Digital Commons Network^™

Attainment And Distribution Of Competitive Equilibrium In Tropical Grass-Legume Mixtures, P G. Tow

IGC Proceedings (1977-2023)

An experiment under controlled conditions, using the de Wit competition model, has provided an explanation of competitive relationships in mixtures of Panicum maximum var. trichoglume (green panic) cv. Petrie and Neontonia wightii cv. Tinaroo glycine. Experiments in a tropical upland environment with summer rainfall dominance (to which they ore adapted) have provided further understanding of their relationships. Over a period of 2 years for well-wafered plants in containers and 4 years in a rain-fed field experiment, competitive gains by one species alternated with-gains by the other, and neither species gained significantly overall. Gains by the grass were favoured by …

Managing Woody Weeds In Grazing Ecosystems: Application For Tropical Woodlands Of North-Eastern Australia, Joel R. Brown, John G. Mcivor, Andrew J. Ash

IGC Proceedings (1977-2023)

Shrub invasion of tropical woodlands is reducing the viability of native ecosystems as well as the livestock industry, After shrub invasion, forage supply is reduced and over-grazing and soil erosion are exacerbated. We propose a non-equilibrium model of the system and use that model to develop hypotheses and design experiments to test both competition- and disturbance-based management regimes. This model proposes that disturbance in the form of burning is the primary limiting factor in excluding and limiting shrub seedling establishment and suggests that management decisions focus on maintaining adequate herbaceous biomass for a burning regime that limits woody plant success.

Fire And Grazing Interact To Manipulate Pasture Composition In Heteropogon Contortus (Black Speargrass) Pastures, D M. Orr, C J. Paton

IGC Proceedings (1977-2023)

Aristida spp, (wiregrasses) are invading areas of Heteropogon contortus (black speargrass) pastures in southern Queensland. Interim results from 2 field experiments indicate that increasing the frequency' of annual spring burning over 3 years, with and without grazing, results in a progressive reduction in the yield of Aristida spp. H. contortus yields also increased with increasing frequency of burning under non-grazing but not when grazed, H. contortus yields have increased after burning when grazing has been deferred or where the stocking rate has been halved after the fire. The results suggest that botanical composition in these pastures can be manipulated readily …

Impact Of Grazing Pressure On The Plant Population Dynamics Of Heterpogon Contortus (Black Speargrass) In Subtropical Queensland, D M. Orr, C J. Paton

IGC Proceedings (1977-2023)

Heteropogon contortus is a palatable pasture grass which is being threatened by , increases in grazing pressure, particularly during drought. This paper presents interim results plant population dynamics of H. contortus., as affected by stoc.1s tak. legume augmentation (mainly Stylosanthes sabra cv. Seca) and p1 Jvision of a dry-season supplement for cattle. The study began in 1%8. By 1991, basal ara of H. co11tortus was highest at the light .. Jt stocking rate of 0.187 steers/ha and declined linearly to be longest at the heaviest stocking rate of 0,5 steers/ha. Similarly, survival of the H. contortus tussocks initially present …

Seca Stylo (Stylosanthes Scabra Cv. Seca) Populations Increase Faster Under Light Grazing, D M. Orr, C J. Paton

IGC Proceedings (1977-2023)

Augmentation of native pastures with legumes such as Stylosanthes scabra can increase cattle live-weight gain relative to that from native pasture. In the longer term, however, Stylosanthes spp, density can increase and populations of native grasses may become unstable. This paper reports interim results from a study aimed al monitoring changes in the density of S. scabra cv. Seca in relation to stocking rates, The density of Seca monitored in permanent quadrats increased from 15 plants/m2 in 1988 to 100 and 25 plants/m2 in 1992 at 0.25 and 0.5 beasts/ha respectively. These increases resulted from both the survival of the …

Clover-Based Pasture Systems For Intensive Sheep Production In The Central Highlands Of Papua New Guinea, S Sivasupiramaniam, A K. Benjamin, J Pitala

IGC Proceedings (1977-2023)

This paper describes some of the studies that have been conducted since 1985 to develop clover-based pasture systems for intensive sheep production in the central highlands of Papua New Guinea. The clovers tested were Trifolium repens cv. Haifn (Haifa white clover) and Trifolium semipilosum cv. Safari (Kenya white clover). They were sown together, with setaria (Setaria sphacelata cv. Nandi) and signal grass (Brachiaria decumbens cv. Basilisk) at Menifo (1400 m asl) and with setacia and kikuyu (Pennisetum clandestinum cv. Whittet) at Tambul (2240 m) and Yogos (1950 m) in the central highlands. At Menifo, when rotationally grazed …

