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Up to 75% of nitrogen (N) taken up during cauliflowers production is allocated to leaves, which are left as crop residues after harvest. The inclusion of cauliflower, cultivated alone or intercropped with legumes, in rotation schemes, is a promising tool to optimize N availability to subsequent crops. This original study assessed, for the first time in South Tyrol, Italy, the effect of removal or soil incorporation of cauliflower and clover residues on the growth and N uptake of subsequent lettuce. In 2015, cauliflower was sole-cropped or intercropped with clover, under different N regimes (N0, N1, N2, N3 = 0, 75, 150, 300 kg N ha−1). Cauliflower and clover residues were either removed or incorporated in the soil in 2016. The effects of the residual fertility left by the N fertilizer, the two cropping systems, and the crop residues were assessed on the yield and N uptake of two subsequent lettuce crops. Isotopic 15N-labeled cauliflower residues were additionally used to quantify the N contribution of cauliflower residues to lettuce growth. During the first lettuce crop, residues incorporation was the only factor increasing lettuce yields (+41%) and N uptake (+58%). The residual effect of N1 and N2 rates increased the lettuce N uptake when clover residues were incorporated. During the second lettuce crop, residues incorporation increased lettuce yields (+26%) and N uptake (+44%). On average, 64% and 35% of the lettuce N amounts, in the first and second cycles, respectively, derived from cauliflower residues, and accounted for 38% of the total N contained in cauliflower residues (214 kg N ha−1). Results from this experiment, uncommon for the examined species, demonstrate that incorporation of cauliflower and clover residues provides an excellent source of N for lettuce. Incorporating residues of the preceding cauliflower crop, alone or intercropped with clover, before establishing the lettuce crop, substantially reduce the N fertilization needs of subsequent lettuce crops. [ABSTRACT FROM AUTHOR]

Specialized metabolites from plants are important for human health due to their antioxidant properties. Light is one of the main factors modulating the biosynthesis of specialized metabolites, determining the cascade response activated by photoreceptors and the consequent modulation of expressed genes and biosynthetic pathways. Recent developments in light emitting diode (LED) technology have enabled improvements in artificial light applications for horticulture. In particular, the possibility to select specific spectral light compositions, intensities and photoperiods has been associated with altered metabolite content in a variety of crops. This review aims to analyze the effects of indoor LED lighting recipes and management on the specialized metabolite content in different groups of crop plants (namely medicinal and aromatic plants, microgreens and edible flowers), focusing on the literature from the last 5 years. The literature collection produced a total of 40 papers, which were analyzed according to the effects of artificial LED lighting on the content of anthocyanins, carotenoids, phenols, tocopherols, glycosides, and terpenes, and ranked on a scale of 1 to 3. Most studies applied a combination of red and blue light (22%) or monochromatic blue (23%), with a 16 h day−1 photoperiod (78%) and an intensity greater than 200 μmol m−2 s−1 (77%). These treatment features were often the most efficient in enhancing specialized metabolite content, although large variations in performance were observed, according to the species considered and the compound analyzed. The review aims to provide valuable indications for the definition of the most promising spectral components toward the achievement of nutrient‐rich indoor‐grown products. © 2021 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]

Urban horticulture is increasingly popular for social and economic benefits. However, edible urban crops may be contaminated by airborne pollutants, thus leading to serious health risks. Therefore, a better understanding of contamination risks of urban cultivation is needed in order to define safe practices. In particular, whereas it is commonly accepted that the contamination of urban-grown food comes from airborne pollutants, little is known on a possible contamination by soils. Here, we studied trace metal risk in horticultural crops grown in an experimental urban allotment garden in Bologna, Italy. Seven experiments were conducted between June and November 2015 on tomato, sweet basil, onion, lettuce, kale, bulb fennel and radish. Treatments included two growing systems, soil and soilless, and two fertilization managements, mineral and organic. Trace metal concentrations were measured in soils, substrates and edible plant tissues. We identified preferentially translocated metals by partitioning analysis of tomato, sweet basil and kale. Results showed that crops grown in a soilless system have a lower metal content of −70 % for Cr, −61 % for Cu, −45 % for Cd and −81 % for Ni, compared with those grown in soil. This finding demonstrates that the major contamination risk in an urban area is unexpectedly related to soil pollution. [ABSTRACT FROM AUTHOR]

