ASHS 2025 Conference

A calcium-mobilizing chemical biostimulant has been developed to improve crop growth and quality by promoting calcium uptake and mobilization. Although designed to be applied as a foliar spray, it can potentially be added to the nutrient solution in controlled-environment hydroponic systems. Although it has been shown to mitigate calcium deficiency-induced tipburn while maintaining biomass in hydroponic lettuce (Lactuca sativa), its efficacy in other emerging hydroponic leafy greens remains unclear. The objective of this study was to determine the influence of this biostimulant, when added to the nutrient solution, on the growth traits of four hydroponic leafy greens: arugula (Eruca sativa) ‘Astro’, kale (Brassica oleracea var. sabellica) ‘Starbor’, lettuce ‘Rex’, and pac choi (Brassica rapa var. chinensis) ‘Win-Win Choi’. After 11 days of germination and seedling propagation under indoor sole-source lighting, we transplanted seedlings of all crops into actively aerated deep-water-culture trays in a summer greenhouse environment. The trays had the same nutrient solution without and without the added biostimulant at a concentration of 0.25 mL⋅L−1 in three blocks of a randomized complete block design. Plant data were collected 21 and 28 days after transplanting (DAT). At 21 DAT, the added biostimulant decreased shoot fresh and dry mass of arugula, kale, and pac choi by 21% to 31% but increased that of lettuce by 23% to 25%. At 28 DAT, the added biostimulant also increased shoot fresh and dry mass of lettuce by 24% to 29%, did not influence shoot fresh mass of the other crops, and decreased shoot dry mass of kale and pac choi by 14% to 21%. Tipburn incidence was minimal without or with the added biostimulant at 21 and 28 DAT, although tipburn reduction was observed in arugula and pac choi with the added biostimulant. Chlorophyll concentration index was generally unaffected by the added biostimulant, except for an 11% increase in lettuce with the added biostimulant at 28 DAT. Extension growth of all crops except lettuce had a 9% to 15% reduction with the added biostimulant at 21 DAT but was unaffected by the added biostimulant at 28 DAT. We conclude that the added biostimulant boosted the growth of lettuce, but not the other leafy greens tested, in summer greenhouse aerated hydroponics.

The southeastern U.S. struggles with horticultural production due to a harsh climate that exacerbates issues such as severe weed, soil-borne pests, and diseases. Hydroponic cultivation offers a promising solution by reducing pesticide use and facilitating year-round production. However, there is a lack of regionally research-based guidance on hydroponic cultivation in Mississippi. This study aimed to screen the lettuce cultivars that are suitable for hydroponic cultivation in Mississippi and to evaluate the effects of different hydroponic systems and biostimulants on plant growth. Six lettuce cultivars (Buttercrunch, Adriana, Rex, Rouxai, Oscarde, and Skyphos) were grown in two hydroponic systems (vertical tower and deep-water culture), and subjected to three biostimulant treatments (control, kelp and microbial biostimulant) to assess their impacts on growth parameters. Results indicated that lettuce cultivar significantly affected hydroponic lettuce growth. Adriana showed the highest leaf area and plant biomass while Buttercrunch displayed the highest relative chlorophyll content (SPAD) and shoot fresh weight. Rouxai accumulated the least biomass. Biostimulants demonstrated positive effects on lettuce plant growth; however, their efficacy was specific to both the hydroponic system and lettuce cultivar. Kelp was found to be more effective than microbial biostimulants in enhancing growth parameters. Overall, lettuce plants grown in the deep-water culture system exhibited faster growth compared to those in the vertical tower system. In conclusion, this study demonstrated that hydroponic cultivation is a viable solution for lettuce production in Mississippi, with deep-water culture system and kelp biostimulant significantly enhancing growth parameters.

