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Controlled environment agriculture, including greenhouses and indoor production facilities, is becoming an increasingly important part of the global food system. Totally enclosed, indoor vegetable growing facilities were developed in Japan beginning

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Multilayer vertical production systems using sole-source (SS) light-emitting diodes (LEDs) can be an alternative to more traditional methods of microgreens production. One significant benefit of using LEDs is the ability to select light qualities that have beneficial impacts on plant morphology and the synthesis of health-promoting phytochemicals. Therefore, the objective of this study was to quantify the impacts of SS LEDs of different light qualities and intensities on the phytochemical content of brassica (Brassica sp.) microgreens. Specifically, phytochemical measurements included 1) total anthocyanins, 2) total and individual carotenoids, 3) total and individual chlorophylls, and 4) total phenolics. Kohlrabi (Brassica oleracea var. gongylodes), mustard (Brassica juncea ‘Garnet Giant’), and mizuna (Brassica rapa var. japonica) were grown in hydroponic tray systems placed on multilayer shelves in a walk-in growth chamber. A daily light integral (DLI) of 6, 12, or 18 mol·m−2·d−1 was achieved from SS LED arrays with light ratios (percent) of red:blue 87:13 (R87:B13), red:far-red:blue 84:7:9 (R84:FR7:B9), or red:green:blue 74:18:8 (R74:G18:B8) with a total photon flux from 400 to 800 nm of 105, 210, or 315 µmol·m−2·s–1 for 16 hours, respectively. Phytochemical measurements were collected using spectrophotometry and high-performance liquid chromatography (HPLC). Regardless of light quality, total carotenoids were significantly lower under increasing light intensities for mizuna and mustard microgreens. In addition, light quality affected total integrated chlorophyll with higher values observed under the light ratio of R87:B13 compared with R84:FR7:B9 and R74:G18:B8 for kohlrabi and mustard microgreens, respectively. For kohlrabi, with increasing light intensities, the total concentration of anthocyanins was greater compared with those grown under lower light intensities. In addition, for kohlrabi, the light ratios of R87:B13 or R84:FR7:B9 produced significantly higher anthocyanin concentrations compared with the light ratio of R74:G18:B8 under a light intensity of 315 µmol·m−2·s−1. Light quality also influenced the total phenolic concentration of kohlrabi microgreens, with significantly greater levels for the light ratio of R84:FR7:B9 compared with R74:G18:B8 under a light intensity of 105 µmol·m−2·s−1. However, the impact of light intensity on total phenolic concentration of kohlrabi was not significant. The results from this study provide further insight into the selection of light qualities and intensities using SS LEDs to achieve preferred phytochemical content of brassica microgreens.

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February ( Korczynski et al., 2002 ). Supplemental lighting is often needed to produce high-quality crops in controlled-environment agriculture but can substantially increase production costs. For example, van Iersel and Gianino (2017) estimated that the

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Although crops often respond immediately to enriched CO2 concentrations (e.g., increased photosynthesis), this initial response is often not sustained throughout production, thus reducing the benefit of this input. For horticulture species, the timing and extent of these acclimation responses are still widely uncertain. Therefore, the objective of this research was to determine species-specific acclimation responses to elevated CO2 concentrations for pansy (Viola ×wittrockiana ‘Matrix Blue Blotch Improved’) and petunia (Petunia ×hybrida ‘Dreams Midnight’). Seedlings were transplanted to 11.5-cm pots and placed in growth chambers with air temperature, relative humidity, and radiation intensity setpoints of 21 °C, 55%, and 250 μmol⋅m 2⋅s 1, respectively. Carbon dioxide treatments were established using the two growth chambers with setpoints of either 400 (ambient) or 1000 μmol⋅mol−1 (elevated) maintained during a 16-hour photoperiod. In addition to data collected through destructive harvest, the rate of photosynthesis (A) in response to increasing internal leaf CO2 concentration (A-Ci) and at the operating CO2 concentration (A-Ca) were measured weekly with a portable leaf photosynthesis system at saturating [A-Ci (1000 μmol⋅m 2⋅s 1)] or production [A-Ca (250 μmol⋅m 2⋅s 1)] radiation intensities. For both pansy and petunia, elevated CO2 produced greater total shoot dry mass than ambient CO2 after 4 weeks. However, the decreased maximum rate of photosynthetic electron transport, maximum rate of Rubisco carboxylase, and triose phosphate utilization rate of both species were also observed under elevated CO2. Similarly, A measured at 400 and 1000 μmol⋅mol−1 was reduced for both pansy and petunia grown under the elevated compared with ambient CO2 concentration based on A-Ca responses after 7 days, indicating quick physiological acclimation to this input. These results provide information regarding the timing and extent of physiological acclimation in response to elevated CO2 concentrations. However, because of physiological acclimation potentially occurring within 7 days of treatment initiation, additional research is necessary to develop species-specific recommendations for controlled environment production.