Solar radiation entering a high-wire tomato greenhouse is mostly intercepted by the top of the crop canopy, while the role of lower leaves diminishes with age, turning them into sink organs rather than sources. Accordingly, the defoliation of basal leaves is a widely applied agronomic practice in high-wire greenhouse cultivation management. However, the recent increase in the application of supplemental light emitting diode (LED) lighting for high-density tomato production may affect the role of basal leaves, promoting their source role for fruit development and growth. The present research aims to explore the application of supplementary LED lighting on Solanum lycopersicum cv. Siranzo in the Mediterranean area during the cold season in combination with two regimes of basal defoliation. The defoliation factors consisted of the early removal of the leaves (R) right under the developing truss before the fruit turning stage and a non-removal (NR) during the entire cultivation cycle. The lighting factors consisted of an artificial LED lighting treatment with red and blue diodes for 16 h d−1 (h 8-00) with an intensity of 180 µmol s−1 m−2 (RB) and a control cultivated under natural light only (CK). The results demonstrated a great effect of the supplemental LED light, which increased the total yield (+118%), favoring fruit setting (+46%) and faster ripening (+60%) regardless of defoliation regimes, although the increased energy prices hinder the economic viability of the technology. Concerning fruit quality, defoliation significantly reduced the soluble solid content, while it increased the acidity when combined with natural light. [ABSTRACT FROM AUTHOR]

African agriculture is bound to face challenges for its future food systems development and economic transformation. Indoor vertical farms with artificial lighting represent an opportunity that has been gaining relevance worldwide, thanks to their potential to enable high productivity rates, food quality and safety, year-round production, and more sustainable use of water and mineral nutrients. The present study assesses the potential for vertical farming technology integration within the African continent, targeting the countries where a more sustainable approach could be achieved. A deep analysis of each territory's major opportunities and challenges was built through an updated database of 147 development indicators from 54 African states. Countries such as South Africa, Seychelles, Egypt, Mauritius, Morocco, Tunisia, Algeria, Cape Verde, and Nigeria showed the best prospective for indoor vertical farming implementation. Moreover, Seychelles, South Africa, and Egypt resulted to be the countries where vertical indoor farming could be more sustainable. [ABSTRACT FROM AUTHOR]

African agriculture is bound to face challenges for its future food systems development and economic transformation. Indoor vertical farms with artificial lighting represent an opportunity that has been gaining relevance worldwide, thanks to their potential to enable high productivity rates, food quality and safety, year-round production, and more sustainable use of water and mineral nutrients. The present study assesses the potential for vertical farming technology integration within the African continent, targeting the countries where a more sustainable approach could be achieved. A deep analysis of each territory's major opportunities and challenges was built through an updated database of 147 development indicators from 54 African states. Countries such as South Africa, Seychelles, Egypt, Mauritius, Morocco, Tunisia, Algeria, Cape Verde, and Nigeria showed the best prospective for indoor vertical farming implementation. Moreover, Seychelles, South Africa, and Egypt resulted to be the countries where vertical indoor farming could be more sustainable. [ABSTRACT FROM AUTHOR]

• LED lighting improved postharvest quality of leafy vegetables. • LED light increased weight loss in stored samples. • Yellow, blue and green light reduced microbiological load. • Red and blue light increased antioxidant compounds. The main objective of this study was to evaluate the physiological and quality changes of fresh-cut red chard (Beta vulgaris) and rocket (Diplotaxis tenuifolia) leaves illuminated during storage with monochromatic light emitting diode (LED) lamps, featuring different spectral component (red, green, yellow, white, blue and far-red) and same light intensity (35 μmol m−2 s-1). As control, storage in darkness was assayed. Biomass, colorimetric and microbiological changes were determined up to 10 d of storage at 5 °C. In addition, total antioxidant activity and bioactive compounds changes along the shelf-life were also monitored. Microbial counts were reduced by yellow and blue light in red chard, and by yellow and green light in rocket. Green and white light enabled to preserve colorimetric indexes and chlorophylls content mostly in rocket and, eventually, increasing carotenoids in red chard. Total antioxidant capacity and total phenols content were stimulated in response to red or blue light application for both species. On the other hand, LED light supply increased weight losses during storage as compared to darkness, although more limitedly in response to yellow and far red light. The study provides solid ground for further exploration on how LED lighting treatment during storage of red chard and rocket may foster product qualitative properties, suggesting that different spectral wavebands may alternatively enhance antioxidant properties and reduce microbiological risks. [ABSTRACT FROM AUTHOR]

