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Indoor farming systems enable plant production in precisely controlled environments. However, implementing stable growth conditions and the absence of stress stimulants can weaken plants' defense responses and limit the accumulation of bioactive, health-beneficial phytochemicals. A potential solution is the controlled application of stressors, such as supplemental ultraviolet (UV) light. To this end, we analyzed the efficiency of short-term pre-harvest supplementation of the red–green–blue (RGB, LED) spectrum with ultraviolet B (UV-B) or C (UV-C) light to boost phytochemical synthesis. Additionally, given the biological harm of UV radiation due to high-energy photons, we monitored plants' photosynthetic activity during treatment and their morphology as well as sensory attributes after the treatment. Our analyses showed that UV-B radiation did not negatively impact photosynthetic activity while significantly increasing the overall antioxidant potential of lettuce through enhanced levels of secondary metabolites (total phenolics, flavonoids, anthocyanins), carotenoids, and ascorbic acid. On the contrary, UV-C radiation-induced anthocyanin accumulation in the green leaf cultivar significantly harmed the photosynthetic apparatus and limited plant growth. Taken together, we showed that short-term UV-B light supplementation is an efficient method for lettuce biofortification with healthy phytochemicals, while UV-C treatment is not recommended due to the negative impact on the quality (morphology, sensory properties) of the obtained leafy products. These results are crucial for understanding the potential of UV light supplementation for producing functional plants. [ABSTRACT FROM AUTHOR]

Microorganisms serve as linchpins in agricultural systems. Classic examples include microbial composting for nutrient recovery, using microorganisms in biogas technology for agricultural waste utilization, and employing biofilters to reduce emissions from stables or improve water quality in aquaculture. This mini-review highlights the importance of microbiome analysis in understanding microbial diversity, dynamics, and functions, fostering innovations for a more sustainable agriculture. In this regard, customized microorganisms for soil improvement, replacements for harmful agrochemicals or antibiotics in animal husbandry, and (probiotic) additives in animal nutrition are already in or even beyond the testing phase for a large-scale conventional agriculture. Additionally, as climate change reduces arable land, new strategies based on closed-loop systems and controlled environment agriculture, emphasizing microbial techniques, are being developed for regional food production. These strategies aim to secure the future food supply and pave the way for a sustainable, resilient, and circular agricultural economy. Key points: • Microbial strategies facilitate the integration of multiple trophic levels, essential for cycling carbon, nitrogen, phosphorus, and micronutrients. • Exploring microorganisms in integrated biological systems is essential for developing practical agricultural solutions. • Technological progress makes sustainable closed-entity re-circulation systems possible, securing resilient future food production. Microorganisms connect plant and animal agriculture through complex cycles involving carbon, nitrogen, phosphate, and additional micronutrients. This mini-review outlines the current and potential future roles of microorganisms in agroindustry. [ABSTRACT FROM AUTHOR]

Vertical indoor farming (VIF) with hydroponics offers a promising perspective for sustainable food production. Intelligent control of VIF system components plays a key role in reducing operating costs and increasing crop yields. Modern machine vision (MV) systems use deep learning (DL) in combination with camera systems for various tasks in agriculture, such as disease and nutrient deficiency detection, and flower and fruit identification and classification for pollination and harvesting. This study presents the applicability of MV technology with DL modelling to detect the growth stages of chilli plants using YOLOv8 networks. The influence of different bird's-eye view and side view datasets and different YOLOv8 architectures was analysed. To generate the image data for training and testing the YOLO models, chilli plants were grown in a hydroponic environment and imaged throughout their life cycle using four camera systems. The growth stages were divided into growing, flowering, and fruiting classes. All the trained YOLOv8 models showed reliable identification of growth stages with high accuracy. The results indicate that models trained with data from both views show better generalisation. YOLO's middle architecture achieved the best performance. [ABSTRACT FROM AUTHOR]

Indoor production of basil (Ocimum basilicum L.) is influenced by light spectrum, photosynthetic photon flux density (PPFD), and the photoperiod. To investigate the effects of different lighting on growth, chlorophyll content, and secondary metabolism, basil plants were grown from seedlings to fully expanded plants in microcosm devices under different light conditions: (a) white light at 250 and 380 μmol·m−2·s−1 under 16/8 h light/dark and (b) white light at 380 μmol·m−2·s−1 under 16/8 and 24/0 h light/dark. A higher yield was recorded under 380 μmol·m−2·s−1 compared to 250 μmol·m−2·s−1 (fresh and dry biomasses 260.6 ± 11.3 g vs. 144.9 ± 14.6 g and 34.1 ± 2.6 g vs. 13.2 ± 1.4 g, respectively), but not under longer photoperiods. No differences in plant height and chlorophyll content index were recorded, regardless of the PPFD level and photoperiod length. Almost the same volatile organic compounds (VOCs) were detected under the different lighting treatments, belonging to terpenes, aldehydes, alcohols, esters, and ketones. Linalool, eucalyptol, and eugenol were the main VOCs regardless of the lighting conditions. The multivariate data analysis showed a sharp separation of non-volatile metabolites in apical and middle leaves, but this was not related to different PPFD levels. Higher levels of sesquiterpenes and monoterpenes were detected in plants grown under 250 μmol·m−2·s−1 and 380 μmol·m−2·s−1, respectively. A low separation of non-volatile metabolites based on the photoperiod length and VOC overexpression under longer photoperiods were also highlighted. [ABSTRACT FROM AUTHOR]

The effect of the ratio of red and blue light on fruit biomass radiation-use efficiency (FBRUE) in dwarf tomatoes has not been well studied. Additionally, whether white light offers a greater advantage in improving radiation-use efficiency (RUE) and FBRUE over red and blue light under LED light remains unknown. In this study, two dwarf tomato cultivars ('Micro-Tom' and 'Rejina') were cultivated in three red-blue light treatments (monochromatic red light, red/blue light ratio = 9, and red/blue light ratio = 3) and a white light treatment at the same photosynthetic photon flux density of 300 mmol m-2 s-1. The results evidently demonstrated that the red and blue light had an effect on FBRUE by affecting RUE rather than the fraction of dry mass partitioned into fruits (Ffruits). The monochromatic red light increased specific leaf area, reflectance, and transmittance of leaves but decreased the absorptance and photosynthetic rate, ultimately resulting in the lowest RUE, which induced the lowest FBRUE among all treatments. A higher proportion of blue light (up to 25%) led to a higher photosynthetic rate, resulting in a higher RUE and FBRUE in the three red-blue light treatments. Compared with red and blue light, white light increased RUE by 0.09-0.38 g mol-1 and FBRUE by 0.14-0.25 g mol-1. Moreover, white light improved the Ffruits in 'Rejina' and Brix of fruits in 'Micro-Tom' and both effects were cultivar-specific. In conclusion, white light may have greater potential than mixed red and blue light for enhancing the dwarf tomato FBRUE during their reproductive growth stage. [ABSTRACT FROM AUTHOR]

