ASHS 2024 Conference

Transcriptomic Analysis of Kale (Brassica oleracea) Grown Under Different Light Emitting Diode Wavelengths Revealed Potential Genes Responsible for Phenotypic Changes - Tristan Sanders
Blue Light Mediates Far-Red Light Effects on Increasing Leaf Area and Shoot Mass of Kale and Lettuce - Jiyong Shin
Interactions Between Blue Light and Far-Red Light on Growth of Culinary Herbs - Bridget Knight
Blue and Green Light and Temperature Interactively Regulate Growth, Morphology, Physiology, and Phytochemicals of Lettuce - Sangjun Jeong
Supplemental Blue and UV-B Light Enhances Amino Acid-Derived Flavor Compounds in Greenhouse-Grown Tomatoes - Samikshya Bhattarai
Characterizing the effect of blue light on water relations of unrooted cuttings during indoor acclimation - Ana Sofia Gomez
Shedding Light on Nutrition: The Influence of Supplemental Lighting on Glucosinolate Concentrations in Brassica Plants and Their Potential Anticarcinogenic Effects in Human Diets - Skyler Brazel

Light emitting diodes (LEDs) of different wavelengths significantly influenced kale growth, morphology, and nutrient content. The importance of indoor agriculture is being recognized, but few studies have investigated the influence of LEDs, particularly green wavelengths, on crops at the transcriptome level. The objective of this study was to use RNA sequencing technology to elucidate the genetic response of kale to blue (BV), green (G), and red (RF) LEDs compared to the combination of all the LEDs (RFBVG), control. Results revealed total amount of differentially expressed genes (DEGs) was 1373 for kale grown under BV LEDs, 924 under G LED, and 133 under the RF LED treatments. DEGs enriched in kale grown under RF LEDs played roles in regulating hormone metabolic processes and oxidoreductase activity. In the BV treatment, several enzymes in the phenolic biosynthetic pathway were upregulated compared to the control which may explain previous results reporting higher levels of phenolic content in kale grown under BV LEDs. In the G LED treatment, the expression of genes related to photosynthesis, heme binding, and oxidoreductase activity were upregulated compared to those in the control group. These results may support previous findings of higher iron content in kale grown under G LEDs. Further, the G LED treatment upregulated the expression of cytochrome P450 enzymes, which play key roles in plant growth and stress responses. Understanding the molecular mechanisms underlying the effects of different LED wavelengths by RNAseq provides information to improve indoor cultivation practices that optimize crop growth and nutrient value.

There are contrasting effects of far-red (FR; 700–750 nm) light on leaf area and biomass in plants. These differences have been attributed to photon flux density (PFD) and species/cultivar differences. In a previous experiment, total PFD (TPFD) did not mediate the influence of FR light on leaf area and shoot mass when the TPFD alterations were only of red (R; 600–699 nm) and FR light. Therefore, we hypothesized that blue (B; 400–499 nm) light controls the influence of TPFD in regulating the effects of FR light on leaf area and shoot mass. We cultivated kale (Brassica oleracea var. sabellica) ‘White Russian’ and lettuce (Lactuca sativa) ‘Rex’ and ‘Rouxai’ under 12 lighting treatments with a 24 h∙d−1 photoperiod and TPFDs of 85, 170, 255, or 340 µmol∙m−2∙s−1 and FR fractions [FR-PFD divided by the sum of R and FR PFD] of 0.00, 0.17, or 0.33. The alterations in the TPFDs were solely due to B-PFD; the sum of R and FR PFD was constant in all treatments. Preliminary results indicate that elevated FR fraction did not increase leaf area and shoot mass of all three crops in the absence of B light, when the TPFD was 85 µmol∙m−2∙s−1. However, a high B-PFD and thus TPFD amplified the effects of a high FR fraction at increasing leaf area and shoot mass of all three cultivars. These high FR-fraction effects were correlated with increased biomass partitioning to leaves at a high B-PFD and thus TPFD. These results imply that the contrasting effects of FR light on leaf area and biomass in previous studies could be attributed to the B-PFD. In addition, the influence of TPFD on FR-fraction effects is primarily influenced by the B-PFD.

