ASHS 2024 Conference

Evaluating Efficacy of Organic Herbicides on Common Weed Species - Carly Strauser
Evaluating Fall Cover Crops for Enhanced Soil Properties and No-Till Weed Suppression in Chickpea Production in Virginia - Zelalem Mersha
Impact of Cover Crops and Herbicides on Early Season Weed Control and Sweetpotato Storage Root Yield. - Richard Noel Torres
Effects of Row-middle Cover Crops on Strawberry Plasticulture Production - Jeanine Arana
Palmer Amaranth and Waterhemp in the Pacific Northwest: Glyphosate Resistance Confirmation and Implications for Crop Production - Albert Adjesiwor
Mesotrione and Simazine-Based Tank-Mixes for Late-Season Control of Doveweed in Bermudagrass Turf - Pawel Petelewicz
Simulation-Based Nozzle Density Optimization for Maximized Efficacy of a Machine-Vision Weed Control System for Applications in Turfgrass Settings - Pawel Petelewicz
Implementing Digital Multispectral 3D Scanning Technology for Rapid Assessment of Hemp (Cannabis sativa L.) Weed Competitive Traits - Tyler Campbell
Farmer Experiences with Soil Tarping Across South Dakota - Hannah Voye

Palmer amaranth (Amaranthus palmeri) and waterhemp (Amaranthus tuberculatus) are the two most troublesome pigweeds in crop production systems in the United States. These pigweeds just started to appear in the Pacific Northwest (PNW). A coordinated extension and outreach effort among land-grant universities (University of Idaho and Oregon State University), Amalgamated Sugar, other commodity commissions, and industry was launched to track Palmer amaranth and waterhemp in the PNW. In 2023, tissue samples were collected from pigweeds suspected to be Palmer amaranth and waterhemp and sent to Colorado State University for KASP genotyping test to confirm if the species were Palmer amaranth and waterhemp. The KASP test confirmed that the suspected pigweeds were Palmer amaranth and waterhemp. Since the majority of these pigweeds survived multiple applications of glyphosate, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene duplication analysis was conducted to confirm possible glyphosate resistance in the Palmer amaranth and waterhemp populations. About 70% (17 out of 23) of the Palmer amaranth tissue samples showed gene duplication of up to 184 EPSPS gene copies, indicative of glyphosate resistance. All three populations of waterhemp showed gene duplication of 5.7 to 9.2 EPSPS gene copies indicative of glyphosate resistance. The widespread glyphosate resistance in the samples collected suggests that Palmer amaranth and waterhemp being introduced into the PNW are coming from States where these weeds have developed resistance to multiple herbicide groups. This would have huge implications for weed control in vegetables and other crops in the PNW.

The economic significance of hemp (Cannabis sativa L.) as a source of grain, fiber, and flower is rising steadily. However, due to the lack of registered herbicides, hemp growers have limited weed management options. Slow-growing hemp varieties can be outcompeted by weeds for sunlight, water, and nutrients. Hence, easily adoptable integrated weed management (IWM) strategies are essential. Addressing these challenges necessitates novel approaches to identify quantitative phenotypes and explain the genetic basis of key weed-competitive traits. Plant height and canopy architecture may affect crop-weed competition. However, manually measuring these parameters is a time-consuming process. The PlantEye (PE) multispectral 3D scanner was selected as the high-throughput digital phenotyping technology for the evaluation of plant architecture. In this study, the suitability of digital phenotyping was evaluated at the Clemson University Coastal Research and Education Center to screen diverse hemp varieties with different plant habits. Digital plant biomass, plant height, and plant 3D-leaf area (including leaf area index, leaf angle, and light penetration) were periodically monitored. We performed a range of validation tests for morphological features (digital biomass and plant height). A significant correlation (P < 0.001) was observed between digital biomass and manually measured biomass (R = 0.89), as well as between digital height and manually measured height (R = 0.94), indicating the high precision and usefulness of 3D multispectral scanning in measuring morphological traits. Multispectral analyses used in this study are non-destructive, rapid techniques with minimal error and human interference, which have great potential for use in planning weed management.

