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Why Are Women Tired? Examining Sex-Dependent Effects Of Behavioral Rhythms On Perceived Sleepiness, Maricel Schuler

Theses and Dissertations--Psychology

Sleep complaints in women emerge at menarche and coincide with reproductive hormonal fluctuations throughout the monthly menstrual cycle. To our knowledge, we are the first study (N = 44) to utilize a validated algorithm that uses actigraphy-derived light and activity data in a novel approach to estimate circadian phase, referred here as the photobehavioral phase. We hypothesize that women will have earlier photobehavioral phases, larger phase angles, poorer perceived sleep quality, and greater sleepiness compared to men. In addition, we hypothesize that the perimenstrual phase will be associated with poorer sleep within a subsample of women (N = 15). Contrary …

Examining Values In The Treatment Of Borderline Personality Disorder: A Single-Case Experimental Design, Nicole Stumpp

Theses and Dissertations--Psychology

Borderline personality disorder impacts roughly 1.6% of the general population yet only a quarter of people with BPD are able to access treatment. Understanding the mechanisms that promote behavior change in treatment is crucial for improving care for this population. Experiential avoidance has been linked to risky behaviors, a prevalent and debilitating symptom observed in BPD. Values identification may be a fruitful avenue for engaging experiential avoidance in treatment. The goal of the present study is to understand the unique and combined effects of values identification and behavior change skills (i.e., opposite actions, exposure) on experiential avoidance (target), maladaptive behavior …

Randomized Controlled Trial Of A Single-Session Mechanism-Focused Intervention For Suicidal Thoughts And Behaviors, Martina Fruhbauerova

Theses and Dissertations--Psychology

Suicide remains a critical public health concern, with increasing rates and millions experiencing suicidal ideation annually. Although evidence-based treatments exist, many are time-intensive, underutilized, and often inaccessible to high-risk individuals, especially those recently discharged from inpatient psychiatric care. Brief, scalable interventions targeting core psychological mechanisms implicated in suicidal thoughts and behaviors (STBs) are needed. This study evaluated a novel Single Session Mechanism-Focused Intervention (SSMFI) designed to reduce hopelessness and negative perceptions of social relatedness among adults hospitalized for STBs. In a randomized controlled trial (N = 38) conducted on two inpatient psychiatric units, participants were assigned to either the SSMFI …

A Multidisciplinary Approach To The Thermal And Non-Thermal Mechanisms In Galaxy Clusters, Sheng-Chieh Lin

Theses and Dissertations--Physics and Astronomy

Galaxy clusters form at the intersections of the cosmic web and carry imprints of the structure formation history of the universe. As massive, multi-component systems, they offer unique insights into the astrophysical processes that govern both structure formation and galaxy evolution. Observable across the full electromagnetic spectrum, clusters emit photons through a variety of mechanisms, each tracing different physical processes. This dissertation investigates both the thermodynamic and non-thermal properties of the intracluster medium (ICM) to better understand the physical processes shaping observed phenomena. It comprises three main studies, each targeting a different aspect of galaxy cluster physics. In the second …

Patterns Of Inpatient Antibiotic Utilization By Race And Ethnicity At Us Children’S Hospitals, Bethany A. Wattles, Jeffrey I. Campbell, Theresa Kluthe, Yana B. Feygin, Kahir Jawad, Michelle D. Stevenson, Deborah Winders Davis, Jennifer Porter, V. Faye Jones, Matt Hall, Michael J. Smith

