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The Diverse Effects Of Continual Organic Inputs On Soil Biogeochemical Properties And Microbial Communities In Sandy Ultisols Under Organic Production, Zhine Wang

All Dissertations

The objectives of this study were to understand how continual organic amendment inputs improve Nitrogen (N) cycling, microbial diversity and functional traits. Fully crossed factorial experiments were designed to test four cover crop treatments (cereal rye, hairy vetch, mixture of the rye and vetch, and no cover crop fallow) and two levels of manure compost application (with manure application and blank control) in organic vegetable production from 2020 to 2023. Cover crop biomass, soil chemical and biological properties were analyzed for the distribution and availability of soil labile N (Chapter 2), the abundance of N-cycling genes (Chapter 3), the structure …

Rice Response To Struvite And Other Phosphorus Fertilizers In A Phosphorus-Deficient Soil Under Simulated Furrow-Irrigation, Jonathan B. Brye, Diego Della Lunga, Kristofor R. Brye

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

Wastewater-recovered phosphorus (P), in the form of the mineral struvite (MgNH₄PO₄⋅6H₂O), may provide a sustainable alternative to decreasing rock-phosphate reserves. Struvite can be generated via precipitation methods, potentially reducing the amount of P runoff to aquatic ecosystems. The objective of this greenhouse tub study was to evaluate the effects of chemically- and electrochemically precipitated struvite (CPST and ECST, respectively) on above- and belowground plant response in a hybrid rice (Oryza sativa) cultivar grown using furrow-irrigation compared to other common fertilizer-P sources [i.e., triple super phosphate (TSP) and diammonium phosphate (DAP)]. Rice was …

Site Position, Tillage, And Soil Depth Effects On Soil Properties In A Furrow-Irrigated Rice Field On A Silt-Loam Soil, Hannah Nobles, Kristofor Brye, Diego Della Lunga

Crop, Soil and Environmental Sciences Undergraduate Honors Theses

The fundamental agronomic shift from conventional agricultural methods to conservation agriculture relies on understanding soil nutrient stratification with depth and under different tillage treatments. Assessment of nutrient stratification in the dynamic conditions of furrow-irrigated rice (Oryza sativa) systems in eastern Arkansas is absent. The objective of this study was to evaluate the effects of tillage [i.e., conventional tillage (CT) and no tillage (NT], site position (i.e., up-, mid-, and down-slope), soil depth interval (i.e., 0-10 and 10-20 cm), and their interaction on the difference (i.e., end of the season minus beginning of the season) in select soil chemical …

Comparison Of Statistical And Machine Learning Genomic Prediction Methods In Plant Breeding: Case Studies In Maize And Soybean, Igor Kuivjogi Fernandes

Graduate Theses and Dissertations

Plant breeding is essential to increase genetic gain and food production worldwide. This study was conducted to evaluate new ways to use machine learning (ML) to tackle plant breeding challenges, where two ideas were tested — the first chapter focuses on how to combine genetic and environmental data using ML to improve the prediction of maize grain yield in multi-environment trials, while the second chapter centers on how to couple feature selection of molecular markers with ML to enhance prediction of yield in soybean, and, in both cases, ML approaches were compared to well-established statistical methods greatly adopted by the …

Characterization Of An Acetogenin-Carrying Nanosuspension And Its Effect On Bacteria Of Interest In The Poultry Industry, Brandon A. Lopez-Romero, Gabriela Aguilar-Hernandez, Billy M. Hargis, Maria De Lourdes Garcia-Magana, Ulises M. Lopez-Garcia, Rosa I. Ortiz-Basurto, Adalberto Zamudio-Ojeda, Juan D. Latorre, Efigenia Montalvo-Gonzalez

Poultry Science Faculty Publications and Presentations

This work aimed to develop a nanosuspension (NSps) as an acetogenin (ACGs) carrier, using soy lecithin (SL) and hydroxypropyl-β-cyclodextrin (βCD) named NSps-βCDSL-ACGs. It was characterized by various spectroscopic techniques (DLS, FTIR, UV-vis diffuse reflectance). Moreover, the NSps morphology was observed by transmission electron microscopy (TEM). Also, the antibacterial activity of NSps-βCDSL-ACGs was evaluated against strains of interest in the poultry sector. NSps-βCDSL-ACGs presented nanometric size (207–239 nm), acceptable polydispersity index (PDI) values (0.13–0.17) and a high Z potential value (−47.17–50.36 mV), demonstrating high stability. The presence of ACGs in NSps-βCDSL-ACGs was confirmed by FTIR analysis. The nanoparticles had a spherical …

