ASHS 2025 Conference

Weed overgrowth in high-value crops like onions remains a major challenge due to labor costs, herbicide resistance, and environmental concerns. Robotic laser-based weed control offers a precise, chemical-free alternative capable of targeting individual weeds while protecting crop health and the environment. This research introduces the application of a Clavel-based delta parallel robot for precision weed elimination using a high-power diode blue light laser. The delta robot employed in this study features three degrees of freedom and is capable of achieving maximum accelerations up to 20 m/s². It consists of aluminum proximal arms connected to servo motors and carbon fiber distal arms, reducing weight and enhancing agility. These servo motors are housed within a top base constructed from ABS 3D printed parts. Movement calculations and inverse kinematics are managed by an embedded ARM Cortex-M3 controller integrated with the servo motors. A 450 nm, 10W diode laser serves as the robot's end-effector, actuated using the Transistor-transistor logic (TTL) signals. Both robot movements and laser activation are simultaneously controlled through an external Arduino Mega 2560 microcontroller, leveraging a custom-developed C library to ensure workspace safety and precision. Experiments conducted to assess positional accuracy involved 100 trials, resulting in a mean radial positional error of 0.83 mm. Further experiments measured laser exposure time and stand-off distance. The results showed complete weed destruction in less than 6 seconds at distances of up to 100 mm. These results support the robot's effectiveness in targeted weed management for precision agriculture.

The use of pre-emergence herbicides under plastic mulch is an effective strategy for weed control in plasticulture beds in vegetable production systems. S-metolachlor is a pre-emergence herbicide labeled for application in soil prior to laying plastic mulch in tomato production in Florida. However, the risk of crop injury has limited its adoption in plasticulture systems, highlighting the need for crop-safe herbicide application approaches. This study aimed to evaluate the potential of herbicide safeners including chemical seed treatments and activated charcoal in mitigating tomato transplant injury from herbicides such as S-metolachlor. A greenhouse experiment was conducted at the Southwest Florida Research and Education Center (SWFREC) in Immokalee, FL, across two trials: March–June (Trial I) and August–November (Trial II) of 2024. Field soil was collected and used in pots for both trials. Treatments included tomato seed pre-treatments with benoxacor or fenclorim, and transplant root treatments with activated charcoal applied either as a root dip or poured into planting holes. All treated transplants and non-treated controls were grown in S-metolachlor-treated soil. Seed pre-treatment with benoxacor or fenclorim reduced crop injury by over 63% compared to non-treated controls. Activated charcoal applied to transplant roots reduced injury by 40–70% in Trial I and by over 70% in Trial II. Chlorophyll content was consistently higher in safener-treated plants, with activated charcoal increasing levels by more than 16% at 2 weeks after transplanting (WAT) and by 11–20% at 6-WAT. Similarly, benoxacor and fenclorim treatments improved chlorophyll content by 12–19% at 6-WAT. Root biomass in non-treated transplants was reduced by 56–70% due to S-metolachlor exposure. In contrast, both activated charcoal and seed-applied safeners helped preserve root biomass, with benoxacor and fenclorim reducing root weight loss by 65–70% compared to untreated controls. Overall, the results demonstrate that both seed-applied (benoxacor, fenclorim) and root-applied (activated charcoal) safeners are effective in mitigating S-metolachlor injury in tomato transplants and may offer viable strategies for enhancing crop safety in plasticulture-based vegetable production.

A successful Christmas tree production requires a good and effective weed management program. Most common weed control practices in Christmas tree production involve mechanical mowing and the application of chemical herbicides. Repeated applications of the existing herbicide options have resulted in the development of herbicide-resistant weed species. It is also important to test newer herbicides to expand the list of herbicide options. Hence the objectives of this research were to evaluate labeled (1X) and double (2X) rates of newer herbicides for weed control efficacy and for phytotoxicity in Fraser fir variety of Christmas tree. Field experiments were conducted in summer and fall 2024 at a commercial Christmas tree farm located at Gobles, MI. Christmas tree variety chosen for the experiment was four-year-old Fraser fir (Abies fraseri). The herbicide treatments included glyphosate trifloxysulfuron-sodium, glyphosate flumetsulam, glyphosate flumetsulam clopyralid, glyphosate chlorimuron, glyphosate cloransulam, glyphosate topramezone, glyphosate flumioxazin. Out of these treatments, the last two were considered as industry commercial standards. The control treatment included only glyphosate. All herbicides were tested for their labeled (1X) rates and double (2X) rates. Treatments were applied before bud break as directed application towards the lower 18 inches of the trees with a carbon dioxide backpack sprayer calibrated at 27 gallons per acre output. The experiments were complete randomized block design with four replications of each treatment. Data were collected at 1, 2, 3, and 4 months after treatment (MAT) which included visual estimation of weed control based on a scale of 0% to 100% (0% meaning no weed control and 100% meaning complete weed control) and phytotoxicity based on a scale of 0% to 100% (0% meaning no plant injury and 100% meaning complete death of a branch). Dominant weed species were recorded as well. Data were analyzed by ANOVA in SAS 9.4 and means were separated out by Tukey’s HSD test. Results showed that 1X rates of glyphosate chlorimuron and glyphosate trifloxysulfuron-sodium provided 70%-90% weed control till 4 MAT and their 2X rates showed no significant injuries to the Fraser fir variety till 4 months. Hence, glyphosate chlorimuron and glyphosate trifloxysulfuron-sodium can be additional options for Christmas tree growers for weed control in future. However, long-term multiple year studies are still required based on different herbicidal rates and on different varieties of Christmas trees for expansion of these herbicide labels.

