ASHS 2024 Conference

Will Increasing the Potassium to Nitrogen Ratio Benefit Hydroponic Strawberry Production? - Jonathan Ries
Impact of Diurnal Chilling on Vegetative and Floral Development of Strawberry (Fragaria x annanassa) cvs. ‘Albion’, ‘Chandler’, ‘Monterey’, ‘Sensation’ Tray Plants in a Controlled Environment - Michael Palmer
Utilizing Controlled Environment Agriculture to Enhance the Yield and Flavor of Strawberries - Nicholas Cooley
Impact Of Elevated CO2 And Two Daily Light Integrals on the Production Efficiency of Strawberry (Fragaria × ananassa ‘Monterey’) Daughter Plants - Samson Humphrey
Unraveling Strawberry Stock Plant Architecture, Morphology, and Tips’ Spatial Distribution under Three Photoperiods to Facilitate Future Propagation System Design: A Comparative Study on Monterey as a Long-day Cultivar - Moein Moosavi
Stratified Wood Substrates for Optimizing Growth of Greenhouse-Grown Strawberries and Blueberries - Brandan Shur
Effect of Light Intensity on Strawberry Runner Tips Propagated Indoors - Lian Duron
Characterizing the Growth, Morphology, Productivity, and Fruit Quality of Twenty-five Strawberry Cultivars in Vertical Farm Environment - Yiyun Lin

Strawberries (Fragaria × ananassa) are increasingly being grown in hydroponic systems, where effective nutrient management is critical for optimizing crop production and yield. Among essential mineral nutrients, potassium is a key nutrient that affect fruit quality in many fruiting crops. This study investigated how potassium to nitrogen (K:N) ratios regulate strawberry growth and development in a deep-water culture hydroponic system. We hypothesized that increasing the K:N ratios would enhance vegetative growth, fruit yield, and fruit quality. Bare-root plants of strawberry ‘Monterey’ and ‘San Andreas’ were grown indoor under a 23 °C air temperature and an 18-h photoperiod with an extended photosynthetic photon flux density of 350 µmol∙m–2∙s–1. The N level was kept constant at 77 ppm, while the study tested K:N ratios ranging from 1.5:1 to 4:5:1. Three weeks after nutrient treatments, strawberry plants showed similar crown number, crown diameter, leaf number, leaf area, and shoot dry mass regardless of K:N ratios in both cultivars. Increasing K:N from 1.5:1 to 4.5:1 linearly increased the root dry mass of Monterey’ but not in ‘San Andreas’. During the fruit production, K:N ratios did not affect the total number of fruits or total fresh mass of fruits. However, there was a linear decrease in the diameter, length, and fresh mass of individual fruits with increasing K:N ratio from 1.5:1 to 4.5:1 in both 'Monterey' and 'San Andreas'. Additionally, increasing K:N ratio from 1.5:1 to 4.5:1 slightly increased total soluble solids in ‘San Andreas’, but led to a greater increase in titratable acidity compared to the increase in total soluble solids in both ‘Monterey’ and ‘San Andreas’. These results suggest that increasing K:N ratios from 1.5:1 to 4.5:1 has little beneficial effect on overall plant growth, fruit yield and fruit quality for hydroponic strawberry production in deep-water culture systems.

In US open field nurseries, strawberry transplants for fruit production accumulate diurnal chilling hours (hours between -2 and 7°C) in the field prior to harvest and receive supplemental chilling as bare root plants in a cooler before being transplanted into a fruit production system. In nurseries in Northwestern Europe, tray plants are placed outside after rooting to accumulate diurnal chill hours and are moved into the cooler with leaves and substrate for supplemental chilling before being transplanted. The optimal amount of chilling varies among cultivars but is thought to contribute to a proper balance of vegetative vigor and floral development leading to best fruiting after transplanting into the production system. Climate change, labor cost and related issues cause problems in both nurseries and production. Therefore more and more growers and start-up companies venture into controlled environment production systems. Due to high cost, these systems require transplants that are optimally conditioned for early flowering. We evaluated the impact of diurnal chilling on vegetative and floral development of 250 cc strawberry tray plants in a controlled environment. 28 day old ‘Albion’, ‘Chandler’, ‘Monterey’, and ‘Sensation’ rooted daughter plants were moved into growth chambers where they received 0 (15°C 24 hours), 100 (4°C, 16°C), 250 (4°C, 19°C), or 450 (4°C, 24°C) chill hours over a six week period. Within each treatment, the same amount of chill hours were applied each day for the six week period. Among treatments, the non-chill temperature increased as the number of chill hours increased to ensure the same daily average temperature of 15°C. Chambers were fixed at 50% RH, 450 ppm CO2, 130-40 µmol m-2 s-1 for all treatments and a 12 hour photoperiod for ‘Chandler’ and ‘Sensation’ and a 16 hour photoperiod for ‘Albion’ and ‘Monterey’. After the treatment, all plants were dissected under the microscope to determine the number and development of floral meristems (flower mapping). Our results show that the plants in the 100 and 250 hour treatments produced more floral meristems and branch crowns than the 0 and 450 hour treatments across all cultivars. Additionally, in ‘Albion’ and ‘Monterey’, the plants of the 100 and 250 hour treatments had greater fresh mass and higher crown diameter than the plants in the 0 and 450 hour treatments. Finally, all cultivars except ‘Sensation’ had more flowers on plants in the 100 and 250 hour treatments than those of the 0 and 450 hour treatments.

Presentation: Oral ASHS 2024 Keywords: CEA, greenhouse, Fragaria ×ananassa, temperature Utilizing Controlled Environment Agriculture to Enhance the Yield and Flavor of Strawberries Nicholas Cooley, Joshua Vanderweide, and Roberto Lopez In the U.S., strawberries (Fragaria ×ananassa) are the most popular berry fruit with a value of $2.8B. In 2022, strawberries experienced 12% growth in annual sales, with the majority of field production occurring in California and Florida. To meet consumer demand for flavorful, fresh, local, and year-round fresh strawberries, the industry is expanding controlled environment (CE) production of day-neutral (everbearing) cultivars in greenhouses and indoor farms. Within CEs, growers can potentially meet these demands through the manipulation of environmental parameters such as temperature, light, vapor pressure deficit, and carbon dioxide concentration. Despite the recent growth, CE growers are reporting low profitability. This imbalance of production and profitability stems from high energy costs, supra-optimal greenhouse temperatures during parts of the year, and low yield from the industry standard cultivar ‘Albion’. For producers to be considered profitable, they must reach an approximate annual yield of 15 kg∙m–2, which equates to a weekly yield of around 0.3 kg∙m–2. The objectives of our research are to 1) quantify the yield of other day-neutral cultivars in greenhouses; 2) determine how day and night temperature influence yield and fruit quality parameters; and 3) develop a model to predict the cardinal temperatures of each cultivar. Three cultivars, ‘Albion’, ‘Cabrillo’, and ‘Monterey’ 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 DLI of 15 mol·m–2·d–1. Fruits were harvested three times weekly and at harvest, berry weight, diameter, color, shape, distortion, brix content, and flavor-related volatile organic concentrations were recorded. After 12 weeks of harvest, the highest average weekly yield was 0.17, 0.19, and 0.24 kg∙m–2 for ‘Albion’, ‘Cabrillo’ ‘Monterey’ at 18/10, 24/16, and 24/16 C, respectively. While the highest combined overall yield for all three cultivars was at 24/16 °C, the highest average berry weight differed. At day and night temperatures of 18/10, 18/10, and 15/7 °C, ‘Albion’, ‘Cabrillo’, and ‘Monterey had the highest average berry weights, respectively. Our results collectively indicate there are higher yielding day-neutral cultivars than the industry standard ‘Albion’.