Managing weeds is one of the most significant challenges, especially in organic vegetable production systems. Farmers control weeds in various ways, many of which can have negative environmental impacts. Cultivation is a common way many organic vegetable growers will manage weeds; however, it leads to decreased soil health properties. Hand weeding is extremely time-consuming and labor-intensive. Conventional herbicides have raised public concern for their impact on human health and the environment. Organic herbicide products are used as a burndown, post-emergence product but can be cost-prohibitive. In addition, there is a lack of current research comparing organic herbicide effectiveness on a range of common weed species. This study aimed to explore the efficacy of five Organic Materials Review Institute-approved organic herbicides. These products included citrus oil (Avenger®), ammonium nonanoate (AXXE®), acetic acid (Green Gobbler®), caprylic acid capric acid (HomePlate®), and clove oil cinnamon oil (Weed Zap®). Water was used as a control, and glyphosate (Ranger Pro®) was used as a positive control. Each herbicide was tested on six common weed species: Chenopodium album (common lambsquarters), Portulaca oleracea (common purslane), Setaria viridis (L.) Beauv. (green foxtail), Digitaria sanguinalis (L.) Scop. (large crabgrass), Amaranthus retroflexus (redroot pigweed), and Abutilon theophrasti (velvetleaf). Products were sprayed according to label recommendations using a calibrated spray chamber at the Iowa State University greenhouses. Each weed species, 10 plants per replication, was sprayed after reaching an average height of seven centimeters. Percent weed cover using digital image analysis software (Turf Analyzer) and percent visual injury was recorded. These data parameters were collected 24 hours, 3 days, 10 days, 17 days, and 21 days following herbicide application. Weed biomass was collected and dried 21 days after herbicide application for all species. AXXE® was a fast-acting herbicide on common lambsquarters, common purslane, redroot pigweed, and velvetleaf. These species showed over 85% injury three days after AXXE® application. Weed Zap® stunted the majority of examined weed species soon after application, but the injury effects were less significant 21 days after application. Visual injury assessments showed Avenger®, Green Gobbler®, HomePlate®, and Weed Zap® had no significant injury on green foxtail and large crabgrass 21 days after herbicide application. Results from this study provide growers with practical and applied data to make informed decisions regarding the use of organic herbicides.

Industrial hemp is receiving attention for its numerous benefits, particularly in the fiber industry. Weed competition is a primary concern for hemp cultivation causing reduced yields and inferior-quality fiber. However, little is known about herbicide application in hemp since a limited range of herbicides are available for hemp production. Therefore, a field study was conducted in 2023 to investigate the effect of different herbicides and application timings on weed suppression, crop injury, growth, and biomass yield of hemp. A randomized complete block design was conducted with six herbicide treatments including, early POST [2 weeks after planting (WAP)] and late POST (5 WAP) emergence applications of S-metolachlor, clopyralid, and ethalfluralin, with an untreated control to make comparisons. Plant stand showed no significant difference among treatments. Early POST herbicides application significantly reduced the weed biomass compared to untreated control at 7 WAP. By 10 WAP, weed biomass became comparable across treatments. At harvest, untreated control recorded comparatively higher weed biomass than early POST treatments and late POST ethalfluralin. Plant height remained non-significant among treatments until 10 WAP. At harvest, control showed no variation with late POST treatments but recorded an average 63% lower plant height than early POST applications. Treatments showed no significance for hemp biomass at 10 WAP. However, early POST S-metolachlor and ethalfluralin herbicides exhibited lower weed biomass and greater plant height, resulting in greater hemp biomass accumulation compared to untreated control at harvest. In conclusion, early POST S-metolachlor and ethalfluralin could be used as POSTemergence herbicides for hemp cultivation.