Enhancing Selection Intensity With High-Throughput Phenotyping Data In Plant Breeding, Ashmita Upadhyay

Graduate Theses and Dissertations

Genomic prediction (GP) has proven to be an essential tool to accelerate the cultivar development pipeline by predicting the performance of un-phenotyped lines in the field of plant breeding. However, the prediction accuracy is bounded by the heritability of the target trait, limiting the efficiency of the single-trait GP model. To overcome the limitation, a multi-trait genomic prediction model using high-throughput phenotyping (HTP) data can be used to leverage secondary traits to boost the predictive ability of the target trait. This study aimed to assess the efficiency of the multi-trait (MT)- GP model powered by HTP derived secondary traits in …

Association Mapping For Water Use Efficiency In Soybean Identifies Previously Reported And Novel Loci And Permits Genomic Prediction, Siva K. Chamarthi, Larry C. Purcell, Felix B. Fritschi, Jeffrey D. Ray, James R. Smith, Avjinder S. Kaler, C. Andy King, Jason D. Gillman

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

Soybean is a major legume crop cultivated globally due to the high quality and quantity of its seed protein and oil. However, drought stress is the most significant factor that decreases soybean yield, and more than 90% of US soybean acreage is dependent on rainfall. Water use efficiency (WUE) is positively correlated with the carbon isotopic ratio ¹³C/¹²C (C13 ratio) and selecting soybean varieties for high C13 ratio may enhance WUE and help improve tolerance to drought. Our study objective was to identify genetic loci associated with C13 ratio using a diverse set of 205 soybean maturity …

Broad-Spectrum Resistance To Fungal Foliar Diseases In Wheat: Recent Efforts And Achievements, Amira M.I. Mourad, Asmaa A.M. Ahmed, P. Stephen Baenziger, Andreas Börner, Ahmed Sallam

Department of Agronomy and Horticulture: Faculty Publications

Wheat (Triticum spp.) is one of the most important cereal crops in the world. Several diseases affect wheat production and can cause 20-80% yield loss annually. Out of these diseases, stripe rust, also known as yellow rust (Puccinia striiformis f. sp. tritici), stem rust (Puccinia graminis f. sp. tritici), leaf rust (Puccinia recondita), and powdery mildew (Blumeria graminis f. sp. tritici) are the most important fungal diseases that infect the foliar part of the plant. Many efforts were made to improve wheat resistance to these diseases. Due to the continuous advancement in …

Efficacy Of Banana Fibre Paper For The Management Of The Root-Knot Nematode, Meloidogyne Incognita, On Potato (Solanum Tuberosum) In Kenya, Dorris W. Kamau, Wanjohi Waceke, Laura Cortada, Onesmus Mwaura, Tahira Pirzada, Tim L. Sit, Eric Davis, Dick Guenther, Reny Mathew, Lokendra Pal, Saad Khan, Solveig Haukeland, James Kisaakye, Charles Opperman, Danny Coyne

All Peer-Reviewed Publications

Globally, potato (Solanum tuberosum) is a key staple food crop. In Kenya, it is the second most important food crop after maize. Among the various constraints to potato production are plant-parasitic nematodes. In particular, root-knot nematodes (Meloidogyne spp.) are a significant impediment to potato production, suppressing yield and reducing the quality of harvested tubers. The current study was undertaken to evaluate the efficacy of a lignocellulose fibre matrix (banana paper) either impregnated with a chemical or drenched with a biologically-based nematicide for the management of root-knot nematodes on potatoes, in Kenya. The experiment was conducted in both field and pot …

Disentangling Genotype And Environment Specific Latent Features For Improved Trait Prediction Using A Compositional Autoencoder, Anirudha Powadi, Talukder Zaki Jubery, Michael C. Tross, James C. Schnable, Baskar Ganapathysubramanian

Department of Agronomy and Horticulture: Faculty Publications

In plant breeding and genetics, predictive models traditionally rely on compact representations of high-dimensional data, often using methods like Principal Component Analysis (PCA) and, more recently, Autoencoders (AE). However, these methods do not separate genotype-specific and environment-specific features, limiting their ability to accurately predict traits influenced by both genetic and environmental factors. We hypothesize that disentangling these representations into genotype-specific and environment-specific components can enhance predictive models. To test this, we developed a compositional autoencoder (CAE) that decomposes high-dimensional data into distinct genotype-specific and environment-specific latent features. Our CAE framework employed a hierarchical architecture within an autoencoder to effectively separate …