Antibiotic persistence in the environment, including water sources, is a significant concern due to the increasing prevalence of antibiotic-resistant bacteria. Tylosin is a common macrolide antibiotic used as a growth promoter in cattle, with 71% of feedlots administering it. Antibiotics such as tylosin, can persist as residual contaminants in surface water, groundwater, and wastewater. This poses a risk when these contaminated waters are used for irrigation. Such practice can result in the uptake of antibiotics by plants, which in turn may contribute to the development of antibiotic resistance in both human and living organisms. To determine the antibiotic uptake and its effects on crops, we spiked the nutrient solution with 2 levels of tylosin and grew lettuce (Lactuca sativa) in a nutrient film technique (NFT) hydroponics system. Two replicated experiments utilized the NFT hydroponic systems and included tylosin at concentrations of 5 mg/L and 10 mg/L, with reverse osmosis (RO) water as the control. Growth parameters were measured after 4 weeks at harvest, including aerial weight, head diameter, plant height, root weight, and root length. The results indicated that tylosin treatments had a negative impact with decreased root weight and length in the first experiment, whereas aerial measurements did not differ between treatments. The 10 mg/L tylosin treatment in the second experiment resulted in significantly wider head diameters and longer roots. Tylosin concentrations in lettuce leaf tissue were higher in both treatments compared to the control, although the 5 mg/L and 10 mg/L treatments showed similar responses. Water analyses throughout the experiments showed a decrease in tylosin concentration in the treated water over time, with no tylosin detected in the control treatment at any time. Multivariate correlation analysis revealed negative correlations between tylosin concentration and all growth parameters. These findings highlight the potential effects of tylosin on hydroponically grown lettuce and raise important considerations for using recycled or alternative water sources in hydroponic agriculture, particularly concerning food safety and crop productivity.

Despite adequate caloric intake of food, developed nations are still struggling with the problem of “hidden hunger” due to overconsumption of nutrient-poor foods. Biofortification with vitamins and nutrients offers a solution to mitigate this issue by increasing nutrient and vitamin content in crops through different techniques such as agronomic practices, conventional plant breeding and modern biotechnology. This study investigates agronomic Vitamin C biofortification in lettuce through foliar sprays in two different hydroponics systems: Deep water (DW) and nutrient film technique (NFT). For this, replicated experiments were conducted. Seedlings were first grown to maturity in each system, then two days prior to harvest, foliar sprays of 200 and 400 ppm ascorbic acid (AsA) rate along with a control (DI water) were applied to each system. At harvest, plants were measured for fresh biomass, processed, and then flash frozen in liquid nitrogen prior to lyophilization. Certain samples remained fresh to determine persistence of Vitamin C at room and refrigerated temperatures (4C) at 24, 48, and 72 hrs. after harvest. Ascorbic acid (AsA) and total ascorbic acid (TAsA) content were measured for all samples. Overall, biomass was higher for DW grown lettuce compared to NFT. While biofortification rate did not affect DW grown lettuce, NFT biofortified lettuce treated with 200 ppm AsA had greater AsA and TAsA content. In the shelf-life study, AsA declined over time. Temperatures also affected AsA, where refrigerated lettuce treated with 400 ppm had greater TAsA content. These data show higher variability of AsA among the different hydroponics systems. In conclusion, this study demonstrates the potential of foliar spray of ascorbic acid to enhance the Vitamin C content of lettuce grown in hydroponics system. The observed variability between different systems suggests that system-specific optimization is necessary to achieve the benefits of biofortification.