• Optimal LED light intensity for lettuce and basil indoor growing is addressed; • Maximum yield and leaf area is achieved at 250 μmol m-2 s-1; • 250 μmol m-2 s-1 increased chlorophyll and improved stomatal functions in leaves; • In lettuce, PPFD ≥ 200 μmol m-2 s-1 raised antioxidant capacity, phenolics and flavonoids; • Water, energy and light use efficiencies were optimized at 250 μmol m-2 s-1; Indoor plant cultivation systems are gaining increasing popularity because of their ability to meet the needs of producing food in unfavourable climatic contexts and in urban environments, allowing high yield, high quality, and great efficiency in the use of resources such as water and nutrients. While light is one of the most important environmental factors affecting plant development and morphology, electricity costs can limit the widespread adoption of indoor plant cultivation systems at a commercial scale. LED lighting technologies for plant cultivation are also rapidly evolving, and lamps for indoor cultivation are often designed to optimize their light emissions in the photosynthetically active spectrum (i.e. red and blue), in order to reduce energetic requirements for satisfactory yield. Under these light regimens, however, little information is available in literature about minimum photosynthetic photon flux density (PPFD) for indoor production of leafy vegetables and herbs, while existing literature often adopts light intensities from 100 to 300 μmol m-2 s-1. This study aims at defining the optimal PPFD for indoor cultivation of basil (Ocimum basilicum L.) and lettuce (Lactuca sativa L.), by linking resource use efficiency to physiological responses and biomass production under different light intensities. Basil and lettuce plants were cultivated at 24 °C and 450 μmol mol-1 CO 2 under red and blue light (with red:blue ratio of 3) and a photoperiod of 16 h d-1 of light in growth chambers using five PPFD (100, 150, 200, 250 and 300 μmol m-2 s-1, resulting in daily light integrals, DLI, of 5.8, 8.6, 11.5, 14.4 and 17.3 mol m-2 d-1, respectively). A progressive increase of biomass production for both lettuce and basil up to a PPFD of 250 μmol m-2 s-1 was observed, whereas no further yield increases were associated with higher PPFD (300 μmol m-2 s-1). Despite the highest stomatal conductance associated to a PPFD of 250 μmol m-2 s-1 in lettuce and to a PPFD ≥ 200 μmol m-2 s-1 in basil, water use efficiency was maximized under a PPFD ≥ 200 μmol m-2 s-1 in lettuce and PPFD ≥ 250 μmol m-2 s-1 in basil. Energy and light use efficiencies were increased under a PPFD of 200 and 250 μmol m-2 s-1 in lettuce and under a PPFD of 250 μmol m-2 s-1 in basil. Furthermore, in lettuce grown under 250 μmol m-2 s-1 antioxidant capacity, phenolics and flavonoids were higher as compared with plants supplied with PPFD ≤ 150 μmol m-2 s-1. Accordingly, a PPFD of 250 μmol m-2 s-1 seems suitable for optimizing yield and resource use efficiency in red and blue LED lighting for indoor cultivation of lettuce and basil under the prevailing conditions of the used indoor farming set-up. [ABSTRACT FROM AUTHOR]

Simplified soilless cultivation (SSC) systems have globally spread as growing solutions for low fertility soil regions, low availability of water irrigation, small areas and polluted environments. In the present study, four independent experiments were conducted for assessing the applicability of SSC in the northeast of Brazil (NE-Brazil) and the central dry zone of Myanmar (CDZ-Myanmar). In the first two experiments, the potentiality for lettuce crop production and water use efficiency (WUE) in an SSC system compared to traditional on-soil cultivation was addressed. Then, the definition of how main crop features (cultivar, nutrient solution concentration, system orientation and crop position) within the SSC system affect productivity was evidenced. The adoption of SSC improved yield (+35% and +72%, in NE-Brazil and CDZ-Myanmar) and WUE (7.7 and 2.7 times higher, in NE-Brazil and CDZ-Myanmar) as compared to traditional on-soil cultivation. In NE-Brazil, an eastern orientation of the system enabled achievement of higher yield for some selected lettuce cultivars. Furthermore, in both the considered contexts, a lower concentration of the nutrient solution (1.2 vs. 1.8 dS m−1) and an upper plant position within the SSC system enabled achievement of higher yield and WUE. The experiments validate the applicability of SSC technologies for lettuce cultivation in tropical areas. [ABSTRACT FROM AUTHOR]

