Urban Horticulture - New Trends and Technologies

A special issue of Horticulturae (ISSN 2311-7524). This special issue belongs to the section "Protected Culture".

Deadline for manuscript submissions: closed (10 March 2022) | Viewed by 46564

Special Issue Editors


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Guest Editor
Texas A&M AgriLife Research, Texas A&M University, 17360 Coit Road, Dallas, TX 75252, USA
Interests: controlled environment agriculture; hydroponics; indoor vertical farming; environmental stress physiology; urban landscape water conservation
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Guest Editor
Environmental Horticulture Dept., University of Florida, 1529 Fifield Hall, 2550 Hull Rd., Gainesville FL 32611-0670, USA
Interests: indoor plant production; sole-source lighting; urban gardening; hydroponics

Special Issue Information

Dear Colleagues,

Urban horticulture is the study of the relationship between horticultural crops and the urban environment. Traditionally, urban horticulture has been dominated by backyard gardeners, community gardeners, and small-scale commercial growers in urban and peri-urban spaces. Backyard and community gardeners are typically hobbyists who enjoy raising their own vegetables, fruits, herbs, and sometimes flowers, in decks, balconies, covered patios, community plots, or residential rooftops, to supplement their diets. Although economic gain from gardening is not their primary focus, some of these gardeners sell their produce at seasonal farmers’ markets.

In recent years, interest in urban horticulture has increased due to rapid urbanization, the expansion of cities, and increased consumer demand for locally grown fresh produce. Moreover, a new type of urban horticulture—indoor vertical farming (VF)—has gained momentum among young entrepreneurs and urban growers. For this type of urban horticulture, the application of highly efficient production systems such as hydroponics and aquaponics with different environmental control techniques is preferred. The size of VF ranges from mini-indoor farms to large-scale commercial facilities with automation. Although the number of large-scale operations is still limited, small-scale VFs have burgeoned in large cities in recent years. These small VFs usually sell their products directly to up-end restaurants and grocery stores. The main crops are typically microgreens, herbs, baby leafy greens, and edible flowers, although interest is increasing for fruiting vegetable crops like strawberries, tomatoes and peppers.

In this Special Issue, we would like to provide a platform for researchers to share their opinions and research findings relevant to all types of urban horticulture.

Prof. Dr. Genhua Niu
Dr. Celina Gómez
Guest Editors

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Keywords

  • Aquaponics
  • Community gardening
  • Controlled environment agriculture
  • Hydroponics
  • Indoor gardening
  • LED lighting
  • Organic gardening
  • Pick-and-eat
  • Rooftop gardening
  • Urban agriculture
  • Urban gardening

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Published Papers (8 papers)