Field production hemp trials were conducted in 2020 and 2021 in Baton Rouge, Louisiana without success. In both seasons, the hemp was planted in spring and harvested in early summer. Over 50% of the plants dies from disease and or initial root rot because of excessive rain and wet soils. Faculty at the LSU AgCenter were successful in growing hemp in 2021 in greenhouse settings but realize not all growers can afford such structures. Therefore, field trails were established in the fall 2023 (October) and early spring (January and February 2024) planting dates. Day length neutral hemp was planted. The off-season trials were planted in attempt to field produce hemp during cooler and drier weather to prevent plant loss from disease. Unfortunately, the field plantings in October 2023, January and February 2024 yielded small plants with little harvestable flowers. At this time, we do not recommend field planting hemp in south Louisiana.

Quantitative and Qualitative Characteristics of High Quality Cannabis Sativa - Matthew Taylor
A Three-state Summary on the Critical Weed Free Period for Transplanted Floral Hemp. - Harlene HattermanValenti
Impact of Cover Crops on Weed Pressure and Soil Health in No-till Fiber Hemp Production - Ashlee George
Photoperiod Sensitive CBD Hemp Response to Fertigation Nitrogen Inputs in a Raised-bed Plasticulture Growing System - Francesco Di Gioia
Heavy Metal Application Timing Impacts Plant Growth in Cannabis sativa - Harrison Meekins
Field Evaluation of Controlled Release Fertilizer in Support of Best Management Practices for Industrial Hemp in Florida - Shea Keene

Scientific research activities focused on production of high-quality Cannabis sativa continue to grow in both the industry and academic sectors. At the university level in the United States, the majority of the research uses hemp-type or low tetrahydrocannabinolic acid (THCa) cannabis cultivars due to federal restrictions. Only at the industry level and in states with some level of medical or recreational legalization can production research be carried out on high THCa or drug-type Cannabis. Dried female flower inflorescences are the harvested and saleable portion of the Cannabis plant. The quantitative traits of flowers are relatively clear and easily enumerated. To be considered superior quality, THCa concentration should be 25% or greater and the total terpene concentration should be 2% or greater on a dry weight basis (moisture content of 10-12%). While the average cannabis consumer values these characteristics, they also greatly appreciate many of the qualitative characteristics of cannabis flower, which include visual appearance or sometimes referred to as bag appeal, olfactory characteristics when opening the container of cannabis and while breaking apart the flowers, texture, and taste when smoking. These characteristics are more difficult to define and quantify. When conducting research, both quantitative and qualitative characteristics need to be of great consideration when the goal is to produce high quality Cannabis flower.

There is a growing demand for hemp-derived products but because of the crop's criminalization history, there is limited University-produced information describing best production practices. The research objective was to define the critical weed-free period (CWFP) for transplanted floral hemp. Field trials were conducted in 2022 and 2023 at an outlying NDSU Agriculture Experiment Station near Prosper, ND (46.57° N, 97.01° W), the Cornell AgriTech campus in Geneva (42.88°N, 77.01°W), and the Clemson University Coastal Research and Education Center (33.46°N, 79.55°W). Four cultivars were transplanted at NY with three cultivars (Bubbatonic, Sour Space Candy, and Quick Spectrum) in common with ND. Three cultivars were transplanted in SC with two cultivars (Cherry Wine and Bubbatonic) in common with NY. The CWFP treatments were weeded for 0, 1, 2, 4 and 6 weeks, and weed-free. Weeding was accomplished by manually hoeing and hand-weeding. Weed species varied at each location but were mainly annual weed species (both broadleaf and grasses). Plants were harvested after at least a 16-week period in the field and air-dried before removing leaf and floral biomass from stems. At SC, when averaged across cultivars and trial years, a significant increase in mean floral yield with 2, 4, 6, and season long weed-free intervals when compared to 0 weeks weed-free. In addition, a significant decrease in dry weed biomass existed when comparing the same weed-free intervals to the 0 weeks weed-free treatment. At NY, hemp biomass averaged across all cultivars was significantly affected by the duration of weed competition. Per plant yields were reduced >80% when weeds were allowed to compete almost season-long. Biomass production was maximized when weeds were suppressed for at least 6 weeks after transplanting. At ND, results were quite different due to timely rainfall and lack of rain. Under adequate to excellent moisture conditions, the stem diameter, stem number, plant weight:height ratio, and dry biomass yield responses were significantly different only when weed control was provided for one week. However, under extreme season long drought conditions, stem diameter increased 53%, weight:stem ratio increased 172% and dry biomass increased 201% when weeds were controlled the entire season. Results indicate that transplanted hemp is sensitive to competition and preventing weed establishment for several weeks was necessary to reduce competitive interactions. Results also suggested that the need for a weed-free period was exacerbated and most important when rainfall during the growing season was limited.

