analysis was conducted to ascertain the value of various factors influencing system choice, encompassing a literature review, expert opinion solicitation, market survey, and energy simulation. The Analytical Hierarchy Processes methodology was proposed to appraise the factors, aiding in arriving at an informed decision. The paper presents a novel contribution by studying many factors spanning diverse scientific domains. Furthermore, creating an accessible decision-support tool encapsulates a substantial addition to the body of knowledge.

Yield, nutrients uptake and lipid profile of the halophyte Salicornia ramosissima cultivated in two different integrated multi-trophic aquaculture systems (IMTA)

The nutrient removal, biomass production and nutritional value of the halophyte Salicornia ramosissima were evaluated in the context of an Integrated Multi-Trophic Aquaculture (IMTA) system. The experiment consisted of an indoor fish RAS whose effluent was used to feed two different halophyte hydroponic systems: a Nutrient Film Technique (NFT) system or a Deep Water Culture (DWC) system. The highest yield of S. ramosissima was observed in the DWC (320 g m−2 day−1), this system showed significantly higher yields compared to the NFT. Both hydroponic systems were effective in removing nutrients from the fish RAS wastewater, contributing to the wastes valorization process. Maximal nutrient uptake efficiencies were: 82.8% and 68.6% NO3− in the DWC and the NFT, respectively; 72.6% PO43− in the DWC and 82.9% in the NFT; 63.6% NO2− in the DWC vs 56.4% in the NFT; and 89.2% NH4+ in the DWC vs 94.1% in the NFT. The lipid profile of the halophytes in the DWC was analysed. The total lipid content ranged from 2.99% to 3.83%. The fatty acids (FA) profile in the leaves was dominated by polyunsaturated fatty acids (about 66%), which were represented by α-linolenic acid (41%) and linoleic acid (24%), followed by saturated fatty acids (28%) with palmitic acid (22%) as the major component. A small component of monounsaturated fatty acids accounts for about 12% of total FA. Regarding lipid classes, pigments were the most abundant compounds followed by glycolipids, phospholipids, flavonoids and sterols. The study supports the potential of S. ramosissima to valorise aquaculture wastes and its high nutritional interest. The experimental systems minimized waste and maximized resources utilization. Such integrated approaches can contribute to the sustainability and resilience of aquaculture systems while providing additional economic opportunities through the production of high value halophyte products.

Growth performance and metabolic changes in lettuce inoculated with plant growth promoting bacteria in a hydroponic system

Crop cultivation in hydroponic systems is often exposed to both abiotic and biotic stresses, which impact growth. One possible approach to alleviating these stresses and improving plant growth is by utilizing plant growth-promoting bacteria (PGPB). Our previous study has shown the efficacy of two PGPB strains, Pseudomonas lundensis UB 53 and Pseudomonas migulae UB 54, in promoting growth and stimulating the generation of plant defense enzymes to mitigate biotic and abiotic stress in lettuce grown in a nutrient film technique (NFT) hydroponic system. Therefore, this study purposed to assess metabolic changes in lettuce in response to P. lundensis UB 53 and P. migulae UB 54 inoculation in a NFT hydroponic system. The results exhibited that these bacteria enhanced IAA accumulation and lettuce growth in a NFT hydroponic system. A total of 58 metabolites were detected in the root samples, including primary and secondary metabolites. It also influenced 12 metabolic pathways, with emphasis on five pathways, including the metabolism of alpha-linolenic acid, inositol phosphate, pyruvate, sulfur, and the phosphatidylinositol signaling system. These results highlight the significant roles of myo-inositol and acetic acid in metabolic pathways during the interaction between lettuce and PGPB.