Open Access

Baby greens are becoming increasingly popular in the consumer market because of their desired flavor and leaf size. The short life cycles and fast response times to environmental stimuli make baby greens ideal for testing environmental conditions for space crop production. Additionally, far-red (FR) light has been used for microgreen and baby green research to enhance stem elongation, leaf expansion, and biomass; however, how it interacts with nutrient solution nitrogen (N) concentrations remains unclear. During this ground-based study, we characterized how FR light and N concentrations influenced the growth and morphology of Chinese cabbage (Brassica rapa var. chinensis cv. Tokyo Bekana) and kale (Brassica oleracea var. sabellica cv. Red Russian) baby greens under similar superelevated CO2 and low relative humidity to levels observed in spaceflight. Plants were subject to combinations of four sole-source light spectra and three N concentrations (75, 125, and 175 mg⋅L−1). At the same total photon flux density (PFD) of 200 μmol⋅m−2⋅s−1, we maintained the same blue and green PFDs at 25 μmol⋅m−2⋅s−1 each; the remaining 150 μmol⋅m−2⋅s−1 comprised four red (R) and FR PFD combinations (FR: 0, 25, 50, and 75 μmol⋅m−2⋅s−1). Increasing the FR PFD enhanced the typical shade-avoidance morphology of Chinese cabbage ‘Tokyo Bekana’ and kale ‘Red Russian’, exhibiting leaf length increases of 20% to 26% and 31% to 61%, respectively. Edible biomass did not increase with increasing FR PFDs for either species, regardless of the N concentration. Increasing the N concentration increased the Chinese cabbage ‘Tokyo Bekana’ fresh mass and dry mass by 32% to 59% and 37% to 74%, respectively, except under 25 μmol⋅m−2⋅s−1 of FR light, with which shoot fresh mass increased by 55% with an increasing N concentration from 75 to 125 mg⋅L−1; however, the shoot dry mass was unaffected. Increasing the N concentration did not affect kale ‘Red Russian’ growth under various FR PFDs. We conclude that partially substituting incremental FR light for R light elicits the shade-avoidance response, with little influence on the growth, of Chinese cabbage ‘Tokyo Bekana’ and kale ‘Red Russian’ baby greens under superelevated CO2 and continuous light, and that the former, but not the latter, crop can benefit from increased N fertilization.

Open Access

). Growing culinary herbs in controlled environment agriculture (CEA) facilities can enhance yield and quality of herbs through appropriate cultivar and production system selection ( Walters and Currey, 2015 ) and managing mineral nutrition ( De Pascale et al

Open Access

Both, A.J. Albright, L.D. Langhans, R.W. Reiser, R.A. Vinzant, B.G. 1997 Hydroponic lettuce production influenced by integrated supplemental light levels in a controlled environment agriculture facility: Experimental results Acta Hort. 418 45 51 Bouly

Open Access

Far-red photons (700–750 nm) are rarely used in sole-source lighting for controlled-environment agriculture. However, plants have evolved under sunlight for millions of years, and far-red photons comprise ∼16% of photons in ePAR photons (400

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LEDs has made them a prominent addition to controlled environment agriculture ( Kusuma et al., 2020 ). In these plant factories, plant morphology can be manipulated by the specific choice of LEDs, but first it is vital to develop proper metrics to

Open Access