ASHS 2024 Conference

Seventy Years of Evaluations and Selections of Ornamentals by the NDSU Woody Plant Improvement Program. - Todd West
Micropropagation and production of Amur and Norway maple triploids - Ryan Contreras
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.

Acer ginnala (Amur maple) and A. platanoides (Norway) are trees that perform well under challenging urban and suburban conditions. Unfortunately, both are highly fecund and have escaped cultivation in several regions of the United States including becoming invasive. To address this, we have developed seedless triploids. To safely deploy seedless cultivars that present little or no ecological risk, they need to be on their own roots, as opposed to being budded onto seedling rootstocks, as was customary for Norway maple. Growing own-rooted plants prevents possible outgrowth of seedling rootstock. Amur maple roots well from stem cuttings but this is not feasible for Norway maple. Micropropagation presents a path forward both to increase propagules rapidly for initial introduction as well as a viable propagation method for the more recalcitrant Norway maple. Both species were successfully micropropagated and stage III plants were delivered in early April 2023. Plants were acclimatized and grown during the 2023 growing season to produce finished trade gallon whips. Material was variable in size because we effectively grew on everything without culling for inferior material. Both species were demonstrated to be amenable to micropropagation and their growth after acclimatization was better than expected. Micropagation will be further optimized, and as available material increases, size and production will be further standardized. This method will facilitate rapid introduction of seedless triploids and allow growers to be successful and profitable in production.

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.

In the this session, the Nursery LEAP (Labor, Engineering, Automation, and Production) Team will present results culminating from a USDA SCRI planning grant survey and related topics. The team will describe current labor challenges, limitations of the current workforce, and opportunities through multiple visa programs. Team members will also present the correlation between perceived barriers to adoption, nursery business characteristics, and the likelihood of adopting automated technologies; nursery producers’ perceptions and intent to use automated nursery technologies; and an overview of current mechanization and automation levels in nurseries. Founders of Moss Robotics, Inc. will share their approach to developing and commercializing AI, computer vision, and machine-learning-based technology for the nursery industry. The session will conclude with a facilitated panel discussion featuring all speakers.
Coordinator(s)

• Jacob Shreckhise, USDA-ARS, U.S. National Arboretum, McMinnville, Tennessee, United States
• Amy Fulcher, University of Tennessee, Plant Sciences, United States
• Anthony LeBude, NC State University, United States
• James Altland, USDA-ARS, Wooster, OH, United States

Moderator(s)

• Natalie Bumgarner, University of Tennessee, United States

Speaker/Participant(s)

• Anthony LeBude, NC State, United States
  The Nursery Industry’s Labor Dilemma (10 mins)
  Summary: Dr. Anthony LeBude, NC State University, will provide an overview of the US nursery industry’s labor challenges and the threat that these challenges pose to the sustainability of this labor-reliant industry.
• Margarita Velandia, University of Tennessee, Knoxville, Knoxville, Tennessee, United States
  The Role of U.S. Temporary Foreign Worker Visa Program in Addressing the Green Industry Labor Needs: Challenges and Opportunities (20 mins)
  Summary: In this presentation, Dr. Margarita Velandia, University of Tennessee, will give a general overview of the H-2A, H-2B, and the TN NAFTA or TN USMCA visa programs and discuss challenges and opportunities associated with each program in addressing the green industry labor needs.
• Alicia L Rihn, University of Tennessee, Knoxville, United States
  Factors Correlated with the Propensity to Use Automation and Mechanization (20 mins)
  Summary: Several of the U.S. nursery industry’s characteristics and actions to address labor issues are correlated with the use of automated technologies. Dr. Alicia Rihn, University of Tennessee, will explore the correlation between perceived barriers of adoption, nursery business characteristics, and the likelihood of adopting automated technologies.
• Amy Fulcher, University of Tennessee, Plant Sciences, United States
  Nursery Mechanization and Automation Adoption Levels (20 mins)
  Summary: Nursery Mechanization and Automation Adoption Levels – Dr. Amy Fulcher, University of Tennessee, will present current nursery mechanization and automation adoption levels and compare the current percentage of individual tasks that are automated with 2006 levels.
• James Altland, USDA-ARS, Wooster, OH, United States
  Panel Discussion (10 mins)
  Summary: Dr. James Altland, USDA-ARS, will facilitate the panel session through thoughtful prompts and questions from the audience to foster enriching discussion.
• Anthony LeBude, NC State University, will describe collaborative work led by Dr. Laura Warner, University of Florida, on using Diffusion of Innovations theory to understand growers’ perceptions of nursery technology and how these perceptions shape growers’ adoption of automation, as well as results from a Theory of Planned Behavior evaluation of nursery growers’ intent to use automation from 4 technology clusters. 
• Di Hu and Shrijit Singh, founders of Moss Robotics, Inc., will discuss how advancements in autonomous driving and AI have unlocked new possibilities for the green industry. Moss leverages robotics, computer vision, and machine learning to revolutionize field scouting, providing nursery producers with cost-effective solutions for efficient crop management and monitoring. In this presentation Ms. Hu and Mr. Singh will explore Moss’ innovative approach, including a case study demonstrating the transformative impact of their robotic field scouting solution. 

