ASHS 2024 Conference

Seventy Years of Evaluations and Selections of Ornamentals by the NDSU Woody Plant Improvement Program. - Todd West
Tea Plant Propagation for Nursery Production - Carol Miles
Establishment of Fraser Fir Christmas Tree Plantations in Response to Mulch and Root Dips - Bert Cregg
Cultivating Control: Effective Suppression Methods for Jumping Worms in Container Nursery Production - Jenna Simon
Effects of Water Quality and Fertilization Practices on Container Tree Growth in Nurseries - Zachary Davis

The North Dakota State University (NDSU) Woody Plant Improvement Program has been servicing the Northern Great Plains for 70 years, beginning germplasm trial evaluations in 1954. NDSU purchased an 80-acre (~32 hectares) farm in the early 1970s to be established as the NDSU Horticulture Research Farm near Absaraka, ND and began trial plantings in fall of 1974. This research farm provides ideal horticultural soil for evaluation and breeding projects for ND. Approximately 45 acres (~18 hectares) of this farm is used for evaluation, selection and breeding of woody ornamental plants including a 35-acre (~14 hectares) research arboretum. This research arboretum is the most extensive collection of woody ornamental plants in North Dakota and in the Northern Great Plains. There have been over 15,000 accessions obtained, evaluated, and developed since planting began in 1974. Accessions have been collected from local, regional, national, and international sources. After 50 years, this program has introduced 62 superior ornamental woody plants for production and sale with 44 active registered trademarks with the U.S. Patent and Trademark Office. NDSU woody plant introductions have a nursery wholesale sale value of over $2.0 million and a $6.0 million value in retail sales for 2022 alone. Introductions are currently being propagated for sale by commercial wholesale firms in four countries: Australia, Canada, England, and the United States (22 states, including 35 nurseries). The primary focus of this program is with increasing the diversity and availability of woody plants with increased disease/insect resistance and winter hardiness for landscapes throughout North Dakota, region, and nation. One issue that this program is addressing is that native woody (trees and shrubs) plant species diversity is extremely low in the central United States, especially in North Dakota. Most of the available trees and shrubs in the specialty crop nursery trade in North Dakota are non-native introductions. Many non-native plants have been shown to be invasive to native environments. Woody plant research has reacted to this issue utilizing sterility breeding. This results in new cultivars that are not considered invasive and are allowed to be utilized by the commercial nursery and landscape industry, even in states where they are banned. Sterility breeding through polyploid induction has become a focus of the NDSU Woody Plant Improvement Program. The research focus of this project is to induce, or develop, polyploids produce sterile cultivars to be used in the nursery and landscape trade.

Tea (Camellia sinensis) is the second most popular beverage worldwide and the U.S. annually imports 240 million pounds of tea. The limited availability of tea cultivars and limited knowledge for tea plant propagation are primary barriers for tea production in Washington and the U.S. overall. Time of year and section of shoot for propagation cuttings were tested in northwest Washington for tea cultivar Minto Pacific. Shoots were collected on 8 and 21 Sep, 6 and 24 Oct, 3 and 21 Nov, and 8 Dec 2022, and 18 Jan and 8 Feb 2023, then processed into top, mid, and bottom section cuttings. The bottom end of each cutting was scored (1-2 inches depth) using a knife, dipped into rooting hormone for 5-10 seconds, and placed into a treepot filled with propagation media (5:3:2 ratio peatmoss, vermiculite and perlite, pH 4.5) with the bottom node leaves resting on the mix line. Treepots were placed in a mist chamber with 50% shade and 70-80% relative humidity for 4 months. Survival rate was greatest for shoots collected from 21 Sep through 8 Dec 2022: 99.5% on average 4 months after collection. Cuttings from 8 Sep 2022 had the lowest survival rate overall: 77% at 4 months after collection. Top, mid and bottom section cuttings had an average survival of 96.7%, 95.8% and 94.7% at 4 months after collection. Plant height at 4 months after collection was greatest for cuttings collected on 8 Feb (6.6 cm) and lowest for all other dates (4.5 cm on average). Overall, cuttings from the mid and bottom sections had the greatest plant height at all times: average 5.0 cm at 1 month, average 5.1 cm at 2 months, average 5.2 cm at 3 months, and average 5.6 cm at 4 months. The number of new leaves measured in June 2023 was greatest for top and mid sections of the shoot (3.8 leaves on average) while the bottom section had the lowest number of new leaves (2.8 leaves on average). The overall health rating up to 4 months after collection was highest for cuttings collected on 6 and 24 Oct, and 8 Dec (more than 4.5 on average for all months). The top section of the shoot had the highest rating for overall health in all months (≥ 4.5). Keywords: Camellia sinensis, Cuttings, Northwest Washington, Vegetative

In the Great Lakes region of the United States Christmas tree plantations are established by planting seedlings or transplants. Reducing plant moisture stress after planting is crucial to successful establishment of these small conifers. A myriad of products have been marketed to Christmas tree producers with claims to improve transplant success by limiting transplant shock. Since 2021, we have conducted a series of field trials in collaboration with Michigan Christmas tree growers to evaluate the effect of root dips, mulching and other cultural practices on transplant survival and growth. Root dip products applied immediately prior to planting included: DieHard™ Root Dip (endo/ecto mycorrhizae polymer), MycoApply® Injector Ecto (ectomycorrhizae), SoilMoist™ Fines, and Roots® Terra-Sorb® Fine Planting Gel (polymer). Cultural treatments that were applied following planting included: foliar antitranspirant spray (Wilt-Pruf® [25% di-1-p-menthane]), wood chip mulch, shade blocks (20.3 cm x 30.5 cm mesh screen), controlled release fertilizer, and biochar. Root dips did not affect tree survival or growth in any of the trials. Mulch and shade blocks increased shoot growth at several farms. Improved survival of trees under mulch was associated with improved soil moisture. Mulch did not affect foliar nitrogen (N) concentration, indicating that mulch did not ‘tie-up’ N. The application of Wilt-Pruf reduced transpiration but also reduced photosynthetic rate, resulting in a net decrease in shoot growth. Fertilization at planting significantly reduced survival on two of four sites. Overall, the results suggest that cultural treatments, especially mulch, are more likely to improve plantation establishment than root dips.

