The year 2007 marked a critical event in the world history. For the first time, more than half of the world population now lives in cities. In many developing countries, the urbanization process goes ...along with increasing urban poverty and polluted environment, growing food insecurity and malnutrition, especially for children, pregnant and lactating women; and increasing unemployment. Urban agriculture represents an opportunity for improving food supply, health conditions, local economy, social integration, and environmental sustainability altogether. Urban agriculture is present throughout the world in a diversity of farming systems. Urban dwellers ranging 25–30 % are involved worldwide in the agro-food sector. Urban agriculture will gain in recognition for its benefits and services because urban population and rural–urban migration are increasing. The actual scarcity of knowledge on urban agriculture has somehow hindered the relevance of this activity. Here, we review the social, cultural, technical, economic, environmental, and political factors affecting urban agriculture with examples taken in East Asia, South America, or East Africa. We discuss the definition, benefits, and limitations of urban agriculture. Food security benefit of urban agriculture is evidenced by 100–200 million urban farmers worldwide providing the city markets with fresh horticultural goods. Urban agriculture favors social improvement since the poors spend up to 85 % of their income in food purchase and most urban farmers belong to poorest populations. Sociologically urban farming favors both social inclusion and reduction of gender inequalities, as 65 % of urban farmers are women. Urban agriculture has ecological benefits by reducing the city waste, improving urban biodiversity and air quality, and overall reducing the environmental impact related to both food transport and storage. The production of horticultural goods shows the main benefits of urban agriculture. Fruit and vegetable crops give high yields, up to 50 kg m⁻² year⁻¹, a more efficient use of agricultural inputs, high added value, and rapidly perishable products that can easily substitute the rural production in the local market. Urban horticulture is the most competitive branch of urban farming due to the high cost of urban land and with the need of high water- and fertilizer-use efficiency. Traditional urban horticulture systems are classified in four types: allotment and family gardens, simplified extensive systems, shifting cultivation, and intensive systems. We describe also innovative systems including organoponics and simplified soilless cultures.
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
s
, 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
H
O). 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.
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•LED lights may enable indoor cultivation at low energy cost.•LED light may improve both productivity and nutritional quality.•Nitrate level in leafy vegetable is reduced by LED ...application.•Red:blue ratio of 0.7 is needed for proper plant development.
In recent years, the interest toward the applicability of Light-Emitting Diode (LED) lights for indoor cultivation has significantly grown. The present work addressed the physiological and phytochemical plant responses to LED lights in indoor cultivation of leafy and fruit vegetable crops (namely sweet basil, Ocimum basilicum L.; and strawberry, Fragaria×Ananassa), with the final aim of improving both productivity and nutritional quality. Artificial light treatments were applied in a multi-sectorial growth chamber equipped with lamps with different light incidence and spectra (with red:blue ratio ranging 0.7–5.5). In all experiments, increased plant biomass, fruit yield and energy use efficiency (EUE) were associated to LED treatments, confirming the superiority of LED compared to the traditional fluorescent lamps. Interestingly, LED lighting enabled to increase antioxidant compounds and reduce nitrates content in basil leaves. A spectral red:blue ratio of 0.7 was necessary for proper plant development and improved nutraceutical properties in both crops.
•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 CO2 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.
Indoor plant cultivation can result in significantly improved resource use efficiency (surface, water, and nutrients) as compared to traditional growing systems, but illumination costs are still ...high. LEDs (light emitting diodes) are gaining attention for indoor cultivation because of their ability to provide light of different spectra. In the light spectrum, red and blue regions are often considered the major plants' energy sources for photosynthetic CO
assimilation. This study aims at identifying the role played by red:blue (R:B) ratio on the resource use efficiency of indoor basil cultivation, linking the physiological response to light to changes in yield and nutritional properties. Basil plants were cultivated in growth chambers under five LED light regimens characterized by different R:B ratios ranging from 0.5 to 4 (respectively, RB
, RB
, RB
, RB
, and RB
), using fluorescent lamps as control (CK
). A photosynthetic photon flux density of 215 μmol m
s
was provided for 16 h per day. The greatest biomass production was associated with LED lighting as compared with fluorescent lamp. Despite a reduction in both stomatal conductance and PSII quantum efficiency, adoption of RB
resulted in higher yield and chlorophyll content, leading to improved use efficiency for water and energy. Antioxidant activity followed a spectral-response function, with optimum associated with RB
. A low RB ratio (0.5) reduced the relative content of several volatiles, as compared to CK
and RB ≥ 2. Moreover, mineral leaf concentration (g g
DW) and total content in plant (g plant
) were influences by light quality, resulting in greater N, P, K, Ca, Mg, and Fe accumulation in plants cultivated with RB
. Contrarily, nutrient use efficiency was increased in RB ≤ 1. From this study it can be concluded that a RB ratio of 3 provides optimal growing conditions for indoor cultivation of basil, fostering improved performances in terms of growth, physiological and metabolic functions, and resources use efficiency.
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.
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.
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
15
N-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.
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.
The present work, focusing on the theme of food production and consumption in urban areas, analyses the relationships among three factors: city, human well-being and ecosystems. A case study was ...carried out addressing the quantification of the potential of rooftop vegetable production in the city of Bologna (Italy) as related to its citizens’ needs. Besides the contribution to food security of the city, the potential benefits to urban biodiversity and ecosystem service provision were estimated. The methodology consisted of: 1) experimental trials of potential productivity of simplified soilless systems in rooftop gardens (RTGs); 2) detection of all flat roofs and roof-terraces and quantification of the potential surfaces that could be converted into RTGs; 3) identification of the city’s vegetable requirements, based on population and diet data; 4) calculation of the proportion of vegetable requirement that could be satisfied by local RTG production; 5) identification of other benefits (improvement of urban biodiversity through the creation of green corridors and estimation of carbon sequestration) associated with the increased area of urban green infrastructure (GI). According to the present study, RTGs could provide more than 12,000 t year
−1
vegetables to Bologna, satisfying 77 % of the inhabitants’ requirements. The study also advances hypotheses for the implementation of biodiversity roofs enabling the connection of biodiversity rich areas across and close to the city: these would form a network of green corridors of over 94 km length with a density of about 0.67 km km
−2
.
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