A forum for discussion of potential collaborations with regards to ornamentals – i.e. floriculture, nursery crops, breeding, turf, ornamentals industry, botanic gardens, landscape industry, orchids, etc.

A Snapshot of Nursery Container Substrate Prices in Tennessee - Amy Fulcher
Suppression of Stem Elongation of UV-B Treatment Timing and Intensity on Tomato Scion and Rootstock in Plant Factory with Artificial Lighting - Dongcheol Jjang
Effects of Nitrogen on the Nodulation of Ceanothus velutinus - PRAKRITI NEPAL
Evaluating the Effects of Varying Container Height and Volumes on Southern Highbush Blueberry Production - Brandan Shur

In container nursery production, the potting substrate serves as the foundation of the crop, providing essential nutrients, aeration, and moisture retention. A well-chosen substrate is crucial for optimizing plant health and growth, and ultimately influences a nursery’s economic viability since substrate is estimated to be 13% of the total variable costs of 3-gallon production. Our objective is to determine the cost of common potting substrate components. The study goal is to identify opportunities for nursery producers to reduce costs and increase profits by optimizing their substrate components. Email surveys supplemented by interviews were used to collect data from six Tennessee container nursery producers. All growers were within a 117-mile radius of McMinnville, Tennessee, and provided the prices they paid in the last 12 months for the primary components of their potting substrate. Delivery fees and fuel surcharges were not considered in the cost when these expenses were itemized. However, one producer’s prices included delivery expenses. Participating nursery producers self-identified as having 100 (66.7%) acres in container production. Growers in this case study paid an average of $19.07 (SD=$5.53) per yard3 for pine bark; however, the prices ranged from $14.53 to $29.00 per yard3. In general, smaller producers paid more for pine bark. Sand ranged from $40.50 to $49.95 per yd3. Nursery producers paid $1.12 to 1.32 per pound for controlled release fertilizer (CRF), an input estimated at 5% of total variable costs. Therefore, some growers paid 18% more for CRF than others. Growers paid from $0.01 to $0.11 per pound for lime. Tennessee nursery producers were paying on average $66.79 per cubic yard for wood fiber-based substrate and vermicompost, 250% more than the average cost of pine bark but just 46% of the market price for peat. These preliminary data show 1) individual nurseries pay a range of prices for the same potting substrate components, and 2) the relatively high cost of peat replacements, i.e., wood fiber and vermicompost. The data highlight the range of prices being paid for CRF and its relative expense, underscoring the opportunity for growers to reduce costs by optimizing their use and placement of CRF. Additional research is needed to more broadly sample nurseries for these data and determine the influence of nursery size on substrate component costs. cparwutcakwt8uvpamtb