In the face of a changing climate and a rising number of "food deserts" in both rural and urban areas, there is a demand to supply fresh produce year-round to communities at the end of the traditional agriculture supply chain. Vertical indoor farming is a promising mode of next-generation agriculture that boasts reduced water and pesticide usage, improved yields, more consistent quality, year-round cultivation, and cheaper transportation and harvesting costs. Indoor farms can rival industrial greenhouses in size, but small-scale "pod farms" can be deployed to smaller communities and areas where large swaths of land are either unavailable or too costly. These pods are often the size of shipping containers with their temperature, humidity, and plant nutrient supply carefully controlled. Plants inside the pods are grown hydroponically with light supplied by panels of LEDs and, thus, this mode of farming is fundamentally different from greenhouse farming. Many indoor farming pods have recently become commercially available claiming high energy efficiency, but little analysis and optimization work has been done to prove these claims. To drive innovation in the design of these physical systems, we have developed a digital-twin and genomic optimization framework for the optical design of vertical indoor farming pods. We model a completely enclosed indoor farming pod with plants in the three mutually-orthogonal planes and illuminated by LED "walls." We employ ray-tracing methods and a genetic algorithm to determine the LED source tube area size, beam aperture spread, and power requirements for maximal power absorption by the plants. [ABSTRACT FROM AUTHOR]

Societal Impact Statement Cultivation of strawberry plants in urban production systems, whether in green open‐air spaces or under some form of protected horticulture such as vertical farming, has demonstrated to be challenging to new farmers and businesses. Commercial strawberry producers have an advanced understanding of strawberry plant physiology, enabling them to grow the crop successfully and profitably. Lack of knowledge exchange between commercial growers and new urban farmers seems to result in the abandonment of strawberries as crop of choice in urban systems. This review will confront the specific plant science challenges urban growers need to address to incorporate this nutritional crop into their revolutionary urban growing systems, whilst achieving good quality produce with high yields. Summary To ensure a sustainable future of farming, urban horticulture (UH) will need to be a key part of our everyday life. There are increasing demands for higher productivity and more locally produced food, even close to densely populated urban areas, to address environmental pressures and accelerate the resilience of modern food systems. UH is a broad term and can include numerous cultivation methods; rooftop gardens, public spaces, vertical walls, indoor vertical farms, as well as an array of crops including, salads, soft fruits and trees. Crops such as strawberries are expected to soon make a significant contribution to UH. Urban strawberry production promises all‐year round fruit availability, reduced reliance on imports, increased self‐sufficiency, lower food miles, a supply of high‐quality fresh fruits from hyper‐local spaces, increased employment opportunities, welfare benefits and an opportunity to promote a sense of community. Strawberry is a complex perennial crop with agronomical challenges, which requires specialist knowledge that is not always available to new urban farmers. Achieving an urban version of a strawberry field will require knowledge exchange between the commercial rural strawberry producers and the newly entered urban growers. Plant physiology, management of plant pathogens, choice of propagation material, fertigation, pollination and environmental requirements are the most common challenges for urban strawberry production. This review aims to consolidate the common bottleneck challenges of UH for new urban strawberry facilities.

In the United Kingdom, around 20% of dairy farms house cows all year round. Research suggests that farmers value animal health and comfort over the expression of natural behaviour through grazing. The concept of natural behaviour is notoriously complex, however. The article reframes the topic of grazing through a relational approach to understand farmer views on the practice in Great Britain, using qualitative interviews. The article also considers critiques of the relational approach. In this study, participants were reluctant to see a distinction between farms that graze and those that do not in terms of animal welfare, but they also valued the positive affective experience of grazing their cows on their own farm. The article argues that the latter account is not adequately included in debates about grazing. What this account excludes is the situated nature and limitations of relationships on farm even when cows graze. [ABSTRACT FROM AUTHOR]

Introduction: Indoor agriculture, especially plant factories, becomes essential because of the advantages of cultivating crops yearly to address global food shortages. Plant factories have been growing in scale as commercialized. Developing an on-site system that estimates the fresh weight of crops nondestructively for decision-making on harvest time is necessary to maximize yield and profits. However, a multi-layer growing environment with on-site workers is too confined and crowded to develop a high-performance system. This research developed a machine vision-based fresh weight estimation system to monitor crops from the transplant stage to harvest with less physical labor in an on-site industrial plant factory. Methods: A linear motion guide with a camera rail moving in both the x-axis and y-axis directions was produced and mounted on a cultivating rack with a height under 35 cm to get consistent images of crops from the top view. Raspberry Pi4 controlled its operation to capture images automatically every hour. The fresh weight was manually measured eleven times for four months to use as the ground-truth weight of the models. The attained images were preprocessed and used to develop weight prediction models based on manual and automatic feature extraction. Results and discussion: The performance of models was compared, and the best performance among them was the automatic feature extraction-based model using convolutional neural networks (CNN; ResNet18). The CNN-based model on automatic feature extraction from images performed much better than any other manual feature extraction-based models with 0.95 of the coefficients of determination (R2) and 8.06 g of root mean square error (RMSE). However, another multiplayer perceptron model (MLP_2) was more appropriate to be adopted on-site since it showed around nine times faster inference time than CNN with a little less R2 (0.93). Through this study, field workers in a confined indoor farming environment can measure the fresh weight of crops nondestructively and easily. In addition, it would help to decide when to harvest on the spot. [ABSTRACT FROM AUTHOR]

The rise in agricultural innovation has led to the use of sustainable farming practices, such as aeroponics, which increase crop production. Aeroponics, a soil-free indoor precision farming system, cultivates crops using vertical towers, garnering global attention for its environmentally friendly and productive cultivation methods. Aeroponic systems can grow lettuce, a popular green-leafy vegetable, quickly and with minimal water usage. However, yield prediction is a tedious task in real-world scenarios. To efficiently predict lettuce yield, various scientific experiments have integrated IoT and machine-learning techniques. This research work utilized various machine-learning regression models, including linear, support vector, random forest, and XGBoost, to estimate lettuce yield based on specific growth parameters such as pH, EC, temperature, total dissolved salts (TDS), turbidity, humidity and light. After implementation, the results showed a high prediction accuracy of 93% and minimal error rates produced by the XGBoost regression model when compared with the other regression models. Further, fine-tuning the model parameters enhanced the XGBoost model's performance, enhancing its generalization capability to handle new realtime data. This indicates that optimizing the lettuce yield involves not only using indoor aeroponic farming methods but also utilizing advanced sustainable food production systems. [ABSTRACT FROM AUTHOR]

Bacopa monnieri, a cognitive-enhancing herb crucial in health supplements, faces quality variations and contamination by toxic substances in conventional field cultivation, which hinders industrial use. Here, indoor cultivation of diploid (2x) and tetraploid (4x) B. monnieri using hydroponic and soil systems was studied. Soil cultivation promoted longer shoot lengths but resulted in lower biomass and chlorophyll contents compared to hydroponic cultivation. Conversely, soil cultivation significantly elevated total phenolics, total triterpenoids, bacoside A3, and bacopaside X contents in both lines, showing 1.7- to 3.3-fold increases over hydroponic cultivation. Furthermore, 4x plants grown in soil had higher bacopaside II and total bacoside contents than hydroponically grown plants, with 2- and 1.5-fold increases, respectively. Yet, no significant differences were observed in growth and pigment between 2x and 4x lines under the same system. Similarly, no significant differences in bioactive compound productions were found between 2x and 4x hydroponically grown plants. However, in soil, 4x plants exhibited higher total phenolic content, bacopaside II, and total bacoside contents compared to 2x plants. Interestingly, 2x plants grown in soil were the top performers for bacoside production per plant. These findings optimize cultivation practices to meet industry demands, warranting further research into large-scale production techniques. [ABSTRACT FROM AUTHOR]