Current fiber hemp (Cannabis sativa <0.30% total THC) production systems rely on pre-emergent herbicides to manage weeds prior to canopy closure. Due to the rapid growth of fiber hemp, paired with the plastic nature of the crop, the need for weed suppression is most critical in the first month after planting. No-till systems with a rolled cover crop residue may be able to provide weed suppression without the use of herbicides, which can lower the cost of inputs, reduce the risk of negative environmental impacts associated with herbicide use, and improve soil health. Four cover crops - crimson clover (Trifolium incarnatum), hairy vetch (Vicia villosa), cereal rye (Secale cereale), and triticale (xTriticale)- were roller-crimped into a mulch, and fiber hemp was no-till drilled into the residue. Each cover crop plot was paired with two bare ground plots, one of which was weeded weekly, while the other remained weedy. This design was repeated in three locations in the coastal-plain region of North Carolina (Kinston, Clinton, and Goldsboro). Crop emergence, weed counts and biomass, and fiber hemp biomass and yield were measured in each plot. Cover crop biomass was measured before planting and after retting to determine whether this residue may be a potential contaminant during baling. Soil health parameters were compared among cover and bare plots. Hairy vetch resulted in greater hemp emergence in Kinston, but emergence was not affected by the mulches otherwise. Hairy vetch plots had less weeds than others in Clinton and Goldsboro. Soil respiration and potentially oxidizable carbon did not differ by treatment, with the exception of higher soil respiration in grass covers in Goldsboro. Cover crop biomass remaining after retting was higher in grass plots than legume plots, indicating a potential for bail contamination. These preliminary results indicate that fiber hemp can be grown in a no-till system.

Cannabis sativa is a known hyperaccumulator of heavy metals (HM), and testing of hemp medicinal products is required for HM contaminants including arsenic (As), cadmium (Cd), and lead (Pb). The objective was to evaluate how the timing of HM applications impacts hemp growth. A plant experiment was conducted where 40 Cannabis sativa ‘Wife’ hemp plants were grown in deep water culture systems in a growth chamber. Aqueous nutrient solutions including combined As, Cd, and Pb were applied directly into the hydroponic solution on a weekly basis, with HM concentrations of 0.0, 0.5, and 1.0 mg HM/L. During the first six weeks, plants were grown under long days to promote vegetative growth, and 15 plants were harvested at the end of this vegetative growth phase. The remaining 25 plants were grown under short days to initiate flowering, with harvest 6 weeks later. Total dry mass (P < 0.05), shoot dry mass (P < 0.05), and root dry mass (P < 0.01) were significantly affected by HM application timing. The total and shoot dry mass was the highest for the control group, followed by the plants that received HM at 0.5 or 1.0 mg/L during the reproductive phase, and the least growth occurred in plants that received HM at 0.5 or 1.0 mg/L during the vegetative phase. Root dry mass decreased as HM concentration increased (P < 0.05). Flower dry mass was not significantly affected by HM application timing or concentration. Results highlight how exposure to HM at 0.5 to 1.0 mg/L markedly reduce biomass accumulation, especially when exposure occurs early in the production cycle.