In Northern Europe, the use of light–emitting diodes (LEDs) is widely adopted in protected horticulture, enabling to enhance plant growth by ensuring needed radiative fluxes throughout seasons. Contrarily, the use of artificial lighting in Mediterranean greenhouse still finds limited applications. In this study, the effects of supplemental LED interlighting on vegetative development, fruit growth, yield, and fruit quality of high-wire tomato plants (Solanum lycopersicum L. cv. 'Siranzo') during spring and summer season were addressed in a hydroponic greenhouse in Italy. Plants were either grown under natural solar radiation (control), or by adding supplemental LED interlighting. LED treatment featured red (R) and blue (B) light (RB ratio of 3) and a photosynthetic photon flux density of 170 µmol m−2 s−1 for 16 h d−1. Supplemental LED interlighting enhanced yield as a result of increased fruit weight and dimension. While no effects on soluble solids content and fruit color at harvesting were observed, supplemental LED interlighting accelerated ripening by one week in spring and two weeks in summer and this also resulted in increased cumulated productivity (+16%) as compared to control treatment. Overall, supplemental LED interlighting can represent a feasible technology for tomato greenhouse production also in the Mediterranean region. [ABSTRACT FROM AUTHOR]

Water use efficiency is a main research target in agriculture, which consumes 70% of global freshwater. This study aimed at identifying sustainable water management strategies for the lettuce crop in a semi-arid climate. Three independent experiments were carried out on a commercial variety of lettuce (Lactuca sativa L.) by applying different irrigation levels based on crop evapotranspiration (ETc), estimated through both the Hargreaves–Samani and Penman–Monteith equations. In the first experiment, one treatment was also guided by soil moisture sensors. In the second and third experiments, a factorial combination was used, combining the different irrigation levels with two soil mulching treatments, namely soil without mulch, and soil mulched with dried rice straw residues. The application of different irrigation levels significantly affected plant growth, yield, and physiology. Both the adoption of sensors for guiding irrigation and the application of mulching with straw promoted higher yield. As the irrigation water level was reduced, the WUE (water use efficiency) increased. WUE was also increased by covering the soil with mulch. The experiments point out that accurate management of irrigation water using a drip irrigation system associated with soil mulching increases yield and improves the WUE of lettuce crops in the Central Dry Zone, Myanmar. [ABSTRACT FROM AUTHOR]

LED lighting in indoor farming systems allows to modulate the spectrum to fit plant needs. Red (R) and blue (B) lights are often used, being highly active for photosynthesis. The effect of R and B spectral components on lettuce plant physiology and biochemistry and resource use efficiency were studied. Five red:blue (RB) ratios (0.5-1-2-3-4) supplied by LED and a fluorescent control (RB = 1) were tested in six experiments in controlled conditions (PPFD = 215 μmol m−2 s−1, daylength 16 h). LED lighting increased yield (1.6 folds) and energy use efficiency (2.8 folds) as compared with fluorescent lamps. Adoption of RB = 3 maximised yield (by 2 folds as compared with RB = 0.5), also increasing leaf chlorophyll and flavonoids concentrations and the uptake of nitrogen, phosphorus, potassium and magnesium. As the red portion of the spectrum increased, photosystem II quantum efficiency decreased but transpiration decreased more rapidly, resulting in increased water use efficiency up to RB = 3 (75 g FW L−1 H2O). The transpiration decrease was accompanied by lower stomatal conductance, which was associated to lower stomatal density, despite an increased stomatal size. Both energy and land surface use efficiency were highest at RB ≥ 3. We hereby suggest a RB ratio of 3 for sustainable indoor lettuce cultivation. [ABSTRACT FROM AUTHOR]

Light composition modulates plant growth and defenses, thus influencing plant–pathogen interactions. We investigated the effects of different light-emitting diode (LED) red (R) (665 nm) and blue (B) (470 nm) light combinations on Actinidia chinensis performance by evaluating biometric parameters, chlorophyll a fluorescence, gas exchange and photosynthesis-related gene expression. Moreover, the influence of light on the infection by Pseudomonas syringae pv. actinidiae (Psa), the etiological agent of bacterial canker of kiwifruit, was investigated. Our study shows that 50%R–50%B (50R) and 25%R–75%B (25R) lead to the highest PSII efficiency and photosynthetic rate, but are the least effective in controlling the endophytic colonization of the host by Psa. Monochromatic red light severely reduced ΦPSII, ETR, Pn, TSS and photosynthesis-related genes expression, and both monochromatic lights lead to a reduction of DW and pigments content. Monochromatic blue light was the only treatment significantly reducing disease symptoms but did not reduce bacterial endophytic population. Our results suggest that monochromatic blue light reduces infection primarily by modulating Psa virulence more than host plant defenses. [ABSTRACT FROM AUTHOR]