Abstract: Strawberry nurseries face many challenges, and are considering controlled environment propagation as an alternative to conventional open-field propagation. Limiting factors to economic feasibility include stock plant yield (number of daughters produced per stock plant). From published research we know that increasing CO2 concentration and light intensity increases strawberry photosynthetic rate, however there has been no research on the effects of these treatments on the total stock plant yield of daughters. Our hypothesis is that higher light intensity and CO2 concentrations will improve plant growth and lead to greater total daughter plant production. The objective of this experiment is to increase stock plant yield by increasing CO2 concentration (500, 850, and 1200 μmol mol-1) and light intensity (DLI 14.4 and 28.8 mol m-2 d-1). Strawberry (Fragaria × ananassa Duch., ‘Monterey’) stock plants were transplanted into three controlled environment growth chambers, under combinations of CO2 and DLI treatments in a split plot design under 26°C, 65% relative humidity, and a 16-hour photoperiod. The stock plants were grown under treatment conditions for 70 days, and newly-formed daughters were logged every day. At the end of the experiment the stock plants and their daughter plants were harvested, and each daughter plant was evaluated based on its size (number of leaves, leaf area, and fresh/dry mass). Increasing CO2 concentration linearly increased stock plant yield, leading to 23.96% more daughter plants per mother plant from the 500 to the 1200 μmol mol-1 treatment. Plants under higher light intensity (500 μmol m-2 s-1) had 38% higher stock plant yield than those under 250 μmol m-2 s-1. These data support our hypothesis that increasing CO2 concentration and light intensity increase the total yield of daughter plants produced per stock plant. By optimizing CO2 concentration and light intensity, strawberry nurseries may be able to grow more daughter plants more efficiently in controlled environment nurseries than in the conventional open-field system.

The US strawberry industry needs healthy, high-quality transplants every year for fruit production. Following the challenges in open-field nurseries, research is focused on controlled-environment agriculture as a potential alternative to not only increase strawberry tip yield but also to produce healthier, virus-free transplants (rooted tips). Growing stock plants indoors where the runners grow vertically downward increases the yield and quality of tips, however, there is a lack of information on the general architecture of plants especially the spatial distribution of daughter plants and also the leaf area index (LAI) distribution of the daughter plants’ canopy in the growing space. This information is vital for future system design as it determines the distance between the shelves and the potential need for intracanopy lighting. Furthermore, besides temperature, photoperiod strongly affects the trade-off between runner Vs. flower production. Yet, there is also a lack of information on how photoperiod will change the yield, quality, and architecture of stock plants in CEA, specifically on long-day cultivars. Here, we examined 12, 16, and 20 h photoperiods with the same DLI of 26 mol m-2 d-1 on ‘Monterey’ as a long-day cultivar with two replications in time. The chamber environment was maintained at a high temperature of 26 °C, ambient CO2, and 65% relative humidity. The plant density was 9 plant m-2. Following 64 days of growth, parameters related to yield, architecture, and quality were recorded. Results showed that even under relatively high temperatures, with shortening the photoperiod, a linear increase in the number of tips was observed, increasing from ~36.3 to ~44.3 (18%) with the same DLI. Regardless of the photoperiod, the highest proportion of tips (30.8%) were harvested on the runners from 40 – 80 cm distance from the mother plant, though the highest LAI (53.2%) was recorded on the tips from 0 – 40 cm, causing a sudden drop (92.8%) in the light intensity after 40 cm where most of the tips are growing. This information shows the need for intracanopy lighting under 40 cm depth from the mother plants. Around 98% of the tips were harvested from 0 – 160 cm, showing the needed space for the growth of runners (i.e., the distance between the shelves). Several morphology and photosynthetic parameters were also recorded. The information from this study will be used as a base for a follow-up experiment comparing top versus intracanopy lighting.

As the demand for locally grown produce, particularly fresh fruits like blueberries and strawberries, continues to surge, the imperative for year-round production becomes increasingly evident. While these fruits are globally recognized for their extended-season production potential in controlled environments, the intricate environmental factors crucial for improved production and profitability remain partially understood, including the impact of soilless substrates. Amid growing concerns about the availability of internationally sourced substrates, such as coconut coir, this study explores an alternative approach to reduce reliance on such components, particularly in the cultivation of two small fruits rapidly integrated into controlled environments. Substrate stratification, involving the vertical layering of substrates within a single container, has shown promise in nursery and greenhouse settings, enhancing resource efficiency in terms of water and fertilizer inputs. However, no research has assessed the application of stratified substrates for fruit crops with the specific aim of reducing coir inputs in greenhouse production. Thus, the objective of this study was to investigate whether stratifying coir over low-cost, hammer-milled processed tree fiber could effectively decrease coir usage, dependency, and associated costs within the controlled environment fruit production industry. 'Albion' strawberries and 'Star' blueberries were cultivated in five substrate treatments, ranging from 100% coir to various stratified layers beneath coir, including 25%, 50%, and 75% coir compositions, as well as a 100% processed tree fiber treatment. Results suggest that employing substrate stratification enhanced plant growth for both fruit crops, indicating its potential utility in optimizing controlled environment fruit production while reducing reliance on costly substrate materials like coir. Further analysis will elucidate the full implications of this innovative approach on production efficiency and profitability.

Indoor propagation systems that use sole-source lighting in controlled environments can facilitate year-round production of disease-free, uniform strawberry liners. However, optimal conditions to propagate strawberry runner tips indoors are unknown. Runner tips of ‘Albion’ and ‘Fronteras’ strawberries were propagated indoors for 28 d under four photosynthetic photon flux density (PPFD) treatments: 75, 150, 225, or 300 ± 5 μmol·m–2·s–1 provided for 24 h·d–1 by white light-emitting diode fixtures. Runner tips were also propagated in a shaded greenhouse under mist. After propagation, plants were moved to a common greenhouse compartment and grown for 7 weeks to evaluate carryover effects on fruit yield (‘Albion’) or daughter-plant production (‘Fronteras’). Treatment responses were similar for both cultivars, except that shoot dry mass (DM) of ‘Fronteras’ followed a quadratic response with increasing PPFD, which peaked at 225 μmol·m–2·s–1. In contrast, shoot DM of ‘Albion’ linearly increased with increasing PPFD. Root DM of both cultivars also followed an increasing response with PPFD. However, there were no treatment differences in the number of shoots produced per plant or the length of the longest root. Interestingly, plants propagated under ≥150 μmol·m–2·s–1 had several dead shoots (up to 20%), likely attributed to plant stress. After the carryover phase, ‘Albion’ propagated under 225 or 300 μmol·m–2·s–1 were statistically different and produced the lowest fruit fresh mass compared to those grown in the greenhouse, whereas values were similar among plants propagated in the greenhouse or indoors under 75 or 150 μmol·m–2·s–1. No treatment differences were measured in the number of daughter plants produced by ‘Fronteras’. These findings suggest that although higher PPFD indoors promoted rooting and growth, plants propagated in the greenhouse were likely better adjusted to the dynamic greenhouse environment, which enabled them to reach the same growth and development of indoor-propagated plants at the end of the carryover phase.