Nitrogen (N) fertilization plays a key role in determining the productivity and quality of horticultural crops and limited information is available on the N requirements of photoperiod-sensitive CBD hemp (Cannabis sativa L.). With the objective of providing recommendations on N fertilization to CBD hemp growers a field study was conducted in Pennsylvania to evaluate the response to N inputs of two photoperiod sensitive CBD hemp genetic resources: a clone named ‘FunDip’ (The Hemp Mine) propagated using rooted cuttings and ‘Sour Kush’ (Kayagene) propagated using feminized seeds. Both selections were planted mid-June on raised beds mulched with black polyethylene film and served by drip irrigation. Plants were established at 1.5-m in-row and 2.4-m between rows. After planting both CBD hemp selections were fertigated weekly with urea (46-0-0) using seasonal application rates equivalent of 84, 168, 252, and 336 kg/ha of N. An unfertilized control was used to account for the N available through the soil and to estimate the crop N use efficiency. Treatments were arranged according to a split plot experimental design with four replications. Nitrogen treatments were randomized within the main plots while hemp selections were randomized within subplots. Each experimental unit had a minimum of 12 plants, unfertilized border rows and in-row areas were used as buffer zones to avoid fertilizer cross-contamination between different N applications rates. Plant response to N inputs was evaluated conducting biometric assessments during the growing season and at final harvest. Representative plants were sampled to measure leaf and inflorescence, stem, and total plant fresh and dry biomass. Oven-dried plant tissue samples were analyzed for their total N content to estimate the plant N accumulation during the growing season. At every biometric assessment, soil samples were collected and analyzed for pH, EC, and nitrate (NO3-) content. A quadratic response to N inputs was observed in both selections. At final harvest, the total fresh plant biomass of both genotypes was maximized with the application of 252 kg/ha of N and declined at higher N rate. However, no increase in plant dry biomass were observed in plants fertigated with over 168 kg/ha of N in both genotypes. An accumulation of NO3-N and associated increase in EC was observed with the progression of the growing seasons especially in plots fertigated with over 84-168 kg/ha of N, in Sour Kush and FunDip, respectively, which suggest an excess of N was applied with N rates exceeding 84-168 kg/ha.

Successful field cultivation of hemp (Cannabis sativa L.) in Florida is restricted to summer months when rainfall is highest, as hemp is exceptionally sensitive to daylength. Given the prevalence of soils in Florida with poor nutrient and water holding capacities, controlled release fertilizer (CRF) could be ideally suited for outdoor cultivation due to its slow-release profile. To assess the effectiveness of CRF to support plant growth while minimizing water quality risks, the plant growth and biomass production of four hemp cultivars (‘Wife’, ‘Sunset Improved’, ‘FunDip’, and ‘Belle’) were evaluated in response to nitrogen and phosphorous availability from ten CRF formulations in Apopka, Florida during the summer of 2023. Plant growth was assessed post-transplant and monthly thereafter until harvest by measuring the height, widest width, and width perpendicular to the widest width of each hemp plant. At harvest, plants were severed at the soil surface and dried at 70 degrees Celsius for three days. For each plant, the total plant biomass and total flower biomass was measured. Significant differences in plant growth and biomass production were found among varieties; however, minimal differences were found in plant growth and biomass production within variety in response to varying CRF formulations. These results suggest that CRF can provide adequate levels of fertility for the growth and development of hemp cultivated outdoors in Florida, and that selection of hemp cultivar affects plant growth and yield.

In-vitro Screening of Native Plant Crude Extracts Against Major Plant Pathogens Affecting Cannabis and Specialty Food Crops of Louisiana - Jennifer Blanchard
Investigating Fiber Hemp Seed Size Impact on Germination, Emergence, and Early Growth Rate - Samantha Carroll
Modified Media and Lighting for Repeated In Vitro Cutting Cycles of Cannabis Sativa - Molly McKay
Differential effects of macro- and micronutrients on secondary metabolite production in drug-type (medical) cannabis - Nirit Bernstein
QTL mapping and gene discovery for seed traits in hemp (Cannabis sativa L.) F2 mapping populations - Luis Monserrate
Dynamics of Cannabinoid Accumulation and Morphological Changes in Cannabis Inflorescences - Samuel des Bordes
Variable Planting Date Influences on Growth and Development of Floral Hemp in North Dakota - Brock Schulz