• Dose-response curves with increasing far-red radiation and constant photon flux density. • Role of phytochrome effects in optimizing the use of light and energy. • Increase in lettuce leaf fresh and dry weight up to 0.3 of far-red fraction. • Far-red radiation increases relative growth rate but decreased net assimilation rate. • Far-red radiation allows to increase light interception even with high leaf area index. Recently, far-red wavelengths (FR, 700–750 nm) have been largely investigated in indoor cultivation systems due to their morphological effects on plants (e.g., leaf expansion and stem elongation), resulting also in increasing yield. This work investigated the effect of substituting part of the red (R) and blue (B) radiation with far-red radiation, while keeping constant the photon flux density, in the light spectrum for lettuce grown in a vertical farm. Lettuce (Lactuca sativa var. Canasta) plants were transplanted and grown in an ebb-and-flow system for 29 days. During the cycle, plants were subjected to five different light treatments: a control treatment consisting of an optimized R and B spectrum (ratio of 3; RB 3) with a photosynthetic photon flux density of 200 µmol m−2 s−1, and four treatments in which R and B were partially replaced by 10, 30, 50 and 70 µmol m−2 s−1 of FR light, resulting in an increasing FR fraction. Biomass production and most of the morphological parameters were affected from 15 days after transplanting (DAT), while stomatal conductance from 22 DAT. Leaf greenness and specific leaf area values were influenced by the FR radiation starting from 8 DAT. At 29 DAT, substitution of an amount of R and B photons equal to 30 (RB 3 –30) or 50 (RB 3 –50) µmol m−2 s−1 with the same amount of FR radiation resulted in increased leaf biomass in both fresh (+49 and +47%, respectively) and dry weight (+45 and +42%, respectively). With RB 3 –30, the increase was due to leaf area expansion (+103%), whereas stomatal conductance (g s) and quantum efficiency of photosystem II (ΦPSII) did not change compared with the spectrum with only R and B. With RB 3 –50, g s and ΦPSII decreased compared with RB 3 (-27 and -6%, respectively), but the greater biomass accumulation was supported by the greater leaf expansion (+119 %). The adoption of RB 3 –30 and RB 3 –50 also promoted light use efficiency (+45 and +42 %, respectively), lighting energy use efficiency (+48 and +53 %, respectively) and therefore the overall energy performance of the system. The adoption of RB 3 –30 and RB 3 –50 is a valid strategy to increase yield for lettuce production, but further studies, also in relation to blue radiation intensity, are needed to avoid the negative effect on leaf pigmentation. [ABSTRACT FROM AUTHOR]

In indoor vertical farms, energy consumption represents a bottleneck for both a system's affordability and environmental footprint. Although switching frequency (sf) represents a crucial factor in determining the efficacy of light emitting diodes (LED) lighting systems in converting electricity into light, the impact of sf is still underexplored. The aim of this work was to investigate the effect of LEDs sf on the productive and qualitative responses of lettuce (Lactuca sativa L.), also considering the resource use efficiency. Plants were grown for 14 days under red and blue LEDs (215 μmol m−2 s−1 and 16/8 h light/dark, with a red:blue ratio of 3) characterized by two different sf for the blue diode, namely high sf (850 kHz) and low sf (293 kHz). A fluorescent light (same light intensity and photoperiod) was included. LED sf did not alter plant morphological parameters, including fresh or dry biomass, leaf number, leaf area, or water use efficiency. A low sf increased the energy use efficiency (EUE) by 40% as compared to high sf. The latter enhanced the leaf antioxidant capacity, as a consequence of increased concentrations of caftaric and chicoric acids, isoquercetin, and luteolin, consistent with the upregulation of a few genes related to the biosynthetic pathway of phenolic compounds (4C3H and DFR). The study highlights that different sf may significantly affect the EUE as well as crop nutritional properties. [ABSTRACT FROM AUTHOR]