As the interest in strawberry production in controlled environment agriculture is ascending, the demand for cultivars that yield premium-quality fruit is rising. To identify strawberry suitable for vertical farm production, 25 strawberry (Fragaria × ananassa) cultivars were selected for premium flavor from USDA National Clonal Germplasm Repository. Fruit productivity and quality traits, plant vegetative phenotypes, and photosynthetic rates were evaluated using strawberries grown in a walk-in growth chamber where photoperiod altered between short day and long day to promote flowering and fruit production. Our results show that strawberry ‘Mara des Bois’ produced the earliest harvest, and ‘Hood’ had the highest maximum productivity coefficient. The largest fruit was produced by ‘Chandler’, and the reddest fruit was produced by ‘Marshall’. Among the 25 cultivars, 11 exhibited fruit Brix levels above 0.9, and 3 had a fruit Brix:TA ratio of 1.0. Ongoing fruit flavor analysis aims to identify unique flavor compounds within these strawberries. Correlations linked time to first harvest and maximum productivity coefficient with canopy area, shoot height, and photosynthetic rate per plant, revealing the intricate sink-source dynamics in strawberry plants. Interestingly, no correlation was found between maximum productivity coefficient and any fruit quality trait, challenging the commonly held belief in the constant competition between crop productivity and quality. The information of strawberry growth and production in vertical farm environment provided in this study can assist indoor growers in cultivar selection and potentially contribute to future strawberry breeding programs.

Urban Agriculture Efficiency: A Year-Long Evaluation of Kale Yield and Energy Use in a Shipping Container Farm - Skyler Brazel
Production of Red Leaf Lettuce at Vertical Farm Equipped with Blue LED According to Anthocyanin Concentration and Its Gene Analysis - Junjira Satitmunnaithum
Interlighting Improves Tomato Yield in Northern Greenhouses - Meriam Karlsson
Effect of low root-zone temperature and UV radiation on growth and gene expression of secondary metabolite pathways in Nicotiana benthamiana - KiHo Son
Effects of Short-Wavelength UV-B, UV-A, and Blue Light on the Rose Flower Color Transition Phenotype - Navdeep Kaur
Arduino Uno Can Reliably Log Substrate Moisture from a Bus of Digital Sensors and Control a Drip-Irrigation System - Stephanie E Burnett
The Effect of Climate Change on Plants: A Case Study with Wheat - Kira Webster

Urban expansion is a threat to agricultural land. As cities increase in size and residential areas are being built on arable land, a new solution to growing food in urban area needs to be considered. Shipping container farms are designed to grow a high number of plants in a small area. These farms are programmable to fit the environmental parameters that are optimal for each type of crop. In this experiment, ‘Toscano’ kale was grown inside the farm and harvested weekly for one year to simulate farm production. The average day/night temperature in the farm was 22.8C and 15.6C with a photoperiod of 20 hours. Sole sourced lighting was supplied by light emitting diodes with an 80:20 red:blue ratio and an intensity of 100 mol . m -2. s -1 for a daily light integral of 7.2 mol . d -1 . Electrical energy use of the farm was collected on three categories of energy usage: Lighting, HVAC, and all Other Energy usage. Seeds were sown four weeks prior to transplant. Plants were transplanted weekly into vertical channels and harvested 12 weeks after sowing. This experiment was a complete block design with block nested in time. Yield data was collected at time of harvest, including plant number, fresh mass, dry mass, plant height, canopy area, and leaf number. The mean number of plants per replication was 320. The mean fresh mass per plant by block was 43.34g, 48.84g, 53.17g, 59.15g, 57.88g, and 53.29g, respectively, while mean dry mass was 3.31g, 3.66g, 3.94g, 4.42g, 4.3g, and 4.08g, respectively. Daily mean lighting and other energy consumption exhibited no variation across all 48 harvests. Daily mean HVAC energy consumption varied based on outdoor environmental conditions, with increased usage during summer months and a maximum of 33.53 kWh/day. Overall, fluctuations across mean fresh mass needs to be investigated further as the optimal harvest date for this farm may occur prior to 12 weeks, for both plant yield and energy consumption levels.

At the last ASHS annual conference, I, Satitmunnaithum et al., (2023), presented our study on the effect of blue and white LED light ratio on red leaf lettuce, however, the effect of blue LED on red coloration during its growth is still unclear. Thus, at this year’s conference, we aim to clarify the mechanisms of red coloration under blue LED based on anthocyanin biosynthesis gene analysis and its content in vertical farming condition to stabilize its production for high market demand. To elucidate the effect of blue LED light on the red coloration of red leaf lettuce, green and red leaf lettuce (Lactuca sativa L.) were selected for this study. Both were hydroponically cultivated at the Advanced Plant Factory Research Center at Meiji University, Japan. The cultivation temperature was set at 22 ℃ with a humidity of 60%. Seeds were sown under white LED for 24 hours. Ten-day-old seedlings were transplanted to different light conditions: white LED and blue LED. The photoperiod was set for 16 hours. The nutrient solution was supplied at an EC of 1.6 mS/m^2 with a pH of 6.0 ± 0.5. Both light treatments had a PPFD of 100-120 µmol/m^2/s. After 20, 25, and 30 days of transplantation, lettuces were harvested. The red area on leaf lettuce, along with the total anthocyanin content and its precursors, as well as the expressions of anthocyanin biosynthesis-related genes such as ANS, CHS, bHLH, DFR, and HY5, were evaluated. Blue light shows a large red area on red leaf lettuce at most of the development stages resulting in a high red area percentage, while green leaf lettuce remained completely green in both light conditions. The interested genes were upregulated mostly in blue light irradiated red leaf lettuce which led to high total anthocyanin content. This can be assumed that blue LED light enhances anthocyanin synthesis in red leaf lettuce which can contribute to the stable production of red leaf lettuce in vertical farms.

This year Conviron is launching three new products:
•             GEN1000-ECO (introduction date: April 16, 2024)
•             ConvironDirect (introduction date: March 4, 2024)
•             PGR15/E15 LED Retrofit (introduction date: Jan 5, 2024)
GEN-1000-ECO:
The GEN1000-ECO is a new compact reach in chamber ideal for short and tall plant research that comes standard with humidity control and energy efficient features such as a smaller compressor and LED lighting - for up to 15% reduced energy consumption. Low, medium and high light options are available to meet a range of research requirements.
ConvironDirect:
ConvironDirect is a new premium software tool that enables users to manage chamber setpoints and actual conditions remotely through any building LAN connected desktop, notebook or handheld mobile device. ConvironDirect is ideal for users that have Conviron reach-in plant growth chambers or walk-in rooms and want a seamless connection to their chamber, their plants, and their data from virtually anywhere.
PGR15/E15 LED Retrofit:
Fluorescent lamps such as T5, T8 and T12 have been the standard for many years and have been used in tens of thousands of plant growth chambers around the world. However, fluorescent lighting is trending towards obsolescence and replacement lights are increasingly difficult to source economically. Conviron is now offering a retrofit for aged PGR15-E15 chambers to enable users to take advantage of the latest LED lighting technology and save up to 80% on energy costs.