Specialty and organic crop weed management strategies are challenging due to limited chemical control products with good efficacy that are cost effective. The need for new bioherbicide modes of action has become increasingly urgent in modern agriculture as most bioherbicides have nonspecific modes of action with no systemic activity. Introducing new bioherbicides that are also registered as organic is essential to diversify weed control strategies. By fostering innovations in bioherbicide development agricultural systems can be more environmentally friendly by preserving ecosystems while maintaining the ability to feed a growing global population. Manuka oil is derived from the leaves and branches of the Manuka tree (Leptospermum scoparium) and contains β-triketones. The β-triketone rich fraction contains leptospermone that inhibits a key enzyme, p-hydroxyphenylpyruvate dioxygenase (HPPD). This process directly inhibits carotenoid biosynthesis, upstream in the biochemical pathway, which causes damage to the photosynthetic apparatus and leads to bleaching of the leaf tissue which eventually kills the plant. There were three studies that examined the efficacy of β-triketone extract against Lolium multiflorum, Amaranthus retroflexus, and Abutilon theophrasti. The studies were 1) pre-emergence β-triketone extract ranging from 0 to 2.5 mg ml-1, 2) post-emergence β-triketone extract ranging from 0 to 6%, and 3) post-emergence β-triketone extract at 0.5 and 2.0% with five different organic adjuvants. In the pre-emergence study, there were significant differences between the β-triketone extract treatments and 100% weed control down to 0.625 mg ml-1. In the post-emergence study, there was significant decreases in weed height and fresh and dry mass when compared to the control treatment. However, the adjuvants did not have any effect on weed height and fresh and dry mass. Thus, there is significant evidence that commercializing a water soluble β-triketones enriched extract of Manuka oil can be an effective weed control, especially as a pre-emergent bioherbicide for specialty and organic crop production.

Advances in crop lighting using light-emitting diodes (LEDs) have enabled the application of targeted light spectra to elicit specific plant responses during cultivation. However, there is a lack of comparative studies evaluating the effects of different spectral regions within the same crop. We comprehensively quantified how various light spectra, ranging from ultraviolet-B to red, affect plant growth and the accumulation of beneficial phytochemicals, including anthocyanins, phenolics, and ascorbic acid, in red leaf lettuce (Lactuca sativa) cultivars ‘Red Salad Bowl’ and ‘Rouxai’. Plants were grown under a background white LED light of 200 µmol m-2 s-1 for 16 hours per day (control), and supplemented with red (peak at 659 nm), blue (444 nm), violet (404 nm), ultraviolet-A (UVA; 368 nm) radiation at 60 µmol m-2 s-1, or ultraviolet-B (UVB; 309 nm) radiation at 3 µmol m-2 s-1 during the last 7 days of a 28-day production period (end-of-production stage, EOP). For both lettuce cultivars, red, blue and UVB treatments significantly enhanced leaf anthocyanin content compared to the control, with UVB being the most effective despite its low application dosage, followed by the blue and red light treatments. UVB radiation significantly increased total phenolic content in both cultivars (by 80%–99.1% compared to the control), while blue light treatment increased total phenolics by 31.4% in ‘Red Salad Bowl’ only. However, supplemental UVB radiation did not affect total ascorbic acid in either cultivar; the other EOP treatments (red to UVA) increased total ascorbic acid by 19%–35% in ‘Red Salad Bowl’ but had no significant effects in ‘Rouxai’. Notably, crop yield under the UVB treatment was the lowest in both cultivars, with 8.9%–49% lower shoot fresh weight compared to other treatments. In contrast, the violet light treatment resulted in the highest leaf area and shoot biomass in both lettuce cultivars, although it was not effective in enhancing anthocyanins and total phenolics. Our result indicated that there is often a tradeoff between nutritional quality and crop yield, and specific light spectra can be strategically used to enhance nutritional quality or biomass. Low-intensity UVB was the most effective at maximizing anthocyanins and total phenolics, followed by blue light, while supplemental violet light most significantly enhanced lettuce leaf expansion and biomass compared to other light spectra.