Sustainability of Growth Performance, Water Quality, and Productivity of Nile Tilapia-Spinach Affected by Feeding and Fasting Regimes in Nutrient Film Technique-Based Aquaponics

Aquaponic systems offer an innovative approach to sustainable agriculture, where the interplay between fish and plant cultivation can be optimized. The choice of feeding and fasting schedules plays a crucial role in system efficiency and overall productivity. This study aims to investigate the impacts of various feeding and fasting schedules on water quality, and the growth performance of Nile tilapia, Oreochromis niloticus fingerlings, and spinach productivity in an aquaponic system based on the nutrient film technique (NFT). O. niloticus fingerlings with an initial weight of 13.47 ± 0.14 g were randomly stocked at a density of 6 kg/m3, and spinach plants (Spinacia oleracea) were included. The study employed a completely randomized block design with five replications. Various water quality parameters were monitored, and the effects of different feeding/fasting schedules on fish and spinach were assessed. The data revealed significant differences (p < 0.05) in water quality parameters, all of which remained within acceptable ranges for aquaponic systems. The one-day feeding/one-day fasting treatment resulted in reduced final body weight, weight gain percentage, and specific growth rate, compared to other treatment groups (p < 0.05). Higher levels of glucose and plasma cortisol were observed in this treatment. Economic efficiency was highest in the daily feeding treatment (40.05%), with no statistical difference (p > 0.05) observed in the group subjected to three-day feeding/one-day fasting (39.03%). Spinach yield varied significantly between treatments (p < 0.05), with the daily feeding treatment recording the highest yield (2.78 kg/m2) and the one-day feeding/one-day fasting cycle having the lowest yield (1.57 kg/m2). The findings suggest that the three-day feeding/one-day fasting regime in an NFT-based aquaponic system results in efficient nutrient utilization, higher productivity, and profitability for Nile tilapia. Additionally, this approach supports marketable biomass production for spinach. Different feeding and fasting schedules have distinct effects on water quality, fish growth, and spinach productivity in aquaponic systems. The three-day feeding/one-day fasting schedule emerges as an effective strategy for optimizing resource utilization and increasing overall productivity.

Trocas gasosas, eficiência fotoquímica e crescimento de quiabeiro hidropônico sob estresse salino e ácido salicílico

ABSTRACT Okra (Abelmoschus esculentus L.) is a shrub belonging to the Malvaceae family, which stands out for its rusticity and adaptation to soil and climatic conditions, being cultivated by small farmers, especially in the semi-arid region of Northeast Brazil. In this context, the objective of this study was to evaluate the effect of foliar application of salicylic acid as an attenuator of salt stress on leaf gas exchange, photochemical efficiency, and growth of okra cv. Canindé in a hydroponic system. The experiment was carried out using a Nutrient Film Technique - NFT hydroponic system in a greenhouse, in Pombal, PB, Brazil, from January to March 2022, in a completely randomized design, in a split-plot scheme, with the four levels of electrical conductivity of the nutrient solution - ECns (3.0, 5.0, 7.0, and 9.0 dS m-1) considered as plots and four concentrations of salicylic acid – SA (0, 1.2, 2.4, and 3.6 mM) considered as subplots, with three replicates and two plants per plot. Increase in ECns levels from 3.0 dS m-1 inhibited leaf gas exchange, photochemical efficiency, and growth of okra cv. Canindé in hydroponic cultivation, at 34 days after transplanting. Foliar application of SA at concentrations of 2.2 and 1.5 mM promoted increments in stomatal conductance and transpiration, respectively. Salicylic acid at concentration of 1.9 mM associated with saline nutrient solution of 9.0 dS m-1 increased the variable fluorescence of okra plants cv. Canindé, at 34 days after transplantation.

Design, Development, and Performance Evaluation of Plastic-based Radial-flow Settling Unit for NFT Aquaponics