This study aimed to determine the optimal conditions of UV-B exposure for regulating the growth of tomato grafted seedling in Plant Factory with Artificial Lighting by investigating growth characteristics, rhizosphere development, and chlorophyll fluorescence of seedlings. Tomato scion and rootstock were used in the experiment. UV-B treatment timing was divided into three stages from sowing to grafting. UV-B intensities were set at 1.44, 2.88, and 5.76 kJ·m−2·d−1. Results showed that morphology of plants did not exhibit significant differences up to 2.88 kJ·m−2·d−1 for tomato scion and rootstock. However, side effects such as leaf wilting were observed at 5.76 kJ·m−2·d−1. The length of hypocotyl, which is closely related to scion and rootstock suppression of stem elongation, was shortest when treated with 5.76 kJ·m−2·d−1 during the mid-growth stage across all treatment. Interestingly, rhizosphere characteristics such as root volume, surface area, and average root diameter showed improvement trends regardless of treatment timing when exposed to UV-B at 1.44-2.88 kJ·m−2·d−1. Quality indicators of seedlings showed best when 2.88 kJ·m−2·d−1 during the late-growth stage. Comparisons of chlorophyll fluorescence parameters revealed no significant effects of UV-B treatment on cucumber seedlings and grafting except for PIABS. However, tomato seedlings and grafting exhibited significantly reduced FV/FM and DIO/RC at late-growth stage when exposed to 5.76 kJ·m−2·d−1. Therefore, it is concluded that utilizing UV-B in the range of 1.44-2.88 kJ·m−2·d−1 during cucumber and tomato scion and rootstock production in Plant Factory with Artificial Lighting could minimize plant damage while expecting to suppress grafting effects.

Ceanothus velutinus, commonly known as snowbrush ceanothus, is a nitrogen-fixing species native to North America. It plays a vital role in ecosystem by improving soil fertility through nodulation, a symbiotic process with bacteria that fixes atmospheric nitrogen. The purpose of this study was to identify the effects of various nitrogen concentrations on the nodulation and plant morphological and physiological responses. Ceanothus velutinus seedlings were transplanted in calcined clay and inoculated with 30 mL of soil containing Frankia. Seedlings were treated with 0.0 to 8.4 g·L-1 of controlled released fertilizer (CRF, 15N-3.9P-10K) or a nitrogen-free nutrient solution supplemented with or without 2mM ammonium nitrate (NH4NO3). Plant growth and photosynthesis increased linearly or quadratically along with the increasing CRF application rates with a notable increase observed at 4.2 g of CRF. Nodules were observed only in plants receiving 0.0, 0.3, 0.5, 1.1, or 2.1 g of CRF. However, the number of nodules formed in the treatments was too small to analyze statistically. The study indicates that while CRF significantly boosts C. velutinus growth, nodulation and nitrogen fixing capacity of the plant remains unknown. Further investigation is needed to determine the effect of nitrogen on the nodulation of C. velutinus using peat-based soilless substrate.

Fine-tuning Substrate Stratification Ratios for Shrubs and Flowers - Jeb Fields
Engineered Substrates Improve Nitrogen, Phosphorus, and Water Retention in Nursery Container Production - Henry Gonzalez Hernandez
A 2-Dimensional Analysis of How Root Architecture and Morphology Are Influenced by Stratified Substrate Systems - Kristopher Criscione
Predicted Drought Tolerance of Cephalanthus occidentalis L. for Use in Managed Landscapes - John Larsen
Comparative microbial diversity analysis and isolation of plant growth-promoting rhizobacteria from roundleaf buffaloberry (Shepherdia rotudifolia) - Amita Kaundal
Navigating the Interplay of Climate Stress and Pest Pressure in Shade Tree Nursery Production: Insights from Oregon and Tennessee - Lloyd Nackley
The Effects of Supplemental Nickel on Mouse Ear Disorder of Three Diospyros Species - Alyssa Headley