Keywords: Amynthas spp., Biological Controls, Invasive Species, Soil Health, Temperate Ecosystems Jumping worms (Amynthas spp.) present a significant threat to biodiversity and overall soil health across temperate ecosystems. In forest systems, jumping worms alter ecological dynamics by impacting the organic litter layer, soil structure and chemistry, food web functionality, and nutrient cycling processes. These annual, hermaphroditic worms reproduce through parthenogenesis and inhabit the top few inches of moist soils. They survive extreme temperatures in their cocoon stage with the possibility of remaining dormant for several growing seasons. One inadvertent method of jumping worm spread is through container-grown nursery stock and horticultural substrates. In nursery production, jumping worms modify plant quality by consuming organic matter such as roots, altering substrate structure and chemistry in the container, and contributing to excessive nutrient leaching. The rapid movement of these worms may also impact consumer buying potential and preference. There are currently no products listed for controlling jumping worms in the United States, leading to challenges with the management of their spread. We hypothesize that control methods not yet listed for jumping worms in the United States have the potential to effectively suppress jumping worm populations in container-grown crops. Our objective was to further evaluate chemical and biological approaches for managing jumping worms in container nursery production systems. Treatments included a non-treated control, BotaniGardⓇ (2 Tbsp/gal), Thiophanate-methyl fungicide (0.625 mL/400mL), Sodium lauryl sulfate (2 mL/L ), Cedarwood oil (1.5625 mL/L), ConserveⓇ (0.317 mL/400mL), Castaway 3-0-1 Tea Seed Meal Fertilizer (2.7 g/pot), Slug MagicTM (0.5 oz/pot), and SevinⓇ (8.75 mL/400mL). The results of this work suggest differential efficacy between treatments and highlight options with potential for application in horticultural production. Identifying effective control methods benefits the scientific community and the horticultural industry by providing a foundation for future research activities centered on jumping worm management as well as limiting their spread through horticultural products. These findings support growers by outlining potential management practices that demonstrate efficacy for controlling jumping worms in the Amynthas genus.

The Covid-19 pandemic and ensuing lockdowns led to an increase in revenue and production for green industry products in early 2020. In Study 1. an evaluation of fertigation (liquid feed, quick release) and controlled release fertilizers (CRFs, slow release) were applied to container-grown (7 gallon) live oak (Quercus virginiana) and Nutall oak (Quercus nuttallii) trees (100% Liquid feed, 0% CRF, 67% Liquid feed, 33% CRF, 33% Liquid feed, 67% CRF, 100% Liquid feed, 0% CRF). Live oak trees fertilized with CRFs had increased stem calipers (>30%). Nuttall stem caliper and height were significantly increased by 62% and 58%, respectively, with substrate incorporation of CRFs. Live oak tree height was increased by 35% and stem caliper when CRFs were incorporated. In study 2, the effect of alkaline water quality on live oak tree production was initiated at a nursery in Point Coupee Parish. Ca and Mg sources were used to study the impact of water quality on live oak tree container-growth and study the benefits of using different rates of lime and gypsum [0% dolomitic lime (Ca, Mg), 100% gypsum (Ca) Epsom salt (Mg), 25% dolomitic lime (Ca, Mg), 75% gypsum (Ca) Epsom salt (Mg), 50% dolomitic lime (Ca, Mg), 50% gypsum (Ca) Epsom salt (Mg), 75% dolomitic lime (Ca, Mg), 25% gypsum (Ca) Epsom salt (Mg), 100% dolomitic lime (Ca, Mg) 0% dolomitic lime]. Live oak tree growth measurements increased with the reduction of dolomitic lime and increase of Epsom salt and gypsum applications. Leaf Na content was significantly reduced using higher proportions of gypsum and Epsom salt. Soil pH was also reduced by more than 1 pH unit after a growing season. Soil pH did increase when irrigated with highly alkaline water. Growers using alkaline water need to manage irrigation water and soil pH and consider using gypsum and Epsom salt reducing dolomitic lime rates as a source of Ca and Mg. All Ca and Mg sources provided greater than the threshold levels of leaf Ca and Mg content.

A Mentor-Mentee Undergraduate Scientific Communications Course - Danielle Jaden Yamagata Santos
Growth and Volatile Compounds on Thai Herbs at Different Cultivation Systems in Vertical Farming - Akira Kakai
Growth, Anthocyanin Content and Its Gene Expression in Purple Color Paprika Fruit Applying Blue Light at Night - Ryuhei Mitsuzuka
The Effect of Mixing Artificial Seawater into Hydroponic Solution to Tomato Fruit Growth and Ion Contents - Miyuki Baba
Detection of Postharvest Quality of Cut Roses using Vis/NIR Spectroscopy - Ji Yeong Ham
Developing Utah’s Own Sap Drinks - Catherine Sun
Effect Of Temperature Alterations On Phytochemicals Accumulation Among Two Variety Of Feverfew Cultivars - Jalynn Greer
Increased Airflow Improves Yields of High Density Indoor Micro Dwarf Tomato - Matthew Arrington
Assessing the Impact of Urban Environments on the Biomolecular Composition of 'Mosco' Chili Peppers - Kathryn Braun
Growth and Physiology of Three Buckwheat Cultivars under Reduced Substrate Water Contents - Sawyer Zook