BACKGROUND The main objective of this study was to evaluate physiological and quality changes of minimally processed broccoli sprouts illuminated during postharvest storage under blue, red and far‐red LED lighting as compared to darkness or illumination with fluorescent light, as control treatments. RESULTS: Morphological and microbiological changes were determined during 15 days at 5 °C. In addition, total antioxidant activity and bioactive compound changes throughout the shelf life were also monitored. Results showed that far‐red LED lighting increased hypocotyl and sprout length, decreased microbial growth and improved the total antioxidant and scavenging activities, compared to darkness and fluorescent lighting treatments. However, it did not stimulate the biosynthesis of phenolic acids. In contrast, blue LED light reduced by 50% the total antioxidant capacity of broccoli sprouts compared to far‐red treatment, as well as morphological development. In addition, total scavenging activity was increased under far‐red LED light compared with the other treatments by 12–10% (darkness and fluorescence) and 33–31% (blue and red LEDs). CONCLUSIONS: Our results suggest that minimally processed sprouts may benefit from LED lighting during shelf life in terms of quality, although further experiments should be conducted to optimize a proper exposure cycle and intensity aiming for use in the distribution chain. The results also open the way for further development towards the integration of this technology in the food distribution chain. [ABSTRACT FROM AUTHOR]

Canopy reflectance sensors are a viable technology to optimize the fertilization management of crops. In this research, canopy reflectance was measured through a passive sensor to evaluate the effects of either crop features (N fertilization, soil mulching, appearance of red fruits, and cultivars) or sampling methods (sampling size, sensor position, and hour of sampling) on the reliability of vegetation indices (VIs). Sixteen VIs were derived, including seven simple wavelength reflectance ratios (NIR/R460, NIR/R510, NIR/R560, NIR/R610, NIR/R660, NIR/R710, NIR/R760), seven normalized indices (NDVI, G-NDVI, MCARISAVI, OSAVI, TSAVI, TCARI), and two combined indices (TCARI/OSAVI; MCARI/OSAVI). NIR/560 and G-NDVI (Normalized Difference Vegetation Index on Greenness) were the most reliable in discriminating among fertilization rates, with results unaffected by the appearance of maturing fruits, and the most stable in response to different cultivars. Black mulching film did not affect NIR/560 and G-NDVI behavior at the beginning of the growing season, when the crop is more responsive to N management. Due to a moderate variability of NIR/560 and G-NDVI, a small sample size (5–10 observations) is sufficient to obtain reliable measurements. Performing the measurements at 11:00 and 14:00 and maintaining a greater distance (1.8 m) between plants and instrument enhanced measurement consistency. Accordingly, NIR/560 and G-NDVI resulted in the most reliable VIs. [ABSTRACT FROM AUTHOR]

Urban agriculture has become a common form of urban land use in European cities linked to multiple environmental, social and economic benefits, as well as to diversified forms (from self-production allotments to high-tech companies). Social acceptance will determine the development of urban agriculture and specific knowledge on citizens’ perception is required in order to set the basis for policy-making and planning. The ecosystem services provided by urban agriculture can be determinant in this process. The goal of this paper is to evaluate the social acceptance and the perceived ecosystem services of urban agriculture in the city of Bologna (Italy), as an example of a Southern European city. In particular, we evaluated the preferences for urban land uses, for different typologies of urban agriculture and for the resulting products, the perceived provision of ecosystem services and the willingness to engage in new initiatives. A survey that investigated these topics (including open questions, closed questions and Likert-scale evaluation) was performed on the citizens of Bologna (n = 380) between October and November 2016. Results showed that urban agriculture is widely accepted by the inhabitants of Bologna, particularly regarding vegetable production. Although intensive farming systems were the least preferred forms to be implemented in Bologna, citizens highly accepted a large variety of urban agriculture goods, with preference for those obtained from plants as compared to animal products. The willingness-to-pay for urban food products was mostly the same as for conventional ones, although the participants recognised the social values, proximity and quality of the former. Socio-cultural ecosystem services were perceived as more valuable than environmental ones. Policy-making recommendations can be extracted from the results to facilitate the development of urban agriculture plans and policies. [ABSTRACT FROM AUTHOR]