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13 pages, 1516 KiB  
Article
Evaluation of Compact Tomato Cultivars for Container Gardening Indoors and under Sunlight
by Stephanie Cruz, Edzard van Santen and Celina Gómez
Horticulturae 2022, 8(4), 294; https://doi.org/10.3390/horticulturae8040294 - 30 Mar 2022
Cited by 6 | Viewed by 4416
Abstract
Numerous compact tomato cultivars are available for home gardening. However, evaluations under different environmental conditions are limited. The aim of this study was to characterize the growth and productivity of 20 compact tomato cultivars grown indoors under environmental conditions that resembled a residential [...] Read more.
Numerous compact tomato cultivars are available for home gardening. However, evaluations under different environmental conditions are limited. The aim of this study was to characterize the growth and productivity of 20 compact tomato cultivars grown indoors under environmental conditions that resembled a residential space (11 mol·m−2·d−1 of white light, constant 22 °C, and moderate relative humidity) or in a greenhouse with sunlight only. Plants in the greenhouse were generally larger and yielded more fruit than those grown indoors, likely due to the various differences in environmental conditions and corresponding effects of water and nutrient availability. Considering growth and yield variables, all cultivars evaluated in this study are recommended for outdoor gardening. However, ‘Little Bing’, ‘Sweet SturdyTM F1—Grace’, ‘Sweet SturdyTM F1—Jimmy’, ‘Sweet SturdyTM F1—Jo’, and ‘Tarzan F1′ are likely too large to be grown in most space-limited indoor environments. Furthermore, ‘Little Bing’, ‘Rosy Finch’, ‘Sweet ‘n’ Neat Yellow’, and ‘Yellow Canary’ were affected by intumescence when grown indoors, which could negatively affect gardening experiences until recommendations to mitigate this disorder become available. Results from this study provide baseline information for the use of compact tomato cultivars for container gardening indoors and under sunlight. Full article
(This article belongs to the Special Issue Urban Horticulture - New Trends and Technologies)
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11 pages, 253 KiB  
Article
Producing Cherry Tomatoes in Urban Agriculture
by Matthew L. Richardson and Caitlin G. Arlotta
Horticulturae 2022, 8(4), 274; https://doi.org/10.3390/horticulturae8040274 - 22 Mar 2022
Cited by 7 | Viewed by 3900
Abstract
Agriculture in urban and urbanizing areas will be increasingly critical to enhancing food security and food sovereignty, creating income, strengthening social interactions, and improving health outcomes in cities. We used three roofs, a hydroponic system, an aquaponic system, and field rows in an [...] Read more.
Agriculture in urban and urbanizing areas will be increasingly critical to enhancing food security and food sovereignty, creating income, strengthening social interactions, and improving health outcomes in cities. We used three roofs, a hydroponic system, an aquaponic system, and field rows in an urban environment to grow six dwarf tomato cultivars: ‘Micro Tom’, ‘Red Robin’, ‘Sweet ‘n’ Neat’, ‘Terenzo’, ‘Tiny Tim’, and ‘Tumbler.’ We measured the marketable yield and non-marketable yield, mass of non-marketable tomatoes exhibiting defects, and the content of 12 mineral nutrients in fruits. We found the productivity often varied among cultivars within a cropping system. ‘Terenzo’ and ‘Tumbler’ were always some of the most productive cultivars, whereas ‘Micro Tom’ was normally among the least productive cultivars. The production from ‘Red Robin’, ‘Tiny Tim’, and ‘Sweat ‘n’ Neat’ was more variable, sometimes producing high, moderate, or low mass. The mineral content was especially variable across the cultivars and we did not identify cultivars that were consistently high or low in mineral content across systems, indicating that the mineral content was highly influenced by a genotype x environment interaction. The amount of 5 minerals differed across cultivars in aquaponics, 9 differed in hydroponics, and 6–12 differed in the roof systems. A high-yielding cultivar should be selected first and production methods can then be modified to maximize the nutrient content. Full article
(This article belongs to the Special Issue Urban Horticulture - New Trends and Technologies)
14 pages, 1818 KiB  
Article
Optimization of the Yield, Total Phenolic Content, and Antioxidant Capacity of Basil by Controlling the Electrical Conductivity of the Nutrient Solution
by Xiaowei Ren, Na Lu, Wenshuo Xu, Yunfei Zhuang and Michiko Takagaki
Horticulturae 2022, 8(3), 216; https://doi.org/10.3390/horticulturae8030216 - 1 Mar 2022
Cited by 11 | Viewed by 3490
Abstract