Low natural light and high heating costs limit northern winter greenhouse production. Technology advancements now offer opportunities to improve delivery of light to and within crop canopies. The greenhouse tomato cultivars Bigdena and Beorange were chosen to evaluate high pressure sodium irradiance with LED interlighting. Plants were grown in a high-wire drip irrigation system using dutch (bato) buckets (17.7 L volume) filled with a 50/50 mixture of perlite and a peatlite medium (Pro-Mix BX). The containers were placed in alternating rows across a drainpipe. Seeds were sown on 8 Sep and two seedlings were transplanted into each container 38 d later (17 Oct). Day temperature was 22 ± 2°C and reduced to 18 ± 2°C during the night. Lower leaves were removed as fruit ripened and the study was terminated at a plant height of ~250 cm (128 d from transplanting). The photoperiod was 18-h. In addition to overhead 400-W HPS lighting, LED fixtures designed for placement within the canopy were evaluated (GE current Arize® Integral). Two horizontal LED bars were positioned 30 cm (12 inches) apart with the upper bar adjusted within 30 cm of the top of the plants throughout the study. The integral lighting provided a spectrum with blue (peak 450 nm) and red (peak 660 nm) wavelengths in a 12:88 ratio. The perpendicular horizontal distance from the LED bars to the plant stems was 30 to 35 cm. The intensity (400-700 nm) measured at the plant stems horizontally from the LEDs averaged 195 ± 30 µmol m-2s-1. Overhead HPS provided ~130 ± 20 µmol m-2s-1, 100 cm below the fixtures. Seasonally short days and low sun angles limited natural light during the study. The first ripe tomatoes were harvested 62 d from transplanting (18 Dec). Interlighting resulted in higher plant yields with 6.3 ± 0.82 kg for Bigdena and 4.9 ± 0.67 kg for Beorange. In comparison, 4.1 ± 0.37 kg (Bigdena) or 3.4 ± 0.80 kg (Beorange) was recorded for plants receiving only HPS lighting. Five or six additional tomatoes were harvested with interlighting for Bigdena (25 ± 2.0 versus 19 ± 1.8) and Beorange (22 ± 2.5 versus 17 ± 1.9). Average tomato size increased from 217 ± 11.9 g to 250 ± 19.3 g (Bigdena) or from 199 ± 36.1 g to 227 ± 20.2 g (Beorange) with interlighting.

This study explored the effects of low root-zone temperature (LT) and UV radiation (UV) alone and combined on changes in growth, transcription, and gene expression related to secondary metabolite in Nicotidana benthamiana. The plants were grown in a controlled environment (25/20°C, 16/8 h [light/dark], 70% relative humidity, 1,000 µmol·mol−1 CO2 with photosynthetic photon flux densities of 100 and 200 µmol·m−2·s−1 for 10 and 18 d, respectively). Twenty-eight days after sowing, the seedlings were treated with LT (15°C), 0.3 W·m−2 of UV radiation, and a combined treatment with LT and UV (LT*UV) for 3 d. Results found that the treatment with UV alone decreased the quantum efficiency of photosystem II by approximately 1.5 times, and most growth characteristics decreased under the UV (approximately 1.5 times) and LT*UV treatments. Combined treatment with LT*UV significantly inhibited the growth characteristics and photosynthetic rates compared to those under the single LT and UV treatments. In particular, the transcriptome levels of phenylpropanoid and flavonoid biosynthesis were the most significantly affected by LT*UV. This suggests the potential of using LT treatment in hydroponic systems and UV radiation to control the synthesis of health-promoting compounds of secondary metabolites in greenhouses and controlled-environment agricultural facilities.

Light quality plays a crucial role in the growth and development of plants. In this study, we aimed to assess the effects of short-wavelength light on rose genotype '16401-N055’, which exhibits the flower color transitioning trait: the flowers change colors from yellow to pink in sunlight. Roses that exhibit this flower phenotype are termed transitioning-type roses. Specifically, we analyzed and compared the impact of six different light treatments [a sunlight control in open field and five spectral treatments created using light-emitting diodes (LEDs)] on various physiological and morphological characteristics. The five LED treatments included white light, blue light, UV-A white light, UV-B white light, and 80% blue 20% white light. Each treatment had two replications where one-year-old rose plants were the experimental unit. The total light intensity was maintained at 300-350 micromol m-2 s-1 for a photoperiod of 16 h light and 8 h darkness. The morphological traits measured included height, width, number of buds, number of flowers, and node density. The color scale parameters L* [luminance of the color ranging from 0 (black) to 100 (white)], a* [red (positive values) and green (negative values) color levels], and b* [yellow (positive values) and blue (negative values) color levels] were measured using a colorimeter. Additionally, the chlorophyll concentration index (CCI) was measured using a chlorophyll meter. Fully pigmented pink flowers were only observed in the UV-B white light treatment with an average L* value of 44.1 and a* value of 50.6. A slight pink hue was observed on the outer sections of petals in blue and blue white light treatments. The average L* and a* values of flowers in the blue treatment were 87.21 and 6.24, and in blue white treatment were 90.9 and 1.86, respectively. The flowers in the white UV-A treatment remained white with the highest average L* value of 92.4 and the lowest average a* value of -1.86. The CCI of plants under sunlight (23.5) was significantly lower than the plants treated with blue (34.4), and blue white (33.7) light. No significant differences in morphological traits were detected after two weeks. The plants will be monitored for longer periods and more data will be collected every two weeks for one month to document additional changes. The results obtained will provide additional information on morphological and floral changes in this genotype under different light treatments.

Inexpensive Arduino microcontrollers can be programmed to operate and log data from environmental sensors and operate other accessories such as irrigation solenoids. We describe our efforts to build a modified version of Arduino Uno systems previously developed at the University of Georgia, which operated analog moisture sensors and opened solenoid valves to drip emitters when moisture fell below user-defined thresholds. We attempted to 1) replace analog sensors with a bus of digital sensors that use the SDI-12 communication protocol, 2) include programming to parse digital output from two popular SDI-12 sensors (Decagon GS3 and Campbell Scientific 5TM), 3) use 12VDC solenoid valves that were less expensive and smaller (1/2”) than alternatives, and 4) overcome several challenges encountered in the construction and programming of the Arduino-based system. These included an approach to more easily manage the connection of numerous wires, the inclusion of a reversed diode at the solenoid terminals to prevent electrical interference from intermittently resetting the Arduino program, and the adoption of programming strategies to work around memory limitations that initially rendered our Arduino systems with digital sensors unreliable. We overcame these challenges to develop a robust, reliable, and easy-to-deploy Arduino-based environmental logger and automated drip-irrigation system that can operate numerous digital sensors. Sensor type and thresholds for volumetric water content are defined in a single location within the program, enabling the user to easily make minor adjustments to the system. We also included extensive line-by-line documentation of the source code. A list of the hardware used in this system is available. In 2023, eight of these systems operating 64 total sensors proved their reliability over a two-month experiment on the drought stress physiology of wetland shrubs. We conclude that this system is an effective solution for in-house sensor-automated irrigation with high customizability for end users.

Anthropogenic climate change (ACC) will have considerable effects on plants, though the extent to which these effects are positive or negative has been controversial. For this poster, a fully factorial experiment combining water and temperature over broad ranges (10-90% soil water content under 16°C-40°C) was carried out to address three shortcomings that might help explain the contrasting effects of climate change on plants: testing only one climate variable (e.g., only water or only temperature), failure to account for nonlinear responses to climatic variables, and studying a limited number of response variables. The experiment utilized wheat as the model species and found that most dependent variables related to grain production showed the highest performance under 23-33°C and low water (

Effects of Light Sources and Fertilizers on Biomass Production of Nine Lettuce Cultivars in a Hydroponic Nutrient Film Technique System - Dario Rueda Kunz
Enhancing Lettuce Yield: Strategies for Fertility Management in Soilless Growth Systems. - Bryce Waugh
Effect of ZnO and SiO2 Nanoparticles on Growth and Physiology of Hydroponic Lettuce Under Salinity Stress - Chungkeun Lee
An Intermediate Calcium-mobilizing Biostimulant Concentration Controls Tipburn of Two Greenhouse Hydroponic Lettuce Cultivars Without Affecting Growth -Shem Msabila
Optimizing Sampling Methods for Sap Extraction to Enhance Plant Nutrient Analysis in CEA - Husnain Rauf
Effects of Potassium and Iron Supplements and Late Nitrogen Restriction on Aquaponic Taro (Colocasia esculenta) Corm Production - Andrew Bohringer
Advantages of a novel in situ pH measurement for soilless media - Hikari Skabelund