Lettuce (Lactuca sativa) tipburn is a calcium-related physiological disorder that affects enclosed young leaves, leading to browning, necrosis, and curling of leaf margins and reduced marketability. While greenhouse vertical airflow fans (VAFs) have been proven effective at controlling tipburn, they have not been widely adopted due to cumbersome installation, sunlight obstruction, and electricity consumption. Recent research showed that a calcium-mobilizing biostimulant, when added to the nutrient solution, mitigated tipburn in greenhouse hydroponic lettuce by enhancing calcium mobility. However, how it compared to VAFs was unknown. We investigated the effects of this biostimulant and VAFs on lettuce tipburn and growth in a greenhouse hydroponic system during summer. Seedlings of lettuce ‘Rex’ were propagated indoors and, on day 14, transplanted into deep-water-culture trays in a climate-controlled greenhouse. In a split-plot randomized complete block design with two blocks, plants were subject to six treatments per block: three biostimulant concentrations (0, 0.25, and 0.5 mL⋅L–1) with and without VAFs promoting vertical airflow at ≈1 m⋅s–1. Plants were sampled on 14, 21, and 28 days after transplant (DAT). Compared to plants without the biostimulant or VAFs that progressively exhibited severe tipburn, plants with either the biostimulant (at 0.5 mL⋅L–1) or VAFs had similar tipburn reduction and shoot fresh mass on 21 and 28 DAT. Without VAFs, increasing the biostimulant concentration from 0 to 0.5 mL⋅L–1 reduced the tipburn rating and the number of tipburn-affected leaves by 96% and 94%, respectively, on 21 DAT and by 75% and 71%, respectively, on 28 DAT. Compared to no VAFs, VAFs eliminated or minimized tipburn throughout, regardless of the biostimulant. Increasing the biostimulant concentration from 0 to 0.25 mL⋅L–1 did not affect shoot fresh mass, whereas increasing it from 0 to 0.5 mL⋅L–1 decreased it by 26% to 32% on 14 and 21 DAT. Compared to no VAFs, VAFs generally did not affect plant growth, except that they decreased shoot fresh mass and total leaf number by 25% and 11% at the biostimulant concentration of 0.5 mL⋅L–1 on 21 DAT. However, neither the biostimulant at any concentration nor VAFs affected shoot fresh mass on 28 DAT. We conclude that the calcium-mobilizing biostimulant is as effective as VAFs at tipburn control of hydroponic lettuce in summer greenhouse environments where VAFs may be undesirable, and that the biostimulant mitigates tipburn without incurring any yield penalty at final harvest.

Controlled environment agriculture will play an important role in feeding the increasing world population as urbanization is expanding, and arable land is decreasing. Higher yields will help offset the initial high cost for building hydroponic production facilities. Beneficial bacterial endophytes have been receiving more attention in sustainable agriculture practices because they can promote plant growth, enhance nutrient uptake, and inhibit pathogen growth. Bok Choy (Brassica rapa subsp. chinensis) is a cruciferous vegetable that's often used in Asian cooking. It is a nutrient-dense vegetable high in fiber, vitamins A, C, K, calcium and vitamin B6. The entire Bok Choy plant is edible, including the leaves, stalks, and flowers. Initially, seven bacterial endophytes from our bacterial endophyte library were chosen to test plant growth promotion in two Bok Choy cultivars (Wan Wan Qing and White Stem) in pots with clay pebble under controlled environmental conditions. The results showed that bacterial endophytes (IALR1786 and IALR1368) significantly increased shoot fresh weight of cv. White Stem by 26.9% and 20.8%, respectively. Bacterial endophytes (IALR1368, IALR1629, IALR1422 and IALR1786) significantly increased shoot fresh weight of cv. Wan Wan Qing by 44.7%, 34.3%, 26.1%, and 22.0%, respectively. Then, the 3 best bacterial endophytes (IALR1368, IALR1629, and IALR1786) were chosen to further test in pots with clay pebble, as well as in nutrient film technique (NFT) units. In pots with clay pebble, IALR1629 increased shoot fresh weight of cv. White Stem by 13.5% but not significantly. IALR1786 significantly increased root fresh weight of cv. White Stem by 25.9%. Similar results were obtained in cv. Wan Wan Qing. In NFT units, IALR1786 significantly increased shoot fresh weight and root dry weight of cv. White Stem by 23.3% and 33.3%, respectively. All 3 bacterial endophytes significantly increased shoot fresh weight of cv. Wan Wan Qing by from 19.1% to 41.8%. IALR1786 also significantly enhanced root dry weight of cv. Wan Wan Qing by 30.8%. These bacterial endophytes will be identified using 16S sequencing and tested with other cultivars. In Summary, IALR1786 performs best and consistently achieves growth promotion in two different cultivars under different conditions.