BACKGROUND: Bacterial contamination of produce is a concern in indoor farming due to close plant spacing, recycling irrigation, warm temperatures, and high relative humidity during production. Cultivars that inherently resist contamination and photo‐sanitization using ultraviolet (UV) radiation during the production phase can reduce bacterial contamination. However, there is limited information to support their use in indoor farming. RESULTS: Lettuce (Lactuca sativa) cultivars with varying plant architectures grown in a custom‐built indoor farm exhibited differences in E. coli O157:H7 survival after inoculation. The survival of E. coli O157:H7 was lowest in the leaf cultivar (open architecture) and highest in the romaine and oakleaf cultivars (compact architecture). Of the different UV wavelengths that were tested (UV‐A, UV‐A + B, UV‐A + C), UV A + C at an intensity of 54.5 μmol m−2 s−1 (with 3.5 μmol m−2 s−1 of UV‐C), provided for 15 min every day, was found to be most efficacious in reducing the E. coli O157:H7 survival on romaine lettuce with no negative effects on plant growth and quality. CONCLUSION: Contamination of E. coli O157:H7 on lettuce plants can be reduced and the food safety levels in indoor farms can be increased by selecting cultivars with an open leaf architecture coupled with photo‐sanitization using low and frequent exposure to UV A + C radiation. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Societal Impact Statement: Cultivation of strawberry plants in urban production systems, whether in green open‐air spaces or under some form of protected horticulture such as vertical farming, has demonstrated to be challenging to new farmers and businesses. Commercial strawberry producers have an advanced understanding of strawberry plant physiology, enabling them to grow the crop successfully and profitably. Lack of knowledge exchange between commercial growers and new urban farmers seems to result in the abandonment of strawberries as crop of choice in urban systems. This review will confront the specific plant science challenges urban growers need to address to incorporate this nutritional crop into their revolutionary urban growing systems, whilst achieving good quality produce with high yields. Summary: To ensure a sustainable future of farming, urban horticulture (UH) will need to be a key part of our everyday life. There are increasing demands for higher productivity and more locally produced food, even close to densely populated urban areas, to address environmental pressures and accelerate the resilience of modern food systems. UH is a broad term and can include numerous cultivation methods; rooftop gardens, public spaces, vertical walls, indoor vertical farms, as well as an array of crops including, salads, soft fruits and trees. Crops such as strawberries are expected to soon make a significant contribution to UH. Urban strawberry production promises all‐year round fruit availability, reduced reliance on imports, increased self‐sufficiency, lower food miles, a supply of high‐quality fresh fruits from hyper‐local spaces, increased employment opportunities, welfare benefits and an opportunity to promote a sense of community. Strawberry is a complex perennial crop with agronomical challenges, which requires specialist knowledge that is not always available to new urban farmers. Achieving an urban version of a strawberry field will require knowledge exchange between the commercial rural strawberry producers and the newly entered urban growers. Plant physiology, management of plant pathogens, choice of propagation material, fertigation, pollination and environmental requirements are the most common challenges for urban strawberry production. This review aims to consolidate the common bottleneck challenges of UH for new urban strawberry facilities. [ABSTRACT FROM AUTHOR]

A tunable LED panel with multiple types of LEDs on a panel can provide various spectra for optimal plant growth. However, it is difficult for a lighting panel with multiple types of high-power LEDs to achieve uniform lighting. We demonstrated that by using optical reflectors at the sides of an LED panel to trap photons of LED arrays or using both the above-mentioned reflectors and optical lenses on each LED, high lighting uniformity can be achieved at a short distance to plants. The ray tracing simulation results show that the LED panel equipped with reflectors and optical lenses can achieve a high uniformity of >0.80 when the LED-plant distance is at half of the LED array's pitch. We further verified that an LED panel (at a size of 88 cm × 54 cm) installed with reflectors can achieve light uniformities around 0.90 at a 15 cm LED-plant distance for the 6 types of LEDs (4 color LEDs and 2 white LEDs) on the panel. Compared with a branded tunable LED panel, our LED panel saves >25 cm vertical distance for each tier of plants and has 92.5% higher photon efficacy for 660 nm LEDs that exist on both panels. [ABSTRACT FROM AUTHOR]

Accurate and rapid determination of moisture content is essential in crop production and decision-making for irrigation. Near-infrared (NIR) spectroscopy has been shown to be a promising method for determining moisture content in various agricultural products, including herbs and vegetables. This study tested the hypothesis that NIR spectroscopy is effective in accurately measuring the moisture content of Genovese basil (Ocimum basilicum L.), with the objective of developing a respective calibration model. Spectral data were obtained from a total of 120 basil leaf samples over a period of six days. These included freshly harvested and detached leaves, as well as those left in ambient air for 1–6 days. Five spectra were taken from each leaf using a handheld NIR spectrophotometer, which covers the first and second overtones of the NIR spectral region: 950–1650 nm. After the spectral acquisition, the leaves were weighed for fresh mass and then put in an oven for 72 h at 80 °C to determine the dry weight and calculate the reference moisture content. The calibration model was developed using multivariate analysis in MATLAB, including preprocessing and regression modeling. The data obtained from 75% of the samples were used for model training and 25% for validation. The final model demonstrates strong performance metrics. The root mean square error of calibration (RMSEC) is 2.9908, the root mean square error of cross-validation (RMSECV) is 3.2368, and the root mean square error of prediction (RMSEP) reaches 2.4675. The coefficients of determination for calibration (R2C) and cross-validation (R2CV) are consistent, with values of 0.829 and 0.80, respectively. The model's predictive ability is indicated by a coefficient of determination for prediction (R2P) of 0.86. The range error ratio (RER) stands at 11.045—highlighting its predictive performance. Our investigation, using handheld NIR spectrophotometry, confirms NIR's usefulness in basil moisture determination. The rapid determination offers valuable insights for irrigation and crop management. [ABSTRACT FROM AUTHOR]

The effect of artificial lighting with different light spectra and photoperiods/daily light integrals (DLIs) on the yield, bioactive compounds and antioxidant capacity of the common ice plant (Mesembryanthemum crystallinum) was studied. Four-week-old seedlings were selected and subjected to four different light spectra made up of different combinations of blue (400–500 nm), green (500–600 nm) and red light (600–700 nm), with a total photosynthetic photon flux density (PPFD) of 180 µmol.m−2.s−1. Concurrently, the effect of the daily light integral (DLI) was also studied, with the light treatment photoperiod set at 18 h and 21 h. Biometric parameters such as fresh mass weight, leaf area, leaf width, and dry mass, together with plant metabolite contents such as total antioxidant capacity (TAC), vitamin C, chlorophyll a and b content, and total carotenoids and nitrates, were investigated. It was found that the plants grew better when exposed to light with a higher proportion of the red and blue spectrum, with the highest fresh mass of 68 g observed at a photoperiod of 18 h. On the other hand, green spectrum light was not found to yield any significant improvement in shoot weight, leaf area, or leaf size. It was also found that dry mass, chlorophyll b and nitrates were not influenced by the light spectrum but were influenced by the photoperiod duration. While both the dry mass and nitrate content increase as the photoperiod increases, a longer photoperiod had a negative effect on chlorophyll a, chlorophyll b and total carotenoids, with their content decreasing by as much 29% for chlorophyll a, 59% for chlorophyll b and 29% for total carotenoids. TAC content was seen to increase by more than 24% under the influence of 66% more green light, and 38% more under the 21 h photoperiod. [ABSTRACT FROM AUTHOR]