This study investigated the impact of two light sources and fertilizers on the growth of nine lettuce cultivars in a hydroponic nutrient film technique system. The research was prompted by reduced plant growth and acidity issues observed in the nutrient solutions in which Lettuce (Lactuca sativa cv. Salanova) was growing in previous experiments. The hypothesis posited that adjusting the ammonium/nitrate ratio in the nitrogen fertilizer source could mitigate acidity drops in the nutrient solution and consequently enhance biomass production. This experiment was conducted at Texas Tech University's Horticulture Gardens and Greenhouse Complex from October 10 to November 22, 2023. Treatments included combinations of two light sources (WhiteLEDs and LumiGrow TopLight Node™) and two fertilizer brands (Oasis and MaxiGro) containing different ratios of ammonium:nitrate; Oasis with 21.25:78.75, and MaxiGro with 15:85. Both fertilizers were maintained at the same concentration of nitrogen throughout the experiment, although the rates were changed according to developmental stage. The nutrient solutions initially contained 100 ppm N fertilizer for three weeks, followed by a water change and an increase to 150 ppm N.The pH and EC levels were closely monitored throughout the experiment. Results revealed significant differences among cultivars for all measured variables, with Salvius demonstrating superior performance in most aspects. The light source had no significant impact on aerial growth variables, while the MaxiGro fertilizer brand significantly and positively influenced plant weight, height, and root weight. Although there were significant interactions between light source, cultivar, and fertilizer for above-ground variables, these were highly dependent upon fertlizer. In conclusion, the choice of fertilizer brand is crucial for optimal lettuce growth in hydroponic systems. This study highlights the importance of selecting appropriate fertilizer characteristics to avoid detrimental effects on biomass production. Further trials are recommended to validate these findings and address concerns for home and commercial growers in hydroponic lettuce production.

A forum for discussion of potential collaborations with regards to fruit, vegetable, and edible crops – i.e. citrus, breeding, production systems, postharvest, pomology, crop management, viticulture, etc.

The focus on sustainability and effective resource management is expanding along with the upward trend in greenhouse production. Precise application of fertilizers is becoming more and more important in a variety of agricultural systems. The physical and chemical characteristics of soilless growth media differ from those of soil, which causes differences in their ability to retain nutrients. As such, accurate rates of fertilizer are crucial. This study looked at 14 different fertilizer blends with varying percentages of potassium (0-200ppm), phosphorus (0-100ppm), and nitrogen (0-200ppm). Pots were filled with Berger BM6 media and then ‘Buttercrunch’ lettuce seeds were planted. With each treatment fertilizer rate, the plants were hand-watered once a week to maintain a 10% leaching fraction. The number of leaves, dry shoot weight, fresh root weight, dried root weight, and SPAD readings were among the end measurements. The study found that a mix of high rates of nitrogen, phosphorous, potassium fertilizer treatments increased fresh shoot weight. This emphasizes the need for additional study to determine the best fertilizer rates for various specialty crops grown in soilless greenhouse environment.

Nanoparticles have unique physical and chemical properties, which can positively and negatively impact crop growth and tolerance to abiotic stresses. This study evaluated the potential of ZnO and SiO2 nanoparticles in alleviating salinity stress in hydroponically cultivated lettuce. Two-week-old lettuce seedlings (Lactuca sativa cv. Green Forest) were transplanted into a 5-L deep water culture system and grown for four weeks in a customized growth chamber set at 25°C with 230 µmol/m2/s PPFD. The nutrient solution was maintained at an electrical conductivity (EC) of 1.5 dS/m and pH 5.8, and replenished weekly. A factorial design was employed with four salinity stresses (non-saline, 50 mM NaCl, 33.3 mM CaCl2, 25 mM NaCl 16.6 mM CaCl2) and three nanoparticle treatments (no nanoparticle, 100 ppm ZnO, 100 ppm SiO2). Under non-saline conditions, both ZnO and SiO2 treatments showed no significant differences in shoot growth compared to the control plants. However, ZnO application reduced shoot biomass, leaf area, SPAD, chlorophyll fluorescence and net photosynthetic rate under CaCl2 and NaCl CaCl2 stress. SiO2-treated plants had higher SPAD than the control plants under CaCl2 stress but presented lower values under NaCl CaCl2 stress. Root growth also showed contrasting results based on the stress conditions. SiO2 application resulted in increased root dry weight, total root length and surface area under non-saline and CaCl2 stress, while they decreased under NaCl stress. Similarly, ZnO application enhanced root growth under non-saline conditions, but demonstrated negative effects under all salinity stress conditions. In conclusion, SiO2 nanoparticle application did not improve salinity tolerance in lettuce, except for root growth under CaCl2 stress, and ZnO nanoparticle treatments showed phytotoxicity in both shoots and roots under all salinity stress conditions.

Lettuce (Lactuca sativa) tipburn is a physiological disorder that leads to unappealing browning or necrosis of young leaf tips and stems, caused by localized calcium deficiency. It negatively impacts crop quality and yield, making proactive management essential for achieving optimal production. The objective was to evaluate the efficacy of a calcium-mobilizing chemical biostimulant, applied in the nutrient solution, on lettuce growth and tipburn. We conducted a greenhouse experiment on two lettuce cultivars (‘Dragoon’ and ‘Rex’) using a randomized complete block design. The seedlings were grown indoors under continuous white light from light-emitting diodes (LEDs) with a mean daily light integral (DLI) of 26 mol⋅m−2⋅d−1. We transferred 11-day-old seedlings to deep-water-culture hydroponic trays in a greenhouse. The two cultivars were subjected to three replications and five biostimulant concentrations (BC) of 0 (control), 0.125, 0.25, 0.5, and 1 mL⋅L−1 of the nutrient solution. Plants were grown under an 18-h photoperiod with a mean DLI of 16.6 ± 2.0 mol⋅m−2⋅d−1 from both sunlight and supplemental white LEDs, an air temperature of 24.6 ± 3.1 °C, and relative humidity of 33.2% ± 9.5%. Plant data were collected 14, 21, 28, and 35 days after transplant (DAT). There was no visible tipburn 14 DAT; however, plant diameter and shoot mass (fresh and dry) decreased with increasing BCs. We observed tipburn 21 DAT in both cultivars. The control had the highest severity on a 0–5 scale (0 = no tipburn; 5 = severe tipburn) for ‘Dragoon’ (0.6) and ‘Rex’ (1.3), whereas no tipburn occurred under higher BCs (i.e., 0.5 and 1 mL⋅L−1). Tipburn progressed 28 DAT, when increasing the BC from 0 to 1 mL⋅L−1 decreased the tipburn rating from 3.3 to 0 for ‘Dragoon’ and from 4.1 to 0 for ‘Rex’. Plant growth was stunted under the highest BC (i.e., 1 mL⋅L−1). At 35 DAT, both cultivars had severe tipburn under the control but had decreasing tipburn severity as the BC increased. Plant growth was unaffected under the control and low BCs (i.e., 0, 0.125, 0.25 mL⋅L−1). Under the highest BC, ‘Dragoon’ had the longest roots, but ‘Rex’ had the shortest. In contrast, plants experienced phytotoxicity (reduced biomass and chlorophyll concentration) under the highest BC, i.e., (1 mL⋅L−1) though no tipburn was recorded. In conclusion, the optimal calcium-mobilizing BC was 0.5 mL⋅L−1, which minimized tipburn of greenhouse hydroponic lettuce without affecting biomass accumulation or causing phytotoxicity during later development stages.