Rising global temperatures are contributing to increased Urban heating affecting human well-being and ecosystems. Vegetation can help mitigate heat by providing shade and evaporative cooling. This study evaluates the cooling potential of two ornamental vines, Vitis × californica × vinifera ‘Rogers Red’ and Lonicera x heckrottii ‘Goldflame’ (goldflame honeysuckle), grown under different volumetric water content (VWC) regimes. The vines were grown on trellises in a greenhouse setting, with substrate VWC maintained at 0.15, 0.25, or 0.35 m³·m⁻³ for two months. A total of 12 vines per species were grown using an automated irrigation system. Canopy and background temperatures were measured using a FLIR thermal camera. Results showed that water stress impaired canopy growth in Rogers Red, whereas no significant effect was observed in the honeysuckle. In Rogers Red, lower VWC (0.15 m³·m⁻³) reduced leaf number, specific leaf area, and dry biomass, while honeysuckle exhibited consistent growth across all treatments. SPAD, NDVI, photosynthetic rate, and net assimilation rate did not differ significantly across treatments for either species. The higher cooling potential of Rogers Red compared to honeysuckle was attributed to its larger leaf size. Both vines demonstrated evaporative cooling potential, as indicated by lower canopy temperatures relative to the background temperature. However, Rogers Red exhibited significantly greater cooling potential at 0.35 m³·m⁻³ VWC, whereas honeysuckle maintained a similar cooling effect across all treatments due to its similar canopy area. These findings suggest that ornamental vines can provide cooling benefits however species selection can make a difference. Incorporating vine covers in urban areas can help in mitigating urban heat as cities continue to warm due to climate change.

Indoor vertical farms can provide local, fresh, and nutritious food to densely populated urban regions as an alternative approach to food production. They enable growers to precisely adjust cardinal environmental factors, including CO2, per crop requirements to enhance growth and nutritional quality. As the substrate of photosynthesis, CO2 enrichment can enhance crop growth; however, how crops respond to sequential CO2 changes is not yet well understood. In a randomized complete block design, we studied how pre- and/or post-transplant CO2 concentration influenced lettuce growth. Lettuce ‘Rex’ and ‘Rouxai’ were grown from seed in four growth chambers with CO2 concentrations set randomly at 400, 800, 1200, and 1600 µmol·mol−1, under the same photoperiod of 24 h, photosynthetic photon flux density of 180 µmol·m−2·s−1 (blue:green:red = 20:40:120), temperature of 22 °C, and relative humidity of 60%. On day 11, biomass and morphological data on seedlings were collected while three additional uniform seedlings per chamber per cultivar were transplanted in hydroponic units in each of the four growth chambers, creating 16 sequential CO2 treatments. On day 28, biomass and morphological data were collected on mature plants. Preliminary data showed that pre-transplant CO2 enrichment from 400 to 1600 µmol·mol−1 increased seedling shoot fresh and dry mass of ‘Rex’ by 53% and 37%, respectively. In contrast, pre-transplant CO2 enrichment from 400 to 1200 µmol·mol−1 maximally increased shoot fresh and dry mass of ‘Rouxai’ by 81% and 122%, respectively. In mature plants, pre-transplant CO2 enrichment did not influence final ‘Rex’ biomass. In contrast, pre-transplant CO2 enrichment from 400 to 1200 µmol·mol−1 increased final shoot fresh mass of ‘Rouxai’ by 25%, whereas enrichment from 400 to 800 µmol·mol−1 saturated the increase in final shoot dry mass by 22%. Post-transplant CO2 enrichment had greater influence on final biomass of both cultivars than pre-transplant CO2 enrichment. Post-transplant CO2 enrichment from 400 to 1200 µmol·mol−1 saturated the increase in final biomass by 22% to 32% in ‘Rex’ and by 58% to 60% in ‘Rouxai’. Final leaf number, length, and coloration were generally unaffected by pre- or post-transplant CO2 enrichment. In all cases, there was no interaction between pre- and post-transplant CO2 concentration. We conclude that pre- and/or post-transplant CO2 enrichment independently influenced lettuce growth, with no CO2 acclimation. Post-transplant CO2 enrichment determined final biomass, with 1200 µmol·mol−1 being the saturation point. Keywords: carbon dioxide, controlled environment agriculture (CEA), indoor vertical farming, elevated CO2 concentration, growth chamber, whole-plant photosynthesis