The ornamental production industry utilizes either controlled greenhouse or open-air nursery production systems. Both rely upon the use of soilless substrates, with regular application of water and mineral nutrients, to maintain profitability and quality crop growth and development. However, the leading base substrates components used, peat moss and bark, present sustainability concerns for producers. Peat moss sustainability concerns surround harvest, supply, and cost (environmental, social, and economic; three tiers of sustainability) of the material. Pine bark sustainability in production is due to inefficiency in water and mineral nutrient retention (environmental, social, and economic). Nevertheless, a solution to help improve the sustainability of both substrates across the greenhouse and nursery industry has developed. Soilless substrate stratification is a practical management strategy that entails layering two unique substrates, either derived from the same substrate or different substrates, atop one another in the container. Stratifying substrates has been shown to reduce peat use and reliance in the greenhouse industry by upwards of 50%. Moreover, stratifying substrates can reduce irrigation and fertilizer applications by 25- and 20%, respectively. To date, stratified substrate research has utilized an even 50:50 stratified depth layer partition. As growers adopt this technique, more understanding of the balance and opportunities is needed. Thus, a series of experiments was developed to explore varying ratios of stratification. In two experiments, popular greenhouse (Petnas) and nursery (Rosa) crops were grown in different stratified depth layer ratios with peat-based (greenhouse) and bark-based (nursery) systems. Ratios included a non-stratified treatment (100% filled), a 75:25 percent by vol. layer partition, a 50:50, and a 25:75. In the greenhouse experiment, peatlite mix was layered over unscreened bark and irrigation was lysimeter-actuated. In the nursery experiment, fine bark particles were layered over coarse particles. Moreover, different fertilizer rates were applied (low, medium, high). The results showed in the greenhouse study, a Pentas crop can be grown with equal growth (and similar quantities of water) as traditional greenhouse crop when ≥50% peatlite is used by vol. In the nursery experiment, low fertilizer application rates can be used to grow a crop similar to a traditional nursery-grown crop when grown in a stratified system. While there are discrete differences, it primary take away is that stratification does not need to be overly technical to generate impact and improve efficiency; however, there is a limit to the ability to use “filler” material which tends to be about 50% of the volume.

Container nursery production is the fastest-growing sector in the nursery industry. High volumes of runoff containing nitrogen (N) and phosphorus (P) from container production result in wasted high-quality fresh water, loss of costly applied fertilizer, and increased risk of nutrient management regulations, especially near receiving waters prone to eutrophication. The authors hypothesize that stratified substrates, in which a fine textured substrate is placed atop a coarse substrate amended with ferrous sulfate (FeSO4), can reduce water use and decrease N and P losses while yielding a high-quality container crop. This research was conducted at the Horticulture Teaching and Research Center in Holt, Michigan on three replicate simulated nursery pads per treatment, each having 45 containers consisting of Buddleja x ‘Miss Violet’, Ilex crenata ‘FARROWSK6’, Hydrangea paniculata ‘Limelight’, Physocarpus opulifolius ‘Seward’, Cornus sericea ‘SMNCSBD’, Cotinus coggygria ‘MINCOJAU3’, Rosa x ‘ChewDelight’. Substrate treatments consisted of an 85:15 (by vol.) pine bark:sphagnum peat uniform profile (Conv), an 85:15 pine bark:sphagnum peat uniform profile fully amended with 3 kg/m3 FeSO4 (Conv Fe), stratified substrate (Strat) in which fine sphagnum peat amended bark substrate was atop a coarse bark substrate, and stratified substrate with the coarse bark layer amended with 3 kg/m3 FeSO4 FeSO4 (Strat Fe). All plants were micro-irrigated with a spray stake. Irrigation water usage, N, and P leaching were quantified and compared. Preliminary results indicate that lower amounts of N leached from Strat (12 mg L-1, p = 0.03) and Strat Fe (13 mg L-1, p = 0.02) compared to Conv (23 mg L-1). Similarly, lower P was found in leachate from Strat (6.33 mg L-1, p = 0.01) and Strat Fe (6.74 mg L-1, p = 0.02) compared to Conv (11.78 mg L-1). These preliminary results, in addition to leaching fraction and growth index, will be discussed in this presentation.