Highlights Inclusion of the designed radial flow settler to the aquaponic system helps to remove more than 80% TSS, which is on par with or better in comparison to the TSS removal efficiency of the existing models. Removing excess suspended solids in traditional aquaponic setups could help prevent biofilter choking and hence, water contamination further down the line. The developed radial flow is simple in design, cost-effective, and yet, efficient. Abstract. One cylindrical settler of capacity 200 L (Ø 0.6×0.7 m) with a center-bottom inlet has been designed and developed in High-Density Poly Ethylene (HDPE) under the All-India Co-ordinated Research Project on Plastic Engineering in Agriculture Structures & Environment Management (AICRP on PEASEM) center at ICAR-CIFA, Bhubaneswar for fitting to the developed Nutrient Film Technique (NFT) aquaponics system. The water flow into the settling unit comes from a single-drain fish culture tank with the outlet at the bottom-center with a downward slope of 1:22. The experiment was carried out for the evaluation of the efficiency of Total Suspended Solid (TSS) removal in the developed radial-flow settling unit. The performance is assessed in terms of capturing the suspended solids from the water of aquaculture operation with varying specific gravity (1=SG>2) as well as the skimming of the floating organic surfactants before entering into the biofilter. During the 90 days of study, a total of 60 water samples were collected from the outlet of the fish culture tank and the overflow of the settler, which were filtered through the standard 11 µm pore paper filter for further processing in the laboratory. The average TSS concentration removed was calculated to be 128.55 mg/L on dry weight basis and a mean efficiency of 80.06 ± 9.36% was observed in the experiment with a surface loading rate of 0.00103 m3/min-m2 of the radial flow settler. The right-angle submerged overflow of the settler helped in complete surfactant removal. Keywords: Aquaponics, NFT, Radial-flow, Specific gravity, Suspended solid.

Nutrition control in nutrient film technique hydroponic system using fuzzy method

Hydroponics is a method of growing crops without using soil media, instead, it utilizes water or other porous materials. The automation system is applied to control the nutrient quality of the water. Some sensors were used for measuring nutrient concentration, water level, water supply, and water volume. Temperature, TDS, and ultrasonic sensors are installed on the microcontroller for data measurement. The results of the data are processed using the Mamdani fuzzy logic method. The fuzzy logic results are used in controlling nutrition and water volume. The system can be monitored remotely with the aid of the Blynk app. The results of the automation system concluded that the desired condition reaches an average time of 13 minutes 49 seconds. Finally, the results of the fuzzy logic processing of the system have an accuracy value of 94.24% after being compared with the software simulation.

Seasonal dynamics of lettuce growth on different electrical conductivity under nutrient film technique hydroponic system

Seasonal dynamics of lettuce growth on different electrical conductivity under nutrient film technique hydroponic system

Enhanced Productivity of Lettuce (Lactuca sativa L.) by Fermented Cardaba Banana in a Hydroponic Cultivation System

The study entitled “Enhanced Productivity of Lettuce (Lactuca sativa L.) by Fermented Cardaba Banana in a Hydroponic Cultivation System." The study aimed to determine the productivity and financial feasibility of cultivating lettuce using soilless agricultural methods with the supplemental foliar application from the fermented cardaba banana (FCB). The study was analyzed using a Randomized Complete Block Design (RCBD) consisting of three (3) blocks and four (4) treatments - FCB – 0, 30, 45, 60. Lettuce seeds were sown in a seedling tray and hardened until it was transplanted (21DAS) in the Nutrient Film Technique (NFT). Seven-day interval application of FCB was applied until it was harvested (26 DAT). The data collected the following data - weight at harvest, marketable and non-marketable, yield per cycle, and net income. The results show that FCB-45 (p<0.05) has the highest non-marketable lettuce. On the other hand, FCB-60 (p<0.05) has the highest yield and marketable. Moreover, the FCB-60 shows the highest net income of Php 42,038.51.

Response of gerbera under soil and soil-less production systems

Response of gerbera var. Arka Nesara was studied under different soil-less production systems with the aim to improve quality, productivity and water use efficiency, in completely randomized design with eight treatments viz., deep flow technique (DFT), nutrient film technique (NFT), aggregate wick system (AWS) with pots on NFT bench, AWS with pots on ground, AWS with grow bags on ground, AWS on soil bed, aeroponics and conventional soil-based drip system, which were replicated five times. Results revealed that AWS with pots on ground recorded maximum plant height (31.66 cm), leaf length (21.31 cm), leaf breadth (9.96 cm) and stalk diameter near neck (4.75 mm), minimum stem deviation (1.27 cm) and stem deflection (2.2o), prolonged vase life (9.2 days), greater water use efficiency (92 mL/plant/day) and water saving (83.46%). Hence, cultivation of gerbera var. Arka Nesara under aggregate wick system with pots on ground could be the superior alternative for traditional soil cultivation.