Commercially produced floral hemp (Cannabis sativa L.) is high in cannabidiol (CBD) concentrations relative to tetrahydrocannabinol (THC); this is intentional due to regulatory pressures requiring low THC thresholds. Given the predominant role of genotype in plant development, it is crucial to also explore environmental factors that may allow for optimization of hemp growth, yield, and quality. The goal in this study is to evaluate the extent to which an extended vegetative growing period has on height, width, and yield in irrigated raised bed production of floral hemp in North Dakota. To survey this relationship between planting date, growth, and quality parameters, mother plants were germinated from seed at the beginning of the growing season. Each treatment group of cuttings, separated by approximately two weeks, were excised from their respective cultivar mother plant for four timing treatment groups. Cultivars evaluated were ‘ACDC’, ‘Bubbatonic’, ‘Sour Elektra’, and ‘Umpqua’. The main effect of cultivar did not significantly affect any measured parameters except for height and the top 1/3 portion of dry floral biomass. Planting date treatments significantly affected the wet weight of total above-ground biomass, total dry above-ground biomass, and total floral biomass. Average total above-ground biomass and dry floral biomass was statistically different for each planting date except for the last two planting dates (June 19 and July 3). Total above-ground dry biomass averaged over cultivars, were 4070 g, 2432 g, 1323 g, and 894 g, for dates May 19, June 5, June 19, and July 3, respectively. Mean yields for total dry floral biomass, averaged over cultivars, were 1779 g, 1279 g, 784 g, and 535 g, for dates May 19, June 5, June 19, and July 3, respectively. Earlier planting dates showed an increase in height for three of the four cultivars with the exception of ‘Umpqua’. A cultivar interaction with planting date treatment occurred for the top 1/3 portion of dry floral biomass and indicated that earlier planting date increased the biomass for ‘Bubbatonic’ and ‘Sour Elektra’ while planting date did not influence dry biomass for ‘ACDC’ and ‘Umpqua’. The insights gained from assessing the impact of variable vegetative growing periods on growth and quality parameters of photoperiod-dependent floral hemp could have broader implications for optimizing production practices. Understanding the intricate interplay between genotype, environmental factors, and cultivation practices is essential for advancing sustainable and efficient hemp cultivation strategies.

Louisiana’s hot and humid climate provides the perfect environmental conditions for the growth of fungal and bacterial plant pathogens. These fungal infections are an obstacle to the success of commercial production of Cannabis sativa in the state. Two of the most recent and significant fungal diseases are southern blight caused by Sclerotium rolfsii and stem canker caused by Botrytis cinerea. However, there is a lack of formal and professional knowledge regarding fungi that infect medicinal hemp plants, and practical and effective methods for managing the casual agents of these diseases. The objective of this study was to identify natural plant products from two native plants of Louisiana, that have been reported in the Native American ethnobotanical literature to have antifungal/antibacterial properties. An in-vitro bioassay experiment was conducted using the agar plug diffusion method testing the antifungal inhibition of crude ethanol extracts from the two species against each of the two pathogens Sclerotium rolfsii and Botrytis cinerea, on four plates each of Extract 1 Diospyros virginiana L. and Extract 2 Equisetum hymale L. of 1/4PDA spiked at a dose of 250ppm, 500ppm, 750ppm, and 1000ppm against a control plate of 1/4PDA for six days. Based on this initial crude extract bioassay there is a highly significant difference in the two crude extracts (p=0.000105) when tested against Botrytis cinerea. There is also a significant difference in concentration. The test against Sclerotium rolfsii did not find any significant inhibition from either of the plant extracts tested. From our findings we will continue the research study to test the antifungal potential of crude ethanol extract as well as Hexane, chloroform, ethyl acetate soluble fractions of Extract 1 Diospyros virginiana. The goal of the study is to integrate the antifungal compounds and their application for the development of best practices in Cannabis production.

Fiber hemp (Cannabis sativa L.