An Integrated Approach To Soil-Plat-Animal Interactions On Grazed Legume-Based Pastures On Tropical Acid Soils, M J. Fisher, C E. Lascano, R J. Thomas, M A. Ayarza, I M. Rao, G Rippstein, J.H M. Thornley

IGC Proceedings (1977-2023)

Legume-based pastures developed by the Tropical Pastures Program (TPP) of CIAT give spectacular increases in both stocking rates and animal live-weight gains on the savannas of Latin America, A team within the TPP is addressing the problems of their management for legume persistence and soil-plant-animal interactions, using as Its focus a grazing experiment on 2 oxisols of contrasting texture on the Colombian Llanos. The objective is to model the pastures to forecast the effect of management options on long-term persistence and nutrient cycling in grazed legume•grass associations in the Latin American savannas.

Persistence Of Roundleaf Cassia In Grazed Pastures - A Conceptual Model, R M. Jones, C K. Mcdonald, G A. Bunch

IGC Proceedings (1977-2023)

Roundleaf cassia (Cassia rotudifolla) cv. Wynn is a short-lived perennial that relies on seedling recruitment for long-term persistence. Its persistence is considered in terms of survival of plants from the initial sowing, seed set, seedling recruitment, run-down of reserves of soil seed, and survival of seedlings. The major factor controlling all these stages is soil moisture stress; grazing management 'is less important. A conceptual model of Wynn persistence is presented and progress in mathematical modeiling is reported.·

Variation In Hydrological Characteristics Of The Soils Associated With Grazed Patches In Granitic Landscapes In Northern Australia, M M. Sallaway, D Waters, B Bridge, F P. Wandera

IGC Proceedings (1977-2023)

Under medium to heavy grazing of black speargrass (Heteropogon contortus) landscapes of south-east Queensland, "patchiness" has developed with a change from H. contortus to Aristida spp., Cllrysopogo11 spp. or a,inual grasses. This grazed patch development is associated with changes in soil hydrological characteristics which in turn affect runoff and soil erosion. T!\e soil hydrologic properties were studied using a rainfall simulator and disc permeameter. The remnant H. contortus areas had higher infiltration characteristics mainly due to the maintenance of larger mncropores (1-3 mm). In the Arlstida patches, the contribution of those large macropores has been greatly reduced. Th is effect …

Evaluation Of Pastures For Sustained Beef Production In Subtropical New South Wales, P T. Mears, D L. Garden, R W. Dicker

IGC Proceedings (1977-2023)

Limitations of low-quality grass pastures, soil fertility, mechanisms of legume persistence and the long-term sustainability of pastures for beef production were studied in a humid subtropical environment of New South Wales, Australia. Sustainability of pastures and animal growth responses in 3 experiments (varying from 4 to 10 years' duration) al 2 sites have been analysed and described. Steers or heifers were used lo assess the effects of introducing subtropical or temperate legumes, level of superphosphate and stocking rate on natural grass pastures, Principal factors which improved the level of beef production from pasture were (i) introducing persistent legumes (ii) level …

Bothriochloa Pertusa- A Useful Grazing-Tolerant Grass For The Seasonally Dry Tropics?, R J. Jones, A Kerr

IGC Proceedings (1977-2023)

Data from 2 grazing experiments, small-plot studies, and a vegetation and soil survey showed that Bothriochloa pertusa increased relative to native tufted perennial grasses under heavy grazing pressure and was adapted to a wide range of soils in the 500-1000 mm zone of northern Australia. Ability to grow on low-P soils, lower relative palatability, strong stoloniferous development and good seed production, were features of its success. Annual steer gains on 8. pertusa pastures were similar to those on native pastures, with no species x stocking rate interaction. Steer gains on B. pertusa-Vernno stylo pastures were lower than on Urochloa …

Sustainability Of Sown Pastures In The Tropics And Subtropics, Jose M. Toledo, Daniel Formoso

IGC Proceedings (1977-2023)

Sown pastures in the tropics and subtropics are important components of production systems. Their role in and contribution to land productivity and economic development are well understood; however, their roles in sustainability and environmental protection are rather misunderstood and little known. The main constraints to sustainability of sown pastures fall into two categories: physical, biological and technical constraints include soil and climatic limitations, lack of adaptation of plants to physical and biotic stress and the limitations of farmers or ranchers to apply technology; socioeconomic factors include political instability, poorness of society and the market forces for land, inputs and products. …

Stability In Rangelands: Ecology And Economics, B H. Walker

IGC Proceedings (1977-2023)

Examples of changes in rangelands are presented relating to changes in livestock number, plant species. composition and soil changes (associated with changes in production), The mechanisms Involved are described, using examples, under the headings: event-driven change, threshold effects, non-linear and hysteresis effects, effects of spatial variation, significance of temporal variation, and interactive effects. The implications for management are presented in the form of a proposed optimal control model which maximises a complex function of welfnre based on long-term net economic benefit, in which stocking rate effects on the state of the rangeland feed back on to economic return.