Soilless substrates serve an important role in both the sustainability of specialty crop production and supporting healthy containerized root growth. The requirements and tolerance of containerized roots are essentially what dictates the (i) physiochemical limitations of the substrate, (ii) how production practices are managed (i.e., quantity and quality of irrigation / fertilization), and (iii) the performance of high-quality shoot growth and development, emphasizing the importance of both substrates and roots. Nevertheless, most horticultural crop research primarily focuses on shoot growth and dismisses important root growth traits, often only reporting root biomass at study culmination or during destructive harvests. Information regarding how roots grow throughout the substrate matrix is evidently sparse. More research is needed to develop better understandings of spatial and temporal root development, such as root architecture, which describes how (and where) roots invests carbon throughout the 3-Dimentional substrate matrix. Research regarding popular engineered substrate systems, stratified substrates (i.e., layering different media atop each other), has began to dive deeper into how roots grow in time and space, where stratified-grown roots grow differently than traditionally grown (non-stratified) cropping systems. However, no research to date as explored root architecture, temporally or spatially, in stratified systems. The study herein explored root architecture in time and space using clear acrylic-based RhizoBoxes (8-L vol.). Several different types of crops (nursery- hibiscus; greenhouse- basil; representative crop- sunflower) were grown in different non-stratified and stratified substrate systems, including bark- [non-stratified: 100% unscreened bark; stratified- fine bark (< 6.3 mm) layered over coarse bark (> 6.3 mm)] and peat-based [non-stratified: 100% peat-lite (7:3); stratified: peat-lite layered over unscreened bark] substrates. Root growth was traced frequently and analyzed quantitatively for total visible root length and growing angle, and qualitatively for general shape and patterns. The results showed that stratified grown crops, across cropping systems, had a wider root distribution spreading angle, growing wider and more outward than crops grown in non-stratified systems. Moreover, stratified grown crops typically grew in the upper stratified layer longer than crops grown traditionally, growing more sequentially than continuously. In most cases, stratified-grown crops had longer visible roots growing against the acrylic glass in the upper 50% of the profile. Stratified-grown roots were often longer and finer than non-stratified grown crops. In all, this study highlights that stratified grown crops have superior root growth and development and that RhizoBoxes are a useful tool in studying root architecture in soilless substrate systems.

Buttonbush (Cephalanthus occidentalis) is a valuable landscape shrub revered for its prominent white, globe-shaped blooms which can later develop into brilliant red aggregate fruits. This North American native shrub occurs almost exclusively in riparian habitats, typically in standing water in the wild, but it is curiously adaptable to a range of landscape conditions in cultivation. Because this species appears to perform well when grown using average soil-moisture conditions, we questioned where the limits of drought tolerance occur for this riparian-adapted species. The objective of this study was to evaluate USDA-GRIN germplasm of buttonbush to compare unique provenances representing different regions of the native range of the taxon to generate a relative scale of predicted drought tolerance for the species. Utilizing vapor pressure osmometry, this study examined seasonal osmotic adjustment and predicted leaf water potential at the turgor loss point (ᴪpo) among ten Cephalanthus occidentalis populations grown at the Morton Arboretum in Lisle, Illinois. All populations evaluated demonstrated a minor ability to osmotically adjust (Δᴪ𝝿100) throughout the growing season. NA 79917 exhibited the most osmotic adjustment (-0.22 MPa) whereas NA 61271 exhibited the least (-0.08 MPa). Estimated spring ᴪpo and summer ᴪpo across populations was -1.75 MPa and -1.91 MPa, respectively. NA 79705 exhibited the highest ᴪpo in both spring (-1.56 MPa) and summer (-1.68 MPa). NA 82190 exhibited the lowest ᴪpo in spring (-1.92 MPa ), whereas NA 73814 exhibited the lowest in summer (-2.17 MPa). These data indicate that drought tolerance in buttonbush varies across populations, suggesting that this trait can be improved in landscape selections through selective breeding efforts.

The world is haunted by climate change and global warming, posing critical challenges to plant health and productivity. Hence, it is now imperative to think about ecosystem resilience and conservation. Microbiomes from extreme environments with plant growth-promoting and stress-relieving properties can be used as inoculum for growing plants during stress. Hence, our study aims to explore the root and soil microbiome of native and hardy Shepherdia species available in Utah, USA. The native Shepherdia species, S. rotudifolia was selected for the study. We compared the microbial diversity of S. rotudifolia from three different locations in Utah. The plants' bulk soil, rhizosphere, and root were collected for the study from Torrey, Colorado City, and Cannonville in Utah and brought to the Utah State University, Logan, for further processing. DNA extraction was done from all the samples and sequenced for 16S rRNA region. The bulk soil of roundleaf buffaloberry from Torrey is highest in organic matter, while that from Colorado City is highest in salinity but lowest in NPK and most micro-nutrients. Bulk soil and rhizosphere bacterial alpha diversity differ significantly (p=0.05) among the locations of roundleaf buffaloberry; however, there is no difference in root endosphere alpha diversity among the locations. The bacterial community composition of roundleaf buffaloberry from Torrey is significantly different from the other two locations. Proteobacteria and Actinobacteriota are the dominant phyla in the bulk soil and rhizosphere of roundleaf buffaloberry from all three locations; however, Actinobacteriota dominates in root in all three locations. The genus composition of bulk soil, rhizosphere, and root of roundleaf buffaloberry is very diverse among the three locations. Frankia, the well-known nitrogen-fixing bacteria, is prevalent in the root samples of S. rotundifolia from Cannonville and has lesser abundance in the other two locations. Fifty-seven bacteria were isolated from the rhizosphere of the S. rotudifolia on different nutrient media. These isolates are being tested for eight plant growth-promoting traits, such as the production of indole acetic acid, siderophore, catalase, protease, ACC deaminase activity, nitrogen fixation, phosphate solubilization, and sulfur-oxidizing activity