Micropropagation usually involves cytokinin in single-harvest batches. We report two in vitro studies with multiple harvest: (1) fed batch process with modified physical states and (2) LED light treatments. In (1), genotypes of Cannabis sativa were observed in stationary agar (A), stationary Oasis® infused with liquid (OIL) and agitated Oasis® infused with liquid (AOIL).Fifteen explants were planted in vessels with 120 mL DKW medium harvested on 3-week cycles, with 0 or 15 mL additional media. Harvested shoots, length, and dry mass from repeated cycles were recorded. Genotypes T1 and Peach failed on multiple harvest cycles and were eliminated, although single cycle had higher quality in OIL. BaOx and Cherry1 on OIL/AOIL with additions were better quality than A in five cycles. Shoots harvested increased from 15 to 30 in cycles 1-3 in OIL/AOIL, but in A were approximately 20, while length was longest in OIL/AOIL. By cycle 3, all measured responses were decreasing until cycle 5 where a minimum of 7 shoots per vessel or more were only in OIL, but shoots were too short to plant in greenhouse. In (2), blue and supplemental far-red were observed with in vitro shoots of BaoX and Cherry1. OIL treatments were placed in LED polychromatic and dichromatic light (white, high red:blue, medium red:blue, white w/5% far-red, high red:blue 5% far-red, medium red:blue w/5% far-red, low red:blue w/ 5% far-red) at similar intensities (190-240 µmols·m-2·s-116 h-photoperiod). Media additions were made with responses recorded bi-weekly. Five randomly selected microcuttings per vessel rooted ex vitro on mist bench for 16 days. Over multi-cycles, plants treated with 5% far-red increased number and length, while plants under higher blue light increased dry mass. Shoot number increased to 28 in cycles 1-3 with far-red, and 18 without before decreasing to initial 15 during cycle 5. The accumulated shoots per vessel over 5-cycles (10-weeks) was 108 with far-red, and 84 without. Shoot length in far-red-treated plants increased from 19 - 25 mm in cycle 3 before decreasing to 10 mm in cycle 5. Plants without far-red had 10 – 15 mm length the entire experiment. Dry mass was highest during cycle 1 with blue light before decreasing 50% in cycle 3, where it remained until cycle 5. Sixty-eight percent of shoots rooted regardless of prior in vitro treatment. OIL with media addition allowed shoots to be harvested five cycles, while signaling response of far-red light allowed increased productivity and length.

Hemp (Cannabis sativa L.) is a highly versatile crop that has attracted considerable attention among farmers due to its diverse applications. Recent studies have sought to establish a fundamental understanding and baseline of the nutritional requirements of hemp, opening up possibilities for organic hemp production. Our research focuses specifically on evaluating the productivity of a floral hemp variety using different regenerative practices, with a particular emphasis on organic soil amendments that promote soil health in Piedmont area of North Carolina. The field experiment was conducted at North Carolina A

The medical potential of cannabis (Cannabis sativa L.) is based on the complex chemical profile, comprising hundreds of secondary metabolites including cannabinoids, terpenoids and flavonoids. Cultivation conditions were demonstrated to affect plant development, function and production of secondary metabolites in cannabis. Understanding regulation of plant response to environmental conditions is key for development of optimal chemical profile for modern medicine. We have recently demonstrated sensitivity of the secondary metabolite profile in medical cannabis to mineral nutrition, with considerable responses to N, P, and K nutrition. Therefore, knowledge on the cannabis plant response to fertigation schemes is essential for the optimization of cultivation for production of high quality standardized material for the medical market, as well as for development of plant products containing specific desirable phytochemical profiles. In the talk, we will discuss our recent results concerning the potential of additional macronutrients and micronutrients to regulate plant development and the profile of active secondary metabolites in ‘drug-type’ medical cannabis. In pot experiments under controlled conditions, we demonstrated differential induction of changes in the cannabinoid and terpene profiles in ‘drug-type’ medical cannabis also by Ca, Mg, Zn and Mn. Furthermore, rate of uptake and deposition in the plants of individual macronutrients and micronutrients changes between the vegetative and the reproductive developmental stages, and along the reproductive phase.