Biostatistics Faculty Publications

Background and Objectives: Racial and ethnic variations in antibiotic utilization are well-reported in outpatient settings but little is known about inpatient settings. Our objective was to describe national inpatient antibiotic utilization among children by race and ethnicity. Methods: This study included hospital visit data from the Pediatric Health Information System between 01/01/2022 and 12/31/2022 for patients <20 years. Primary outcomes were the percentage of hospitalization encounters that received an antibiotic and antibiotic days of therapy (DOT) per 1000 patient days. Mixed-effect regression models were used to determine the association of race-ethnicity with outcomes, adjusting for covariates. Results: There were 846,530 hospitalizations. 45.2% of children were Non-Hispanic (NH) White, 27.1% were Hispanic, 19.2% were NH Black, 4.5% were NH Other, 3.5% were NH Asian, 0.3% were NH Native Hawaiian/Other Pacific Islander (NHPI) and 0.2% were NH American Indian. Adjusting for covariates, NH Black children had lower odds of receiving antibiotics compared to NH White children (aOR 0.96, 95%CI 0.94–0.97), while NH NHPI had higher odds of receiving antibiotics (aOR 1.16, 95%CI 1.05–1.29). Children who were Hispanic, NH Asian, NH American Indian, and children who were NH Other received antibiotic DOT compared to NH White children, while NH NHPI children received more antibiotic DOT. Conclusions: Antibiotic utilization in children’s hospitals differs by race and ethnicity. Hospitals should assess policies and practices that may contribute to disparities in treatment; antibiotic stewardship programs may play an important role in promoting inpatient pharmacoequity. Additional research is needed to examine individual diagnoses, clinical outcomes, and drivers of variation.

Leveraging Machine Learning Models To Explore Disparities In Prostate Cancer Diagnosis, Treatment, And Survival, Reuben Adatorwovor, Rasaq Oladapo, Parisa Ghasemi, Gaurav Kumar, Daniel J. Morton, Motolani E. Ogunsanya, Olufunmilola Abraham

Biostatistics Faculty Publications

Introduction: Prostate cancer (CaP) is the second most common cancer in men globally and a leading cause of cancer-related mortality, particularly among older men. In the United States, disparities in incidence, stage at diagnosis, and outcomes persist across racial, socioeconomic, and geographic lines. Men in medically underserved regions like Appalachia experience higher mortality due to limited access to timely screening and treatment. Given the complex interplay of clinical, behavioral, and sociodemographic factors, machine learning (ML) offers promise in identifying survival predictors that traditional models may overlook. This study applies ML models to assess the impact of age at diagnosis, treatment …

Clinical Criteria For Limbic-Predominant Age-Related Tdp-43 Encephalopathy, David A. Wolk, Peter T. Nelson, Liana Apostolova, Konstantinos Arfanakis, Patricia A. Boyle, Cynthia M. Carlsson, Nick Corriveau-Lecavalier, Penny Dacks, Bradford C. Dickerson, Kimiko Domoto-Reilly, Brittany N. Dugger, Rebecca Edelmayer, David W. Fardo, Michel J. Grothe, Timothy J. Hohman, David J. Irwin, Gregory A. Jicha, David T. Jones, Claudia H. Kawas, Edward B. Lee, Karen Lincoln, Gladys E. Maestre, Elizabeth C. Mormino, Chiadi U. Onyike, Ronald C. Petersen, Gil D. Rabinovici, Rosa Rademakers, Rema Raman

Biostatistics Faculty Publications

Limbic predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC) is highly prevalent in late life and a common co-pathology with Alzheimer's disease neuropathologic change (ADNC). LATE-NC is a slowly progressive, amnestic clinical syndrome. Alternatively, when present with ADNC, LATE-NC is associated with a more rapid course. With the emergence of anti-amyloid therapeutics, discrimination of LATE-NC from ADNC is critical and will lead to greater clinical recognition of amnestic patients without ADNC. Furthermore, co-pathology with LATE-NC may influence outcomes of these therapeutics. Thus there is a need to identify patients during life with likely LATE-NC. We propose criteria for clinical diagnosis of …

A Myostatin Inhibitory Antibody Combined With Insulin, Partially Rescues The Musculoskeletal Phenotype Of Female Insulin-Deficient Diabetic Mice, R. Clay Bunn, Reuben Adatorwovor, Philip D. Ray, Alexander R. Keeble, Christopher S. Fry, Sasidhar Uppuganti, Jeffry S. Nyman, John L. Fowlkes, Evangelia Kalaitzoglou

Biostatistics Faculty Publications

Introduction: Type 1 diabetes is associated with deficits in both skeletal muscle and bone. Inhibition of myostatin, a negative regulator of muscle mass, was explored as a druggable target to improve the musculoskeletal phenotype associated with insulin-deficient diabetes in female mice. Methods: We investigated whether administration of an inhibitory myostatin antibody (MyoAb) in streptozotocin-induced diabetes in female mice is protective for skeletal muscle and bone. DBA/2J female mice were injected with low-dose streptozotocin or with citrate buffer (vehicle). Subsequently, mice were implanted with insulin-containing or vehicle pellets, with groups being randomized to myostatin or control antibody for 8 weeks. At …