Microgreens are increasingly cultivated indoors using artificial lighting, which can be energy-intensive and depending on the species, can have varying effects on yield, commercial quality and nutritional profile. Understanding how light conditions influence plant physiological processes, including growth, phytochemical composition, and nutrient accumulation, is essential for optimizing indoor farming systems. Previous studies indicate that a light intensity of 300 µmol/m²/s enhances growth in microgreens, increasing dry weight and phytochemical content. Extending photoperiods with lower photosynthetic photon flux density (PPFD) has been proposed as a strategy to improve efficiency and plant biomass accumulation under controlled environment. Some photosynthetically active pigments may also be influenced by light manipulation. Carotenoids, a group of pigments that are beneficial to human health, are known to be protective of the photosynthetic system in plants, by regulating the flow of energy and mediating the damage caused by excess light absorption. Continuous lighting can be used to reduce energy costs in microgreen production; however, this may exceed species-specific tolerance thresholds, causing physiological stress. Nevertheless, there is limited information on the effect of continuous lighting on microgreens. To this purpose, a study was conducted in the spring of 2024, at the Penn State greenhouse facilities. We assessed the growth and nutritional responses of pea, radish, and sunflower microgreens under a factorial combination of 16- and 24-hour photoperiods and 150 or 300 µmol/m²/s light intensity. Photoperiod and light intensity impacted all three species of microgreens. Yield was highest under a 24-hour photoperiod at 150 µmol/m²/s. Dry matter content was unaffected by photoperiod but was highest at 300 µmol/m²/s. Regarding phytochemical content, carotenoids increased under continuous lighting and improved at 300 µmol/m²/s. Total antioxidant levels were higher at 300 µmol/m²/s compared to 150 µmol/m²/s. On the other hand, nitrate content increased under shorter photoperiods and lower light intensity, a trend also observed for total nitrogen, and iron concentration at 16-hour photoperiod and 150 µmol/m²/s. These findings indicate that all three microgreen species tested tolerate continuous lighting with positive or no effects on yield and nutritional quality, suggesting that light intensity and continuous lighting can be used in controlled environment systems to enhance the commercial quality and nutritional profile of microgreens.

Microgreens are emerging as a culinary novelty ingredient, with rich nutritional content and fresh taste. It can be produced within just a few weeks and is becoming popular among chefs and health-conscious consumers. Cold stress is one of the abiotic stresses, it may induce the accumulation of phytochemical properties in plants. This study investigated the effects of short-term, pre-harvest cold treatment on the nutritional contents of microgreens. Four microgreens including buckwheat, pea, sunflower and watercress, were grown in a growth chamber maintained at a constant temperature of 25°C. The photoperiod was set for a 15-hour light cycle. We treated these four microgreens with a short-term treatment including control and cold treatment at 4°C for 24h before harvesting. The results showed that shoot length, stem diameter, and shoot dry weight in four microgreen species were not affected by cold treatment compared to the control. But cold treatment increased the fresh weight of watercress and the SPAD values in pea and sunflower. Cold treatment significantly affected soluble sugar content. Specifically, it increased fructose, glucose, and sucrose contents in pea microgreen compared to the control. In sunflower microgreen, it improved fructose and glucose content by 65% and 78%, respectively, but had no effect on sucrose levels. Buckwheat microgreen under short-term cold treatment showed increased sucrose content, while fructose and glucose levels remained unchanged. In watercress microgreen, short-term cold treatment increased fructose content by 39% but decreased glucose content by 29%. These findings suggest that buckwheat, pea, sunflower, and watercress microgreens have different responses to a 24h short-term cold treatment regarding plant growth and specific phytochemical contents. While this treatment did not have a negative effect on the yield of the four microgreens, it influenced their flavor by significantly increasing fructose, glucose, and sucrose levels. Given the small space required for a microgreen tray, a short-term 4°C cold treatment is easily achievable in refrigerators. This innovative pre-harvest cold treatment presents an accessible method for enhancing the flavor and nutritional quality of microgreens. Future research will explore the impact of short-term cold treatment on other phytochemicals in microgreens.