The emergence of a thriving hemp industry in the U.S. will depend on the breeding of high-yielding regionally adapted cultivars. Despite the latest research efforts, little is known regarding the genetic basis of important agronomic traits in hemp. The objective of this research was to identify and characterize genomic regions associated with seed morphology and quality traits. F 2 mapping populations were developed by crossing hemp germplasm bred or cultivated for cannabinoids (‘FL 58’ × ‘TJ’s CBD’), grain (GVA- H-20-1179 × ‘Picolo’), or fiber (‘Si-1’ × GVA-H-21-1003) market classes. These populations were investigated due to their variation in seed size and seed crude protein. The cannabinoid, grain, and fiber populations were grown and seed was harvested in 2021, 2022, and 2023, respectively. Harvested seeds were phenotyped for thousand seed weight (TSW) and crude protein content predicted by near-infrared (NIR) spectroscopy. The high-cannabinoid population was genotyped using an Illumina array, while the fiber and grain populations were genotyped using an Agilent SureSelect Custom Target Enrichment Probe Set. Marker-associated sequences were aligned to the CBDRx v.2.0 reference genome to align the physical and genetic maps. The TSW and protein content in the cannabinoid population ranged from 9.62 to 23.93 g and 19.25 to 31.89 %, respectively. In contrast, the TSW of the fiber and grain populations ranged from 7.34 to 45.17 g and 8.73 to 31.42 g, respectively. Numerous quantitative trait loci (QTL) of varying effect sizes were identified genome-wide. Notably, in the high- cannabinoid population, major and minor effect QTL for TSW were detected on Chr01 corresponding to 642 kb and 5.56 Mb genetic regions, respectively. Our results in the cannabinoid population highlight the importance of developing more than one F 2 mapping population in a given cross to capture the effect of more alleles due to high heterozygosity in hemp and evaluating distinct pedigrees to sample additional alleles in diverse genetic backgrounds. Narrowing the region around or identifying candidate genes will allow the development of high-throughput molecular markers for beneficial alleles across mapping pedigrees. These findings will accelerate hemp breeding programs through the implementation of marker-assisted selection for high-yielding and high-quality hemp cultivars for grain production.

Cannabis (Cannabis sativa L.) is cultivated for its cannabinoids, which have applications for therapeutic and recreational use. This phenomic evaluation explores accumulation of 16 cannabinoids of interest and associated morphological changes in Cannabis flowers. Eight cultivars of interest were grown in containers within an environmentally controlled greenhouse for 150 days (72 days reproductive). Light intensity, light duration, temperature, and relative humidity were regulated. Monitoring floral development, we observed a consistent increase in cannabinoid concentration as flowers matured, peaking in advanced stages of development. This accumulation pattern was consistent across diverse cultivars, which indicates this accumulation pattern to be the result of a fundamental biological mechanism. Concurrent with cannabinoid accumulation, we noted morphological changes in trichomes, which are widely utilized as markers of maturation within industry. Trichomes transitioned from sparse and translucent to abundant, enlarged, and displaying orange/amber hues as flowers matured, signifying floral maturation and trichome senescence. Importantly, a significant linear correlation emerged between cannabinoid accumulation and trichome morphological changes across all cultivars. This underscores a tight relationship between cannabinoid biosynthesis and trichome development, shaped by genetic factors. In summary, our findings demonstrate the intricate relationship between cannabinoid accumulation and floral morphology in Cannabis. Insights gained are invaluable for cultivar selection, breeding, and cultivation practices aimed at optimizing cannabinoid quantity and time to harvest. Understanding the underlying molecular mechanisms of cannabinoids promises tailored approaches for the optimization of cannabinoid production and the fostering of therapeutic and industrial advancements in Cannabis.

A forum for discussion of potential collaborations with regards to specialty crops – i.e. hemp, herbs, medicinal plants, and tropicals, breeding, production, etc.