Diagnosing Statistical Education Needs Of Health Science Learners, Amy S. Nowacki, Ann M. Brearley, Robert A. Oster, Emily Slade, Katrina L. Devick, Matthew J. Hayat, Sally W. Thurston

Biostatistics Faculty Publications

Many types of health science learners, including clinical and translational scientists, students, researchers, and clinicians, seek to increase their knowledge of biostatistics. These learners are heterogeneous in their field, career stage and career focus. Based on the collective experience of an expert panel with over 115 years teaching statistics to health science learners, we propose a framework for considering the needs of health science learners motivated by their career goals. This framework defines four types of health science learners seeking statistical training: (a) consumers, (b) “milestone makers”, (c) biomedical researchers with statistical support, and (d) biomedical researchers without statistical support. …

Expression Of Dementia Biomarkers In Appalachian And Non-Appalachian Elvo Patients During Thrombectomy, Neha Anil, Christopher J. Mclouth, Hunter S. Hazelwood, Elise Dahlke, Jacqueline A. Frank, Nathan Millson, Mais Al-Kawaz, Jordan P. Harp, Will Cranford, Shivani Pahwa, David Dornbos, Justin F. Fraser, Keith R. Pennypacker

Biostatistics Faculty Publications

Background/Context: Vascular Cognitive Impairment and Dementia (VCID) affects 25-30% of stroke patients and includes cognitive impairments caused by vascular injury, such as post-stroke dementia. Rehabilitation has the potential to improve the quality of life for patients at risk of developing dementia. However, there is currently no reliable method to identify those at risk of dementia after a stroke. Several biomarkers, including ADRD (Alzheimer’s disease and related dementias) biomarkers (Ab, tau, NfL, and GFAP) and angiogenic factors (VEGF, Flt-1, Tie-2, PIGF, and FGF) have been associated with the development of dementia. Populations in Appalachia experience a higher incidence of stroke and …

A Review Of The Association Between Dietary Intake And Brain Iron Levels In Older Adults: Preliminary Findings And Future Directions., Valentinos Zachariou, Christopher E. Bauer, Colleen A. Pappas, Brian T. Gold

Behavioral Science Faculty Publications

Background/Objectives: Non-heme iron is essential for critical neuronal functions such as ATP generation, synaptogenesis, neurotransmitter synthesis, and myelin formation. However, as non-heme iron accumulates with age, excessive levels can contribute to oxidative stress, potentially disrupting neuronal integrity and contributing to cognitive decline. Despite growing evidence linking high brain iron with poorer cognitive performance, there are currently no proven methods to reduce brain iron accumulation in aging or to protect cognitive function from iron’s negative effects. Recent studies suggest that nutrition may influence brain iron levels, though the evidence remains limited and mixed. Methods: In this review, we explore recent findings, …

Differential Infiltration Of Key Immune T-Cell Populations Across Malignancies Varying By Immunogenic Potential And The Likelihood Of Response To Immunotherapy., Islam Eljilany, Sam Coleman, Aik Choon Tan, Martin D. Mccarter, John Carpten, Howard Colman, Abdul Rafeh Naqash, Igor Puzanov, Susanne Arnold, Michelle L. Churchman, Daniel Spakowicz, Bodour Salhia, Julian Marin, Shridar Ganesan, Aakrosh Ratan, Craig Shriver, Patrick Hwu, William S. Dalton, George J. Weiner, Jose R. Conejo-Garcia, Paulo Rodriguez, Ahmad A. Tarhini

Markey Cancer Center Faculty Publications

Background: Solid tumors vary by the immunogenic potential of the tumor microenvironment (TME) and the likelihood of response to immunotherapy. The emerging literature has identified key immune cell populations that significantly impact immune activation or suppression within the TME. This study investigated candidate T-cell populations and their differential infiltration within different tumor types as estimated from mRNA co-expression levels of the corresponding cellular markers.