The need to reconfigure current supply models to address future climate and demographic scenarios has driven researchers and investors to experiment with innovative production systems that have reconnected agricultural production to the point of consumption, namely cities. The technological acceleration of the past decade has led to the emergence of new urban architectures and metabolisms, often created within regulatory gaps and constraints arising from the obsolescence of zoning plans or building regulations. This paper outlines the state of the art of technological innovation and how, along with design, it has reshaped norms. [ABSTRACT FROM AUTHOR]

Indoor farming systems enable plant production in precisely controlled environments. However, implementing stable growth conditions and the absence of stress stimulants can weaken plants’ defense responses and limit the accumulation of bioactive, health-beneficial phytochemicals. A potential solution is the controlled application of stressors, such as supplemental ultraviolet (UV) light. To this end, we analyzed the efficiency of short-term pre-harvest supplementation of the red–green–blue (RGB, LED) spectrum with ultraviolet B (UV-B) or C (UV-C) light to boost phytochemical synthesis. Additionally, given the biological harm of UV radiation due to high-energy photons, we monitored plants’ photosynthetic activity during treatment and their morphology as well as sensory attributes after the treatment. Our analyses showed that UV-B radiation did not negatively impact photosynthetic activity while significantly increasing the overall antioxidant potential of lettuce through enhanced levels of secondary metabolites (total phenolics, flavonoids, anthocyanins), carotenoids, and ascorbic acid. On the contrary, UV-C radiation-induced anthocyanin accumulation in the green leaf cultivar significantly harmed the photosynthetic apparatus and limited plant growth. Taken together, we showed that short-term UV-B light supplementation is an efficient method for lettuce biofortification with healthy phytochemicals, while UV-C treatment is not recommended due to the negative impact on the quality (morphology, sensory properties) of the obtained leafy products. These results are crucial for understanding the potential of UV light supplementation for producing functional plants.

Indoor production of basil (Ocimum basilicum L.) is influenced by light spectrum, photosynthetic photon flux density (PPFD), and the photoperiod. To investigate the effects of different lighting on growth, chlorophyll content, and secondary metabolism, basil plants were grown from seedlings to fully expanded plants in microcosm devices under different light conditions: (a) white light at 250 and 380 μmol·m−2·s−1 under 16/8 h light/dark and (b) white light at 380 μmol·m−2·s−1 under 16/8 and 24/0 h light/dark. A higher yield was recorded under 380 μmol·m−2·s−1 compared to 250 μmol·m−2·s−1 (fresh and dry biomasses 260.6 ± 11.3 g vs. 144.9 ± 14.6 g and 34.1 ± 2.6 g vs. 13.2 ± 1.4 g, respectively), but not under longer photoperiods. No differences in plant height and chlorophyll content index were recorded, regardless of the PPFD level and photoperiod length. Almost the same volatile organic compounds (VOCs) were detected under the different lighting treatments, belonging to terpenes, aldehydes, alcohols, esters, and ketones. Linalool, eucalyptol, and eugenol were the main VOCs regardless of the lighting conditions. The multivariate data analysis showed a sharp separation of non-volatile metabolites in apical and middle leaves, but this was not related to different PPFD levels. Higher levels of sesquiterpenes and monoterpenes were detected in plants grown under 250 μmol·m−2·s−1 and 380 μmol·m−2·s−1, respectively. A low separation of non-volatile metabolites based on the photoperiod length and VOC overexpression under longer photoperiods were also highlighted.

The main objective of this study was to characterize intumescence injury of three susceptible tomato cultivars grown in a greenhouse or indoors using two types of soilless culture systems. Plants of cultivars Maxifort, Camaro, and Patio were grown in either an indoor environment with broadband white and red light-emitting diode (LED) fixtures providing a daily light integral (DLI) of 12.7 mol·m-2·day-1 [photosynthetic photon flux density (PPFD) of 220 ± 3 mmol·m-2·s-1 for 16 h·d-1] or in a glass-glazed greenhouse with supplemental lighting provided by high-pressure sodium lamps that delivered a PPFD of ~150 μmol·m-2·s-1. Plants were grown using deep-water culture hydroponic systems or containers with a peat-based substrate. The growing environment had a larger effect on intumescence incidence and severity than the growing system, likely due to differences in ultraviolet radiation (100 to 400 nm), but other factors such as day/night temperature and relative humidity (RH), could have affected the response. Across cultivars, the probability of developing intumescence was higher indoors (>91%) than in the greenhouse. Indoor-grown plants also developed symptoms of the disorder from 2 to 6 days earlier than those in the greenhouse. Similarly, intumescence incidence was higher in plants from all cultivars grown indoors than in the greenhouse, but differences between the two environments were generally greater for Patio and Camaro than for Maxifort, which was the most susceptible cultivar. Greenhouse conditions were more conducive to active plant growth. For example, plants in the greenhouse were more than 2 times taller and had at least 12 times greater leaf area than those indoors, which resulted in large differences in shoot dry mass. However, environmental effects on intumescence response also contributed to differences in growth, as plants that were most affected by the disorder experienced severe leaf abscission and/or senescence. Our overall findings show that intumescence is greatly affected by the production environment, but injuries are likely to change based on genetic susceptibility. [ABSTRACT FROM AUTHOR]

Significant efforts have been made to optimise spectrum quality in indoor farming to maximise artificial light utilisation and reduce water loss. For such an improvement, green (G) light supplementation to a red–blue (RB) background was successfully employed in our previous studies to restrict both non-photochemical quenching (NPQ) and stomatal conductance (gs). At the same time, however, the downregulation of NPQ and gs had the opposite influence on leaf temperature (Tleaf). Thus, to determine which factor plays the most prominent role in Tleaf regulation and whether such a response is temporal or permanent, we investigated the correlation between NPQ and gs and, subsequently, Tleaf. To this end, we analysed tomato plants (Solanum lycopersicum L. cv. Malinowy Ozarowski) grown solely under monochromatic LED lamps (435, 520, or 662 nm; 80 µmol m−2 s−1) or a mixed RGB spectrum (1:1:1; 180 µmol m−2 s−1) and simultaneously measured gs and Tleaf with an infrared gas analyser and a thermocouple or an infrared thermal camera (FLIR) during thermal imaging analyses. The results showed that growth light quality significantly modifies Tleaf and that such a response is not temporal. Furthermore, we found that the actual adaxial leaf surface temperature of plants is more closely related to NPQ amplitude, while the temperature of the abaxial surface corresponds to gs. [ABSTRACT FROM AUTHOR]