TPSS 491 Scientific Communications is a new one-credit undergraduate course in the TPSS Department. It was offered for the first time in Fall 2023 with six undergraduate students. The objective was to enable personalized instruction and mentoring of students on their projects. Consulting with the instructor, each student decided on two projects to work on. Students indicated what specific feedback they were looking for, and the instructor provided individualized assistance. One-to-one meetings enabled more detailed personal instruction. Students were more motivated when working on their own projects. This course’s flexible meeting dates and times allowed tailoring it to each student’s schedule. TPSS 491 helped me to develop and complete personal projects that are crucial in professional development. The flexibility of the course allowed me to partake in one-on-one meetings that worked with my schedule as a full-time student which was one factor why I decided to take this course. Being able to receive personalized feedback on my projects allowed me to make constant improvements that made me feel confident in my work, especially as I plan to use these as tools to enter the professional setting after graduation. The course’s flexible scheduling and wide choice of projects were very appealing to me. As an upper-class student, I had multiple ongoing research projects, more classes than usual, and a research-based part-time position. Each commitment involved weekly meetings, assignments, and demanded a significant portion of my time and attention. However, the flexibility of the “To Be Determined” scheduling of the course created more freedom within my schedule, providing me with the necessary time to complete my other projects and courses. Having the choice to decide which projects to work on enabled me to receive valuable feedback on an important graduate school funding application and a research project. Without this flexibility, I might not have received as much feedback on these important parts of my academic journey. In conclusion, TPSS 491 is an important course for undergraduate students to receive valuable feedback from the instructor regarding scientific communication. TPSS 491 proved to be an invaluable course for me. The constructive feedback I received on my projects was instrumental in my personal and academic growth. This course allowed me to focus on projects that held significance for my academic and professional development and provided the flexibility needed to balance various commitments required to advance my experience as an early-career researcher.

Thai culinary herbs such as coriander and sweet basil become popular. For production of them in vertical farming, we need to investigate the suitable growing conditions, especially the relationship between nutrition condition in the root zone and vegetation growth. Moreover, we investigated the aroma quality under these conditions. Here, we report the comparing of nutrient conditions at both of perlite and hydroponic cultivation. Thai coriander (Coriandrum sativum ‘Saisamorn’) and Thai sweet basil seeds (Ocimum basilicum ‘Micro’) were sown under white LEDs for 24 hr. After 14 days, seedlings were transplanted into deep flow hydroponic culture in environment-controlled growth chamber at air temperature of 25℃, 60% relative humidity, and luminance at PPFD 450 µmol/m/s. The photoperiod was set for 16 hr. light and 8 hr. dark. Different concentrations ranged from EC 1.6, 2.0, and 3.5 at pH 5-6 of nutrient solution were supplied to hydroponic system and perlite system. The perlite system was used by mixing vermiculite with perlite at ratio of 1:2. The mixture of vermiculite and perlite was poured into planter for herb cultivation. Dripping tubes were provide for irrigation. After 40-50 days of transplant, vegetative growth; fresh weight, shoot growth, root length, and stem growth were measured. The major aromatic compounds for coriander such as Decanal, Dodecanal, (Z)-3-hexenol, (Z)-3-hexenyl acetate, and trans-2-dodecenal, and major aromatic compounds for sweet basil such as linalool, eugenol, methyl eugenol, estragole, eucalyptol were evaluated by using GC-MS. The growth and volatile compounds of coriander and sweet basil are varied toward nutrient solution condition and cultivation systems. As the result of this study, it can be assumed that we have found one of the optimum conditions to cultivate Thai herbs in a controlled environment.

In this study, we investigated the effect of night blue lighting on anthocyanin content and expression of its transcription factors and structural genes in purple paprika fruits. Purple paprika fruits (Capsicum annuum L. ‘Tequila’) were used for this experiment. Before light treatment, we used fifty plants grown under hydroponic conditions (EC 2.5, pH 6.0) in a greenhouse. At 10 days after pollination, we started irradiating the fruits at night with blue LEDs light at wavelength 460 nm and radiation intensity at 500 W-m-2. Control is non-irradiated treatment. Fruits were harvested at 15, 20, and 40 days after pollination, for fresh weight evaluation, then following analysis was performed. In the pigment analysis, anthocyanin content was determined based on cyanidin-3-glucoside. By adding 10% acetic acid to frozen ground fruit sample overnight at 4C, the absorbance was measured at 530 nm. In the gene analysis, RNA was extracted from fruit and cDNA was transcripted using kit with gDNA eraser. Then, cDNA template was mixed with PCR Master Mix for quantitative RT PCR analysis. The result was calculated as relative expression to UBI. As the results, fresh weight was not affected by light. Anthocyanin content of treated fruit increased approximately twice as much as that of control fruits at 15, 20, and 40 days after pollination. Furthermore, the expression levels of transcription factors; HY5, MYB, bHLH, and WDR, and structural genes; PAL, CHS, F3H, ANS, DFR, and UFGT increased in treated fruits. These results indicate that blue light irradiation enhanced anthocyanin synthesis in purple paprika fruits, by increasing the expression of its transcription factors and structural genes.

NaCl has been frequently used for applying salt stress to plants. However, in this study, we tested to use sea salt instead of NaCl for applying salt stress to tomato plants. Plants were grown under hydroponic conditions, mixing artificial seawater to nutrient solution (liquid fertilizer). To estimate strength of the stress treatment, we used EC (Electrical Conductivity) value to control it. Fifty-six seedings of two tomato varieties ('Momotaro York' and 'Saturn') were grown at deep flow technique in a greenhouse, and the stress treatments were applied 10 days after the first truss bloomed. In experiment 1, we designed 3 treatments (EC was set for 5.0, but the ratio of Liquid Fertilizer : Artificial Seawater were 5.0 : 0, 1.5 : 3.5 and 2.5 : 2.5, respectively). In experiment 2, we designed 3 treatments (EC for liquid fertilizer was set at 1.5, but the concentration of artificial seawater was different as Liquid Fertilizer : Artificial Seawater were 1.5 : 0, 1.5 : 3.0 and 1.5 : 6.0, respectively). Fruits were harvested at almost 90 days after blooming and fruit weights were measured. The contents of 5 cations and 3 anions in fruit were analyzed by high-performance liquid chromatography (HPLC), then we added all of the ions contents as total ion contents. As a result, fruit weight was not different significantly at experiment 1, but decreased when EC value was increased at experiment 2. In experiment 1, when the ratio for liquid fertilizer was increased, the total ion contents were increased, especially Na in treatment at (1.5 : 3.5) and Ca2 in treatment at (5.0 : 0) were increased. At experiment 2, total ion contents increased when the ratio of sea salt was increased. In conclusion, we estimated various strength of stress by EC value in this study. Then the different ratio of liquid fertilizer and artificial seawater caused different ion contents in tomato fruits. This result was similar for the two varieties.