Methods: We analyzed the mRNA co-expression levels of cellular biomarkers that define stem-like tumor-infiltrating lymphocytes (TILs), tissue-resident memory T-cells (TRM), early dysfunctional T-cells, late dysfunctional T-cells, activated-potentially anti-tumor (APA) T-cells and Butyrophilin 3A (BTN3A) isoforms, utilizing …

Students Participating As Ambassadors For Research In Kentucky (Spark): A Health Equity Undergraduate Research Training Program, Ariel A. Arthur, Rebecca L. Delacerda Allen, Fidelis Y. Sesenu, Maxwell A. Groznik, Carrie B. Oser, Madeline Dunfee, Philip A. Kern, Nancy Schoenberg

UK CARES Faculty Publications

The Students Participating as Ambassadors for Research in Kentucky (SPARK) program provides novel health equity research training and targeted mentorship for undergraduates, particularly those from groups underrepresented in the biomedical and behavioral research and workforce. SPARK aims to address inadequate diversity in the medical and scientific research fields by providing comprehensive research mentorship and skill-building. Unlike most existing research training programs that are brief, focus on laboratory research, or are limited to graduate students and junior faculty, SPARK delivers a 16-month intensive behavioral and population health science training, equipping students with needed tools to conceptualize, plan, execute, and analyze their …

Myosin Xva Isoforms Participate In The Mechanotransduction-Dependent Remodeling Of The Actin Cytoskeleton In Auditory Stereocilia, Ana I. López-Porras, Ava M. Kruse, Mark T. Mcclendon, A. Catalina Vélez-Ortega

Neurology Faculty Publications

Auditory hair cells form precise and sensitive staircase-like actin protrusions known as stereocilia. These specialized microvilli detect deflections induced by sound through the activation of mechano-electrical transduction (MET) channels located at their tips. At rest, a small MET channel current results in a constant calcium influx which regulates the morphology of the actin cytoskeleton in the shorter ‘transducing’ stereocilia. However, the molecular mechanisms involved in this novel type of activity-driven plasticity in the stereocilium cytoskeleton are currently unknown. Here, we tested the contribution of myosin XVA (MYO15A) isoforms, given their known roles in the regulation of stereocilia dimensions during hair …

Apoa2 Increases Cholesterol Efflux Capacity To Plasma Hdl By Displacing The C-Terminus Of Resident Apoa1, Snigdha Sarkar, Jamie Morris, Youngki You, Hannah Sexmith, Scott E. Street, Stephanie M. Thibert, Isaac K. Attah, Chelsea M. Hutchinson Bunch, Irina V. Novikova, James E. Evans, Amy S. Shah, Scott M. Gordon, Jere P. Segrest, Karin E. Bornfeldt, Tomas Vaisar, Jay W. Heinecke, W. Sean Davidson, John T. Melchior

Saha Cardiovascular Research Center Faculty Publications

Abstract The ability of high-density lipoprotein (HDL) to promote cellular cholesterol efflux is a more robust predictor of cardiovascular disease protection than HDL-cholesterol levels in plasma. Previously, we found that lipidated HDL containing both apolipoprotein A-I (APOA1) and A-II (APOA2) promotes cholesterol efflux via the ATP-binding cassette transporter (ABCA1). In the current study, we directly added purified, lipid-free APOA2 to human plasma and found a dose-dependent increase in whole plasma cholesterol efflux capacity. APOA2 likewise increased the cholesterol efflux capacity of isolated HDL with the maximum effect occurring when equal masses of APOA1 and APOA2 coexisted on the particles. Follow-up …

Untargeted Lipidomics Reveals Novel Hdl Metabotypes And Lipid-Clinical Correlates, Peer W. F. Karmaus, Scott M. Gordon, Marcus Y. Chen, Alison A. Motsinger-Reif, Rodney W. Snyder, Timothy R. Fennell, Suramya Waidyanatha, Reshan A. Fernando, Alan T. Remaley, Michael B. Fessler

Saha Cardiovascular Research Center Faculty Publications

Plasma high-density lipoprotein (HDL), originally studied for its role in lipid transport, is now appreciated to have wide-ranging biological functions that become defective during disease. While >200 lipids have collectively been detected in HDL, published HDL lipidomic analyses in different diseases have commonly been targeted to prespecified subsets of lipids. Here, we report the results of untargeted lipidomic analysis of HDL isolated from 101 subjects referred for computed tomographic coronary imaging for whom multiple additional clinical and lipoprotein metadata were measured. Unsupervised clustering of the total HDL lipidome revealed that the subjects fell into one of two discrete groups, herein …