Smart farming using technology-monitored controlled environment agriculture (CEA) has recently evolved to optimize crop growth while minimizing land use and environmental impacts, especially for climate-threatened regions. This study focuses on characterizing crop production using system dynamics (SD) modeling, which is a relatively new approach in CEA settings. Using tomatoes in a hydroponic growing system, we explore an alternative food resource potentially accessible to underserved areas in rural and/or urban settings under abrupt climate variability. The designed autonomous indoor farming platforms (AIFP) are equipped with the Internet of Things (IoT) to monitor the physiological parameters, including electrical conductivity (EC), pH, and water temperature (WT) associated with plant growth. Two varieties of tomato (Solanum lycopersicum) plants were used in this study with two different nutrient inputs (N-P-K ratios of 2-1-6 and 5-5-5) to assess the nutrient application impact on yield, especially focusing on the early stages of tomato to conceptualize and parametrize SD modes. Repeated measure analysis was conducted to investigate the effects of the environmental factors (EC, pH, and WT) in response to changing plant nutrients. The results show that different nutrient compositions (N-P-K ratios) have a noticeable effect on both pH and WT (p < 0.001) as opposed to EC. The study indicates that the proposed AIFP would be a promising solution to produce other crops for indoor farming in a changing climate. We anticipate that the proposed AIFP along with SD tools will be widely adopted to promote indoor farming in changing climates, ultimately contributing to community resilience against food insecurity in disadvantaged areas for years to come. [ABSTRACT FROM AUTHOR]

This study presents a solar lighting system designed for indoor farming to provide natural light. The proposed system uses a parabolic dish concentrator integrating with polymethyl methacrylate optical fibers to direct concentrated light into a desired place. A water cooling mechanism is also used to prevent heat transmission to the optical fibers. The indoor sunlight's distribution is studied using a designed darkroom. The evaluation is carried out in 7 days, from November 23 to 29, from 8 a.m. to 4 p.m., to ensure the stability of the system under various weather conditions. The results of the experiments show that the receiver's temperature can remain at 63 °C on sunny days under a clear sky, even when the maximum value of solar radiation is about 982 W m−2 with the highest air temperature of 19 °C. During the experiments, the solar illuminance ranges from a maximum of 118,821.85 lx to a minimum value of 374.9.6 lx. The overall optical efficiency of the system, considering optical components, ranges from 31% to 32% under various outdoor illuminance levels. Overall, it is confirmed that the developed solar lighting system offers a applicable method to naturally illuminate protected agricultural environments, enhancing the quality of the growing crops. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the optimal temperature difference in day–night indoor cultivation conditions to enhance the flower yield and functional component contents of female hemp plants. Hemp clones were cultivated under five distinct day and night temperature differences (DIF) during the reproductive stage. The daytime and nighttime temperature settings were as follows: 18:30 °C (negative 12 DIF), 21:27 °C (negative 6 DIF), 24:24 °C (0 DIF), 27:21 °C (positive 6 DIF), and 30:18 °C (positive 12 DIF). Seven weeks after transplantation, the growth parameters, leaf gas exchange, total phenolic compounds, 2,2-diphenylpicrylhydrazyl scavenging activity, and cannabinoid contents were analyzed. The total shoot biomass based on dry weight was highest at 21:27, reaching 41.76 g, and lowest at 30:18, measuring 24.46 g. However, the flower biomass, which is the primary production site, was highest at 24:24 and lowest at 18:30, showing a 4.7-fold difference. The photosynthesis-related parameters were temperature-dependent and strongly correlated with biomass production. The cannabinoid content of the hemp leaves increased at 21:27, whereas that of the hemp flowers increased at 27:21. The findings of this study indicate that the optimal temperature condition for female hemp flower production in a limited space is positive 6 DIF treatment, which corresponds to 27:21 °C. These results can contribute to advancements in indoor crop cultivation technology. [ABSTRACT FROM AUTHOR]

The use of LEDs for plant lighting (phytolighting) provides a more energyefficient alternative to traditional lighting methods. Combination of LEDs with different spectral composition and the possibility to change the composition of resulting radiation in a single lighting device allows one to improve the efficiency of phytolighting systems and optimize them for different conditions of plant growth and development. In this work, we have investigated quasi-monochromatic LEDs specialized for efficient phytolighting and efficient white LEDs with different CRI. Being based on the research, the most effective LEDs for building phytolighting systems have been identified, and their optimal ratio with red quasi-monochromatic LEDs for building phytolighting systems in rooms with a constant presence of people (greenhouses, winter gardens, etc) has been determined. [ABSTRACT FROM AUTHOR]

Far-red light (FR; wavelength: 700–800 nm) is known for its effects on plant morphology and photosynthesis. However, its effects on stomatal responses and transpiration are not well understood. This study investigated the effects of FR on stomatal development and evapotranspiration in sweet basil grown under red, blue, and green (RGB) light-emitting diodes (LED). FR was provided for 10 days at 0, 30, 100, and 130 μmol·m−2·s−1 with the same base light (RGB ratio of 6:2:2; a photosynthetic photon flux density of 200 μmol·m−2·s−1). Evapotranspiration was measured using a load cell, and stomatal development was monitored microscopically. FR increased the height of sweet basil mostly due to the shade avoidance syndrome. The photosynthetic rate was not improved with FR, probably due to insufficient base light intensity. Despite similar leaf area and root growth, daily evapotranspiration increased with FR, resulting in higher water use. Although the stomatal density and guard cell area were similar across treatments, the stomatal aperture area was larger in plants with FR, thus increasing evapotranspiration. In conclusion, FR with the base RGB light intensity of 200 μmol·m−2·s−1 enhanced the evapotranspiration of sweet basil by regulating stomatal opening, but it did not enhance photosynthesis. [ABSTRACT FROM AUTHOR]

Bacopa monnieri, a cognitive-enhancing herb crucial in health supplements, faces quality variations and contamination by toxic substances in conventional field cultivation, which hinders industrial use. Here, indoor cultivation of diploid (2x) and tetraploid (4x) B. monnieri using hydroponic and soil systems was studied. Soil cultivation promoted longer shoot lengths but resulted in lower biomass and chlorophyll contents compared to hydroponic cultivation. Conversely, soil cultivation significantly elevated total phenolics, total triterpenoids, bacoside A3, and bacopaside X contents in both lines, showing 1.7- to 3.3-fold increases over hydroponic cultivation. Furthermore, 4x plants grown in soil had higher bacopaside II and total bacoside contents than hydroponically grown plants, with 2- and 1.5-fold increases, respectively. Yet, no significant differences were observed in growth and pigment between 2x and 4x lines under the same system. Similarly, no significant differences in bioactive compound productions were found between 2x and 4x hydroponically grown plants. However, in soil, 4x plants exhibited higher total phenolic content, bacopaside II, and total bacoside contents compared to 2x plants. Interestingly, 2x plants grown in soil were the top performers for bacoside production per plant. These findings optimize cultivation practices to meet industry demands, warranting further research into large-scale production techniques.

A tunable LED panel with multiple types of LEDs on a panel can provide various spectra for optimal plant growth. However, it is difficult for a lighting panel with multiple types of high-power LEDs to achieve uniform lighting. We demonstrated that by using optical reflectors at the sides of an LED panel to trap photons of LED arrays or using both the above-mentioned reflectors and optical lenses on each LED, high lighting uniformity can be achieved at a short distance to plants. The ray tracing simulation results show that the LED panel equipped with reflectors and optical lenses can achieve a high uniformity of >0.80 when the LED-plant distance is at half of the LED array’s pitch. We further verified that an LED panel (at a size of 88 cm × 54 cm) installed with reflectors can achieve light uniformities around 0.90 at a 15 cm LED-plant distance for the 6 types of LEDs (4 color LEDs and 2 white LEDs) on the panel. Compared with a branded tunable LED panel, our LED panel saves >25 cm vertical distance for each tier of plants and has 92.5% higher photon efficacy for 660 nm LEDs that exist on both panels.