Visible and Near-infrared (Vis/NIR) spectroscopy is widely used to analyze plant physiological state and chemical properties non-destructively and rapidly. Recently, Vis/NIR spectroscopy has been used to analyze and estimate the photosynthesis capacity, water content, and soluble solids content (SSC) in various horticultural crops such as fruits and vegetables. Cut roses are often sensitive to water stress under unfavorable conditions during storage and transportation. Water stress of cut flowers generally leads to premature wilting of leaves and petals, thus decreasing the vase life of cut flowers. In this study, we measured the water content and SSC and evaluated the postharvest quality of cut roses using Vis/NIR spectroscopy to screen the quality of cut rose flowers for promoting exportation. Cut roses underwent either wet transport (WT), dry transport (DT), or dry and sucrose treatment, to identify the characteristics of reflectance wavelengths (RW) closely correlated with water content of cut flowers based on Vis/NIR data. Our results showed that dry treatment reduced the vase life and maintenance of positive water balance (PWB) and initial fresh weight of cut roses. Sucrose treatment exhibited a longer duration of retaining PWB and increased SSC in the petals and leaves of cut rose flowers. WT resulted in cut roses with a longer vase life of 1.4 d, compared to DT. DT treatment also decreased the capacity of the cut flowers to maintain PWB by 0.7 d compared to WT. Our results also showed that the Vis/NIR reflectance of the rose petals in the wavelength range 620-720 nm differed among treatments. In particular, the water balance of cut roses showed a positive correlation with RW735 nm and a negative correlation with RW680/RW(620 720) nm, while the SSC of cut roses was positively correlated with RW680/RW(620 720) nm. These results imply that it is possible to evaluate and screen the postharvest quality of rose flowers based on the water relation of cut flowers using Vis/NIR spectroscopy data.

Maple products, such as syrup, sap-based beverages, soft drinks, candies, and butters, are significant agricultural commodities in Canada and the northeastern United States. In recent years, syrup derived from various maple sources, including bigtooth maple (Acer grandidentatum), boxelder maple (Acer negundo), Norway maple (Acer platanoides), silver maple (Acer saccharinum), and sugar maple (Acer saccharum), has been commercialized in the Intermountain West. However, producing one gallon of maple syrup requires approximately 40 gallons of sap and consumes substantial amounts of energy and time due to the need for extensive heating and evaporation. Utilizing sap as a drink can help conserve energy, expand the sap product market, and retain essential minerals with potential health benefits. The purpose of this study was to develop and evaluate beverages made from sap obtained from bigtooth maple, boxelder maple, and Norway maple. Sap samples were gathered from maple trees in Cache County, Utah, filtered through a food-grade filter, bottled in 12 oz glass containers, sealed, and then autoclaved at 121°C. Sugar concentration in both raw and autoclaved sap samples was determined utilizing a refractometer, while comprehensive mineral analyses were conducted by submitting samples to the Utah State University Analytical Laboratories. These drinks contain rich mineral nutrients, varying with plant species. A Utah’s Own designation will be applied to these drinks.

Feverfew, a member of the Asteraceae family, has a long history of traditional use for various health purposes, including anxiety and depression management, and alleviating arthritis and inflammation. Feverfew consists of a specific chemical compound named parathenolide which is a phytochemical naturally found in Tanacetum parthenium, which plays a significant role in being responsible for feverfew’s anti-inflammatory effects. This study aims to investigate the effect of the temperature changes in parathenolide accumulation among two varieties Matricaria Tetra White and Matricaria Tetra Virgo Feverfews based on their genetic differences. Feverfew cultivars will be grown in a container containing potting mix which has enough nutrients for plant growth and development. The two varieties will be randomized with each variety receiving varying temperature differences (low, medium, and high). The accumulation for parathenolide will be analyzed using HPLC analysis to evaluate the accumulation of the phytochemical in each variety in response of the differences in temperatures. Among the phytochemicals of interested in this study include an understanding the effect of temperature on the accumulation and synthesis of the phytonutrients can highly assist scientists and health care professionals to increase and promote medicinal plants. Feverfew can benefit low-income communities like urban areas where majority of the community members are incapable to afford medication that can treat sickness such as anxiety and depression.

Indoor agriculture production allows producers to control all of the environmental parameters given a system with enough sophistication. However, the expense of comprehensive systems is prohibitive from an economic standpoint, in most cases. Identifying the most important parts of the plant environmental experience to control is a critical part of building efficient and economical indoor farms. In this study with temperature, nutrition, lighting and other aspects of the farm being controlled, airflow was manipulated. Micro dwarf cherry tomato varieties (Solanum lycopersicum ‘Tiny Tim’ and ‘Pinocchio Orange’) were grown in an NFT style hydroponic systems for 90 days. All plants were grown in a greenhouse with natural and supplemental lighting. Control plants received airflow native to the greenhouse environment, mixing fans, ridge line vents and pad fan based HVAC control. The treated plants experienced a “high air flow” condition. The results indicate a clear improvement in the fruit weight, number of fruit per plant, and fruit diameter for plants which experienced increased airflow. These results, while preliminary, demonstrate the clear advantage of additional airflow targets for indoor plant production and provide the basis for an important indoor production lever to improve yields in micro dwarf cherry tomatoes.