Because indoor vertical farms require sole-source lighting, light spectra that maximize desired crop attributes are pivotal. Although previous research has revealed growth responses of leafy greens to blue (B), red (R), and far-red (FR) light, the combined effects of the FR fraction [FR:(R FR)] and the B photon flux density (PFD) on biomass accumulation and nutrient uptake in lettuce (Lactuca sativa) remain unclear. We conducted an indoor hydroponic experiment on red-leaf lettuce ‘Rouxai’ using a randomized complete block design (with four blocks) to investigate how the FR fraction and the B PFD influenced growth, morphology, coloration, and nutrient uptake. The first two blocks and the second two blocks were performed over time. From day 0 to 11, we grew plants from seed in rockwool indoors under continuous warm-white light-emitting diodes (LEDs), with a mean photosynthetic PFD of 180 μmol∙m−2∙s−1. From day 11 to 28, we grew plants in hydroponic units under nine continuous LED lighting treatments, which were combinations of three FR fractions (0%, 25%, and 40%) and three B PFDs (30, 60, and 90 μmol∙m−2∙s−1). The mean air temperature and humidity were 23.6 °C and 62.5%, respectively, in the first two blocks, and 25.0 °C and 20.0%, respectively, for the second two blocks. Foliage coloration was measured on day 26, while growth and morphology data were collected on day 28. Increasing the FR fraction from 0% to 40% increased shoot biomass (by 24%–78%), leaf length (by 21%–41%), and plant diameter (by 17%–32%) across the three B PFDs. Decreasing the B PFD from 90 to 30 μmol∙m−2∙s−1 also increased shoot biomass (by 24%–50%) across the three FR fractions and increased plant diameter (by 9%–11%) at FR fractions of 0% and 25%, but not 40%. Despite some interactions, the FR fraction and the B PFD mostly influenced plant growth and morphology independently. Interestingly, chlorophyll index and coloration were largely unaffected by light spectra, indicating that the lowest B PFD might have saturated pigmentation. Increasing the FR fraction or decreasing the B PFD generally increased total nitrogen uptake to support growth promotion, but decreased tissue nutrient concentrations of nitrogen and potassium, possibly due to the dilution effect. We conclude that increasing the FR fraction (from 0% to 40%) or decreasing the B PFD (from 90 to 30 μmol∙m−2∙s−1) generally increased shoot biomass, leaf expansion, and nitrogen demand in indoor hydroponic lettuce ‘Rouxai’, without influencing foliage coloration.

Determining optimal cultivars and lighting conditions for teen-leaf lettuce in protected cultivation (Controlled Environment Agriculture, CEA) is critical to support the growing leafy greens industry segment. Teen-leaf lettuce is considered to be more mature than baby-leaf and less mature than head lettuce. It is typically harvested at 24-30 days. As teen-leaf lettuce is a relatively new part of the leafy greens industry segment, foundational research into environmental conditions and cultivars is currently lacking. The objective of this experiment is to observe a diverse set of lettuce cultivars growth in response to light intensity. This study provides insight into how different lettuce cultivars respond to varied light intensities and also highlights phenotypic traits to be evaluated to potentially further improve CEA-grown lettuce. Eight cultivars (Azirka, Danstar, Gladius, Ilema, Klee, Muir, Oscarade, Volcana) representing seven lettuce ‘sub-types’ (Crunchleaf, Romaine, Lollo, Salanova, Batavia, Oakleaf, Bibb) were evaluated under two different lighting conditions low DLI (targeting 10 mol m⁻² d⁻¹) and high DLI (targeting 20 mol m⁻² d⁻¹). Fourteen day old seedlings were planted in Deep Water Culture (DWC) systems with three repeated blocks under each lighting treatment. Seedlings were grown in the systems for an additional 21 days. Weekly destructive harvests took place between days 14 and 35 to establish growth curves for several measured parameters: fresh mass, dry weight, leaf count, growth index, and plant diameter for each plant. Cultivars Danstar and Muir had significantly higher fresh weight when grown under the higher light treatment. Higher light also significantly increased dry weight regardless of cultivar, however dry mass responsiveness varied between cultivars. Cultivars Danstar, Gladius, Muir, and Oscarade exhibited significantly higher dry weight when grown under the higher light treatment. Leaf number was not significantly affected by light, except for cultivar Ilema which had significantly more leaves when grown under the higher lighting treatment. The findings of this study provide insight into which cultivars are more shade tolerant and which are better suited for CEA production. Future research will further investigate the phenotypic traits present in these cultivars and identifying anatomical traits (such as stomatal density) that may be associated with higher crop performance, guiding future breeding efforts.