With growing consumer interest in health-promoting diets, microgreens have gained importance as nutrient-rich and functional leafy greens. These crops are increasingly grown indoors under LED lighting and the manipulation of light quality has been identified as a critical factor influencing plant growth, yield, and nutritional quality. Blue and red LED are both considered critical for plant growth, have high photon efficiency and can be readily absorbed and utilized by plants. However, each wavelength has different effects on the plant physiology and metabolism and there is a need to understand how their combination in different proportions may affect microgreens yield, morphology and nutritional quality. Therefore, we conducted a study aimed at evaluating the effects of different combinations of blue and red LED light on the yield and nutritional composition of radish and broccoli microgreens. Microgreens were grown in a walk-in growth chamber under a 14-hour photoperiod and six LED treatments (%): 100 white, 100 red, 100 blue, and blue: red ratios of 50:50, 25:75, and 75:25. The average photosynthetic photon flux density was 165 μmol m−2 s−1. Radish and broccoli were harvested after 7 and 8 days, respectively. Microgreens grown under 100% blue, red, and white LED light showed higher shoot height than those grown under mixed blue:red treatments, with 100% blue producing the tallest shoots. Dry biomass accumulation differed among treatments, with 100% blue LED light resulting in the lowest dry biomass. At the phytochemical level, antioxidant activity showed to be highest under 100% blue light, with a 16.3% increase across both species, while 100% red resulted in the lowest levels. The mineral composition was also affected by LED treatments, as microgreens grown under blue: red 50:50, 25:75, and 75:25 treatments resulted in the highest iron concentrations, averaging 10.4% higher compared to monochromatic red and blue light or to broad-spectrum white light. These findings are consistent with previous studies indicating that blue light enhances secondary metabolite accumulation and that combined red and blue light influences mineral uptake, highlighting the importance of light optimization for the commercial quality of microgreens grown in controlled environment.

Microgreens have become popular due to their high nutritional value, quick production time, and versatile culinary applications. Color has been known to influence consumer purchasing habits but can also inform consumers perception of the nutritional quality. To improve the economic feasibility of controlled environment microgreen production, altering light intensity can be a tool to achieve the desired color and aesthetic profile of microgreens, improve yield, and increase nutritional quality. The objective of this research was to determine the effect of light intensity on the growth, color, and nutritional quality of ‘Red Rambo’ and ‘Daikon’ radish (Raphanus sativas) and ‘KX-1’ and ‘Toscano’ kale (Brassica oleracea), and the subsequent effect on consumer preference and perception of nutritional quality. Radish cultivars were grown for 7 days and Kale cultivars were grown for 14 days in 28 x 28 cm trays filled with a peat-based substrate, irrigated with 12N-1.8P-13.4K fertilizer at 100 ppm N supplemented with 15 ppm MgSO4 in reach-in growth chambers at 22 °C. Light intensities of 175 and 575 µmol·m−2·s−1 at a 16-h photoperiod were provided with broad-spectrum white LEDs. At harvest, growth and nutritional quality were quantified, and representative photographs were taken of each treatment to assess plant color. Photographs were then used in a survey of a representative population of the state of Tennessee made up of 821 participants. Consumers perceived higher nutritional content in the green ‘Daikon’ radish and ‘Toscano’ kale yet dark purple ‘Red Rambo’ radish and ‘KX-1’ kale, achieved with high intensity lighting, ranked higher for overall liking. These results were used in conjunction with appearance and nutritional quality data to assess consumer accuracy in identifying nutritional quality. Thus, the impact of light intensity on radish and kale microgreen appearance and nutritional quality can be linked to consumer perceptions to create effective production and marketing strategies for producers.