Design and Development of an Agricultural Parameter Monitoring System for Hydroponics

The global surge in population, surpassing environmental carrying capacity, poses challenges in ensuring food security, especially in densely populated urban areas. As the demand for food is projected to increase by 60% by 2050, innovative solutions are sought to address constraints like limited land, time, and motivation for traditional agriculture. The study explores hydroponics, a soilless farming method, as a viable solution to enhance food production in confined spaces. Hydroponics involves cultivating plants directly in nutrient-rich water, presenting an efficient and space-saving alternative. The paper details various hydroponic techniques, including Nutrient Film Technique (NFT), Deepwater Culture, and Aeroponics, illustrating their structures and advantages. However, implementing hydroponics in urban settings faces challenges related to time constraints and limited farming knowledge among residents. To address these challenges, the study introduces an innovative PLC-controlled system for hydroponic farming with automated features. The system precisely regulates environmental conditions such as temperature, humidity, water pH, and light intensity through algorithms. Leveraging cloud technology, users can remotely monitor and control the system, ensuring optimal plant growth. An integrated alarm system provides timely alerts, reducing the need for constant physical inspections. The methodology outlines the development stages of the monitoring system, emphasizing the selection of sensors, PLC programming, and integration with the cloud platform. Results indicate successful implementation, with the hydroponic system demonstrating effective communication with the cloud and optimal growth conditions for lettuce. The study concludes with future perspectives, suggesting improvements such as renewable power integration and advanced monitoring features. The proposed automated hydroponic system aims to make urban farming more accessible and manageable, contributing to sustainable and efficient food production.

Alat Kendali Ph Air dan Nutrisi Sayur Selada Berbasis Arduino Dengan Sistem Nutrient Film Technique

Indonesia's population growth has increased every year which has an impact on the conversion of agricultural land into settlements. Hydroponics is a solution to the conversion of agricultural land. Hydroponics is a farming system without soil. In hydroponics, pH and nutrient levels are very important to keep plants growing properly. However, there are obstacles in the hydroponic farming system, namely in terms of controlling pH and nutrient levels which are still done manually. the result of not optimally controlling pH and nutrient levels in hydroponics will result in less optimal plant growth and even plant death. Therefore, we need a tool that can control pH and nutrient levels by using an Arduino microcontroller as a controller, a pH meter sensor to measure pH levels, and a TDS meter to measure nutrient levels. In this research, the hydroponic system used is the Nutrient Film Technique system, which is a hydroponic system that uses shallow water flow. This research was conducted in the hydroponic lab at the University of Perjuangan, Tasikmalaya, which still controls the levels of nutrients and the pH of the water used for hydroponic plants, which is still done manually. The results of this research are that the tool is designed to be able to maintain pH levels and nutrient levels for hydroponic lettuce plants with an error rate of 1.6% for pH sensors and 0.6% for TDS sensors which allows pH and nutrient levels for lettuce to be sufficient and stable.

Evaluation of the chemical composition and nutritional value of lettuce (Lactuca sativa L.) biofortified in hydroponics with iodine in the form of iodoquinolines

Iodine deficiency in the diet creates the need to search for innovative, more sustainable and more effective strategies for enriching food with this microelement. The adopted research hypothesis assumed that the use of organic forms of iodine for supplementation of lettuce (Lactuca sativa L.), compared to mineral iodine, has a more favorable effect not only on the concentration of iodine, but also on the yield and the content of other chemical components determining its nutritional and health-promoting value. Lettuce was planted in a nutrient film technique (NFT) hydroponic study in a greenhouse. The following application of iodine compounds (all in 5 µM molar mass equivalents) were tested in the studies: control (without of iodine application); potassium iodate (positive iodine control), 8-hydroxy-7-iodo-5-quinolinesulfonic acid, 5-chloro-7-iodo-8-quinolinol, 5,7-diiodo-8-quinolinol and 4-hydroxy-8-iodo-3-quinolinecarboxylic acid. In this work, it was shown for the first time that iodoquinolines can be 1) a source of iodine for plants; 2) they have a biostimulating effect on their yielding and 3) they increase the resistance of crops to stress (due to a significant increase in the level of polyphenolic compounds). Lettuce with the addition of 8-hydroxy-7-iodo-5-quinolinesulfonic acid was characterized by the highest content of iodine, which was 221.7 times higher than in control plants. The weight gain of the whole plant was particularly visible in the case of lettuce enriched with 5-chloro-7-iodo-8-quinolinol and amounted to 26.48% compared to the control. Lettuce biofortified with iodine in the form of iodoquinolines can successfully become part of a sustainable diet based on plant products, which has a low impact on the environment and contributes to the long-term good health of an individual or community. Reducing iodine deficiency through the use of organoiodine compounds can help achieve the sustainability goal of eliminating hidden hunger, improving nutritional status and promoting sustainable agriculture.