Maintaining optimal daily light integrals (DLI) and nutrient solution concentrations is essential for enhancing growth traits of leafy greens such as lettuce (Lactuca sativa L.) in greenhouse production systems. Research is needed to better understand the synergistic effect of supplemental lighting and nitrogen (N) concentrations on hydroponic lettuce production during seasons of low natural light. The objective of this study was to determine the effects of narrowband supplemental lighting treatments and nitrogen concentrations on the growth, yield, and physiological traits of lettuce cultivars in a nutrient film technique (NFT) hydroponic system. Three lettuce cultivars (cvs. Nancy, Salvius, and Thurinus) were grown in the fall of 2024 (Nov 13. to Dec 18.) and the winter of 2025 (Jan 29. to March 03.) under three light treatments including supplemental 80% red and 20% blue light (80R/20B); 80R, 10B, and 10% far red light (80R/10B/10FR); non-supplemental natural light (control) and two nitrogen concentrations (100 and 200 ppm N). Both light treatments supplemented a DLI of 6 mol.m-2.d-1. Supplemental lighting treatments had limited effects on the weekly net assimilation rate, averaging 11.124 and 10.130 µmol.m-2.s-1 versus 12.046 and 10.564 µmol.m-2.s-1 in the control treatments in fall and winter cycles, respectively. In fall with 200 ppm N, the 80R/20B and 80R/10B/10FR light treatments significantly increased the fresh yield by 90% and 45% respectively when compared to the control treatment. While in winter with 200 ppm N, these increases were only 10% and 1%, suggesting a relatively limited benefit of supplemental lighting during this season. With 100 ppm N during the winter cycle, compared with the non-supplemented light, 80R/20B and 80R/10B/10FR lights increased the yield by 58% and 30% respectively while contrasting results were observed with the light treatments with 100 ppm N in the fall cycle. Supplemental light in the fall cycle increased the average leaf area index (LAI) by 27% only when combined with 200 ppm N but not with 100 ppm. In contrast, in winter, supplemental light increased LAI by 11% only with 100 ppm N but not with 200 ppm N. Overall, the beneficial effect of supplemental lighting on the growth and yield traits was greater in fall when combined with 200 ppm N but was greater in winter when combined with 100 ppm N.

Successful cultivation of lettuce in indoor agriculture relies on precise control of environmental factors to optimize crop yields. However, some controlled environment facilities may lose control of humidity due to the net moisture input of transpiration from high-density lettuce overwhelming dehumidification and cooling systems. This study observed the effects of different lighting treatments and air velocities on lettuce at varying levels of humidity as a means of mitigating deleterious effects of elevated humidity. Romaine lettuce (Lactuca sativa, cv. Teton) was cultivated in three growth chambers under three different humidity levels (70%, 80%, and 90%). Each room contained three hydroponic trays setup up for ebb and flow, with one lighting treatment per tray: white light (W), white light supplemented with far red (WFR), and wide amber supplemented with far red (WA). Additionally, each tray contained a low and high velocity zone at 0.5 and 1 m/s respectively, delivered by a polyethylene tube attached to a duct fan. Average velocity ranged from 0.23–3.0 m/s, but no correlation between air velocity and any growth parameter was observed for any treatment. However, tipburn for all treatment combinations was either less severe or eliminated altogether. This can be attributed to the general improvements in plants’ transpiration rates as the air velocity increased. Increasing humidity enhanced growth parameters except for fresh mass, where 70% and 90% RH did not differ significantly but both outperformed 80% RH by 9%. For other metrics—height, head diameter, chlorophyll content, and dry mass—80% RH and 90% RH performed better than 70% RH but did not significantly differ. WA performed the best for all growth parameters, with 7.4% and 14% greater leaf area than W and WFR respectively. Compared to WA, WFR underperformed in most metrics despite also having far-red supplementation, indicating potentially more synergistic interactions of FR with amber wavelengths than blue or red wavelengths. Gas exchange results varied based on the treatments, but it was generally observed that photosynthetic rates were higher at higher air velocities and under WA. The results of this study indicate the effectiveness of air velocity levels up to 3.0 m/s at eliminating tipburn in lettuce up to 90% RH without causing additional stress responses. Further improvements can be achieved with WA supplemented with far-red, improving both morphological development and physiological processes even at higher humidity levels.