While recommendations for optimal daily light integral (DLI) exist for numerous food crops grown in controlled environments, this is not the case for spring radish (Raphanus raphanistrum subsp. sativus. This experiment set out to quantify the effect of DLI on growth of spring radishes cultivated in ebb-and-flood hydroponic systems. Seeds of two spring radish cultivars, ‘Red Castle’ and ‘Crunchy King’, were sown into separate 72-cell commercial plug trays filled with a soilless peat-based substrate and placed into one of five ebb-and-flood irrigation systems in a climate controlled greenhouse. To create the DLI treatments, frames were constructed over each flood table and commercial shade cloth was installed to create five differing levels of DLI; ‘very low’ (≤ 2.0 mol·m–2·d–1), ‘low’ (2.0–5.9 mol·m–2·d–1) ‘medium’ (6.0–9.9 mol·m–2·d–1), ‘high’ (10.0–14.9 mol·m–2·d–1) and ‘very high’ (≥ 15.0 mol·m–2·d–1). One frame was left uncovered to create the ‘very high’ treatment. Supplemental light was provided by high pressure sodium lamps with a target intensity of 150 µmol·m2·s1 and were operated to provide a 16-h photoperiod throughout the study. Samples were subirrigated once daily for the first 14-d of the experiment, with an additional irrigation added during the final 14-d. A complete, balanced, water-soluble fertilizer providing 200 ppm nitrogen was supplied at every irrigation. 28-d after seeding, samples were harvested and data collected. Radishes on the edges of the trays were discarded and a block of 10 samples was selected to ensure uniformity. The diameter of the hypocotyl in addition to fresh and dry mass were recorded. Data was additionally taken on shoots, including the number of mature leaves, length of the longest leaf, and fresh and dry mass of excised tissues. Finally, relative chlorophyll concentration was measured using a soil-plant analysis development (SPAD) meter. Results indicate that hypocotyl diameter of spring radish is maximized at 15.2 mol·m–2·d–1 with fresh and dry mass positively correlating strongly with diameter. Additionally, the number of mature leaves increased by up to 2 leaves up to 10.0 mol·m–2·d–1 but not beyond, while leaf length and SPAD decrease beyond DLIs of 14 mol·m–2·d–1. Shoot fresh and dry mass were greatest at DLIs of 14.0-17.0 mol·m–2·d–1. This study provides valuable information for producers interested in incorporating spring radish in their operation, and to those looking to maximize yield and overall plant quality.

Temperature moderates various plant physiological processes, in turn affecting the overall rate of development, and is utilized in controlled environment food crop production to influence product yield, quality, and to manage crop scheduling. Root crops, including spring radish (Raphanus raphanistrum subsp. sativus), currently represent a niche segment within commercial controlled environment food production. The lack of reliable cultural information has been noted as a reason producers may be hesitant to introduce new crops to their operations. To expand commercial adoption, this study aims to quantify the effect of air temperature on spring radish development, specifically determining minimum temperature (Tmin), optimum temperature (Topt), maximum temperature (Tmax), and linear temperature range. Two cultivars of spring radish, ‘Crunchy King’ and ‘Red Castle’, were grown in separate climate-controlled environmental growth chambers providing continuous target air temperatures of 8, 13, 18, 23, 28, and 33 °C, a range of 25 degrees. Samples were grown in commercial 72-cell plug trays filled with peat-based substrate and fertigated with custom ebb-and-flood systems providing 200 ppm nitrogen at every irrigation. A 16-h photoperiod was provided, with a target light intensity of 200 µmol·m2·s1. Samples were harvested 28-d after seeding and data collected, including diameter of the hypocotyl, number of mature leaves, and length of the longest leaf. A measure of relative chlorophyll concentration was recorded, and finally, fresh and dry mass of the hypocotyls and shoot tissue was measured. Results indicate that hypocotyl diameter increases linearly from Tmin at 3 °C, reaching a maximum at Topt of 23 °C. Beyond this point, diameter is reduced, with Tmax occurring at 35 °C. Hypocotyl fresh and dry mass followed similar patterns, correlating strongly with diameter. Leaf number was observed to be maximized at 18 °C, with no significant increase beyond this temperature. Leaf length was maximized at 23 °C and decreased with increasing temperature. Average daily temperature was observed to have no significant effect on relative chlorophyll concentration. Notably, we found that there was no significant difference between the two cultivars in their response to air temperature. The results of this study offer important guidance to producers interested in introducing spring radish into their operation, while maximizing crop quality and yield.