The Effects Of Mosaicism On Biological And Clinical Markers Of Alzheimer's Disease In Adults With Down Syndrome, Laura Xicota, Lam-Ha T. Dang, Alice Lee, Sharon Krinsky-Mchale, Deborah Pang, Lisa Melilli, Sid E. O’Bryant, Rachel L. Henson, Charles Laymon, Florence Lai, H. Diana Rosas, Beau Ances, Ira Lott, Christy Hom, Bradley Christian, Sigan Hartley, Shahid Zaman, Elizabeth Head, Mark Mapstone, Zhezhen Jin, Wayne Silverman, Nicole Schupf, Benjamin Handen, Joseph H. Lee, Alzheimer’S Biomarker Consortium – Down Syndrome (Abc-Ds)

Neurology Faculty Publications

Background Individuals with Down syndrome (DS) are at high risk of early-onset Alzheimer’s disease (AD); yet, some 20 percent do not develop any signs of dementia until after 65 years or in their lifetime. Mosaicism could contribute to this phenotypic variation, where some disomic cells could lead to lower levels of gene products from chromosome 21.

Methods We examined longitudinal neuropsychological and biomarker data from two large studies of DS: the Alzheimer Biomarker Consortium–Down syndrome study (ABC-DS) (n = 357); and a legacy study (n = 468). We assessed mosaicism using karyotyping or GWAS data. Participants had data on plasma …

Targeted Long-Read Sequencing To Quantify Methylation Of The C9orf72 Repeat Expansion, Evan Udine, Nicole Finch, Mariely Dejesus-Hernandez, Jazmyne L. Jackson, Matthew C. Baker, Siva Arumugam Saravanaperumal, Eric Wieben, Mark T. W. Ebbert, Jaimin Shah, Leonard Petrucelli, Rosa Rademakers, Björn Oskarsson, Marka Van Blitterswijk

Neurology Faculty Publications

Background The gene C9orf72 harbors a non-coding hexanucleotide repeat expansion known to cause amyotrophic lateral sclerosis and frontotemporal dementia. While previous studies have estimated the length of this repeat expansion in multiple tissues, technological limitations have impeded researchers from exploring additional features, such as methylation levels.

Methods We aimed to characterize C9orf72 repeat expansions using a targeted, amplification-free long-read sequencing method. Our primary goal was to determine the presence and subsequent quantification of observed methylation in the C9orf72 repeat expansion. In addition, we measured the repeat length and purity of the expansion. To do this, we sequenced DNA extracted from …

Physicochemical Property Effects On Immune Modulating Polymeric Nanoparticles: Potential Applications In Spinal Cord Injury, Daniel J. Kolpek, Jaechang Kim, Hisham Mohammed, John C. Gensel, Jonghyuck Park

Markey Cancer Center Faculty Publications

Nanoparticles (NPs) offer promising potential as therapeutic agents for inflammation-related diseases, owing to their capabilities in drug delivery and immune modulation. In preclinical studies focusing on spinal cord injury (SCI), polymeric NPs have demonstrated the ability to reprogram innate immune cells. This reprogramming results in redirecting immune cells away from the injury site, downregulating pro-inflammatory signaling, and promoting a regenerative environment post-injury. However, to fully understand the mechanisms driving these effects and maximize therapeutic efficacy, it is crucial to assess NP interactions with innate immune cells. This review examines how the physicochemical properties of polymeric NPs influence their modulation of …

Independent Evolution Of Oleate Hydratase Clades In Bacillales Reflects Molecular Convergence, Robert J. Neff, Priscilla C. Lages, Shannon K. Donworth, James D. Brien, Christopher D. Radka

Markey Cancer Center Faculty Publications

Oleate hydratase (OhyA), a flavoenzyme that catalyzes the hydration of unsaturated fatty acids, has been identified in various Bacillales organisms, including those in the Listeria, Lysinibacillus, Paenibacillus, and Staphylococcus genera. In this study, we combine structural biology with molecular and phylogenetic analyses to investigate the evolutionary dynamics of the OhyA protein family within the Bacillales order. Our evolutionary analysis reveals two distinct OhyA clades (clade I and clade II) within Bacillales that, while sharing catalytic function, exhibit significant genomic and structural differences. Our findings suggest that these OhyA clades originated from independent evolutionary processes through convergent evolution rather than gene …