This study evaluated the growth, yield, and water use of four lettuce cultivars (Lactuca sativa L. cv. ‘Green Forest’ (GF), ‘New Red Fire’ (NRF), ‘Paris Island’ (PI), and ‘Rouxai’ (R)) cultivated in three different hydroponic system types: Deep-Water Culture (DWC), Nutrient Film Technique (NFT), and Vertical System (VS). Trials were conducted across three seasons (S1: Oct–Nov 2023; S2: Mar–Apr 2024; S3: Apr–May 2024) in a high tunnel at the Texas A

Better understanding of food production using in situ resources such as lunar regolith is necessary as we advance to establish an ongoing presence on the moon. The potential of lunar regolith to serve as a viable substrate for plant growth has yet to be studied. We investigated the feasibility of using lunar regolith for cultivation of two lettuce cultivars (‘Outredgeous’ and ‘Rex’) in two types of simulants, JSC-1A (lunar mare) and OPRH4W30 (lunar highlands), compared to inert substrates peat and rockwool, with and without a complete nutrient solution. The experiment was conducted under controlled conditions (200 µmol m-2 s-1, 25/22 °C, and 70% relative humidity) in a walk in growth chamber, assessing seed germination, seedling growth, and biomass accumulation over three consecutive plantings. In the first harvest, peat and rockwool with nutrient supplementation yielded the greatest fresh and dry mass, while regolith with deionized water severely stunted growth. Nutrient supplementation enhanced plant growth in regolith, with an 8.4-fold increase in shoot fresh weight and a 7.3-fold increase in leaf area for ‘Rex’ grown in JSC-1A compared to those grown with deionized water. Similar responses were observed in ‘Outredgeous’ and in the OPRH4W30 simulant. However, plant growth in simulants was substantially reduced, up to 13.5 times smaller, compared to rockwool and peat, even when supplemented with the same nutrient solution. However, growth in both regolith types with nutrient supplementation improved with subsequent plantings. Seed germination varied across substrates in initial planting, averaging 67% in OPRH4W30, 77% in the JSC-1A, and 88-93% in peat and rockwool, but increased to over 85% in both regoliths in the second and third plantings. These results highlight regolith’s potential to support crop growth with proper nutrient management strategies and recycling for lunar agriculture, underscoring the possibility for using in situ lunar resources for food production for long-term lunar habitation.

Controlled Environment Agriculture (CEA) is gaining momentum as a viable strategy for addressing food security in urban areas while mitigating the environmental pressures associated with conventional agriculture. However, the environmental sustainability of these systems remains under scrutiny due to their high energy and resource demands. This study presents a comprehensive Life Cycle Assessment (LCA) and operational scenario analysis of hydroponic lettuce production within a growth chamber using a nutrient film technique (NFT) system. By integrating experimental measurements, plant growth modeling, and LCA methodologies compliant with ISO 14040–14044 standards, the study evaluates environmental trade-offs under five different lighting scenarios ranging from 200 to 1000 µmol m⁻² s⁻¹ photosynthetic photon flux density (PPFD), while keeping temperature and CO₂ constant. A mechanistic plant growth model was utilized to simulate fresh biomass yield under varying PPFD conditions. Model predictions closely aligned with experimental data, yielding R² values of 0.95–0.98 for both fresh weight and leaf area across light scenarios. Water consumption was estimated by establishing linear relationships between plant biomass and evapotranspiration rates, while electricity usage for lighting and HVAC was continuously monitored using a Fluke 1735 Power Logger. Results indicated substantial increases in yield, water use, and energy consumption with increasing light intensity. For example, yields ranged from 1.69 kg at 200 PPFD to 14.06 kg at 1000 PPFD, while electricity usage increased from 257 to 361 kWh per growth cycle. The LCA adopted a cradle-to-gate system boundary and a functional unit of 1 kg fresh lettuce, covering inputs including lighting, climate control, water, nutrients, system materials, post-harvest processing, and transportation. Impact categories were assessed using ReCiPe 2016 midpoint (H) indicators: global warming potential (GWP100), terrestrial acidification potential (TAP), fossil fuel potential (FFP), freshwater and marine eutrophication potential (FEP, MEP), and water consumption potential (WCP). Environmental impacts showed strong inverse relationships with light intensity up to 600 PPFD, beyond which impacts plateaued. GWP100 decreased from 69.09 kg CO₂-eq at 200 PPFD to 12.87 kg CO₂-eq at 1000 PPFD, primarily due to increased yield efficiency. Across all scenarios, the lettuce production stage was the dominant contributor to environmental impacts, followed by system manufacturing, with minor contributions from post-harvest processes and waste management. Optimal light intensity for balancing yield and sustainability was identified between 400–600 PPFD. Notably, the integration of dynamic plant modeling enabled scenario-specific inventory estimation, enhancing the robustness of the LCA compared to conventional top-down methods.