Genome-Wide Association Analysis And Genomic Prediction Of Salt Tolerance Trait In Soybean Germplasm, Rongqing Xu, Qing Yang, Zhi Liu, Xiaolai Shi, Xintong Wu, Yuenhan Chen, Xingyu Du, Qiqi Gao, Di He, Ainong Shi, Peijun Tao, Long Yan

Horticulture Faculty Publications and Presentations

Introduction:

Soybean is an important protein and oil crop, and improving yield has traditionally been a major breeding goal. However, salt stress is an important abiotic factor that can severely impair soybean yield by disrupting metabolic processes, inhibiting photosynthesis, and hindering plant growth, ultimately leading to a decrease in productivity.

Methods:

This study utilized phenotypic and genotypic data from 563 soybean germplasms sourced from over 20 countries. Employing four distinct models—we performed a genome-wide association study (GWAS) using four models, including MLM, MLMM, FarmCPU, and BLINK in GAPIT 3, we conducted a Genome-Wide Association Study (GWAS) to identify single nucleotide …

Multi-Decadal Aspen Dynamics Show Recruitment Bottleneck Across Complex Mountain Community, Michael T. Stoddard, Kyle C. Rodman, Connor D. Crouch, David W. Huffman, Peter Z. Fulé, Kristen M. Waring, Margaret M. Moore

Aspen Bibliography

Changes in forest structure and shifts in tree species composition have occurred globally due to climate change and altered disturbance regimes. With climate trending toward warmer and drier conditions, these altered forest communities may reorganize in diverse and unpredictable ways. This is especially true in mountain environments where a range of vegetation types and abiotic conditions coexist. In this study, we used long-term permanent plot data from a site spanning broad environmental gradients to assess regeneration and mortality patterns in populations of aspen (Populus tremuloides). The study site, located on the San Francisco Peaks, Arizona, USA, is near …

Industrial Hemp Biomass Negatively Affected By Herbicide Drift From Corn And Soybean Herbicides, Milos Zaric, Bruno Canella Vieira, Barbara Houston, Guilherme Sousa Alves, Samuel E. Wortman, Julie A. Peterson, Greg R. Kruger

Department of Agronomy and Horticulture: Faculty Publications

The establishment of industrial hemp (Cannabis sativa L.) fields near row crops has raised concerns about the potential adverse effects of herbicide drift on hemp production. This study examined hemp susceptibility to drift of herbicides registered for use in corn and/or soybeans. Herbicide solutions (2,4-D, dicamba, glufosinate, glyphosate, imazethapyr, lactofen, mesotrione) were applied separately in the wind tunnel (3.6 m s⁻¹ airspeed), simulating drift scenarios, with conventional TP95015EVS (TP) and air inclusion AI95015EVS (AI) flat fan nozzles calibrated to deliver 140 L ha⁻¹ carrier volume at 230 kPa. Mylar cards and hemp plants (20–25 cm tall) were placed …

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.

Importance Of Tropical Pasture Seed Quality And Factors Affecting It In Smallholder Farming System, H F. Chin, C C. Wong

IGC Proceedings (1977-2023)

Most tropical pastures are associated with and confined to smaJlholder animal production in developing countries of the tropics, with the exception of Australia. At present, tropical pasture seeds are very variable and poor in quality, as tropical herbage seed production is relatively new compared with that for temperate systems. Many tropical species are relatively wild and have yet to be domesticated and selected for pasture use, let alone for seed production characteristics. The unfavourable production and storage environment of the wet tropics, coupled with a lack of appropriate technology, also contributes towards poor quality in tropical pasture seeds. In this …

The Benefits Of Seed Quality In Intensive Temperate Forage Systems, Jeffrey J. Steiner

IGC Proceedings (1977-2023)

Seed quality has traditionally been considered to consist of two components: physiologic and genetic quality. The benefits of using high quality seeds have been widely documented and are generally not questioned. These henefits came about as a result of a first­generation of seed quality aware11ess which began more than a century ago. In intensive temperate forage production systems, the producer usually has a ready supply of high-quality seeds available for purchase. For the consumer, seed quality is not a major constraint to system productivity, However, many forage producers are not realising all of the potential benefits from using high quality …

New Realities For The Management Of Tussock Grasslands In New Zealand, I.G C. Kerr

IGC Proceedings (1977-2023)