Light quality can regulate growth and quality characteristics of young plants, but responses of culinary herb transplants are not well understood. Blue light generally inhibits extension growth while far-red light promotes stem elongation and leaf expansion. The objective of this study was to investigate the interaction between blue (400-499 nm) and far-red (700-750 nm) light on six culinary herb species, basil ‘Nufar’, cilantro ‘Santo’, parsley ‘Giant of Italy’, sage ‘Extraka’, mint ‘Spearmint’, and oregano ‘Greek’, with the goal of producing high-quality transplants with compact growth. Six indoor lighting treatments were tested with blue light photon flux densities (PFDs) of 20, 60, or 100 µmol∙m−2∙s−1 and far-red light of 0 or 60 µmol∙m−2∙s−1, with red light (600-699 nm) added so that the total PFD was 210 µmol∙m−2∙s−1 in all treatments. Seeds were sown in 72-cell trays at a constant 23 °C under a 16-h photoperiod and grown for 28-44 days until harvest. As expected, treatments with the highest far-red and lowest blue light PFDs had the greatest extension growth and those with no far-red and high blue light were the most compact. Preliminary results indicate basil, cilantro, and mint exhibited the greatest leaf area under high blue and far-red light. Generally, all species had the highest shoot fresh mass when grown with far-red light. We conclude that blue light and far-red light interact to regulate plant height and leaf area, especially in basil and sage. Therefore, including blue and far-red in the light spectrum should be considered to manage the morphology of young culinary herb plants.

Substituting green (G; 500-600 nm) for blue (B; 400-500 nm) light can enhance crop yield through increasing leaf expansion and photon capture in indoor farming. In addition to yield, the concentration of phytochemicals may also be influenced by varying B to G light ratios. Those responses to B and G light are primarily mediated by cryptochrome photoreceptors. However, cryptochrome activity is further dependent on temperature. We hypothesized that B and G light and temperature could interactively regulate plant morphology, physiology, and secondary metabolites, consequently impacting crop yield and nutritional quality. Two cultivars of lettuce (Lactuca sativa L.), ‘Rouxai’ and ‘Rex’, were grown under three temperatures (20, 24, and 28 ℃) and five spectral treatments composed of B, G, and red (R; 600-700 nm) light (B40G0R60, B30G10R60, B20G20R60, B10G30R60, and B0G40R60). The subscript number following each light type represents its percentage in total photon flux density (TPFD; 400-800 nm). TPFD was maintained at a constant level of 200 μmol·m-2·s-1, with R photon flux of 120 μmol·m-2·s-1 (60% of TPFD) in all treatments. Results revealed that light spectra and temperature interactively influenced plant morphology. Specifically, in Rouxai, increasing G light from 0% to 40%, coupled with decreasing B from 40% to 0%, linearly increased total leaf area at all three temperatures. Notably, the substitution of G for B light caused the greatest leaf expansion at 24 ℃ (a 64% increase at 20 ℃, a 90% increase at 24 ℃, and a 32% increase at 28 ℃). In Rex, substituting G light for B light up to 30% increased total leaf area at 20 and 24 ℃, but not at 28 ℃. Similar to Rouxai, the spectral effect on the leaf expansion of Rex was greater at 24 ℃, compared to 20 ℃. Shoot dry weight responded to spectral and temperature treatments similarly as total leaf area. Secondary metabolites (e.g., phenolics and flavonoids) and antioxidant capacity consistently decreased with increasing G light (or decreasing B from 40% to 0%), but the decline was more pronounced at warmer temperatures. Without significant interaction between light spectrum and temperature, chlorophyll and carotenoid contents decreased with increasing G light. Thus, we concluded that the proportion of B and G light and temperature interactively regulated plant morphology and secondary metabolites, ultimately affecting crop yield and nutritional quality. Our study emphasizes the importance of considering the interaction between light spectrum and temperature in optimizing production systems.

Tomato production under controlled environmental conditions presents challenges due to the selective permeation of solar radiation within enclosed structures or the limited wavelengths produced by artificial light sources. Despite these challenges, growers increasingly opt for such production systems due to the enhanced uniformity and yield of fruit compared to open-field cultivation. However, controlled environment conditions, particularly greenhouses, often limit specific wavelengths of light, including blue and UV-B radiation. This limitation has the potential to alter flavor and overall fruit quality. Therefore, the present investigation examined how supplemental blue and UV-B light, independently and in combination, influence the levels of amino acid–derived flavor compounds, particularly those derived from branched-chain and aromatic amino acids, in two tomato varieties, Plum Regal (PR, commercial) and TAM HOT-Ty (THT, Texas A