Optimizing the light environment for indoor strawberry production is critical for ensuring high productivity and fruit quality. Short-day (SD) strawberries require SD conditions for flower induction. However, SD can also cause semi-dormancy symptoms that inhibit strawberry plant growth and production. Current strategies to address this challenge in SD strawberry production is extension of photoperiod to prevent semi-dormancy. This preliminary study investigated the effect of photoperiod adjustment and light quality modification by analyzing two SD strawberry cultivars ‘Earliglow’ and ‘Nyohou’ under three photoperiod treatments (SD, LD, or alternating SD/LD) with or without supplemental far-red (FR) treatments (56 % FR over total photon flux density, 400-750 nm). Plants under continuous SD conditions exhibited a typical semi-dormancy like morphology with shorter petioles and peduncles. Supplemental FR treatment significantly extended petiole and peduncle length, regardless of daylength. Strawberry total yield, percent marketable yield, and total number of fruit were improved in plants with supplemental FR treatment. Supplemental FR light treatment also increased soluble solid concentration (SSC, brix %) and SSC-to-TA ratio regardless of cultivar. No significant differences in leaf net photosynthetic rates were observed among photoperiod or FR treatments. The increase in productivity and fruit SSC was partly attributed to improved plant morphology under supplemental FR light, which enhanced photoassimilates allocation to fruit. Addition of FR light seems to be beneficial in indoor production of SD-type strawberry cultivars for preventing semi-dormancy and enhancing yield and fruit quality.

In the United States (U.S.), strawberries (Fragaria ×ananassa) are the most popular berry fruit with a value of $2.8B. To meet consumer demand for flavorful, fresh, local, and year-round strawberries, the industry is expanding into controlled environment (CE) production of day-neutral (everbearing) cultivars in greenhouses and indoor farms. Within CEs, growers can potentially improve flavor through the manipulation of environmental parameters such as temperature, light, vapor pressure deficit, and carbon dioxide concentration. The objectives of this study were to 1) quantify flavor related compounds of day-neutral cultivars in greenhouses; 2) determine how day and night temperatures influence fruit quality; and 3) develop a model to predict the cardinal temperatures of yield and flavor for each cultivar. Four cultivars, ‘Albion’, ‘Mara Des Bois’, ‘San Andreas’, and ‘Seascape’ were grown at day/night temperatures (12 h/12 h) of 15/7, 18/10, 21/13, 24/16, or 27/19 °C, under a 16-h photoperiod, and a target daily light integral of 15 mol·m–2·d–1. Berries were harvested twice weekly for three months and at harvest, yield, marketable yield, berry mass, and diameter. Berries were then cut into quarters, with ¼ being saved in a –80 °C freezer, and the other ¾ being used for destructive chemistry measurements. This included titratable acidity (TA), total soluble solids (TSS) content, pH, total anthocyanins, and the concentration and composition of flavor-related volatile organic compounds (VOCs). After 12 weeks of harvest, the highest TA was measured from berries harvested at 27/19 °C. ‘Albion’, and ‘Seascape’ harvested at 18/10 °C had the highest TSS, whereas the TSS of ‘Mara Des Bois’ and ‘San Andreas’ harvested at 15/7 °C was highest. The TSS/TA ratio was found to be correlated with day and night temperatures and a good indicator of consumer preference. Differences were also observed among cultivars and temperature treatments for anthocyanin and flavor-related VOCs. Our results collectively show that day and night temperatures influence the yield and flavor of strawberries.

Strawberry (Fragaria × ananassa) is one of the most popular fruits consumed in the United States, valued for its taste, nutritional benefits, and economic importance. Achieving year-round production in the United States has become essential to meet the growing consumer demand for fresh, locally grown strawberries. Controlled environment agriculture (CEA), including greenhouse and vertical farm-based productions, hold great promise for year-round strawberry production. A key factor in achieving year-round strawberry production is understanding the regulations of flowering. While genetic aspects of flowering in strawberries have been widely studied, the role of hormonal regulation remains relatively understudied. This experiment aims to characterize the hormonal regulations of flowering in the perpetual strawberry cultivars (‘Albion’ and ‘Seascape’). We investigated the flowering time and pattern of two perpetual strawberry cultivars grown from bare-root transplants under greenhouse conditions. Additionally, we used an untargeted hormonomics approach using ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS) at three key developmental stages: 3-leaf, runnering, and flowering. The cultivar variations in runnering and flowering were observed. ‘Albion’ showed flowering approximately eight weeks post-transplantation, whereas ‘Seascape’ primarily exhibited vegetative growth, characterized by minimal flowering and significantly higher runner production than ‘Albion’. The hormonomics analysis identified 102 hormone-related compounds in ESI mode, spanning several hormonal pathways such as cytokinins (CK), tryptophan (Trp) derivatives, gibberellins (GA), melatonin, jasmonic acid (JA), salicylic acid (SA), abscisic acid (ABA), auxins (IAA), and brassinosteroids (BR). CK was the most abundant group (27%), followed by Trp derivatives (23%) in both cultivars. Partial least squares–discriminant analysis (PLS-DA) showed that among the hormones, CK, GA, and precursor of JA and IAA are primary discriminants between two cultivars and different developmental stages. In the seascape, the accumulations of CK (N6-benzyladenine-7-glucoside, thidiazuron) and GA (gibberellin A5) increased as the developmental stage progressed. Conversely, accumulation of cis-12-oxo-phytodienoic acid (OPOD), a precursor for the JA biosynthesis, increased in the ‘Albion’ as developmental stages progressed. This obtained data reveals a complex interaction of phytohormones involved in the regulation of strawberry flowering. CK and GA accumulation are favorable for vegetative growth, while JA may play a significant role in strawberry flowering. These findings improve our understanding of phytohormonal regulation of perpetual strawberry flowering and could lead to effective strategies for managing flowering time and sustainable year-round strawberry production in CEA.