The rapid increase in urban populations and urbanization, coupled with the increasing demand for natural resources, has underscored the critical significance of global sustainability. Urban farming has been recognized as a promising solution to address these challenges. Despite the growing popularity of urban agriculture, there is a lack of research on how the built environment and urban micro-climates impact plant growth and food crops cultivated in cities. Our study aims to address this gap in knowledge by investigating how urban climates impact the growth and quality of 'Mosco' chili peppers, a significant crop in the Southwest United States. Peppers were cultivated in four different locations at the CSU Spur research facility in Denver, Colorado, including a ground-level plot, two rooftop areas with varying sunlight exposure, and a rooftop site under a solar panel array. Throughout the growing season, climate data and plant growth metrics were consistently monitored. Post-harvest, we characterized the biomolecular composition of the peppers using standardized methods from the Periodic Table of Food Initiative (PTFI). Collectively, the results of this study offer valuable insights into the impact of urban environments to the production and quality of peppers, informing sustainable urban farming practices and enhancing our understanding of plant adaptability in city settings.

Instances of water scarcity attributed to insufficient precipitation have amplified across the western United States (U.S.), leading to restrictions on ornamental plant irrigation. Fagopyrum esculentum (buckwheat) is widely used in pollinator-friendly U.S gardens due to its ornamental value and significance to pollinators. However, buckwheat's drought tolerance has not been widely investigated. The objectives of this research are to determine the effects of substrate volumetric water content on the visual quality, growth, and physiology of F. esculentum (common buckwheat), F. esculentum ‘Rose Red Soba’ and F. esculentum ‘Takane Ruby’. Cultivars were grown in an electromagnetic sensor-based automated irrigation system at substrate volumetric water content of 0.10 m3·m-3 (drought) and 0.40 m3·m-3 (control) for 35 days in a greenhouse. Plant growth index [(height (width 1 width 2)/2)/2], proportion of visibly wilted leaves, and the number of flowers were recorded weekly throughout the experiment. Gas exchange parameters were recorded at the termination of the experiment. Decreased substrate volumetric water content increased the number of visibly wilted leaves on three buckwheat cultivars. The plant growth index and number of flowers also declined as substrate volumetric water contents decreased from 0.40 to 0.10 m3·m-3. Alternatively, 'Rose Red Soba' and common Buckwheat exhibited a lower net photosynthesis rate in decreased substrate volumetric water content. Drought treatment also led to decreased stomatal conductance among all three buckwheat cultivars. Our results indicate that drought could impair buckwheat's ornamental value and growth due to the increased accumulation of visibly wilted leaves and decreases in plant growth index. Additionally, buckwheat's ability to attract pollinators could decline under drought conditions due to the loss of flower abundance. Nevertheless, 'Takane Ruby' buckwheat could maintain a higher capability of drought tolerance compared with 'Rose Red Soba' and common Buckwheat due to its capacity to maintain photosynthesis rate when substrate volumetric water content decreases.

Revolutionizing Grapevine Breeding: Overcoming Perennial Challenges with Genome Editing - Bridget Bolt
CRISPR/Cas9-Mediated Development of Low Mowing Frequency Perennial Ryegrass and Tall Fescue Varieties - Roshani Budhathoki
Precision Breeding Using CRISPR to Improve Production Traits in Blackberry - Pradeep Marri
Double CRISPR Knockout of Pectin Degrading Enzymes Improves Tomato Shelf-life While Ensuring Fruit Quality - Isabel Ortega Salazar
Functional Characterization of a Candidate Bacterial Wilt Resistance Gene in Tomato - James Duduit
Novel Short Synthetic Promoters for Constitutive Expression in Dicot Species - debao huang

Climate change poses a significant threat to perennial crops like grapevine in the USA, with projections indicating that 50-81% of acreage may become unproductive by 2040. To address this, breeding resilient varieties is imperative. However, traditional breeding for perennials is time-consuming (25-30 years) due to extended evaluation periods. Genome Editing, specifically CRISPR/Cas9, offers targeted modification potential but faces hurdles in perennial crops such as grapevine. These include somaclonal variation, inefficient transformation, transgene removal needs, and industry hesitance. We propose an efficient Genome Editing method for grapevine leveraging the systemic mobility of methylated dicistronic mRNA:tRNA molecules. This approach aims to: 1. Enable genome editing without transgene integration, negating the need for backcrossing and preventing unintended genetic changes. 2. Circumvent in-vitro culture, reducing somaclonal variation risk and preserving existing chimerism. Our method addresses key challenges in Genome Editing adoption for grapevine and could accelerate the development of climate-resilient varieties, crucial for sustainable agriculture in a changing climate.

Tall fescue (Lolium arundinacea Schreb.) and perennial ryegrass (Lolium perenne) are common cool-season turfgrass species. They are widely utilized in home lawns, athletic fields, golf courses, and roadsides. However, these grasses require frequent mowing to maintain lawn quality. Developing low-mowing frequency varieties is highly desirable because it can significantly reduce maintenance costs and fuel consumption. Gibberellin 20-oxidases (GA20ox) are key genes in the gibberellic acid (GA) biosynthesis pathway, mutations in which can induce a dwarf phenotype in plants and, therefore, reduce mowing frequency, as demonstrated by our dwarf turf varieties developed using conventional mutagenesis techniques. We have recently employed CRISPR/Cas9 technology to create knockout or knockdown mutations in the GA20oxidase1 gene to develop dwarf tall fescue and perennial ryegrass lines. The CRISPR/Cas9 construct used for editing LaGA20ox1 and LpGA20ox1 has ZmUbi and OsU6a promoters controlling the expression of Cas9 and sgRNA, respectively. We have delivered the CRISPR/Cas9 construct into tall fescue and perennial ryegrass via Agrobacterium-mediated transformation. We have observed a 35-50% reduction in plant height compared to the parental wild-type plants. Furthermore, the leaf widths in these mutants are reduced by 30-60%. Some mutants display a smoother leaf texture compared to the wild type. The T2 homozygous mutant progenies will undergo field evaluation for mowing frequency and fertilizer requirements. We anticipate that some of these gene-edited lines should exhibit a significant reduction in mowing frequency and fertilizer input.