The main objective of this study was to characterize intumescence injury of three susceptible tomato cultivars grown in a greenhouse or indoors using two types of soilless culture systems. Plants of cultivars Maxifort, Camaro, and Patio were grown in either an indoor environment with broadband white and red light-emitting diode (LED) fixtures providing a daily light integral (DLI) of 12.7 mol·m−2·day−1 [photosynthetic photon flux density (PPFD) of 220 ± 3 µmol·m−2·s−1 for 16 h·d−1] or in a glass-glazed greenhouse with supplemental lighting provided by high-pressure sodium lamps that delivered a PPFD of ∼150 µmol·m−2·s−1. Plants were grown using deep-water culture hydroponic systems or containers with a peat-based substrate. The growing environment had a larger effect on intumescence incidence and severity than the growing system, likely due to differences in ultraviolet radiation (100 to 400 nm), but other factors such as day/night temperature and relative humidity (RH), could have affected the response. Across cultivars, the probability of developing intumescence was higher indoors (≥91%) than in the greenhouse. Indoor-grown plants also developed symptoms of the disorder from 2 to 6 days earlier than those in the greenhouse. Similarly, intumescence incidence was higher in plants from all cultivars grown indoors than in the greenhouse, but differences between the two environments were generally greater for Patio and Camaro than for Maxifort, which was the most susceptible cultivar. Greenhouse conditions were more conducive to active plant growth. For example, plants in the greenhouse were more than 2 times taller and had at least 12 times greater leaf area than those indoors, which resulted in large differences in shoot dry mass. However, environmental effects on intumescence response also contributed to differences in growth, as plants that were most affected by the disorder experienced severe leaf abscission and/or senescence. Our overall findings show that intumescence is greatly affected by the production environment, but injuries are likely to change based on genetic susceptibility.

In controlled environments, supplementing a light spectrum with ultraviolet A (UVA; 315–399 nm) or blue (B; 400–499 nm) light increases the concentrations of phenolic compounds that can increase quality attributes, such as leaf pigmentation and nutritional quality of lettuce (Lactuca sativa). However, B light and sometimes UVA light can inhibit leaf expansion and biomass accumulation when continuously applied, whereas applying it only at the end of the production cycle can increase lettuce quality with little to no effect on crop yield. Our objective was to quantify the persistency of periodic supplemental UVA or B light and compare end-of-production with continuously applied supplemental light during indoor lettuce production on quality attributes and biomass accumulation. We hypothesized that supplemental UVA or B light would be more effective later, rather than earlier, during production with increasing lettuce quality attributes. We grew ‘Rouxai’ red-leaf lettuce hydroponically at an air temperature of 23 °C under 75 μmol⋅m−2⋅s−1 of red (peak = 664 nm) plus 75 μmol⋅m−2⋅s−1 of warm-white light provided by light-emitting diodes. The supplemental lighting treatments consisted of adding 30 μmol⋅m−2⋅s−1 of UVA (peak= 386 nm) or B (peak = 449 nm) light during the seedling phase (P1; days 4–12), growth phase (P2; days 12–20), finishing phase (P3; days 20–28), or the entire time (ET; days 4–28). Supplemental UVA or B light applied at any individual phase did not inhibit biomass accumulation, whereas enriched B light during the entire production period inhibited fresh mass compared with no supplemental light. Additionally, supplemental UVA or B light during P3 or ET similarly increased total phenolic and anthocyanin concentrations. Finally, applying UVA or B light during P1 or P2 had no residual effect on mature plant growth or quality at harvest. We concluded that the end of the production cycle is the optimal time to apply supplemental UVA or B light to improve lettuce coloration and phenolic content, that earlier application elicits transient responses, and that continuous application improves lettuce quality but inhibits biomass accumulation. Finally, there are potential energy savings by using end-of-production supplemental light compared with continuous application of the same spectrum.

Vertical farming is a rapidly expanding type of indoor controlled environment agriculture whose promises have attracted widespread praise and considerable early-stage capital in recent years. Among vertical farming's many claimed benefits, per-area productivity is frequently mentioned, proposing crop yields at least two orders of magnitude higher than outdoor field agriculture. These extremely high yields form the basis for a theory of land use change whereby yield-increasing technologies reduce or reverse the expansionary demands of lower-yielding farms, retaining or returning those areas to "wild nature". In a sensational articulation of this kind of intensification, from 2007 to 2017 many vivid proposals portrayed centrally located skyscraper farms as a key strategy for building self-sufficient cities. This skyscraper articulation of vertical farming captured the public imagination and led to substantial investment into contemporary vertical farming facilities, the majority of which are in large suburban high-ceiling single-story warehouses. This paper traces the politics of vertical farming's land-sparing narratives beginning early in the twentieth century, with a closer analysis of two contrasting historical examples: Othmar Ruthner's 1960s tower greenhouses, which closely resemble the imaginary skyscraper farms of the 2010s; and Noel Davis' 1980s PhytoFarms, which more closely resembles the well-funded warehouse vertical farms of the 2020s. This analysis suggests that, despite their high yields, the extremely high capital investments needed to build the precise controlled environments of today's vertical farms preclude the profitable production of staple crops, rendering them unlikely to fulfil their land-sparing promises. [ABSTRACT FROM AUTHOR]

Light and its spectral characteristics are crucial for plant growth and development. The far-red photon flux mediates many plant processes through the action of phytochrome and also accelerates the photosynthetic electron transfer rate. In this study, we assessed the effects of far-red addition on butterhead lettuce morphology, light use efficiency, optical properties, and phytochemical characteristics. Three-week-old lettuce plants (Lactuca sativa L. cv. Alyssa) were grown for up to 28 days under a 10% blue and 90% red light spectrum (200 µmol m-2 s-1, 16 h photoperiod) to which five different intensities of far-red light (peak at 735 nm) were added (0-9-18-36-72 µmol m-2 s-1). White light-emitting diodes were included as a proxy for sunlight. Increasing supplemental far-red photon flux from zero to 21% increased the light use efficiency (g per mol) by 37% on day 14; 43% on day 21; and 39% on day 28. Measurements of projected head area suggest that this was associated with an increase in leaf expansion and photon capture and not necessarily a direct effect on photosynthesis. Moreover, vegetation indices based on leaf reflectance showed a decrease in chlorophyll-related indices under a high far-red photon flux. This decrease in pigment content was confirmed by chemical analyses, suggesting that the plants may not reach their full potential in terms of photon capture, limiting the overall photosynthetic performance. Furthermore, the stress-related Carter 1 index increased in plants grown under a high far-red photon flux, indicating early plant stress. Far-red tended to decrease the content of total phenolics and increase soluble sugars. The higher sugar levels can be attributed to an improved photochemical efficiency due to photosystem I excitation by far-red wavelengths, also known as the Emerson Enhancement effect. Despite these higher sugar levels, no effect on foliar nitrate content was observed. Our results show that far-red supplementation has the potential to enhance light interception at the early growth stages, although higher intensities of far-red may cause plant stress. [ABSTRACT FROM AUTHOR]

