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Urban farming, also called urban agriculture (UA), represents a promising solution to achieve some of the SDGs (sustainable development goals) identified by United Nations. Indeed, UA is a multifunctional activity that presents interesting social, economic and environmental opportunities. The economic viability of UA is a hot topic, given the recent exponential growth in interest by companies and investors throughout the last ten years. The interest is also reaching public and private investors, being an opportunity for economic advancement in most countries, including EBRD (European Bank for Reconstruction and Development) countries of operation. Despite the growing interest and the manifested potential, some drawbacks are still hindering the development of UA, raising questions especially on the feasibility from a financial point of view. In particular, aspects such as the resource use efficiency, technological inputs and business models, still need to be expanded in order to correctly and efficiently apply and adapt UA to different local environmental and socio-economic conditions. The present paper aims to summarize the ongoing situation of UA, with respect to the main resources, technologies and business models to identify weaknesses and strengths for further improvement of the sector.

In response to the growth of urban population and the reduction of resources availability (e.g., arable land, water, and nutrients), new forms of agriculture that can be developed also in urban environment are gaining increasing popularity. Urban agriculture constitutes a viable opportunity for improving the city food security, also fostering local and circular economies, social inclusion, and environmental sustainability. In the different world regions, a diversity of urban farming systems is encountered, with technological levels varying in response to the local socio-economic context, infrastructural networks, and environmental conditions. In developing economies from the South of the world, most interesting innovations include simplified hydroponics, organoponics, and microgarden technologies; whereas, in the global north, innovative solutions for plant cultivation also include rooftop greenhouses and indoor vertical farms with artificial lighting where vegetable crops, mushrooms, and algae may be grown. Beside plant growing solutions, innovation may also stand in the system integration and mutual relationship with the urban fabric (e.g., in terms of resource use or ecosystem service provisioning), or in the business model adopted. The present review paper will describe a number of innovative solutions for plant cultivation in the urban environment, with a special consideration of the economic, environmental, and social sustainability.

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−2s−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.

Unidad de excelencia María de Maeztu CEX2019-000940-M The metabolism of a building can be connected to a rooftop greenhouse, exchanging energy, water and CO2 flows, therefore reducing emissions and recycling cultivation inputs. However, integrating a rooftop greenhouse onto a building requires the application of stringent safety codes (e.g., fire, seismic codes), to strengthen and secure the structure with safety elements such as thick steel pillars or fireproof covering materials. These elements can shade the vegetation or reduce solar radiation entering the rooftop greenhouse. Nevertheless, application of additional LED light can help to overcome this constraint. The present study evaluated supplemental LED light application in an integrated rooftop greenhouse (i-RTG) at the ICTA-UAB research institute, located in Barcelona (Spain), for tomato cultivation (Solanum lycopersicum cv. Siranzo). The experiment explored the effects of three LED lighting treatments and a control cultivated under natural light only (CK). Applied treatments, added to natural sunlight, were: red and blue (RB), red and blue + far-red (FR) for the whole day, and red and blue + far-red at the end-of-day (EOD), each for 16 h d−1 (8 a.m.-12 a.m.) with an intensity of 170 µmol m−2 s−1. The results indicate that LED light increased the overall yield by 17% compared with CK plants. In particular, CK tomatoes were 9.3% lighter and 7.2% fewer as compared with tomatoes grown under LED treatments. Fruit ripening was also affected, with an increase of 35% red proximal fruit in LED-treated plants. In conclusion, LED light seems to positively affect the development and growth of tomatoes in building integrated agriculture in the Mediterranean area.

In Northern Europe, the use of light&ndash, 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. &lsquo, Siranzo&rsquo, ) 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 &micro, mol m&minus, 2 s&minus, 1 for 16 h d&minus, 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.

In 2019, the international student competition Urban Farm invited students from all over the world and different disciplines to join forces in order to reconvert three abandoned buildings into productive structures using soil-less technologies. One of the target locations was the abandoned school of Orzes village, in the Italian Alps, a mountain area that, along the last decades, has experienced lack of job opportunities and depopulation processes. Building on these social and economic obstacles, a landscape and collective re-generation project was designed in order to offer a new local economic identity, creating a network of indoor farms within abandoned buildings and targeting the production and processing of medicinal mushrooms and herbs. Such a network, called DolomiNet, defined the Orzes School as an administrative reference and productive model to be replicated and exported on the several abandoned buildings within the region. Furthermore, it allowed for the creation of a training and research centre within the former school, where future network members could be trained and investigation on new pharmaceutical products and lighting technologies could take place. The three pillars of innovation of the project stands on the following elements: 1) the forest biosystem: a sustainable productive model inspired by forest connections and based on CO2-O2 exchange among mushroom and plant growing chambers; 2) the green exoskeleton: a bioclimatic greenhouse applied on the building external shell with the double function of increasing productive volumes and provide thermal insulation to the building; 3) coofarming app: an immediate communication system between farmers and administrative centre, which concurrently guarantee a remote control of cultivation parameters.

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.

In recent years, research on light emitting diodes (LEDs) has highlighted their great potential as a lighting system for plant growth, development and metabolism control. The suitability of LED devices for plant cultivation has turned the technology into a main component in controlled or closed plant-growing environments, experiencing an extremely fast development of horticulture LED metrics. In this context, the present study aims to provide an insight into the current global horticulture LED industry and the present features and potentialities for LEDs’ applications. An updated review of this industry has been integrated through a database compilation of 301 manufacturers and 1473 LED lighting systems for plant growth. The research identifies Europe (40%) and North America (29%) as the main regions for production. Additionally, the current LED luminaires’ lifespans show 10 and 30% losses of light output after 45,000 and 60,000 working hours on average, respectively, while the vast majority of worldwide LED lighting systems present efficacy values ranging from 2 to 3 μmol J−1 (70%). Thus, an update on the status of the horticultural LED sector, LEDs’ applications and metrics, and the intense innovation are described and discussed.