Plant sap analysis is a technique for monitoring plant nutrient status in real-time, enabling precise nutrient management to enhance growth and yield in controlled environment agriculture (CEA). Comprehensive sampling techniques are vital for accurate determination of nutrient concentrations, considering the variability of nutrients across different developmental phases of plants. However, questions remain regarding the selection of the appropriate plant tissues, including the number of leaves collected, sampling time, type and age of plant tissue, and frequency. Different crops need specific sampling procedures due to their unique leaf morphology, growth habits, and physiology. Many commercial laboratories only distinguish between new and old leaves. In this series of studies, we determined the most effective sampling method including the number of leaves, the type and age of tissue, as well as the timing and frequency of the collection. Optimal sampling techniques were identified for lettuce and tomato by conducting five different experiments across three cultivars. These experiments varied the number of leaves sampled (10, 20, 30 per sample with three replicates), types of tissue (leaves for lettuce with three replicates, and petioles and leaves for tomatoes with 20 each per sample), age of tissue (new vs. old with 20 leaves per sample and three replicates), time of collection (6, 8, 10 am with three replicates). For lettuce, two developmental stages (half and final harvest maturity), while for tomatoes, sampling frequency at four different growth stages was investigated (first fully expanded leaves, 1/3 and 2/3 of crop development, and final harvest). The results indicate that collecting 20 fully expanded leaves at 8 am, particularly at the final harvest, was considered the best sampling technique for nutrient analysis for both lettuce and tomatoes, providing the most effective sampling technique for optimizing nutrient management.

The growing of taro in aquaponic systems has yielded corms significantly smaller than those grown terrestrially. Previous trials only partially supported the hypothesis that these low yields were due to excessive water and nitrogen levels late in vegetative development. A 2×2 (nitrogen restricted × supplemental fertilizer) factorial designed experiment was replicated 4 times in dual-tub systems. The 4 treatments tested were: 1) Fish effluent supplied throughout 10 months of plant development (T1); 2) Fish effluent restricted from the system at 6 months and fresh water supplied for the remaining 4 months of development (T2); 3) T1 plus supplemental potassium and iron fertilizer (T3); 4) Treatment 2 plus supplemental potassium and iron fertilizer (T4). The results indicate that the supplemental fertilizer was more important than effluent restriction late in development in enhancing corm growth, although effluent restriction did result in a higher maturity index of corms under supplemental fertilizer treatment. The corm yields were 140% higher in T3 (1.5 kg plant-1) than in T2 (0.63 kg plant-1). T4 had significantly more biomass partitioned into the corm (56% of total biomass) compared to T3 (44% of total biomass). The ratio of corm: total biomass is a key indicator of plant maturity and suggests restriction of high nitrogen effluent enhanced photosynthate translocation to the corm under supplemental fertilizer. Corm density was highest in T3 and lowest in T4, perhaps due to starch conversion to sugar in over-mature corms in T4. These results demonstrate the importance of supplementing potassium and iron fertilization, as well as restricting high nitrogen fish effluent late in taro corm development, to optimize taro yields and quality in aquaponic production systems.

Rhizosphere pH determines nutrient bioavailability, but this pH is difficult to measure. Standard pH tests require adding water to growth media. This dilutes hydrogen ion activity and increases pH. We used a novel, in situ, pointed-tip electrode to estimate rhizosphere pH without dilution. Measurements from this electrode matched a research-grade pH meter in hydroponic nutrient solutions. We then compared measurements from this electrode to saturated paste and pour-through methods in peat moss, coconut coir, and pine bark. The pointed-tip electrode was unable to accurately measure pH in the highly-porous pine bark media. Adding deionized water to the other media at container capacity using the saturated paste method resulted in a pH that was 0.59 ± 0.30 units higher than the initial in situ measurement at the top of the container. This increase aligns with established solution chemistry principles. Measurements of pH using the pour-through method were 0.38 ± 0.24 pH units higher than in situ measurements at the bottom of the container. We conclude that in situ pH measurements are not subject to dilution and are thus more representative of the rhizosphere pH than the saturated paste and pour-through techniques.

Introduction and Overview

Speaker: Kathryn Orvis
Professor
Department of Horticulture and Landscape Architecture
Purdue University
625 Ag Mall Drive
West Lafayette, IN 47907-2010

Title: Digital Agriculture and AI on Specialty Crops Production

Description: Digital agriculture is the 4th agricultural revolution and Artificial Intelligence (AI) is part of it. Currently, in the "connected agriculture"; era, many technologies have been released on the marked regarding the use of multispectral
sensors for many purposes in agriculture. This talk is going to cover information on how to use Digital Agriculture online platforms to process multispectral imagery, and how AI can be used to collect individual in-field plant data.

Speaker: Luan Pereira de Oliveira
Assistant Professor and Precision Agriculture Extension Specialist
Department of Horticulture
University of Georgia
139 Engineering Building
2329 Rainwater Road
Tifton, GA 31793

Title: Bringing the Future of AI to the Farm.
Description: In this talk, we will cover the multitude of use cases where AI can be applied in farming – from weed detection and robotics to Generative AI-based farm assistants and Virtual Reality. We go through the industry trends of applied Artificial Intelligence and think big about farm automation for the future.

Speaker: Justin Hoffman
Chief Technology Officer of AgTechLogic


Title: From Concept to Impact: The Evolution of Moss Robotics through Industry-
University Collaboration

Description: Moss Robotics' journey began with a project focused on autonomous driving technology for tree nurseries, born out of a collaboration between Carnegie Mellon University, Robotics Institute and Hale; Hine Nursery in Tennessee. In this talk, we share the story of how we discovered the real value our solution could offer to growers, and how we refined our ideas through continuous iteration. This process transformed moss robotics from a simple concept into the company it is today. We will cover the steps of our evolution, emphasizing the practical benefits of combining academic research with industry needs to innovate effectively. Additionally, we look ahead to how emerging technologies might further influence our growth and the agricultural industry as a whole, aiming for advancements in farming practices that are both technologically sophisticated and grounded in real-world applications.

Speaker: Di Hu
Founder and CEO
Moss Robotics

Title: AI-Enhanced Computer Vision for Crop Monitoring in Controlled Environment
Agriculture

Description: Controlled environment agriculture (CEA) production remains expensive due to high operation costs. Growers can reduce production costs by nurturing crops with data, however, the data is highly diverse, and growers lack the expertise to analyze this data to derive actionable insights for informed decision-making. In addition, traditional crop monitoring is carried out manually, which makes it unfeasible to collect data daily to get actionable insights for high yields. Recent advancements in sensing and computing technologies, such as AI, computer vision, edge computing, and edge-
cloud integration, have opened opportunities to develop data-driven technologies to enhance decision-making capabilities. Integrating AI and computer vision technologies has emerged as a transformative toolset that can collect real-time plant data at high spatial and temporal resolutions, pivotal in optimizing resource management and maximizing production. The CE Engineering lab delves into cutting-edge computer vision applications within CEA, focusing on various applications, including phenotyping leafy greens, yield estimation, disease monitoring, and plant spacing optimization. This presentation will explore the details of lettuce phenotyping, disease classification, strawberry fruit classification, and yield estimation. We will delve into the technical aspects of these algorithms, including image processing techniques, machine learning models, and data integration strategies. This presentation will showcase state-of-the-art deep learning approaches, including segmentation algorithms, model training, and deep classifiers. Overall, this presentation aims to provide insights into the transformative potential of computer vision in CEA, offering a glimpse into the future of data-driven and sustainable CE production.