Significant advancement has been achieved improving electrical efficiency and photon efficacy of light-emitting diodes (LEDs) as the sole source of crop lighting for indoor farming. However, a significant portion of highly efficient photon emissions from improved LEDs is wasted by natural beam spread beyond cropping areas. Additional attention is needed to enhance crop-canopy photon capture efficiency (CCPCE), the fraction of photons emitted from LEDs actually incident upon foliar canopies. We postulate that by taking advantage of unique physical properties of LEDs, such as low radiant heat at photon-emitting surfaces and dimmable photon emissions, reduced vertical separation distance between light-emitting surfaces and light-receiving surfaces will enhance CCPCE by capturing more obliquely emitted photons that otherwise are lost. This “close-canopy-lighting” (CCL) strategy was tested in two ways: For an energy-efficiency strategy, LEDs were dimmed to the same photosynthetic photon flux density (PPFD) of 160 µmol m-2 s-1 at 45-, 35-, 25-, and 15-cm separation distances between lamps and cropping surfaces. For a yield-enhancement strategy, dimming was not applied, so higher PPFDs occurred at each separation distance closer than 45 cm for the same input energy. In the first strategy, the same biomass of lettuce (Lactuca sativa L. cv. Rouxai) was produced at each separation distance, while significantly lower energy was expended for lighting at each closer separation. Significantly higher biomass was produced at reduced separation distances with the same energy expenditure by LEDs using the yield-enhancement strategy. For both strategies, energy-utilization efficiency (g/kWh) doubled at the closest separation distance of 15 cm compared to the standard 45-cm separation distance. Even higher energy-utilization efficiency was achieved at a 25-cm separation distance when growth compartments were enclosed with a reflective curtain in the yield-enhancement strategy. Our findings suggest that CCL is a highly effective energy-saving strategy for overhead LED lighting, suggesting the need for innovative next-generation re-design of height-adjustable LED mounts and controlled air movement between tiers of indoor farms utilizing CCL. [ABSTRACT FROM AUTHOR]

The modern agriculture system based on open-field crops requires a lot of energy and resources in terms of soil, water, and chemicals. Vertical farming (VF) systems could be a viable alternative for some types of cultivation that are receiving interest thanks to their high modularity, optimized water and nutrients use, and LEDs employment as an energy-efficient light source. However, VF design and installation are expensive and require well-tailored optimization depending on the specific crop to increase its competitiveness. This work analyzed the effects of different combinations of NPK (nitrogen-phosphorus-potassium) slow-release fertilizers and LED-based light recipes on the growth of baby leaf lettuce (Lactuca sativa L.), taking advantage of the Design of Experiments (DoE) methodology. The type of slow-release fertilizer, its quantity measured as the number of aggregates from 0 to 6, and the type of light recipe were considered as input factors, and their possible influence on the growth of lettuce (in terms of morphological parameters) in a controlled indoor farming system was measured. Results suggest that using higher fertilizer inputs equal to six aggregates leads to an increase of average leaf area equal to 46% (from 13.00 cm2 to 19.00 cm2), while the fresh weight of lettuce increases by 65% (from 1.79 g to 2.96 g). However, the height of plants also depends on the combination of the light recipes. In particular, the separate coupling of higher inputs of two fertilizers and light recipes leads to an increase in the height of lettuce equal to 33% (from 6.00 cm to 8.00 cm). [ABSTRACT FROM AUTHOR]

Sorting seedlings is laborious and requires attention to identify damage. Separating healthy seedlings from damaged or defective seedlings is a critical task in indoor farming systems. However, sorting seedlings manually can be challenging and time-consuming, particularly under complex lighting conditions. Different indoor lighting conditions can affect the visual appearance of the seedlings, making it difficult for human operators to accurately identify and sort the seedlings consistently. Therefore, the objective of this study was to develop a defective-lettuce-seedling-detection system under different indoor cultivation lighting systems using deep learning algorithms to automate the seedling sorting process. The seedling images were captured under different indoor lighting conditions, including white, blue, and red. The detection approach utilized and compared several deep learning algorithms, specifically CenterNet, YOLOv5, YOLOv7, and faster R-CNN to detect defective seedlings in indoor farming environments. The results demonstrated that the mean average precision (mAP) of YOLOv7 (97.2%) was the highest and could accurately detect defective lettuce seedlings compared to CenterNet (82.8%), YOLOv5 (96.5%), and faster R-CNN (88.6%). In terms of detection under different light variables, YOLOv7 also showed the highest detection rate under white and red/blue/white lighting. Overall, the detection of defective lettuce seedlings by YOLOv7 shows great potential for introducing automated seedling-sorting systems and classification under actual indoor farming conditions. Defective-seedling-detection can improve the efficiency of seedling-management operations in indoor farming. [ABSTRACT FROM AUTHOR]

The global crisis and climate change have resulted in severe food shortages worldwide. One of the solutions is self-farming by using smart farming technology. Smart and efficient agricultural production or smart farming using IoT sensors, big data, and cloud service has proven its value for a decade, but the effect depends on the agricultural environment of the country or society. Hence self-farming is likely the most feasible solution to avoid food scarcity. The smart farming system monitors and maintains essential growth parameters like light, temperature, and humidity to ensure maximum yield. In this paper, we propose a Smart Portable Farming Kit design, which is simple, lightweight, and durable to be placed indoors in an urban area. This prototype design uses the Internet of Things (IoT) based system for cultivating short-duration vegetables and mushrooms in an urban area with minimal user attention. The proposed design proved better than the traditional setup by increasing the mushroom yield. With Smart Portable Farming Kit, urban farming becomes a more viable alternative to increase food security, making oyster mushroom cultivation in the urban area easier and more profitable. [ABSTRACT FROM AUTHOR]

Accurate and rapid determination of moisture content is essential in crop production and decision-making for irrigation. Near-infrared (NIR) spectroscopy has been shown to be a promising method for determining moisture content in various agricultural products, including herbs and vegetables. This study tested the hypothesis that NIR spectroscopy is effective in accurately measuring the moisture content of Genovese basil (Ocimum basilicum L.), with the objective of developing a respective calibration model. Spectral data were obtained from a total of 120 basil leaf samples over a period of six days. These included freshly harvested and detached leaves, as well as those left in ambient air for 1–6 days. Five spectra were taken from each leaf using a handheld NIR spectrophotometer, which covers the first and second overtones of the NIR spectral region: 950–1650 nm. After the spectral acquisition, the leaves were weighed for fresh mass and then put in an oven for 72 h at 80 °C to determine the dry weight and calculate the reference moisture content. The calibration model was developed using multivariate analysis in MATLAB, including preprocessing and regression modeling. The data obtained from 75% of the samples were used for model training and 25% for validation. The final model demonstrates strong performance metrics. The root mean square error of calibration (RMSEC) is 2.9908, the root mean square error of cross-validation (RMSECV) is 3.2368, and the root mean square error of prediction (RMSEP) reaches 2.4675. The coefficients of determination for calibration (R2C) and cross-validation (R2CV) are consistent, with values of 0.829 and 0.80, respectively. The model’s predictive ability is indicated by a coefficient of determination for prediction (R2P) of 0.86. The range error ratio (RER) stands at 11.045—highlighting its predictive performance. Our investigation, using handheld NIR spectrophotometry, confirms NIR’s usefulness in basil moisture determination. The rapid determination offers valuable insights for irrigation and crop management.