Vertical farms (VFs) are innovative urban production facilities consisting of multi-level indoor systems equipped with artificial lighting in which all the environmental conditions are controlled independently from the external climate. VFs are generally provided with a closed loop fertigation system to optimize the use of water and nutrients. The objective of this study, performed within an experimental VF at the University of Bologna, was to quantify the water use efficiency (WUE, ratio between plant fresh weight and the volume of water used) for a lettuce (Lactuca sativa L.) growth cycle obtained in two different growing systems: an ebb-and-flow substrate culture and a high pressure aeroponic system. Considering the total water consumed (water used for irrigation and climate management), WUE of ebb-and-flow and aeroponics was 28.1 and 52.9 g L−1 H 2 O, respectively. During the growing cycle, the contribution generated by the recovery of internal air moisture from the heating, ventilation and air conditioning (HVAC) system, was quantified. Indeed, by recovering water from the dehumidifier, water use decreases dramatically (by 67 %), while WUE increased by 206 %. Further improvement of WUE in the ebb-and-flow system was obtained through ameliorated crop management strategies, in particular, by increasing planting densities (e.g., 153, 270 and 733 plants m−2) and by optimizing the light spectrum used for plant growth (e.g., adjusting the amount of far-red radiation in the spectrum). Strategies for efficient use of water in high-tech urban indoor growing systems are therefore proposed. • Aeroponics increased water use efficiency by 114 % as compared to ebb-and-flow system. • By recovering water from the dehumidifier, water use efficiency increased by 206 %. • 15–25 % of far-red radiation in the spectrum increased water use efficiency. • Dynamic planting density strategy enhanced water use efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • Darkness and Fluorescent lights did not affect the total phenolic content. • Phenolic content was enhanced by 26 % under Yellow LED during shelf life. • Total glucosinolate content was enhanced by 80 % under Yellow LEDs. • Total glucosinolate content was increased by 16 % under Green LEDs. • Darkness and Fluorescent lights reduced in more than 60 % the glucosinolate content. Nowadays, literature is still limited on the effects that LEDs may trigger during postharvest. The present study aimed to investigate the effect of continuous monochromatic Yellow or Green light on total and individual phenolic and glucosinolate content of 9-day broccoli sprouts stored up to 15 days at 5 °C as a ready-to-eat product. In addition, a broad-spectrum White LED light, a Fluorescent light and storage in Darkness were used as treatments. An improvement in the total phenolic content (TPC) of 15 % and 13 % was observed under Yellow and White LED lighting, respectively, throughout the shelf-life as compared to Darkness. While Green LEDs did not affect the TPC, an increase of 34.5 % on the total glucosinolate content (TGC) was associated to this treatment on day 4. The highest increase of the TGC was observed under Yellow lighting (77 %, compared to Darkness). In contrast, Fluorescent and Darkness did not affect the TPC, but reduced the TGC (69 and 62 % compared to values at harvest, respectively). Our study demonstrates that a postharvest Yellow LED lighting stimulates the TPC and the TGC accumulation, opening the way for its further applications along the shelf life of other horticultural commodities. [ABSTRACT FROM AUTHOR]

Rooftop agriculture (RA) is a building-based form of urban agriculture that includes both protected and nonprotected farming practices, such as rooftop greenhouses as well as open-air rooftop gardens and farms. The use of underexploited urban spaces on buildings for farming purposes is considered a useful strategy for targeting global concerns (e.g., the limitations in food security and land access, impacts of climate change or social exclusion). While previous studies have addressed selected RA cases and the general worldwide dissemination of RA, a systematic evaluation integrating the constantly evolving sector and its diversity (both commercial and noncommercial) is currently lacking. Here, we provide an overview of the current status of RA based on a metadata analysis of 185 publicly accessible cases. This paper summarizes the global trends and spatial distribution of RA cases and presents their main features. The results present the global distribution of different RA types over time, their diverging farming purposes and further characteristics (such as farm sizes, building typologies, growing systems, products and reported yields, activities, implementation of resource-efficient practices, or economic and social activities). The results indicate an emphasis on RA cases in North America (44% of the analyzed cases) and show that RA practices are mainly represented by open-air farms and gardens (84%), as the growing sector of rooftop greenhouses is still relatively small. Similarly, commercial cases are scarce, with the majority of RA cases targeting social-educational goals or the improvement of urban living quality. This tendency suggests a range of currently untapped business opportunities that, if developed, may contribute to the evolution of more sustainable and resilient city food systems providing fresh crops from the inner urban fabric. In conclusion, the research showed a rising global interest in RA, although stronger policy intervention is crucial to upscale RA practices to reach decisive environmental, economic and social benefits at the city level. [ABSTRACT FROM AUTHOR]