Ammonium to total nitrogen ratio affects the purslane (Portulaca oleracea L.) growth, nutritional, and antioxidant status

Purslane (Portulaca oleracea L.) is a widespread weed, which is greatly appreciated for its high nutritional value. The present work evaluated the effect of different ammonium/total nitrogen ratios (NH4/Total N: Nr 0.01–0.15) on growth, physiological and biochemical parameters, and nutrient accumulation in different plant parts of hydroponically grown purslane, under two growing seasons, spring and autumn. Young seedlings of purslane were transferred to a Nutrient Film Technique (NFT) system and they were exposed to different Nr levels. The pH and the electrical conductivity of the nutrient solution were kept constant at 5.8 and 2.3 mS cm−1, respectively. After the end of the cultivation periods (19 days for spring and 22 days for autumn), a series of assessments (growth parameters, mineral content in different plant organs, antioxidant status of the plant, etc.) were done. Plant height, leaf number, root fresh weight and plant biomass revealed decreased trends at the higher NH4/total N ratios, especially during the autumn growing season. Total phenols, flavonoids and antioxidant capacity appeared increased at Nr ≤ 0.10 during both seasons (autumn and spring), revealing higher nitrogen accumulation rates and increased water and nutrient use efficiency. Purslane plants grown in Nr 0.05–0.10 revealed a less intense oxidative stress, with decreased lipid peroxidation levels that was the result of the activation of both enzymatic (superoxide dismutase, catalase and peroxidase) and non-enzymatic (ascorbic acid) antioxidant capacity of the plant. Increased Nr resulted in the accumulation of potassium, while calcium and magnesium levels in leaves were decreased. Additionally, the greater water use efficiency was measured for plants grown under Nr 0.01–0.05. Therefore, the recommended ammonium/total nitrogen ratio for purslane production of increased yield, improved nutritional value and efficient use of water and nitrogen sources is to employ Nr of 0.05, while additional care should be addressed during autumn periods as plants are subjected to greater impacts of the Nr ratio.

Hydroponics and Synergetic Technologies: A Deep Dive into Small and Medium-Scale Applications

Hydroponics, the practice of soilless plant cultivation, has undergone significant transformation over the years, evolving from its roots in ancient civilizations to its modern, high-tech systems. This paper explores this journey, focusing on technological advancements that have not only refined the principles of hydroponics but have also democratized its accessibility. Early accounts of hydroponic-like practices can be traced back to the Hanging Gardens of Babylon, the Floating Gardens of the Aztecs, and historical records in China and Egypt. The formalization of hydroponics, however, took place in the 20th century, although the concept had been introduced much earlier by Sir Francis Bacon in 1627. Technological leaps in nutrient solutions have been pivotal; German botanists Julius von Sachs and Wilhelm Knop's work in 1860 set the scientific basis for soilless culture. Modern hydroponic systems such as Nutrient Film Technique (NFT), Aeroponics, and Deep Water Culture (DWC) employ pumps, timers, and nutrient reservoirs for efficient cultivation. These systems have scaled hydroponics from a lab-scale practice to a commercial-scale operation, making it accessible to both hobbyist gardeners and large-scale agriculturalists. Another transformative development is in the area of hydroponic lighting. High-Pressure Sodium (HPS) and Light Emitting Diode (LED) lights offer sustainable and efficient alternatives to natural light, thus enabling year-round, indoor hydroponic farming. The automation of hydroponic systems via computer-controlled environments has drastically reduced the manual labor required, making it accessible to individuals without specialized horticultural skills. Lastly, the paper delves into synergistic technologies like smart monitoring systems, Internet of Things (IoT), and renewable energy sources that are setting new paradigms for hydroponics. Smart sensors and analytics provide real-time data for nutrient and environmental control, while IoT devices offer remote management capabilities. Renewable energy sources like solar and wind power bring sustainability to hydroponic setups, thereby reducing the carbon footprint. These technologies collectively create an environment that is conducive not just for optimal plant growth, but also for operational sustainability and efficiency.