Managing water loss of unrooted cuttings (URC) during acclimation is critical to decrease crop losses and shorten rooting time. Vertical indoor propagation (VIP) systems that use indoor-farming technologies enable the opportunity to optimize the environment for URC acclimation. However, recommend environmental setpoints for VIP systems are unknown. Light quality affects various morphological and physiological processes in plants, and blue light in particular, has an effect on stomatal opening and plant size, both of which regulate water relations of plants. Therefore, the objective of this study was to characterize short-term effects of increasing percentages of blue light on water relations of Chrysanthemum ‘Crystal Bright’ and Begonia ‘Dark Britt’ URC. Four light-quality treatments were evaluated: 15%, 30%, 45%, or 60% blue light. All treatments provided a photosynthetic photon flux density of 70 µmol·m–2·s–1 delivered by broadband and monochromatic-blue light-emitting diode fixtures. Ambient temperature, relative humidity, and carbon dioxide concentration were set at 22 °C, 70%, and 420 μmol·mol–1. Water uptake and water loss were evaluated by placing individual URC in vials with and without water, and exposing them to each treatment for 24 or 48 h, respectively. Changes in water loss were also recorded at various intervals for 24 h. Water uptake of Chrysanthemum linearly increased as blue-light percentages increased. In contrast, water uptake followed a quadratic response for Begonia, which peaked at 45% blue light. Water loss also followed a quadratic response for begonia, with increasing values up to 30% blue light. Water loss of Chrysanthemum followed linear response to increasing blue light. After 24 h, water loss of Chrysanthemum linearly increased with increasing blue light, from 0.65 to 0.76 g under 15% and 60% blue light, respectivey. There were no treatment differences for stomatal conductance, but leaf vapor pressure deficit linearly increased with increasing blue light, regardless of species. These findings show that blue light affects water relations of URC, which should be considered when making lighting recommendations for VIP systems.

Learn about advancements in efficient gas exchange research and quality data collection with the CIRAS-4 Portable Photosynthesis System and our partnerships with users to advance precision plant science. In addition, we will share new research collaborations with the NCSU-CEA coalition and our on-site container farm for CEA research. Talk to our research team about working together to further your research. It will be an action-packed 15 minutes. Don’t miss it!

Brassica plants contain important secondary metabolites, such as glucosinolates, and provide a nutritious addition to the human diet. Glucosinolates, when hydrolyzed, yield isothiocyanates which can affect the carcinogenesis process, and further research into increasing glucosinolate concentrations in plants is important for determining anticarcinogenic properties of brassicas in human diets. Kale (Brassica oleracea var. acephala cv. ‘Toscano’ ) and Arabidopsis (Arabidopsis thaliana, Col-0) were grown in the greenhouse under natural light (control) and subjected to three additional supplemental light treatments to determine the impact of supplemental LED lighting on glucosinolate concentrations. Treatments included no supplemental light (control), 75:25 Red:Blue LED, 50:50 Red:Blue LED, and Warm White LED light at 100 μmol.m-2.s-1 each. Plants were harvested when the first kale treatment group reached a leaf number of 7, and when half of all Arabidopsis flowers began opening. Harvested plants were analyzed for glucosinolate and mineral nutrient concentration. Statistical analysis on Arabidopsis data revealed significant differences among light treatments in glucosinolate concentrations, particularly glucoraphanin and gluconasturtiin. Additionally, significant differences were found in leaf and petiole mass and leaf number of both kale and Arabidopsis at harvest. The no supplemental light control produced the lowest harvest mass compared to plants receiving supplemental light. Preliminary qPCR analysis of Arabidopsis displays variations in the relative expression of genes CYP79B2 and CYP83A1, varying across treatment when compared to the control. Glucosinolate analysis of kale resulted in no statistically significant differences among all four light treatments. However, glucosinolates, including gluconapin, glucoraphanin, gluconasturtiin, and several unknowns, were found to be present across all four treatments. As glucosinolates are stress-response compounds, their lack of variation in kale and significant variation in Arabidopsis under different light environments indicate that other environmental factors also play a crucial role in their production. Further research is necessary to identify abiotic and biotic factors influencing their concentration in the greenhouse environment for both species.

Plant Nutrient Management Interest Group
The purpose of this meeting is to align the ASHS mission to develop nutrient management strategies for horticultural field and controlled environment-grown plants, (1) to maximize plant productivity, and (2) to reduce environmental footprints by restricting nutrient loss where it can impact greenhouse gas emissions and water quality.

Sponsoring Professional Interest Groups
Technology: Coordinator Milt McGiffen - milt.mcgiffen@ucr.edu
Teaching Methods: Coordinator, Kathryn Orvis – orvis@purdue.edu
Controlled Environment: Coordinator, Kent Kobayashi - kentko@hawaii.edu

Supporting Professional Interest Groups
Federal Partners: Matthew Mattia - Matthew.Mattia@usda.gov
Plant Biotech: Kedong Da - kda@ncsu.edu
Ornamentals/Landscape and Turf; Youping Sun - youping.sun@usu.edu
Local Food Systems: Charles H. Parrish II - chip.parrish@pm.me

Artificial intelligence and related topics, e.g., robotics, have been a long time coming in agriculture. For decades there have been predictions of intelligent robots replacing humans, and large farms run by a few humans with many autonomous tractors and other devices. But with the now widespread use of artificial intelligence in everyday life,
the moment has arrived. We developed this colloquium by casting a wide net out to all the Professional Interest Group Chairs, and have assembled talks and demonstrations from general topics to specific applications.