Deficit irrigation presents significant potential for water savings, making it increasingly popular worldwide as a method to reduce freshwater consumption over time. The low water productivity of strawberries is often attributed to excessive water use and the limited ability of cultivars to optimize fruit set and yield in hydroponic systems. This study aimed to evaluate three management strategies—cultivar selection, irrigation frequency, and potassium silicate application frequency—on the growth, water conservation, and production efficiency of hydroponically grown strawberries. The experiment followed a split-plot design, with 'Albion' and 'Chandler' cultivars as the main plot treatments, and a factorial arrangement of irrigation frequency (once/day vs. twice/day) and potassium silicate (AgSil16H) application frequency (6, 9, 12, 15 weeks) randomly assigned to the subplots. Results indicated that foliar application of potassium silicate enhanced plant vigor and contributed to water conservation in hydroponically grown strawberries compared to the control. Notably, a 12-week potassium silicate application boosted photosynthetic rates and improved water conservation, thereby enhancing plant productivity and water use efficiency. For 'Chandler' strawberries, potassium silicate treatment led to a 23% increase in net assimilation rate, a 29% rise in stomatal conductance, and a 33% reduction in transpiration loss. Additionally, electrolyte leakage decreased by 25%, while maintaining steady intercellular CO2 concentrations. Strawberry plants treated with potassium silicate and irrigated once daily reduced water usage by 35% compared to untreated plants. Furthermore, flowering occurred 4 days earlier in treated plants, while fruit set increased by 16% and flower drop decreased by 13% compared to controls. Among all treatments, the 'Chandler' cultivar, irrigated once per day and treated with potassium silicate for 12 weeks, showed superior growth and significant water savings over the control group. Potassium silicate treatment for 12 weeks also resulted in a 20% higher marketable fruit yield compared to the control. Therefore, potassium silicate (AgSil16H) demonstrated its potential as a promising fertilizer under deficit irrigation conditions, effectively conserving water and improving productivity in hydroponically grown strawberries.

The strawberry industry relies on the production of disease-free daughter plants (DPs). Challenges in open-field nurseries have prompted research into controlled-environment agriculture (CEA) as an alternative to improve DP yield and quality. Growing strawberry stock plants indoors with stolons (runners) oriented vertically downward has been shown to increase DP production. However, information on detailed plant architecture and plant-light interactions remains limited. This project evaluated the impacts of photoperiod, light quality, and light distribution on DP yield and quality through a series of experiments. Firstly, shortening the photoperiod from 20 to 12 hours while maintaining the same daily light integral increased DP yield by 18%. Spatial distribution analysis revealed that a majority (60%) of DPs developed under suboptimal light conditions (

Nitrogen (N) fertilizer recommendations exist for controlled environment strawberry (Fragaria ×ananassa) fruit production. However, optimal N fertilizer concentrations may differ for strawberry mother plants, given that vegetative growth rather than reproductive growth is preferred. Our objective was to evaluate the impact of N fertilizer concentration on strawberry daughter plant yield and quality. Strawberry ‘Albion’ and ‘Monterey’ were grown in a greenhouse in 19.1-cm diameter pots filled with a soilless substrate (50 perlite : 25 coco coir : 25 peat). Plants were fertigated with a modified strawberry nutrient solution (Yamazaki) to provide 50, 100, 150, 200, 250, or 300 mg·L-1 N. After 12 weeks of treatment, cultivar but not N concentration impacted total stolon number and total daughter plant number. ‘Monterey’ produced 129% more stolons and 72% more daughter plants than ‘Albion’. Likewise, cultivar but not N concentration impacted branch architecture and where daughter plant formation occurred. The percentage of plants that produced primary, secondary, tertiary, and quaternary stolons was 100%, 97%, 61%, and 7% for ‘Monterey’ and 100%, 82%, 12%, and 0% for ‘Albion’. The distribution of daughter plants produced on primary, secondary, and tertiary stolons was 75%, 24%, and 1% for ‘Albion’, whereas it was 56%, 40%, and 4% for ‘Monterey’. Daughter plant quality exhibited quadratic responses to an increase in N concentration. Calculated maximum values were at 149 mg·L-1 N for daughter plant crown diameter, 172 mg·L-1 N for daughter plant fresh weight, and 187 mg·L-1 N for chlorophyll content index. Daughter plant foliar %N increased linearly as N fertilizer concentration increased from 50 to 300 mg·L-1 N, from 1.76% to 2.86% in ‘Albion’ and from 1.48% to 3.33% in ‘Monterey’. Mother plants also responded quadratically to N fertilizer concentration. Mother plant height, width, crown diameter, fresh weight, and a qualitative root rating assessment were greatest at calculated N concentrations of 154 to 169 ppm N. Necrosis of leaf margins began to appear in mother plants supplied 200 to 300 mg·L-1 N due to high nutrient solution electrical conductivities (ECs). In summary, although N concentration did not impact daughter plant yield, an N fertilizer concentration of 150 mg·L-1 N would optimize daughter and mother plant quality without inducing EC stress.

