Horticulture Commons^™

Addressing Challenges Of Dryland Production Of Sunflowers And Corn In The Semi-Arid High Plains Of Nebraska, Zhan Orazov

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Corn and sunflower are value crops for America. Cultivation of corn and sunflower often vary depending on growing environment. Selecting appropriate planting dates, hybrids and plant density frequently concerns farmers. This concern is understandable because the decision made directly impacts final income. The objectives were to evaluate interaction of corn and sunflower planting dates and hybrid maturity and evaluate interaction of corn flex hybrids and plant density under conditions of western Nebraska. Nine corn hybrids with relative maturity ranging from 86 to 105 days were sown between early May and late June in first and between late April and early …

Understanding The Influence Of Excessive Fertilization And Water Relations On Peach (Prunus Persica (L.) Batsch) Skin Bronzing, Sydney Lykins

All Theses

This project evaluated possible causes of peach skin bronzing, a brown-blotchy skin discoloration on mid to late-season peaches that causes drastic decreases to grower incomes in the Southeastern U.S. It is known that there is no bacterial, insectile, viral, or fungal cause of bronzing; thus, these studies focused on potential nutrient imbalances within the peach. On the ‘PF23’ variety, factors of irrigation, potassium fertilization, and transpiration-inhibiting sprays were tested to see the various effects on the incidence and severity of bronzing. The hypothesis was that excessive irrigation and excessive soil potassium concentrations would induce a higher incidence and severity of …

In Vitro Rooting Techniques In Prunus Spp. For Propagation And Disease Screening For Armillaria Root Rot (Arr) Resistance, John Lawson

All Theses

Prunus is a genus widely cultivated to produce edible fruit including almond (P. amygdalus), peach (P. persica (L.) Batsch), cherries (P. avium and P. cerasus), among others. The cultivation of Prunus is economically important for several regions of the United States and relies on appropriate cultivars and rootstocks that are adapted to a growing region. Encroaching plant pathogens are forcing breeders to use sexually compatible germplasm from related species for introgression of novel alleles that confer tolerance or resistance. This is especially true in the rootstock breeding where interspecific hybridization is often used …

Dahlia Cut Flower Production In Utah, Melanie Stock, Amanda Pratt, Claudia Nischwitz, Eli Oliver, Katie Wagner, Nick Volesky

All Current Publications

Dahlias are tuberous, herbaceous plants that are frost sensitive and therefore grown as a warm-season annual for cut flower production in Utah. Dahlias bloom in summer to fall, with peak production in late summer to early fall, and the season ending with first frost. Plants benefit from pinching to encourage branching and horizontal trellising or staking to promote straight stems and avoid toppling. High tunnels or extended low tunnels with shade, as well as optimum nitrogen and irrigation rates, improve production. As showstoppers in arrangements, dahlia cut flowers are highly desired on local markets and profitable to produce, particularly those …

Image Analysis And Machine Learning In Agricultural Research, Xinzheng Chen

Doctor of Plant Health Program: Dissertations and Student Research

Agricultural research has been a focus for academia and industry to improve human well-being. Given the challenges in water scarcity, global warming, and increased prices of fertilizer, and fossil fuel, improving the efficiency of agricultural research has become even more critical. Data collection by humans presents several challenges including: 1) the subjectiveness and reproducibility when doing the visual evaluation, 2) safety when dealing with high toxicity chemicals or severe weather events, 3) mistakes cannot be avoided, and 4) low efficiency and speed.

Image analysis and machine learning are more versatile and advantageous in evaluating different plant characteristics, and this could …

Exploring Soil-Tree Interactions After Applying Organic Matter Amendments To Peach Orchards In The Subtropical Climate Of The Southeastern United States, Brian Lawrence

All Dissertations

Soil disturbance from the cultivation and intensive management of orchards in hot and humid subtropical climates can reduce soil organic matter (OM). This research explored how the addition of OM amendments impact soil and tree parameters in two field studies and how proximity to OM may elicit unique genomic response of peach roots in a split-root pot study. The first field study applied two rates of compost (1x and 2x) and subsequently reduced fertilizer applications annually to a virgin and replant orchard location. While both compost rates successfully replaced fertilizers, only the 2x rate in the replant location increased soil …

Micronutrient Concentration Effects On Lettuce Growth And Susceptibility To Pythium, Kalyn M. Helms

Graduate Theses and Dissertations

In hydroponic production waterborne pathogens such as Pythium are ubiquitous and continually threaten a wide range of Controlled Environment Agriculture (CEA) crops in hydroponic production, including but not limited to: lettuce, spinach, basil, arugula, cucumber, tomato, sweet pepper, roses, chrysanthemums, and cannabis (Sutton et al., 2006; Gull, 2002; McGehee and Raudales, 2021; Gillespie, 2020). Despite extensive sanitation measures, disease control in hydroponics is fallible and requires constant surveillance and management to minimize outbreaks (Sutton et al., 2006). A potential disease suppression strategy is to increase micronutrient concentrations within hydroponic systems to naturally strengthen plant defenses against pathogens such as Pythium. …