Two online meetings were held, where Professional Interest Groups officers and those interested suggested speakers and discussed topics. Further discussions over email helped fill in the details to create this colloquium.

We will have a block of speakers for the diverse topics we present below, as well as panel discussions on how AI is and can be incorporated into various aspects of Horticulture, so that there is ample time for questions and discussion.

Title: Overview of the Colloquium

Speaker: Milt McGiffen, Cooperative Extension Specialist, Department of Botany and Plant Sciences,
University of California, Riverside, CA.

AI in Ornamentals

Title: FloraCount: An App for Rapid Assessment of Pollinator Attractiveness to Annuals and Perennial Plants.

Description: Customers are interested in buying annuals and perennials that support pollinators. Protocols for rapid assessment in flower trail evaluations are not available. We have developed a mobile app that can be used to analyze in real time the users’ observational data and quantitatively rank the relative utility of observed cultivars to pollinator communities. This app takes into account pollinator groups, relevant floral characteristics and landscape.

Presenter: Harland Patch
Assistant Research Professor
Department of Entomology
Penn State University
549 Ag Sciences & Industries Building
University Park, PA 16802

Title: Approach to Biodiversity Protection: Employing AI and IoT Systems for the
Containment of Box Tree Moth Proliferation.

Description: The box tree moth (BTM, Cydalima perspectalis) is an invasive pest first confirmed in Niagara County, New York in 2021. This invasive pest can significantly damage and potentially kill boxwood (Buxus species) plants if left unchecked. This presentation describes our advances in combining deep learning algorithms for enhanced computer vision with IoT-enabled smart traps, to facilitate the early detection and continuous monitoring of BTM populations and to protect the prevalent ornamental boxwood in U.S. landscapes.

Presenter: Yanqiu Yang (she/her)
Ph.D. Graduate Research Assistant
Department of Agricultural and Biological Engineering
Pennsylvania State University
3 Agricultural Engineering Building
University Park, PA 16802

Title: Landscapes from Words: The Future of Landscape Design with AI.

Description: The ongoing text-to-graphic artificial intelligence (AI) revolution has the potential to change the field of Landscape Architecture dramatically. The ability to produce original high-quality graphics, manipulate the viewer's perspective of images, and amend the rendering style through text inputs are significant advancements that will
inform new design process models. These changes can lead to expanded design exploration, improved accessibility for non-designers to contribute to creating visual concepts, enhanced ability to integrate data analysis and visualizations, and streamlined collaboration between clients and project stakeholders using a shared visual language. This talk focuses on two dimensions of change that may result from the rapid evolution of text-to-graphic AI, including (1) faster iterations and exploration of design options and (2) the advancement of methods that result in more inclusive and responsive design. In the classroom, students are just beginning to acknowledge the existence of text-to-graphic AI, which allows them to experiment with text-based design options that allow them to quickly visualize and explore a wide range of site program alternatives. Nevertheless, how do we manage the ethical and creative boundaries within an academic setting? In a research context, methods supporting rapid manipulation of both generated images and existing landscape photography represent advances that allow for greater collaboration surrounding landscape design decisions (Incorporating resilience strategies, protecting vernacular landscape elements that support a sense of place, or representing new design proposals that modify the landscape). These approaches allow stakeholders to gain remarkable advances in influencing the design process through shared visualization development. However, as with any emerging technology, practitioners, educators, and researchers need to respond to the challenges presented by text-to-graphic AI by developing and testing new design process models and public engagement techniques that can improve landscape decision-making and streamline collaboration.

Presenter: Aaron Thompson
Assistant Professor
Department of Horticulture and Landscape Architecture
Purdue University
625 Ag Mall Drive
West Lafayette, IN 47906

Title: Developing Guidelines for Extension’s Use of ChatGPT and Other Generative AI
Tools.

Description: A new technological era marked by the advent of Artificial Intelligence (AI), particularly generative AI and Large Language Models (LLMs) like ChatGPT has necessitated the need to navigate this domain with a compass of ethicality, safety, and effectiveness. Penn State’s experience developing guidelines for Extension’s use of
generative AI tools which will be shared and discussed.

Presenter: Michael Masiuk
Assistant Director – Horticulture Programs
Penn State Extension
342 Agricultural Administration Building
University Park, PA 16802

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