Salivary Features Of Periodontitis And Gingivitis In Type 2 Diabetes Mellitus, Jeffrey L. Ebersole, Sreenatha S. Kirakodu, Xiaohua D. Zhang, Dolph Dawson, Craig S. Miller

Biostatistics Faculty Publications

Type 2 diabetes mellitus (T2DM) is associated with cellular abnormalities, tissue and organ dysfunctions, and periodontitis. This investigation examined the relationship between the oral microbiome and salivary biomarkers in T2DM patients with or without periodontitis. This cohort (35–80 years) included systemically healthy non-periodontitis (NP; n = 31), T2DM without periodontitis (DWoP; n = 32) and T2DM with periodontitis (DWP; n = 29). The oral microbiome [Operational Taxonomic Units (OTUs)] (16 s rRNA sequencing) and targeted host salivary biomarkers (immunoassays) were assessed. We identified 47 OTUs that were significantly different in abundance between NP samples and any disease subset or between …

Prevalent Atherosclerotic Cardiovascular Disease Among Veterans By Sexual Orientation, Carl G. Streed, Meredith S. Duncan, Kory R. Heier, T. Elizabeth Workman, Lauren B. Beach, Billy A. Caceres, John R. O’Leary, Melissa Skanderson, Joseph L. Goulet

Biostatistics Faculty Publications

BACKGROUND: Seven million lesbian, gay, and bisexual (LGB) adults will be aged >50 years by 2030; assessing and addressing their risk for cardiovascular disease is critical. METHODS AND RESULTS: We analyzed a nationwide cohort using the Veterans Health Administration data. Sexual orientation (SO) was classified via a validated natural language processing algorithm. Prevalent atherosclerotic cardiovascular disease (ASCVD) (history of acute myocardial infarction, ischemic stroke, or revascularization) was identified via International Classification of Diseases, Ninth and Tenth Revision (ICD-9 and ICD-10) codes. The index date was the date of the first primary care appointment on or after October 1, 2009. We …

Towards An Ideal Seed Coating, J M. Scott

IGC Proceedings (1977-2023)

Coated pasture seeds have been formulated in the past based largely on "trial and error" with relatively few objective criteria being employed to define desirable formulations, A description of desirable propelties of various layers of seed coatings and of the seeds themselves is presented.

Lolium Endophyte Viability: Effect Of Seed Storage, M P. Rolston, J R. Crush, M D. Hare, K K. Moore

IGC Proceedings (1977-2023)

The effects of seed storage on the endophyte Acremonium lolii in ryegrass (Lolium perenne L.) were evaluated over 7 years. The long• term effects of 4 seed moisture contents (SMC) 8.6-13.1 %: tempemture (ambient, 5, O, -15°C) 'aitd packaging types: calico, polyethylene fi,Jm. 9-140 µm, and aluminium-polyethylene (AIP) on endophyte viability were assess·ed. • Endophyte viability was maintained by lower seed moisture content and low temperatures. In ambient warehouse conditions endophyte viability declined to zero in 12 months in calico bags,' but was maintained for 3 years at 8.6% SMC in AIP: • Endophyte viability was maintained for …

Effect Of Dormancy-Releasing Treatments On Germination Of Bahiagrass Seed, J. Jeffrey Mullahey, D S. Fisher

IGC Proceedings (1977-2023)

Low seed germination and dormant seed in bahiagrass (Paspalum nonatutum Flugge.) necessitate high seeding rates for successful pasture establishment. A study of dormancy-releasing treatments and age of seed on germination of bahiagrass was conducted in an incubator at the Southwest Florida Research and Education Center near Immokalee, Florida. Five seed treatments (Crop-Start (Solid Matrix Seed Priming, Kamterter Products Inc., Lincoln, NB), potassium nitrate (KNO3), heat/humidity, palea removed, and a check), 2 cullivars (Pensacola, Tifton 9) of bahiagrass and 2 ages (10 and 16 months) of seed were used. A significant (P<0.05) age ·x treatment interaction occurred for all response variables. Based on total germination at 28 days, % dormant seed and rate of germination, Crop-Start and heat/humidity were consistently the best treatments. Additional research on germination with dormancy-releasing treatments is needed to study the Interaction of seed age and bahiagrass cultivar.