Carbon dioxide (CO₂) concentration and light conditions, including both intensity and spectral quality, are key environmental factors influencing plant growth, photosynthetic efficiency, and fruit production in tomatoes. Recent studies on greenhouse tomato varieties have reported that short-term exposure to elevated CO₂ concentration (800 ppm) and higher light intensity enhances plant growth and photosynthetic activities; additionally, long-term exposure to supplementary far-red photons increases dry mass partitioning to fruits, resulting in higher fruit yield. However, limited information is available regarding the interactive effects of CO₂ concentration, light intensity, and far-red photons in dwarf tomatoes for indoor production. Therefore, this study aimed to quantify the interactive effects of CO₂ level, photosynthetic photon flux density (PPFD; 400-700 nm), and supplementary far-red photon on growth, photosynthetic responses, and fruit production in dwarf tomato ‘Red Robin’. Plants were grown under two CO₂ levels (ambient: 400 ppm; elevated: 1500 ppm) × two light intensities [PPFD of 250 µmol m^-2 s^-1 (PPFD250) and 500 µmol m^-2 s^-1 (PPFD500)] × two supplementary far-red levels (0% or 15% of respective PPFD). Plants grown under elevated CO₂ generally exhibited increased plant height and stem biomass than those grown under ambient CO₂ levels. Elevated CO₂ improved fruit yield under low light intensity (PPFD250 with or without far-red supplementation) compared to ambient CO₂; however, this effect was not observed under high light intensity. Light intensity had a stronger impact on total leaf area and fruit mass under ambient CO₂. Specifically, under ambient CO₂, plants grown at PPFD500 showed lower total leaf area but higher fruit biomass than those grown at PPFD250. However, under elevated CO₂, the effects of light intensity became less pronounced, with no significant difference in fruit mass among the light treatments. Supplementation with 15% far-red photons did not cause any significant differences in tomato growth and morphology. Overall, these findings indicate that elevated CO₂ level significantly enhances fruit production under low light intensity treatments, regardless of supplementary far-red photons. However, the potential benefits associated with high light intensity treatments (PPFD500 and PPFD500 + 15% far-red photons) appear to diminish when plants were grown under elevated CO₂ conditions.

Vertical farms and the controlled environmental conditions they provide can produce high-quality food crops, but these facilities have high construction and operation costs. Therefore, characterizing the growth of high-value crops using these systems is important for the sustainability of vertical farming operations. Catharanthus roseus is a strong candidate for production in vertical farms due to its compact growth habit, quick production timeline, and a secondary metabolite profile with diverse therapeutic potential making it a high-value crop. Two medicinally important secondary metabolites derived from C. roseus are the monoterpene indole alkaloids (MIAs) vincristine and vinblastine which are used as anti-tumor chemotherapy drugs. Extracting these metabolites from field-grown C. roseus is challenging due to low plant yields. Cultivating C. roseus in vertical farms has the potential to increase the yield of these and other desirable plant metabolites by using environmental controls to stimulate relevant metabolite growth pathways. Evidence suggests that these pathways may be influenced by light exposure, but there is limited knowledge concerning the production of C. roseus in vertical farms for alkaloid production. The objective of this study was to identify the effect of light quality and intensity on the growth and alkaloid accumulation of C. roseus grown hydroponically in a vertical farm. We tested two light spectrums (white and white red) with three light intensities (~200, 360 and 500 µmol m-2 s-1) arranged in a factorial randomized complete block design with four replications. High-light treatments expectedly increased plant biomass, while low-light treatments unexpectedly increased vinblastine accumulation. These results demonstrate the feasibility of modifying alkaloid production in C. roseus grown with vertical farm systems, but additional work is needed to identify and optimize environmental conditions for maximizing alkaloid production. This work will inform pharmaceutical studies and other downstream uses of these compounds.