Lettuce (Lactuca sativa) is an economically important leafy green widely cultivated in greenhouses, yet the interaction between cultivar and air temperature remains poorly characterized for many of the cultivars currently marketed for controlled environment (CEA) production. Even in climate-controlled greenhouses, internal air temperatures can exceed general recommendations, leading to bolting, excessive stem elongation, bitter flavors, and reduced yields. This study aimed to generate benchmark yield and morphological data for 20 lettuce cultivars grown hydroponically in a greenhouse during a fall (20 °C mean air temperature) and summer (28 °C mean air temperature) production cycle, with harvests at 9 (juvenile stage) and 21 (mature stage) days after transplanting (DAT). Lettuce cultivars were grown in a common nutrient film technique (NFT) system with average pH and electrical conductivity (EC) of 5.6 and 1.5 dS·m−1, greenhouse day and night air temperature setpoints of 21 °C and 18 °C, and a target average daily light integral (DLI) of 17 mol·m−2·d−1. The experiment was set up as a randomized complete block design with two blocks. Depending on the cultivar, air temperature, and harvest time, lettuce shoot fresh mass (SFM) and projected canopy area (PCA) were significantly different. However, regardless of the cultivar or harvest time, yield (kg·m−2·year−1) was always greater at 20 °C than 28 °C. Supraoptimal air temperatures increased stem and leaf elongation, potentially improving light interception and SFM per plant early in production, but required more area per plant to grow without significantly overlapping with neighboring plants, thus reducing planting density and yield potential. Supraoptimal air temperatures decreased specific leaf area (SLA), resulting in thicker leaf lamina. Chlorophyll concentration was more affected by cultivar than harvest date or air temperature. Benchmarking greenhouse lettuce yield and morphology across cultivars and seasons offers growers a valuable tool to reliably assess productivity, select appropriate cultivars, and adjust planting density. These insights also inform breeding efforts to improve the yield from CEA systems, with particular attention to plant architecture and leaf traits suitable for automated harvesting and packaging in greenhouse systems.

Hydroponics, the cultivation technique involving soilless media, offer a potential solution to alleviate food insecurity. For this study, six tabletop hydroponic systems were evaluated for their suitability for Romaine lettuce (Lactuca sativa) cultivation. The systems included Ahopegarden, IDOO, Fulsren, LetPot, MUFGA, and Rainpoint. The experiment was set up as a completely randomized design (CRD), with 6 treatments x 3 replicates. The lettuce seeds were sown in horticultural sponges and suspended in nutrient solutions. Following germination, plant growth parameters were recorded every other day during the experimental period. The electrical conductivity (EC), total dissolved solids (TDS), pH, and dissolved oxygen (DO) were monitored weekly for each nutrient solution. The quality and quantity of the lighting systems were measured as correlated color temperature (CCT), photosynthetic active radiation (PAR), and photosynthetic photon flux density (PPFD). The data collected was subjected to analysis of variance (ANOVA). The results showed that the EC, TDS, DO, and pH did not vary greatly among the systems, except for Letpot that showed significantly lower (p