In-Field And Greenhouse Assessments Of A Selection Of Preemergent Herbicides On Newly Planted Blackberries, Kayla Knepp

Graduate Theses and Dissertations

This field trial assesses some of the preemergence herbicide options available to growers and their effect on newly transplanted blackberries (Rubus L. subgenus Rubus Watson). Weed control has recently been surveyed as a top priority for blackberry growers; however, limited preemergence herbicides are registered for new blackberry plantings. Weed control is an ongoing component of blackberry production and with few in-season postemergence herbicide options available, growers rely on preemergence herbicides to maintain clean fields. The preemergent herbicides assessed in this trial were chosen with the intention to broaden the chemical control options available to growers in new plantings. A two-year …

Deciphering The Genetic Architecture Of Key Female Floral Traits For Hybrid Wheat Seed Production, Juan David Jimenez

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Wheat (Triticum aestivum L.) is a staple cereal that provides 20% of the calories and proteins in human intake (Ray et al., 2013). Global population is projected to increase to 9.7 billion by 2050. Food production must increase by 70% to feed this future population. Wheat production is in crisis due to political and environmental challenges and is projected to decline by 0.8% in 2022 (FAO, 2022). To ensure food security yield genetic gain must increase by around 1.4% annually. Taking advantage of heterosis, hybrid wheat has the potential to boost grain yield. However, hybrid wheat seed production systems …

Nitrogen Use Efficiency Of Pretassel Nitrogen Applications In Corn, Robyn Brittlee Mulloy

Graduate Theses and Dissertations

Corn (Zea mays L.) production continues to be a critical component of row-crop production systems within Arkansas and is seeing a resurgence in recent years. Nitrogen (N) is critical for corn growth and is often one of the single largest input costs associated with corn production. Research objectives for this study were to determine the nitrogen use efficiency (NUE) of late season N applications as influenced by sidedress N rate and timing of pretassel application and to quantify the nutrient uptake and partitioning in modern era corn hybrids within a furrow-irrigated production system. Research was conducted at the Milo J. …

Nitrogen Management In Rice Under Suboptimal Soil Conditions, Payton Suzanne Rhea

Graduate Theses and Dissertations

In Mid-South rice (Oryza sativa, L.) production, nitrogen (N) fertilizer management for pureline varieties is most often recommended as a single preflood (SPF) or two-way split (2WS) application in a direct-seeded, delayed-flood system. Most of the N fertilizer is typically applied at the four- to six-leaf stage onto dry soil, and the second application, if necessary, into the floodwater during early reproductive growth stages (referred to as midseason). Environmental factors frequently prohibit growers from applying early N fertilizer under optimal dry soil conditions. A study was conducted to determine the best N fertilization management practices to utilize in rice when …

A Glass Bead Semi-Hydroponic System For Intact Maize Root Exudate Analysis And Phenotyping, Martha G. Lopez-Guerrero, Peng Wang, Felicia Phares, Daniel P. Schachtman, Sophie Alvarez, Karin V. Van Dijk

Department of Agronomy and Horticulture: Faculty Publications

Background: Although there have been numerous studies describing plant growth systems for root exudate collection, a common limitation is that these systems require disruption of the plant root system to facilitate exudate collection. Here, we present a newly designed semi-hydroponic system that uses glass beads as solid support to simulate soil impedance, which combined with drip irrigation, facilitates growth of healthy maize plants, collection and analysis of root exudates, and phenotyping of the roots with minimal growth disturbance or root damage. Results: This system was used to collect root exudates from seven maize genotypes using water or 1 mM CaCl2, …

Comparative Genome Analysis Of Plant Ascomycete Fungal Pathogens With Different Lifestyles Reveals Distinctive Virulence Strategies, Yansu Wang, Jie Wu, Jiacheng Yan, Ming Guo, Lei Xu, Liping Hou, Quan Zou

Department of Agronomy and Horticulture: Faculty Publications

Background: Pathogens have evolved diverse lifestyles and adopted pivotal new roles in both natural ecosystems and human environments. However, the molecular mechanisms underlying their adaptation to new lifestyles are obscure. Comparative genomics was adopted to determine distinct strategies of plant ascomycete fungal pathogens with different lifestyles and to elucidate their distinctive virulence strategies. Results: We found that plant ascomycete biotrophs exhibited lower gene gain and loss events and loss of CAZyme-encoding genes involved in plant cell wall degradation and biosynthesis gene clusters for the production of secondary metabolites in the genome. Comparison with the candidate effectome detected distinctive variations between …

Biobased Sprayable Mulch Films Suppressed Annual Weeds In Vegetable Crops, Eliott Gloeb, Sibel Irmak, Loren Isom, John L. Lindquist, Samuel E. Wortman