Hydroponic cultivation using nutrient solution (NS) is the main cultivation method employed by plant factories with artificial lighting (PFALs). The electrical conductivity (EC) of NSs influences the yield and quality of vegetables. The purpose of this study was to optimize the yield and [...] Read more.
Hydroponic cultivation using nutrient solution (NS) is the main cultivation method employed by plant factories with artificial lighting (PFALs). The electrical conductivity (EC) of NSs influences the yield and quality of vegetables. The purpose of this study was to optimize the yield and antioxidant accumulation of basil in a PFAL by EC management. In experiment 1, basil plants were grown under four different ECs (0.5, 1.0, 3.0, and 5.0 dS m−1) after transplanting. At 18 days after treatment, the highest levels of shoot fresh and dry weights, leaf fresh and dry weights, and leaf area were observed at an EC of 3.0 dS m−1. However, low-EC treatments (0.5 and 1.0 dS m−1) generated total phenolic content (TPC) and antioxidant capacities that were higher than those of other EC treatments (3.0 and 5.0 dS m−1). In experiment 2, basil plants were grown at an EC of 3.0 dS m−1 for 13 or 15 days, then treated with water or NS with low ECs (0.5 and 1.0 dS m−1) for 5 or 3 days before harvest. The short-term low-EC treatments, especially, water for 3 days and 0.5 dS m−1 for 5 days, significantly increased the TPC and antioxidant capacity of leaves without significantly decreasing the yields of basil, compared with the control. In conclusion, yield of basil was optimized with an EC of 3.0 dS m−1; however, the TPC and antioxidant capacity of basil were significantly increased by low ECs of 0.5 and 1.0 dS m−1. Short-term low-EC treatments (0.5 dS m−1 for 5 days or water for 3 days) could be used to promote the TPC and antioxidant capacity in leaves without sacrificing yield of basil significantly. Full article
(This article belongs to the Special Issue Urban Horticulture - New Trends and Technologies)
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11 pages, 1445 KiB  
Article
Hydroponic Basil Production: Temperature Influences Volatile Organic Compound Profile, but Not Overall Consumer Preference
by Kellie J. Walters and Roberto G. Lopez
Horticulturae 2022, 8(1), 76; https://doi.org/10.3390/horticulturae8010076 - 14 Jan 2022
Cited by 3 | Viewed by 2968
Abstract
Altering the growing temperature during controlled-environment production not only influences crop growth and development, but can also influence volatile organic compound (VOC) production and, subsequently, sensory attributes of culinary herbs. Therefore, the objectives of this study were to (1) quantify the influence of [...] Read more.
Altering the growing temperature during controlled-environment production not only influences crop growth and development, but can also influence volatile organic compound (VOC) production and, subsequently, sensory attributes of culinary herbs. Therefore, the objectives of this study were to (1) quantify the influence of mean daily temperature (MDT) and daily light integral (DLI) on key basil phenylpropanoid and terpenoid concentrations, (2) determine if differences in sensory characteristics due to MDT and DLI influence consumer preference, and (3) identify the sweet basil attributes consumers prefer. Thus, 2-week-old sweet basil ‘Nufar’ seedlings were transplanted into deep-flow hydroponic systems in greenhouses with target MDTs of 23, 26, 29, 32, or 35 °C and DLIs of 7, 9, or 12 mol·m−2·d−1. After three weeks, the two most recently mature leaves were harvested for gas chromatography–mass spectrometry (GC–MS) and consumer sensory analysis. Panel evaluations were conducted through a sliding door with samples served individually while panelists answered Likert scale and open-ended quality attribute and sensory questions. The DLI did not influence VOC concentrations. Increasing MDT from 23 to 36 °C during production increased 1,8 cineole, eugenol, and methyl chavicol concentrations linearly and did not affect linalool concentration. The increases in phenylpropanoid (eugenol and methyl chavicol) were greater than increases in terpenoid (1,8 cineole) concentrations. However, these increases did not impact overall consumer or flavor preference. The MDT during basil production influenced appearance, texture, and color preference of panelists. Taken together, MDT during production influenced both VOC concentrations and textural and visual attribute preference of basil but did not influence overall consumer preference. Therefore, changing the MDT during production can be used to alter plant growth and development without significantly affecting consumer preference. Full article
(This article belongs to the Special Issue Urban Horticulture - New Trends and Technologies)