Pairwise is a technology-focused food and agriculture company that makes tiny alterations to plant genetics to solve big problems. Powered by our best-in-class technology, Pairwise is harnessing new genomics technologies to create innovative new products. With our FulcrumTM platform, we accelerate innovation in plants and plant-based production systems, delivering value to people and our planet. Partnering with Plant Sciences, Inc. to access their elite germplasm, we created a platform to transform and edit tetraploid blackberry (Rubus sub. Rubus). We used the power of genetics and genomic tools to identify the candidate gene for thornless in blackberries and used CRISPR based gene editing to validate the trait. The identification of this gene will enable faster deployment of a thornless trait, an essential production trait, into blackberries. The gene may be broadly applicable to other Rubus species and horticultural crops such as roses.

Tomato fruit is an important and popular commodity worldwide. One of the main challenges for the fresh market tomato industry is postharvest deterioration, which is mainly determined by the rate of softening. This rate can affect tomato shelf-life, pathogen susceptibility, and fruit waste. The softening rate is regulated by multiple factors, but mainly by the pectin composition of the cell wall, which is remodeled, disassembled, and solubilized by enzymes during fruit ripening; a process that induces and determines the fruit softening in fleshy fruits. The main pectin-degrading enzymes that act on the pectin backbone are Polygalacturonases (PG) and pectate lyases (PL). In this study, we generated a double CRISPR knockout PGPL. We investigated the combined functions of SlPG2a and SlPL on fruit quality traits in postharvest, including shelf-life attributes like firmness and water loss, fruit marketability, and disease incidence. We also assessed additional attributes impacting consumer acceptance, such as taste and aroma. Our findings revealed that the tomato ripening enzymes SlPG2a and SlPL act additively, significantly affecting fruit firmness and shelf-life. Additionally, aspects of fruit quality, such as external color, sugar: acid ratio, and aroma volatiles, were improved or not affected in the double CRISPR knockout PGPL when compared to control. The discoveries of this research provide new insights into the influence of pectin backbone degradation on fruit physiology and postharvest quality, which can be used in crop improvement programs to make fruit more resilient in the supply chain without compromising consumer-based quality traits.

Bacterial wilt, caused by Ralstonia solanacearum (Rs), is an economically devastating plant pathogen that causes rapid death and has been widely distributed worldwide. Rs is a soil-borne bacterium that plugs plant xylem vessels, causing wilt and ultimately death in tomatoes (Solanum lycopersicum L.) and many other economically important crops. The most cost-effective and efficient means of managing Rs is planting resistant cultivars. However, acceptable Rs resistance in these genotypes is tightly linked to small fruit size, preventing development of BW-resistant large fruited tomato cultivars. Previous research has shown that a highly resistant cultivar's candidate resistance gene (Sl-BWR) is linked to qualitative resistance of Rs. Our preliminary data indicates that overexpression of the resistant allele in a susceptible cultivar background confers resistance comparable to the wild-type resistant allele. There is ongoing work to generate susceptible allele overexpression lines and knockout lines from the susceptible and resistant cultivars. We hypothesize the resistant allele knockouts will be susceptible to Rs, indicating that the candidate gene is the primary resistance factor. The gene could be functionally characterized to elucidate the Rs resistance mechanism in tomatoes to be deployed in a breeding program to develop resistant cultivars against bacterial wilt.

Determining the promoter motifs involved in regulating transcription, the first process of gene expression, is critical for synthetic promoter engineering. A gene’s promoter contains cis-regulatory elements, or motifs, which are binding sites for transcription factors (TFs) to initiate and drive transcription. Many bioinformatic tools have been developed for determining statistically overrepresented regions, representing sites of potential cis-regulatory elements, that are shared across groups of promoters. Combining the results produced by multiple bioinformatic tools can lead to improved detection accuracy of motifs conferring biological activity. In the present study, we compiled a set of 11 known soybean constitutive gene promoters under the assumption that some of the promoters are regulated by the same transcription factor(s). Seven bioinformatic tools capable of de novo motif discovery were used to determine potentially shared motifs within the promoters, which were then mapped back to the original promoter sequences. A total of 64 overlapping motif regions (OMRs) were commonly detected amongst the 11 constitutive promoters, and each OMR was cloned individually in front of the minimal CaMV 35S promoter driving GUSPlus reporter gene expression. Transient tobacco leaf agroinfiltration and subsequent quantitative GUS activity assays were used to determine each OMR’s ability to drive reporter gene expression. We found that 20 of the 64 bioinformatically-determined OMRs drove functional gene expression significantly higher than the basal levels conferred by the minimal 35S promoter. Of the 20 functional OMRs, 11 drove GUSPlus expression at levels from just twice that of the minimal 35S promoter up to nearly half of the full-length 35S promoter. We also transformed these 20 functional OMRs individually into Arabidopsis. While GUS staining is still ongoing, we identified a few OMRs which showed strong promoter strength in single-copied homozygous Arabidopsis seedlings. These functional OMRs are strong candidates for further characterization and can be used for crop improvement.