The effect of artificial lighting with different light spectra and photoperiods/daily light integrals (DLIs) on the yield, bioactive compounds and antioxidant capacity of the common ice plant (Mesembryanthemum crystallinum) was studied. Four-week-old seedlings were selected and subjected to four different light spectra made up of different combinations of blue (400–500 nm), green (500–600 nm) and red light (600–700 nm), with a total photosynthetic photon flux density (PPFD) of 180 µmol.m−2.s−1. Concurrently, the effect of the daily light integral (DLI) was also studied, with the light treatment photoperiod set at 18 h and 21 h. Biometric parameters such as fresh mass weight, leaf area, leaf width, and dry mass, together with plant metabolite contents such as total antioxidant capacity (TAC), vitamin C, chlorophyll a and b content, and total carotenoids and nitrates, were investigated. It was found that the plants grew better when exposed to light with a higher proportion of the red and blue spectrum, with the highest fresh mass of 68 g observed at a photoperiod of 18 h. On the other hand, green spectrum light was not found to yield any significant improvement in shoot weight, leaf area, or leaf size. It was also found that dry mass, chlorophyll b and nitrates were not influenced by the light spectrum but were influenced by the photoperiod duration. While both the dry mass and nitrate content increase as the photoperiod increases, a longer photoperiod had a negative effect on chlorophyll a, chlorophyll b and total carotenoids, with their content decreasing by as much 29% for chlorophyll a, 59% for chlorophyll b and 29% for total carotenoids. TAC content was seen to increase by more than 24% under the influence of 66% more green light, and 38% more under the 21 h photoperiod.

Significant advancement has been achieved improving electrical efficiency and photon efficacy of light-emitting diodes (LEDs) as the sole source of crop lighting for indoor farming. However, a significant portion of highly efficient photon emissions from improved LEDs is wasted by natural beam spread beyond cropping areas. Additional attention is needed to enhance crop-canopy photon capture efficiency (CCPCE), the fraction of photons emitted from LEDs actually incident upon foliar canopies. We postulate that by taking advantage of unique physical properties of LEDs, such as low radiant heat at photon-emitting surfaces and dimmable photon emissions, reduced vertical separation distance between light-emitting surfaces and light-receiving surfaces will enhance CCPCE by capturing more obliquely emitted photons that otherwise are lost. This “close-canopy-lighting” (CCL) strategy was tested in two ways: For an energy-efficiency strategy, LEDs were dimmed to the same photosynthetic photon flux density (PPFD) of 160 µmol m-2 s-1 at 45-, 35-, 25-, and 15-cm separation distances between lamps and cropping surfaces. For a yield-enhancement strategy, dimming was not applied, so higher PPFDs occurred at each separation distance closer than 45 cm for the same input energy. In the first strategy, the same biomass of lettuce (Lactuca sativa L. cv. Rouxai) was produced at each separation distance, while significantly lower energy was expended for lighting at each closer separation. Significantly higher biomass was produced at reduced separation distances with the same energy expenditure by LEDs using the yield-enhancement strategy. For both strategies, energy-utilization efficiency (g/kWh) doubled at the closest separation distance of 15 cm compared to the standard 45-cm separation distance. Even higher energy-utilization efficiency was achieved at a 25-cm separation distance when growth compartments were enclosed with a reflective curtain in the yield-enhancement strategy. Our findings suggest that CCL is a highly effective energy-saving strategy for overhead LED lighting, suggesting the need for innovative next-generation re-design of height-adjustable LED mounts and controlled air movement between tiers of indoor farms utilizing CCL.

Anthocyanins are a group of human-health-promoting phenolic compounds that influence the pigmentation of red-leaf lettuce (Lactuca sativa). Ultraviolet A (UVA; 315-399 nm) and blue (B; 400-499 nm) light can increase the concentrations of phenolic compounds but also suppress cellular expansion, which can limit harvestable biomass accumulation. It is not known whether UVA or B light is more effective at increasing phenolic compound concentrations when they are each applied at the same photon flux density. Our objective was to evaluate the efficacy of UVA and B light when added during the end of production (EOP) at promoting phenolic compound synthesis and red-leaf coloration without limiting biomass accumulation. We grew red-leaf lettuce 'Rouxai' in a controlled indoor environment at an air temperature of 22°C under warm-white and red light-emitting diodes (LEDs). On day 24, 30 or 60 µmol·m-2·s-1 from UVA, B, UVA plus B, or red plus green LEDs was added during the last 6 days of the 30-day production period. UVA and B light, alone or combined, similarly increased leaf redness (by up to 72%), total phenolic concentration (by up to 92%), total anthocyanin concentration (by up to 2.7-fold), and relative chlorophyll concentration (by up to 20%) and did not inhibit growth, compared with lettuce grown without EOP supplemental lighting. Considering B light was as effective as UVA light at increasing leaf color and phytonutrient density and that B LEDs are more electrically effective, economical, and durable, an enriched blue-light spectrum at the EOP is a comparatively sustainable method to increase crop quality without suppressing biomass accumulation. [ABSTRACT FROM AUTHOR]

The pH range of 7.0 to 7.2 is recommended to ensure reasonable nitrification rates in aquaponics; however, this range is conducive neither to nitrification, a critical process that occurs at pH 8.0, nor to plant growth. To determine the effects of pH in an aquaponic system, Swiss chard (Beta vulgaris L.), kale (Brassica oleracea L.), mustard green (Brassica juncea L.), cilantro (Coriandrum sativum L.), lettuce (Lactuca sativa L.), and arugula (Eruca vesicaria L.) were cultured with tilapia (Oreochromis niloticus) in 5-year-old coupled aquaponic systems at three pH levels, 6.0, 6.5, and 7.0, in comparison with hydroponics. Morphological and physiological growth parameters of vegetable and fish crops were measured regularly, and the ammonia-oxidizing bacteria (AOB) in the aquaponic system were analyzed by qPCR at the end of the production. This study found that feed conversion ratio, fish biomass, and copy number of AOB were not affected by different pH, but similar to hydroponic systems, lower pH in aquaponic systems increased fresh and dry mass and nutrient levels of all plant species tested. This study suggests that pH has a significant impact on plant performance and yield in both aquaponic and hydroponic systems and that, similar to hydroponics, a pH of 6 is desirable for aquaponic systems to improve plant crop yield without compromising nitrification activity and fish yield. [ABSTRACT FROM AUTHOR]

Indoor farming of basil (Ocimum basilicum L.) under artificial lighting to support year-round produce demand is an area of increasing interest. Literature data indicate that diverse light regimes differently affect downstream metabolic pathways which influence basil growth, development and metabolism. In this study, basil was grown from seedlings to fully developed plants in a microcosm, an innovative device aimed at growing plants indoor as in natural conditions. Specifically, the effects of white (W) and blue-red (BR) light under a photosynthetic photon flux density of 255 μmol m−2 s−1 on plant growth, photochemistry, soluble nutrient concentration and secondary metabolism were investigated. Plants grew taller (41.8 ± 5.0 vs. 28.4 ± 2.5 cm) and produced greater biomass (150.3 ± 24.2/14.7 ± 2.0 g vs. 116.2 ± 28.3/12.3 ± 2.5 g fresh/dry biomass) under W light compared to BR light. The two lighting conditions differently influenced the soluble nutrient concentration and the translocation rate. No photosynthetic stress was observed under the two lighting regimes, but leaves grown under W light displayed higher levels of maximum quantum yield of PSII and electron transport rate. Sharp differences in metabolic patterns under the two lighting regimes were detected with higher concentrations of phenolic compounds under the BR light. [ABSTRACT FROM AUTHOR]