Concerns about the potential demise of the tussock grasslands of the Soulh Island of New Zealand have been well recorded in the scientific and official literature. Little effective action has been taken to arrest the process of land degradation that has occurred during the 125 years of utilisation of !he tussock grasslands for pastoralism. A substantial decline in the pastoral productivity and conservation value of the "unimproved" tussock grasslands has been the result, Much of the cause has been the failure of the administrators and the occupiers of the high country to understand, and act on, the evidence. Occupiers and …

Integration Of Recreation With Pastoral Use And Conservation In The High Country Of South Island, New Zealand, P H. Murray, D M. Robertson, C R. Mason

IGC Proceedings (1977-2023)

Over 3 000 000 ha of the South Island high country is Crown (i.e. Govemmcnt)-owned land, held under pastoral lease or conservation estate. There is increasing pressure from recreationists for access to land under both tenures. Permits from Crown agents, with agreement from land occupiers, are required for commercial recreation. Access for non-commercial recreation on pastoral lease land is generally through direct negotiation with the lessee. Conflicts between high country users are occurring where recreation pressure is greatest. A case study in the Remarkables Range near the mountain resort of Queenstown, shows domination by the primary users (pastoral lessees and …

Tradition And Pastoral Sustainability- An Exercise In The Applied Human Ecology Of Mountain Rangelands, David Pitt

IGC Proceedings (1977-2023)

The paper presents the case for regarding some traditional practices and customs as a ba��e for sustainable development in winter cold temperate rangeland pastoralism, The emphasis is on the social forms which maintain a system in which low intensity production, usufruct, kinship dynamics, co-operation, environmentally friendly practices and nomadism are maintained in the face of extreme outside pressures, A typology is elaborated including five situations: independence, coexistence, fluctuation, absorption and interaction. Case studies _are presented from the Middle East, Andes, North Africa, the Alps, the Himalaya and the former Soviet Union. Although these situations are basically historical, or at best …

Integration Of Pastoral And Non-Pastoral Uses On Temperate Rangelands With Cold Winters In Developed Countries, T J. Maxwell, W A. Laycock

IGC Proceedings (1977-2023)

The demands of the relatively wealthy and sophisticated societies of developed countries, with their substantial amounts of leisure time and discretionary income, are having an increasing impact on temperate rangelands in a variety of ways. Some parts of these societies are concerned to protect the landscapes, habitats, wildlife and solitude that can be found there, and wish to constrain any further development within these ecosystems; others also wish .to gain ready access to these resources for hunting, recreation and sport and believe that this requires the exclusion of domesticated livestock. Temperate rangelands are frequently used as water catchments and some …

Effects Of Date Of Harvest On Yield And Quality Of Meadow Fescue Seed, Uwe Simon

IGC Proceedings (1977-2023)

A seed-shattering-resistant cultivar and a normal cultivar of meadow rescue (Festuca pratensis Huds.) were harvested for seed 10 times in regular intervals during a period of 30 days, The effects of harvesting time on yield, water content, germination and weight of seeds, and on costs of seed processing were studied in the 2 types of cultivar. Yield losses due to premature harvest were greater than losses due to delayed harvest. Seed losses due to shattering were smaller in the shattering-resistant cultivar compared with the normal cultivar. The water content of the seeds decreased with advancing maturity, from =50% to .. …

After-Effects Of Grass Seed Production On Subsequent Field Crops, Uwe Simon

IGC Proceedings (1977-2023)

Forage grasses grown for the production of seed are usually components of a crop rotation. The after-effects of 3 grass species compared with 4 crop species on the yields of 5 field crops in the first and second year after grass seed harvest were investigated. Significant differences between the grass species, and between grasses and other field crops on subsequent crops, and between the subsequent crops in their reactions to the preceding crops were obvious in both years after grass seed harvest, Annual and perennial ryegrass excited the most positive effects on subsequent crop yields. Corn and sugarbeets responded particularly …

A New Power Airflow Harvester Improves Grass Seed Yield And Quality In Central Queensland, Australia, J H. Wildin, Dingfa Zhou, A Dobson

IGC Proceedings (1977-2023)

Most perennial tropical grasses produce new seedheads over a period extending up to 4 weeks, Seeds mature and ripen up to 4 weeks after inflorescence emergence. The dilemma for seed producers using one­pass harvesting has been to time the harvesting operation to maxmise. recovery of mature seed, Harvested immature seeds and inert material adversely affect seed purity and germination tests. Light fluffy seeds such as buffel and bluegrasses are generally difficult to harvest with grain crop harvesters, and paddle beater harvesters have been used for simplicity and economy. Over the last 3 years, tractor-mounted brush harvesters using 4 rows of …