Genome-wide Association Study and Genome Prediction of Verticillium Wilt Resistance in Spinach - Kenani Chiwina
Spinach Seed for Grain Consumption: Feasibility and Potential for Genetic Improvement - Carlos Avila
Progress and Insights Into Downy Mildew Resistance Mapping Efforts in Spinach - Gehendra Bhattarai
Screening Baby Leaf Salad Greens for Downy Mildew Resistance - Shunping Ding
Detection of Novel Lettuce Fusarium Wilt Pathogenic Variants in California - Santosh Nayak
Unraveling Gene Regulation on the Interaction of Lettuce (Lactuca sativa L.) and Xanthomonas hortorum pv. vitians Causal Agent of Bacterial Leaf Spot. - Byron Manzanero
Exploring Physiological Traits as Predictors of Heat Content in Chile Peppers (Capsicum annuum L.) - Muhammad Ibrar Khan

Verticillium wilt, caused by Verticillium dahliae Kleb., poses a significant threat to spinach (Spinacia oleracea L.) production, necessitating genetic resistance as the primary defense against this disease. This study conducted a comprehensive genome-wide association study (GWAS) to identify single nucleotide polymorphism (SNP) markers linked to Verticillium wilt resistance in spinach and to evaluate genomic prediction for disease resistance. GWAS utilized a panel of 98 spinach germplasm accessions and 20,742 SNPs obtained from whole-genome resequencing. Various statistical models, including GLM, MLM, FarmCPU, and BLINK, were employed using the GAPIT 3 tool for analysis. Two quantitative trait loci (QTL) regions on chromosome 6 were found to be significantly associated with Verticillium wilt resistance. Specifically, SNP SOVchr6_29382746 at 29,382,746 bp and three SNPs (SOVchr6_86904401, SOVchr6_86906249, and SOVchr6_86906255) at 86,904,401 bp and 86,906,249 bp, respectively, demonstrated notable associations with disease resistance. Genomic prediction exhibited high accuracy, with a prediction ability (GA) represented by an r value of 0.95 for the panel. The identified SNP markers, along with the high prediction ability, offer valuable tools for breeders to select Verticillium wilt-resistant spinach plants and lines through molecular breeding, incorporating marker-assisted selection (MAS) and genomic selection (GS) strategies.

Spinach production is constantly challenged by endemic diseases that significantly reduce producers’ income. Even when resistant cultivars and cultural practices are used, mild disease damage can happen, negatively affecting quality and therefore reducing its commercial value. In contrast, under those conditions, spinach could still produce seed for grain with valuable nutritional content that can fetch premium prices for the gluten-free niche markets. This project evaluated grain production as an additional source of income by assessing yield potential, nutritional quality, and economic feasibility and potential for improvement. A total of ~200 USDA-NPGS accessions were evaluated for GWAS. For all nineteen amino acids evaluated, a wide range in content was observed. E.g. aspartic acid population mean was 106.5 nmol/g with a minimum of 36.2 nmol/g and a maximum of 353.9 nmol/g. Similar results were observed for all eight minerals evaluated. E.g. K population mean was 9,998.1 mg/kg with a minimum of 3,227 mg/kg and a maximum of 24,770 mg/Kg. High diversity can be used to improve nutritional content in spinach seed. Several SNP markers associated with amino acid and mineral content were identified in more than one nutrient, indicating pleiotropic genetic control. Furthermore, protein digestibility tests indicate that spinach provides ~50% of all amino acids required in the diet as compared with Amaranth and Quinoa protein in grain that provided ~20% of all amino acid required. Therefore, indicating spinach grain has a higher nutritional content as compared with highly demanded Amaranth and Quinoa grains. Finally, a partial budgeting approach was used to assess the economic feasibility of producing spinach seeds for grain. The added costs totaled US$ 218.71/ac, including custom harvesting (US$ 24/ac), an additional application of fertilizers (US$ 17.36/ac) and fungicide (US$ 62.54/ac), extra irrigation costs (US$ 60.63), and US$ 54.18/ac in associated interest on production expenses. The break-even price of seeds was estimated to be equal to US$ 0.20/lb when the average experimental yield was considered (i.e., 1,089lbs/ac). Producing seed for grain could expand the farmer portfolio, increase farmed acreage, and fringe products.

Spinach (Spinacia oleracea) is a popular leafy vegetable crop in the US, particularly for the fresh market baby leaf spinach. However, downy mildew (DM), caused by the obligate oomycete Peronospora effusa, poses a significant challenge to spinach cultivation in California and Arizona as it reduces the quality and yield of spinach. This is particularly concerning given that the two production areas contribute over 85% of the total fresh market spinach in the US. The emergence of new races of P. effusa, with nineteen races reported and fourteen identified in the last two decades, presents a persistent threat as new races and variant isolates can overcome the existing resistance in commercially deployed cultivars. Furthermore, over 50% of the spinach market is organic production, so utilizing host genetic resistance is a crucial disease management strategy. To combat this challenge, we conducted screenings of germplasm, cultivars, and multi-parent progeny populations in greenhouse conditions to identify resistant sources and genomic regions associated with resistance to multiple races of P. effusa (specifically race 5, 13, and 16). The spinach population panel was sequenced utilizing genotyping by sequencing (GBS), low coverage resequencing, and 10x coverage whole genome resequencing (WGR) to generate single nucleotide polymorphisms (SNP) markers. Subsequently, genetic analysis was performed using disease phenotype response data obtained and SNP markers for the identification of resistance-associated SNP markers and candidate resistance genes. The molecular analysis and mapping efforts have yielded valuable insights into the basis of downy mildew resistance in spinach, providing essential molecular tools to facilitate breeding for disease resistance. This work will summarize the updated findings from these efforts. This work will enhance our understanding of resistance mechanisms, which will contribute to developing more effective breeding strategies, increasing selection gains and breeding efficiency in spinach.

Downy mildew presents major challenges to baby leaf salad greens production in California. Baby kale (Brassica oleracea) particularly holds substantial economic value in the region with a crop value of over $12 million in 2022. Downy mildew, caused by the oomycete pathogen Hyaloperonospora brassicae, infects baby kale resulting in leaf chlorosis, necrosis, and sporulation, rendering affected leaves unmarketable. Resistant varieties offer an effective solution, reducing the need for pesticides and promoting sustainable disease management in baby kale production. This research aims to screen baby kale plant materials (accessions) for resistance to downy mildew isolates from across California. Initially, 212 baby kale accessions were evaluated for resistance using a downy mildew isolate from Gilroy, CA. Plants were inoculated with downy mildew spores and incubated in high-humidity conditions before being evaluated for disease symptoms. The initial screening indicated an average disease severity of 31%. From this screening, 50 accessions showing the lowest disease severity were further screened against seven additional downy mildew isolates. Among the subset of 50 accessions, disease severities ranged from 0.1% to 7.6%. Notably, nine accessions consistently exhibited a disease severity of 0%, and 17 accessions maintained disease severities of 0.1% or 0.2% across all seven isolates, making an elite secondary subset of accessions. Ongoing research includes replication trials with a secondary subset of accessions and the two most virulent and weak downy mildew isolates. This research will identify resistant baby kale varieties, providing valuable insights for breeders and improving downy mildew management practices in kale production systems.