The plant nursery production industry in Oregon and Tennessee faces escalating challenges from climate change, particularly concerning shade trees like red oak (Quercus rubra) and red maple (Acer rubrum). This research investigated the physiological responses of these species to fluctuations in soil moisture, vapor pressure deficit (VPD), and leaf temperature (Tleaf) through field experiments in Oregon's Willamette Valley and Tennessee's nursery regions. Monitoring stomatal conductance (gs) and stem water potential (Ψs) under varied conditions revealed distinct responses between the two species, with red maple exhibiting greater sensitivity to soil moisture and VPD compared to red oak. Additionally, a novel correlation between VPD and maple gas exchange underscores the significance of atmospheric moisture dynamics in plant water management strategies. Furthermore, assessing the impact of abiotic stressors on flatheaded borer (FB) attacks, we found that drought-stressed red maple trees experienced the highest borer infestations. Plant growth was adversely affected by all stressors, with drought stress exhibiting the most detrimental impact. Our findings underscore the complexity of plant responses to climate stress and highlight the necessity of informed water management practices for sustainable nursery production in diverse regional contexts. Bridging knowledge gaps in plant hydraulic physiology can empower growers to adapt to evolving environmental conditions and ensure the resilience of shade tree production systems. Further research is crucial to deepen our understanding of plant hydraulic physiology and its implications amidst climate change-induced challenges.

American persimmon (Diospyros virginiana L.) is a multipurpose tree endemic to the eastern United States with potential for broader use in managed landscapes or for producing desirable fruits. Whereas most members of this genus originate from tropical and subtropical regions, the American persimmon could expand landscape diversity and fruit production applications in northern climates. Due to purported challenges with transplant success, American persimmon is likely best suited to cultivation in containers. Recent observations of container-nursery crop production indicates American persimmon is susceptible to mouse ear disorder (MED), a function of nickel deficiency. We hypothesized that American and Asian-origin persimmon species are susceptible to MED and that supplementing nickel with a foliar spray will ameliorate the disorder. Our objectives were to characterize symptoms of non-treated MED with American (D. virginiana), Japanese (D. kaki), and dateplum (D. lotus) persimmon as well as to determine if MED could be corrected by foliar application of nickel or other compounds presumed to interact with the urease metabolic pathway, such as urea. In a randomized greenhouse study, seedlings of American, Japanese, and dateplum persimmons were evaluated by comparing a non-treated control (H2O spray), to foliar spray treatments of NickelPlus® (169 ppm), NiCl2 (169 ppm), urea (0.325 g/L), and combined NiCl2 (169 ppm) and urea (0.325g/L). Following treatment, plants were evaluated using a MED severity rating scale, leaf characterization metrics (greenness, count, surface area, dry mass, and specific area), as well as metrics characterizing stem traits (elongation and dry mass). Compared to the non-treated control, leaf surface area increased by ~56%, ~61%, ~25%, and ~52% for the Nickel Plus®, NiCl2, Urea, and combined NiCl2 Urea treatments, respectively, when pooled across species and cultivar. These results suggest nickel supplements are effective at increasing important growth metrics like leaf surface area for Diospyros species displaying MED symptoms. This study offers valuable insights for improving the cultivation of persimmons in container nursery production settings, contributing to the development and advancement of American persimmon as an emerging specialty crop.