Department of Agronomy and Horticulture: Faculty Publications

Biobased sprayable mulch (BSM) films are a potential alternative to herbicides, polyethylene plastic mulch film, and hand weeding for specialty crops. We developed a series of BSM films using locally available biomaterials [including corn (Zea mays) starch, glycerol, keratin hydrolysate, corn gluten meal, corn zein, eggshells, and isolated soy (Glycine max) protein] and tested their effects on weeds and crop yield during a total of seven greenhouse or field trials between 2017 and 2019 in Nebraska, USA. Application rates of BSM films applied in pots (greenhouse), planting holes in plastic film (field), or bed tops (field) …

Comparative Genomics Of Five Valsa Species Gives Insights On Their Pathogenicity Evolution, Guangchao Sun, Shichang Xie, Lin Tang, Chao Zhao, Mian Zhang, Lili Huang

Department of Agronomy and Horticulture: Faculty Publications

Valsa is a genus of ascomycetes within the Valsaceae family. This family includes many wood destructive pathogens such as the well known Valsa mali and Valsa pyri which cause canker diseases in fruit trees and threaten the global fruit production. Lack of genomic information of this family is impeding our understandings about their evolution and genetic basis of their pathogenicity divergence. Here, we report genome assemblies of Valsa malicola, Valsa persoonii, and Valsa sordida which represent close relatives of Valsa mali and Valsa pyri with different host preferences. Comparative genomics analysis revealed that segmental rearrangements, inversions, and translocations …

A Non-Destructive Approach For Measuring Rice Panicle-Level Photosynthetic Responses Using 3d-Image Reconstruction, Jaspinder Singh Dharni, Balpreet Kaur Dhatt, Puneet Paul, Tian Gao, Tala Awada, Harel Bacher4, Zvi Peleg, Paul E. Staswick, Jason Hupp, Hongfeng Yu, Harkamal Walia

Department of Agronomy and Horticulture: Faculty Publications

Background: Our understanding of the physiological responses of rice inflorescence (panicle) to environmental stresses is limited by the challenge of accurately determining panicle photosynthetic parameters and their impact on grain yield. This is primarily due to the lack of a suitable gas exchange methodology for panicles and non-destructive methods to accurately determine panicle surface area.

Results: To address these challenges, we have developed a custom panicle gas exchange cylinder compatible with the LiCor 6800 Infra-red Gas Analyzer. Accurate surface area measurements were determined using 3D panicle imaging to normalize the panicle-level photosynthetic measurements. We observed differential responses in …

Anemone Cut Flower Production Budget, One High Tunnel, Northern Utah, 2022, Shannon Rauter, Melanie Stock, Ruby Ward

All Current Publications

This budget contains costs (preplant and site preparation, establishment and maintenance, and harvest and processing) and returns for the production and sale of anemone cut flowers that were grown in a high tunnel (14 feet by 40 feet). Production methods, yield, costs, and pricing were determined from Utah State University (USU) research trials, as well as feedback from Northern Utah producers. The costs and returns represent typical production in Northern Utah but should be adjusted where necessary for individual situations. Site selection, tunnel use, variety, harvest timing, pest management, and other practices will impact costs and returns to a cut-flower …

The Backyard Garden - Pea Pests, Bridger Carey, Nick Volesky, Marion Murray

All Current Publications

As part of a series, The Backyard Garden, this fact sheet reviews pea pests. It includes general information, symptoms, and management for the following pea pest issues: thrips, spider mites, pea weevil, aphids, pea leaf weevil, damping-off, powdery mildew, fusarium wilt, fusarium root rot, and bacterial blight.

The Backyard Garden - Bean Pests, Nick Volesky, Bridger Carey, Marion Murray

All Current Publications

As part of a series, The Backyard Garden, this fact sheet examines bean pests. Insects and other pests include thrips, spider mites, cutworms and armyworms, Mexican bean beetle, and seedcorn maggot. Diseases include bean common mosaic virus, damping-off, beet curly top virus, common bacterial blight, and halo blight. The fact sheet includes general information about these issues, signs and symptoms on plants, and management.

2022 Seedless Pickling Cucumber Cultivar Trial, Ben Phillips, Jenny Schoonmaker

Midwest Vegetable Trial Reports

A pickling cucumber cultivar trial was planted at the Southwest Michigan Research and Extension Center (42.088261, -86.351980, Benton Harbor, Michigan). Bejo (BJ), Nunhems (NU), and Rijk Zwaan (RZ) seed companies donated parthenocarpic (seedless) cultivars for mechanical once-over harvest. Overall trial quality was marginal due to being the first trial on a new research farm with different equipment parameters, task procedures, and responsibilities. Factors affecting trial quality were logged for next year’s trial, and include machine planting, incorporating the entire nitrogen recommendation ahead of planting, and adjusting final plant population to 30 inch row spacings.