Fusarium wilt (FW), caused by the soilborne fungus Fusarium oxysporum f.sp. lactucae (FOL), is an economically important disease of lettuce (Lactuca sativa L.). Four pathogenic races of FOL have been reported, though only race 1 is known to exist in the United States. Recently, California coastal lettuce growers have experienced changes in the severity and incidence of FW. Some race 1-resistant cultivars have exhibited susceptibility, whereas some susceptible cultivars have displayed a reduction in disease severity. In order to determine whether such changes in disease patterns are responses to potentially novel variants, we collected FW symptomatic plant samples from commercial fields in Salinas Valley and Santa Maria, recovered the fungus, and conducted a series of pathogenicity tests in controlled conditions over two years (2022 and 2023) using a standard set of FOL race differentials. Pathogenicity tests revealed two new FOL variants, Fol621s and 916, that elicited novel disease reaction patterns on the standard differentials which have never been reported in the United States or other parts of the world. Isolate 916 incited severe FW on race 1-resistant ‘Costa Rica No. 4’, whereas Fol621s was less virulent on race 1-suceptible ‘Banchu Red Fire’. This study provides valuable information critical for the development of FW management strategies, including broad-spectrum resistance breeding efforts against multiple FOL races and novel variants.

Bacterial leaf spot (BLS) of lettuce is a sporadic and destructive foliar disease that poses an economic threat to farmers, particularly those within Florida due to the subtropical environmental conditions. The disease is caused by the bacteria Xanthomonas hortorum pv. vitians (Xhv), which has three races. There are no chemical interventions that can effectively control this pathogen, creating a significant challenge for farmers to manage BLS. Additionally, most commercial lettuce cultivars are susceptible to BLS, emphasizing the need to improve host resistance. Resistance to Xhv race-1 has been identified in heirloom lettuce PI 358001-1 and ‘La Brillante’, and PI 667690. To facilitate and accelerate modern plant breeding techniques and the introgression of resistance into new cultivars, the identification of resistance genes is crucial. However, a detailed description on how these genes is regulated in the lettuce genome remains unknown. To aid in the understanding of the interaction between lettuce and Xhv, a gene expression study was conducted. A total of 180 plants each of La Brillante (R), PI 358001-1 (R), PI 667690 (R), and Okeechobee (S) were grown in laboratory conditions for 21 days. Half of the plants were mock inoculated with buffer, and the remaining plants were inoculated with Xhv race-1 isolate L7. Leaf samples were collected at 24-, 72-, and 144-hours post-inoculation, and RNA was extracted for sequencing using the Illumina NovaSeq 6000 platform. The analysis of differentially expressed genes and their associated pathways revealed distinct reactions upon interaction with Xhv. Additionally, similar reactions were observed in other crops and their respective Xanthomonas pathovars, such as the upregulation of peroxidases, chitinases, and proteases, were observed between inoculated and mock-inoculated plants, such response was time point dependent. Primers will be designed and validated for these candidate genes using qPCR with additional time points to confirm their expression across key plant development stages. These findings provide valuable insights into the molecular resistance of lettuce to BLS, unlocking new opportunities for molecular breeding techniques, identification of chemical compounds within the plant that control BLS, and the development of new resistant cultivars. This knowledge will benefit not only the UF/IFAS lettuce breeding program, but also be disseminated to other research groups working to breed BLS-resistant lettuce cultivars.

Chile peppers (C. annuum L.) are valued for their capsaicinoid content, which contributes to their pungency (heat) and has various health benefits, including anti-inflammatory and anti-cancer properties. Assessing photosynthetic efficiency through the LICOR-600 porometer/fluorometer (https://www.licor.com/env/products/LI-600/) provides insights into the physiological vigor of the plants. This study employs a comprehensive suite of machine learning models to investigate the correlation between photosynthetic efficiency (stomatal conductance and chlorophyll a fluorescence) and Scoville Heat Units (SHU) to predict the capsaicinoid content within 20 chile pepper varieties. Photosynthetic data were collected at two sites, Fabian Garcia Science Center and Leyendecker Plant Science Research Center, Las Cruces, NM, with readings taken from three different leaves of each of five plants per genotype. Capsaicinoid levels were quantified using High-Performance Liquid Chromatography (HPLC) for each variety. Correlation and principal component analyses (PCA) were implemented to discern the primary influencers on capsaicinoid production. Five predictive models were explored: Decision trees, Random forests, Ridge regression, LASSO Regression, and Support Vector Regression. Each model was applied to predict both total SHU values and categorical SHU labels (mild, hot, very hot). Among these, the decision tree model was the most superior, achieving an R² of 0.77. Initial findings indicate notable variability in photosynthetic activity and capsaicinoid concentrations across the varieties, suggesting a significant but complex relationship that may guide future genetic improvements. The challenges in modeling can be attributed to data collection constraints. Additionally, uniform growing conditions across all test plants might have limited the variability necessary for more definitive model differentiation. This analysis not only advances our understanding of the physiological and genetic factors affecting capsaicinoid content but also underscores the complexities of modeling agricultural traits under consistent environmental conditions. Future research should consider more frequent data collection and the introduction of environmental stressors to better capture the dynamics influencing capsaicinoid production in chile peppers. Key word: High-Performance Liquid Chromatography, Scoville heat unit, photosynthetic efficiency