Speaker: Azlan Zahid
Assistant Professor,
Department of Biological and Agricultural Engineering
Texas A&M AgriLife Research
Texas A&M University System
Dallas, TX 75252, USA


Panel: 30-minute panel with the above speakers, to allow time for Q&A and discussion.

Carbohydrate Synthesis and Freeze Tolerance of Clonal-type Bermudagrasses as Affected by Mowing Heights During Cold Acclimation and Deacclimation Process - Mingying Xiang
Understanding Photoperiod Effects on Seek and Seedling Quality in Soybean Speed Breeding- Christiane da Silva
Identifying the Optimal Range of pH Management for Hydroponic Leafy Vegetables - Yujin Park
Enhancing Iron Bioavailability in Hydroponic Leafy Greens by Iron Chelators - Asmita Nagila
Effects of Mycorrhiza and Ciochar Interactions on Geraniums - Teal Hendrickson
Exploring Different Nutrient Solution Quantities to Optimize Quantity and Quality in Hydroponic Production - Puja Subedi
How Does Supplementing Dissolved Oxygen Impact Hydroponic Strawberry Production? - Jonathan Ries
Exploring Different EC Levels to Optimize Quantity and Quality in Hydroponic Production - Puja Subedi

Bermudagrass (Cynodon spp.) is a prominent warm-season turfgrass extensively utilized across golf courses, athletic fields, home lawns, and recreational areas due to its excellent heat tolerance, good traffic tolerance, and strong recuperative potential. Despite its strengths, winter survivability in colder climates remains a concern. Research has revealed variations in freeze tolerance across bermudagrass cultivars, yet there's a gap in understanding the underlying physiological mechanisms and the impact of cold acclimation and deacclimation processes. Additionally, the influence of mowing height on carbohydrate synthesis and freeze tolerance has been reported. To address these gaps, a study utilizing turfgrass plugs from different acclimation stages was conducted in a freeze chamber. The objective of this study was to examine freeze tolerance and carbohydrate synthesis in four clonal-type bermudagrass varieties ('Tifway’, ‘Tahoma 31’, ‘Astro’, and ‘TifTuf’) under mowing heights of 0.5” and 1.5” across various cold acclimation and deacclimation stages. The plugs were subjected to soil temperatures ranging from -5°C to -12°C, with survival assessed after three weeks to determine the lethal temperature (LT50) for each condition. Rhizome carbohydrate levels at each stage were determined. The correlation between rhizome carbohydrate level and freeze tolerance was determined. The data from this study is currently being analyzed.

Soybean is a short-day plant, which means that days must be shorter than a critical value to induce flowering. Manipulating the photoperiod regime is a well-known way to shorten plant cycles in speeding breeding programs. However, the impact of the photoperiod on the quality of the produced seeds is not well understood. Here, we investigate how photoperiod affected the seed and seedling quality in soybean plants, grown in a controlled environment. Soybean (Glycine max) plants (var. S16-14801C and CZ7570LL) were grown in growth chambers with controlled temperature (27 ± 0.5˚C), CO2 (475 ± 15 µmol mol-1), humidity (70 ± 5.0%), and light (300 ± 5 µmol m-2 s-1 at table; 20% blue,10% green, 70% red). One week after germination, seedlings were exposed to different photoperiod regimes: i) 10 h (0 w at 18 h), ii) two weeks at 18 h and then 10 h (2 w at 18 h), iii) four weeks at 18 h and then 10 h (4 w at 18 h); iv) six weeks at 18 h and then 10 h (6 w at 18 h). The plants were grown in the described treatments until the R8 stage (95% brown pods), without changing the light fixture height (industry standard practice). A sample of seeds was harvested and analyzed regarding quality while other samples were placed to germinate in seed germination paper to evaluate germination rate and seedling growth for 10 days. Similar results were found for both varieties; plants of all treatments presented different heights, in which plants at 0 w at 18 h were shorter (50 cm) and 6 w at 18 h taller (180 cm). Treatments did not affect the moisture or weight of 100 seeds. Conversely, germination and seedling survival were 30% lower in seeds from plants 0 w at 18 h than in other treatments. Similar results were found for the root (13% lower in 0 w at 18 h) and shoot length (19% lower in 0 w at 18 h) of seedlings. However, the dry weight of seedlings was similar among treatments. Manipulating the photoperiod can speed up the plant cycle and is a good alternative for speed-breading programs. However, extreme photoperiods and low daily light integral can produce seeds and seedlings with lower quality that can influence the production of plants of the next generation.

In hydroponics, the pH of the nutrient solution influences the solubility and availability of essential nutrients. The optimal pH for plant nutrient uptake in many crop species is around 6.0. However, the impacts of precise pH management on plant nutrient uptake, crop yield, and the optimal pH range remain less clear. In this study, we investigated the effects of pH management range on plant nutrient uptake and the growth of hydroponic leafy vegetables. Within an indoor vertical farm, we grew lettuce (Lactuca sativa) 'Rex,' kale (Brassica oleracea var. sabellica) 'Red Russian,' and arugula (Eruca sativa) 'Astro' using deep water culture hydroponics at the air temperature of 22 °C under a photosynthetic photon flux density of 200 μmol∙m−2∙s−1 with a 24-h photoperiod. The experiment included six pH treatments: pH 6, 6±0.5, 6±1.0, 6±1.5, 6±2.0, and without pH control. Compared to managing pH at 6, maintaining pH within 6±1.0 had generally similar impacts on leaf number, leaf area, SPAD index, shoot and root fresh mass, and shoot and root dry mass in all three crops. However, when compared to managing pH at 6, maintaining pH at 6±1.5 or greater reduced leaf area (by 32-47% in lettuce, by 30-41% in kale, or by 56-65% in arugula) and shoot fresh mass (by 33-54% in lettuce, by 37-45% in kale, or by 48-64% in arugula). Furthermore, in comparison to managing pH at 6, maintaining pH at 6±1.5 or greater also decreased leaf number in lettuce by 3-5 leaves and in arugula by 13-15 leaves but increased the root fresh mass of lettuce by 26-43%. Our results suggest that maintaining pH within 6±1.0 can be effective in promoting optimal nutrient uptake and overall plant development in the context of hydroponic cultivation.

Iron is an essential micronutrient for the growth and development of both plants and humans, as it plays vital roles in processes such as protein synthesis, respiration and DNA replication. Leafy greens, vital dietary sources of iron, can be cultivated with increased bioavailable iron through hydroponics by customizing nutrient solutions. Conventionally, iron chelates like EDTA and DTPA, are used in hydroponics, but challenges persist in iron acquisition due to their pH dependency as well as quick oxidation to ferric ion which is harder to uptake by plants. Good sources of chelates that respond well to high pH values, like EDDHA, are often more expensive. Studies suggest that iron complexed with humic substances exhibits higher efficiency, though confirmation in large-scale hydroponic systems is still needed. Fulvic acids are water-soluble humic substances with lower molecular weights that hold promise as alternatives or supplements to synthetic chelates, enhancing iron uptake and stress tolerance. Hydroponic systems, such as Deep-Water Culture (DWC) or Nutrient Film Technique (NFT), impact plant growth and nutrient uptake differently based on temperature, EC, and pH. This research compared the effects of various iron chelators on lettuce and kale cultivation in DWC and NFT systems. Results indicate significant yield loss in iron-deficient kale, while iron-chelated solutions enhanced yields. The addition of fulvic acid to EDTA-chelated solutions notably improved kale yield in DWC compared to no iron and EDTA-only solutions. Leafy greens showed higher chlorophyll fluorescence (Fv/Fm ratio) and chlorophyll content in DWC compared to NFT. The results showed species-specific and system-specific responses. Notably, iron-chelated plants exhibit higher iron content correlating with increased shoot weight and chlorophyll content. The effect of fulvic acids and synthetic chelates might be synergistic, with both providing different advantages that can be complementary in hydroponic solutions. This study highlights the importance of iron management in hydroponics and the way forward for iron fortification techniques.