Spectral composition of LED light differentially affects biomass, photosynthesis, nutrient profile, and foliar nitrate accumulation of lettuce grown under various replacement methods of nutrient solution.

To enhance crop yield and quality, plant cultivation in controlled-growing systems is an alternative to traditional open-field farming. The use of light-emitting diode (LED) as an adjustable light source represents a promising approach to improve plant growth, metabolism, and function. The objective of this study was to assess the impact of different light spectra (red, red/blue (3:1), blue, and white) with an emission peak of around 656, 656, 450, and 449 nm, respectively, under various replacement methods of nutrient solution (complete replacement (CR), EC-based replacement (ECBR), and replacing based on plant needs (RBPN)), on biomass, physiological traits, and macro- and micronutrient contents of two best-known lettuce varieties, Lollo Rossa (LR) and Lollo Bionda (LB), in the nutrient film technique (NFT) hydroponic system. The results indicated that mix of red and blue LED spectra under RBPN method is the most effective treatment to enhance fresh and dry weights of lettuce plants. In addition, red LED spectrum under RBPN, and red and blue light under ECBR nutrient solution significantly increased leaf stomatal conductance, net photosynthesis and transpiration rate, and intercellular CO2 concentration of LR variety. Phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mn) content in LR variety, and iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) content in both varieties increased upon exposure to blue and red LED light spectrum with RBPN method. Our results suggest that exposure to combination of red and blue light along with feeding plants using RBPN and ECBR methods can increase absorption of macro- and micronutrient elements and improve photosynthetic properties, and eventually increase lettuce yield with lower nitrate accumulation.

Influence of Far-Red Intensity during the Seedling Stage on Biomass Production and Photomorphogenic Characteristics in Leafy Greens under Sole-Source Lighting

It has been well documented that far-red radiation (FR; 700–799 nm) elicits a shade-avoidance/shade-tolerance response across a wide range of plant species. Most sole-source lighting is relatively low in FR compared to sunlight (i.e., 2% vs. 20% of photons, respectively, integrated between 400 and 799 nm). The objective of this experiment was to determine if the photomorphogenic response to FR is a useful strategy during the seedling stage to promote leaf expansion in the hopes that subsequently transplanted seedlings would increase radiation capture resulting in higher harvestable biomass. Lettuce (cv. ‘Rex’, ‘Red Oak’, and ‘Green Grand Rapids’) seedlings were exposed to 5, 10, 20, or 30 µmol·m−2·s−1 of supplemental FR for a duration of 10 d in a growth chamber for 20 h daily. During this stage, all seedlings received background light levels of 195 µmol·m−2·s−1 PAR light from white LEDs for 20 h daily. Seedlings were transplanted into a nutrient film technique (NFT) hydroponic system in a separate growth chamber with LED fixtures that supplied white light at 295 µmol·m−2·s−1 for 16 h daily (DLI = 17 mol·m−2·d−1) until they were harvested at 35 d from seeding. At transplant, fresh weight, leaf area, and plant height were significantly greater for all cultivars exposed to 30 µmol·m−2·s−1 of supplemental FR radiation compared to the 5 µmol·m−2·s−1 control. Fresh weight increased by an average of 35% under 30 µmol·m−2·s−1 FR. Mature plant dry biomass increased by 14% when seedlings were exposed to 30 µmol·m−2·s−1 of supplemental FR radiation. Increasing far-red radiation consistently increased plant growth at the seedling stage, but these increases were generally overcome by maturation.

Comparison of growth, phytochemical content, nutrient uptake, and water consumption of lettuce under two hydroponic system designs: nutrient film technique and deep-water culture

Comparison of growth, phytochemical content, nutrient uptake, and water consumption of lettuce under two hydroponic system designs: nutrient film technique and deep-water culture