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14 pages, 3421 KiB  
Article
Root Architecture, Growth and Photon Yield of Cucumber Seedlings as Influenced by Daily Light Integral at Different Stages in the Closed Transplant Production System
by Yifei Wang, Yangyang Chu, Ze Wan, Geng Zhang, Lei Liu and Zhengnan Yan
Horticulturae 2021, 7(9), 328; https://doi.org/10.3390/horticulturae7090328 - 21 Sep 2021
Cited by 9 | Viewed by 3724
Abstract
Optimizing light conditions for vegetable seedling production in a closed transplant production system is critical for plant growth and seedling production. Additionally, energy use efficiency should be considered by growers when managing the light environment. In the present study, cucumber seedlings (Cucumis [...] Read more.
Optimizing light conditions for vegetable seedling production in a closed transplant production system is critical for plant growth and seedling production. Additionally, energy use efficiency should be considered by growers when managing the light environment. In the present study, cucumber seedlings (Cucumis sativus L. cv. Tianjiao No. 5) were grown under six different daily light integrals (DLIs) at 8.64, 11.52, 14.40, 17.28, 23.04, and 28.80 mol m−2 d−1 created by two levels of photosynthetic photon flux density (PPFD) of 200 and 400 μmol m−2 s−1 combined with photoperiod of 12, 16 and 20 h d−1 provided by white light-emitting diodes (LEDs) in a closed transplant production system for 21 days. Results indicated that quadratic functions were observed between fresh and dry weights of cucumber seedlings and DLI at 6, 11, 16, and 21 days after sowing. Generally, higher DLI resulted in longer root length, bigger root volume and root surface area accompanied with shorter plant height and hypocotyl length; however, no significant differences were observed in root length, root volume, and root surface area as DLI increased from 14.40 to 28.80 mol m−2 d−1. Photon yield based on fresh and dry weights decreased with increasing DLI. In conclusion, increased DLI resulted in compact and vigorous morphology but reduced photon yield of cucumber seedlings produced in a closed transplant production system. In terms of plant growth and energy use efficiency, DLI at 14.40–23.04 mol m−2 d−1 was suggested for cucumber seedling production in the closed production system. Additionally, different control strategies should be applied at different growth stages of cucumber seedlings. Full article
(This article belongs to the Special Issue Urban Horticulture - New Trends and Technologies)
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13 pages, 4412 KiB  
Article
Quality Evaluation of Indoor-Grown Microgreens Cultivated on Three Different Substrates
by Roberta Bulgari, Marco Negri, Piero Santoro and Antonio Ferrante
Horticulturae 2021, 7(5), 96; https://doi.org/10.3390/horticulturae7050096 - 2 May 2021
Cited by 40 | Viewed by 8597
Abstract
The microgreens are innovative products in the horticultural sector. They are appreciated by consumers thanks to their novelty and health-related benefits, having a high antioxidant concentration. This produce can be adopted for indoor production using hydroponic systems. The aim of the present work [...] Read more.
The microgreens are innovative products in the horticultural sector. They are appreciated by consumers thanks to their novelty and health-related benefits, having a high antioxidant concentration. This produce can be adopted for indoor production using hydroponic systems. The aim of the present work was to investigate the influence of three growing media (vermiculite, coconut fiber, and jute fabric) on yield and quality parameters of two basil varieties (Green basil—Ocimum basilicum L., Red basil—Ocimum basilicum var. Purpurecsens) and rocket (Eruca sativa Mill.) as microgreens. Microgreens were grown in floating, in a Micro Experimental Growing (MEG®) system equipped with LED lamps, with modulation of both energy and spectra of the light supplied to plants. Results showed high yield, comprised from 2 to 3 kg m−2. Nutritional quality varied among species and higher antioxidant compounds were found in red basil on vermiculite and jute. Coconut fiber allowed the differentiation of crop performance in terms of sucrose and above all nitrate. In particular, our results point out that the choice of the substrate significantly affected the yield, the dry matter percentage and the nitrate concentration of microgreens, while the other qualitative parameters were most influenced by the species. Full article
(This article belongs to the Special Issue Urban Horticulture - New Trends and Technologies)
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13 pages, 3291 KiB  
Article