Biochar has long been proposed to be a substitute for peat in soilless mixes for greenhouse growing. Low levels of biochar have been shown to increase disease resistance, increase nutrient supply and uptake, and immobilize phytotoxic substances. Due to its high porosity and pH, biochar has the potential to provide an ideal habitat for mycorrhizal fungi to partner with plant roots. This study examined how various mycorrhiza sources interacted with different biochar rates to effect geraniums (Pelargonium x hortorum L. ‘Maverick Red’). Four different mycorrhizal sources were used in addition to a control containing no mycorrhiza: two commercial sources, MycoBloom and BioAg Vam-Endo, spores extracted from agricultural soils, and spores extracted from prairie soil, with four biochar rates implemented: 0, 15, 30, and 45%. Media with biochar incorporated remained saturated for longer periods after irrigation than pots filled with straight BM-7 peat-media. Prairie soil combined with 15% biochar-BM7 media formed buds and began to flower before all other treatments. Results suggest that biochar and mycorrhiza may pair well to improve potted plant growing.

Nutrient solutions play a crucial role in determining crop yield and quality, with optimized quantities offering sustainability benefits. However, there is a lack of comprehensive research regarding the optimal nutrient application quantity for various leafy green vegetables in recirculating hydroponic cultivation. To address this research gap, we proposed a project on different nutrient application quantities using the nutrient film technique (NFT) hydroponic system in a greenhouse with three replications during the fall (air temp: 24.22°C, RH: 31.2%), winter (air temp: 15.5 °C, RH: 73.3%) and early spring (air temp: 13.7 °C, RH: 72.4% ). The project focused on exploring different nutrient solution quantities of Low (76 liters), Medium (114 liters), and High (151 liters) nutrient regimens for six different leafy green vegetable species and cultivars common in Kansas including red butter lettuce (Lectuca sativa), green butter lettuce (Lectuca sativa), arugula (Eruca sativa), kale (Brassica oleracea), red malabar spinach (Basella alba), and basil (Ocimum basilicum). Our results showed that green butter lettuce and basil remained unaffected by the treatments throughout the study. Additionally, plant height, leaf count, and SPAD value for all species remained consistent across treatments and seasons. However, during the fall, the shoot fresh weight of red butter lettuce and kale increased by 7.11% and 21.1%, respectively, in the high-nutrient regimen. Moreover, the dry shoot weight of kale increased by 18.7% in the high-nutrient regimen, while the dry shoot weight of the red malabar spinach increased by 10.3% in the low-nutrient regimen. In contrast, during winter, the shoot fresh weight of red butter lettuce increased by 18.9% and 25.0%, respectively, in medium nutrient regimens compared to low and high nutrient regimens. Similarly, the shoot fresh weight of red malabar spinach increased by 15.3% and 25.0%, respectively, in low-nutrient regimens compared to medium and high-nutrient regimens. During early spring, the shoot fresh weight of red butter lettuce increased by 17.9-18.0% and that of arugula increased by 17.8% in the high-nutrient regimen, compared to low and medium nutrient regimens. In summary, the high-nutrient regimen benefited red butter lettuce and kale in fall and arugula in early spring. Conversely, during winter, the medium nutrient regimen benefited red butter lettuce, while the low nutrient regimen benefited red malabar spinach. The results from this experiment identified the optimal nutrient application quantity which helps to reduce nutrient waste for vital leafy vegetables in Kansas for different seasons and offers valuable production guidelines for local growers.

Oxygen is crucial for the growth and nutrient uptake of plant roots, especially in crops like strawberries that demand high levels of oxygen in their root zones. However, in hydroponic systems, the nutrient solution is often inadequately oxygenated. In this study, we examined the effects of supplementing dissolved oxygen (DO) into the nutrient solution on the growth of strawberry plants. Inside an indoor vertical farm, bare-root plants of strawberry ‘Albion’ and ‘Eversweet’ were grown using deep water culture hydroponics under a controlled environment of 23 °C air temperature and an 18-h photoperiod, with an extended photosynthetic photon flux density of 350 µmol∙m –2 ∙s –1 . The DO concentration of the nutrient solution was maintained at control levels (no adjustment) or supplemented using an air pump or an oxygen concentrator. The average DO concentrations in the control condition was 70%, while supplementing the nutrient solution with an air pump or an oxygen concentrator increased the average DO concentration to 85% and 100%, respectively. Supplementing with DO had minimal to no effect on the days to root of strawberry bare root plants in both cultivars. Four weeks after the DO treatments, root length, crown diameter, leaf area, and fresh mass of shoot and root were also similar in both cultivars regardless of DO concentration. The effects of supplementing DO on flowering and fruit production will also be presented.

Efficient nutrient management is the key to successful hydroponic production. However, there is a lack of comprehensive research regarding the optimal electrical conductivity (EC) levels for various leafy green vegetables in recirculating hydroponic cultivation. To address this research gap, we experimented with different EC levels using the nutrient film technique (NFT) hydroponic system in a greenhouse with three replications during the fall (air temp: 24.22°C, RH: 31.2%) winter (air temp: 15.5 °C, RH: 73.3%) and early spring (air temp: 13.7 °C, RH: 72.4%). The experiment was conducted using three different EC levels (1.2, 1.8, and 2.4 mS/cm) for six different leafy green vegetables kale (Brassica oleracea) ‘Winter bor F1’ and ‘Toscano’, swiss chard (Beta vulgaris), basil (Ocimum basilicum) ‘Prospera® Compact DMR (PL4)’ and ‘large leaf’ and red malabar spinach (Basella alba). Our results showed that, during the fall, the shoot fresh weight of the ‘Winter bor F1’ increased by 13.1 % in EC 2.4 compared to EC 1.2 and that of Swiss chard increased by 8.3-20.6% in EC 2.4 compared to EC 1.2 and 1.8 while that of ‘Prospera® Compact DMR (PL4)’ basil increased by 13.1-13.9 % in EC 1.8 compared to EC 1.2 and 2.4. In contrast during the winter, the shoot fresh weight of ‘Toscano’ kale, ‘Winter bor F1’ kale, and ‘large leaf’ basil increased by 11.2-17.8%, 18.9-20.8%, and 13.2-14.7%, respectively in EC 2.4 compared to EC 1.2 and 1.8, while that of ‘Prospera® Compact DMR (PL4)’ basil increased by 19.2 % in EC 1.2 compared to the EC 2.4. However, during the early spring, only the shoot fresh weight of ‘Winter bor F1’ kale in EC 1.8 was increased by 10.0 % compared to EC 1.2, while the plant height and fresh shoot weight of large leaf basil was increased slightly by 3.1-5.6% in EC 2.4 compared to EC 1.2. In summary, this experience suggested that ’Winter bor F1’ kale performed best in EC 2.4 during the fall and winter seasons but grew best in EC 1.8 during the early spring. In addition, the 2.4 mS/cm proved the optimal EC level for Swiss chard during the fall, ‘Toscano’ kale during the winter, and ‘large leaf’ basil during the spring. The results from this experiment identify optimal EC levels of vital leafy vegetables in Kansas for different seasons, aiding Kansas growers in reducing nutrient waste and enhancing leafy vegetable production.