Weed Seed Contamination: Use Of A Seed Testing Database To Identify Processing Limitations, J S. Rowarth, M P. Rolston, A A. Johnson

IGC Proceedings (1977-2023)

A computerised database maintained by the Official Seed Testing Station of New Zealand provided the opporlunity to survey weed seed contamination in clover and grass seed-lots. Broad-leaf weeds such as Slierardia arvensis, Stellaria ,nedia and Chenopodium album were the major contaminants in Trifolium repens seed-lots. In grass seed-lots the main contaminants were seeds of other grasses such as Bromus hordaeceus, Vulpia spp. and Holcus lanatus. Weed seeds were found to be a major reason for downgrading or rejection from certification of clover and grass seed-lots in New Zealand; this reflects strict quality control measures.

An Investigation In To The Effect Of Some Factors On The Germination Of Erodium Seeds, Myrna Johnston, Alfredo Olivares, Gladys Fernandez

IGC Proceedings (1977-2023)

Erodiurn seeds present variable dormancy in and even within each species. Thus, it is important to know the factors that determine this variation as related to the persistence of its species. E. rnoschatmn and E. rnalacoides seeds were collected at the end of the annual cycle at La Rinconada de Maipli (33°28'S and 7S050'W). Effects of seed sour.ce (collecting in 1986, 1988 and 1990), age (keeping seeds under laboratory conditions) and maternal factors (cutting plants at early flowering) were analysed. Seeds were tested for germination capacity and germination rate at a constant temperature of 15°C on Petri dishes provided with …

Long-Term Seed Dormancy In Poa Pratensis L. Northern Norway, Trygve S. Aamlid, Dagfinn Arntzen

IGC Proceedings (1977-2023)

Inadequate gennination has often been obseived when planting Poa pratensis L. cv. Lavang (69°N) in northern Norwegian grasslands. This investigation was intended to elucidate whether this was due lo long­term seed dormancy, Seed-lots grown in different years in northern and southern Norway and stored at O-to•c, were germinated in Jakobsen­type germinators al various combinations of temperature and light. Significant dormancy was expressed at 21 °C even after 10 years of storage. Al this constant temperature, germination was promoted by 8 h fluorescent light compared with darkness and continuous light. Al 21/ I 2°C alternating temperature, seed genninated well irrespective of …

Seed Vigour In Lucerne And White Clover, Y R. Wang, J G. Hampton

IGC Proceedings (1977-2023)

Accelerated ageing (AA) was used to assess the seed vigour of 5 lucerne (Medicago sativa L, cv. Wairau) and 8 white clover (Trifolium repens L. cv. Grasslands Huia) seed-lots. Germination prior to AA ranged from 86-94% and 87-94% for the lucerne and white clover seed-lots respectively. All seed-lots hl\d been harvested in 1988 and were certified either as basic or first generation. Germination after 72 h at 40:t0.5°C (AA test) ranged frcim 31-76% for the lucerne seed­lots and 15-56% for che white clover seed-lots, indicating significant differences in seed.vigour among lots of both species. Time of ageing influenced …

Growing Methods For The Morphological Assessment Of White Clover Cultivars Purity, J G. Hampton, E J. Musukwa

IGC Proceedings (1977-2023)

Three growing methods (field sward, field spaced plants, glasshouse plants) were compared for the morphological assessment of white clover (Trifolium repens L.) cultivar purity. Three cerlified (breeders, basic and first generation) seed-lots of cv. Grasslands Kopu and one first generation Kopu seed lot which had been mixed with seed of another cultivnr (10:1) were used to generate data. After analysis of variance (ANOVA), significant (P<0.05) reductions from the breeders seed lot siandnrd for leaf size, stolon number and leaf length/width ratio were recorded for the mixed seed· 101 in nil three growing methods, and for petiole length with the sward method only. With the glasshouse and spaced-plant melhods, slolon numbers of the basic and first generation seed-lots were reduced (P<0.05), while leaf size was lower (P<0.05) for the first generation seed-lot in lhe glasshouse. However, under OECD certification requirements, leaf size of the mixed seed lot was the only characler for which "off types" were detecled. Data coefficients of variation were no greater for the glasshouse method than the required OECD plot-test method.