Effects of Light-Emitting Diodes on the Accumulation of Phenolic Compounds and Glucosinolates in Brassica juncea Sprouts
by Chang Ha Park, Ye Eun Park, Hyeon Ji Yeo, Jae Kwang Kim and Sang Un Park
Horticulturae 2020, 6(4), 77; https://doi.org/10.3390/horticulturae6040077 - 9 Nov 2020
Cited by 30 | Viewed by 4568
Abstract
Recent improvements in light-emitting diode (LED) technology afford an excellent opportunity to investigate the relationship between different light sources and plant metabolites. Accordingly, the goal of the present study was to determine the effect of different LED (white, blue, and red) treatments on [...] Read more.
Recent improvements in light-emitting diode (LED) technology afford an excellent opportunity to investigate the relationship between different light sources and plant metabolites. Accordingly, the goal of the present study was to determine the effect of different LED (white, blue, and red) treatments on the contents of glucosinolates (glucoiberin, gluconapin, sinigrin, gluconasturtiin, 4-methoxyglucobrassicin, 4-hydroxyglucobrassicin, glucobrassicin, and neoglucobrassicin) and phenolic compounds (4-hydroxybenzonate, catechin, chlorogenic acid, caffeate, gallate, sinapate, and quercetin) in Brassica juncea sprouts. The sprouts were grown in a growth chamber at 25 °C under irradiation with white, blue, or red LED with a flux rate of 90 μmol·m−2·s−1 and a long-day photoperiod (16 h light/8 h dark cycle). Marked differences in desulfoglucosinolate contents were observed in response to treatment with different LEDs and different treatment durations. In addition, the highest total desulfoglucosinolate content was observed in response to white LED light treatment, followed by treatment with red LED light, and then blue LED light. Among the individual desulfoglucosinolates identified in the sprouts, sinigrin exhibited the highest content, which was observed after three weeks of white LED light treatment. The highest total phenolic contents were recorded after one week of white and blue LED light treatment, whereas blue LED irradiation increased the production of most of the phenolic compounds identified, including 4-hydroxybenzonate, gallate, sinapate, caffeate, quercetin, and chlorogenic acid. The production of phenolics decreased gradually with increasing duration of LED light treatment, whereas anthocyanin accumulation showed a progressive increase during the treatment. These findings indicate that white LED light is appropriate for glucosinolate accumulation, whereas blue LED light is effective in increasing the production of phenolic compounds in B. juncea sprouts. Full article
(This article belongs to the Special Issue Urban Horticulture - New Trends and Technologies)
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9 pages, 216 KiB  
Opinion
What You May Not Realize about Vertical Farming
by Farzana A. Lubna, David C. Lewus, Timothy J. Shelford and Arend-Jan Both
Horticulturae 2022, 8(4), 322; https://doi.org/10.3390/horticulturae8040322 - 11 Apr 2022
Cited by 41 | Viewed by 12320
Abstract
Vertical farming (VF) is a newer crop production practice that is attracting attention from all around the world. VF is defined as growing indoor crops on multiple layers, either on the same floor or on multiple stories. Most VF operations are located in [...] Read more.
Vertical farming (VF) is a newer crop production practice that is attracting attention from all around the world. VF is defined as growing indoor crops on multiple layers, either on the same floor or on multiple stories. Most VF operations are located in urban environments, substantially reducing the distance between producer and consumer. Some people claim that VF is the beginning of a new era in controlled environment agriculture, with the potential to substantially increase resource-use efficiencies. However, since most vertical farms exclusively use electric lighting to grow crops, the energy input for VF is typically very high. Additional challenges include finding and converting growing space, constructing growing systems, maintaining equipment, selecting suitable plant species, maintaining a disease- and pest-free environment, attracting and training workers, optimizing the control of environmental parameters, managing data-driven decision making, and marketing. The objective of the paper is to highlight several of the challenges and issues associated with planning and operating a successful vertical farm. Industry-specific information and knowledge will help investors and growers make informed decisions about financing and operating a vertical farm. Full article
(This article belongs to the Special Issue Urban Horticulture - New Trends and Technologies)
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