Performance Of Eight Lettuce Cultivars In A Water Culture System, Ricky C. Young, Hudson M. Cox, Jacob D. Frodge, Mollie K. Mayabb, Brycen C. Shephard, Alireza Rahemi

Posters-at-the-Capitol

Lettuce (Lactuca sativa L.) is one of the most well-known vegetables in the world. About 27 million tons of lettuce were produced in the world in 2022 and global demand for lettuce is increasing steadily, driven by the importance of fiber consumption. Lettuce can be grown in multiple media, including hydroponic systems in a controlled environment agriculture (CEA) system. Growing lettuce in hydroponic systems is an alternative to lettuce production optimization. Since little information is available about lettuce cultivar trials in hydroponic systems, a research project was developed and executed to study the ability of different types of lettuce …

Igc Oral Presentation Summary: Xxv Igc Congress, S. Ray Smith, Echo Elizabeth Gotsick, J. R. Weinert-Nelson, Alayna Jacobs, Christopher D. Teutsch, Will Fleming, D. R. Woodfield, James L. Klotz, Jeff Lehmkuhler, Greg S. Halich, Brittany Davis, Brittany Hendrix, Krista Lea

IGC Proceedings (1977-2023)

This paper will give an overview of the XXV International Grassland Congress thematic, keynote, and plenary sessions. The theme of the XXV IGC Congress meeting was “Grasslands for Soil, Animal, and Human Health.” We had many people attending, presenting, and participating in all these sessions. Within a month after the conclusion of the Congress, the proceeding’s papers presented at the meeting will be available on the IGC app. By the end of 2023 all papers will be available for download through any search engine at internationalgrasslands.org.

Quantification Of Auxin-Cytokinin Response During Primary Root And Lateral Root Development In Common Bean, Gurdeep Singh

Electronic Theses and Dissertations

Roots support water and nutrient uptake, anchorage, and soil interactions through continuous growth at the primary root tip (PRT). In common bean (Phaseolus vulgaris), new cells are produced in an open root apical meristem and subsequently elongate in the elongation zone, and together these processes drive root tip progression through the soil. Lateral roots (LRs) arise in the differentiation zone, where pairs of pericycle founder cells dedifferentiate, divide asymmetrically, and form lateral root primordia (LRP) that pass through defined developmental stages before emergence. Auxin and cytokinin (CK) are central regulators of both primary root growth and LR development, yet their …

Introduction To Hydroponics- 2025-2026 Workshop Handbook, Stacy A. Adams

Department of Agronomy and Horticulture: Faculty Publications

Hydroponically grown plants grow faster than traditional production systems, with greater productivity, greater palatability, and having optimal visual character. Three principal components of a system include the plant support platform, a nutrient solution reservoir, and an interface for the root-solution. This publication provides in-depth explanation to system design, evaluation of water quality, nutrient formulation, and prototype systems that can be easily constructed for those wanting to explore hydroponics, such as educators, organizational leaders, or home enthusiasts.

Generational Exposures To Cerium Oxide Nanoparticles And Perfluorooctanesulfonic Acid Affect The Performance Of Daughter Plants, Preston Clubb

Graduate Theses/Dissertations

The effects of parental stress on the performance of next generation exposed to another contaminant were investigated. Wheat was exposed to cerium oxide nanoparticles (CeO2-NPs) in first and second generations and exposed to perfluorooctanesulfonic acid (PFOS) in the third generation. Phenotypic or metabolic responses were assessed at 21-day (short-term exposure) or 90-day (long-term exposure) exposure periods. Biomass production, chlorophyll content, enzyme activity, and membrane damage were measured at short-term exposure, while elemental and PFOS concentrations, and grain metabolites were analyzed in long-term exposure. Results showed that continued exposures to CeO2-NPs and PFOS enhanced chlorophyll content but reduced concentrations of important …

An Economic And Production Analysis Of Seaweed Farms In California And The Pacific Northwest, Brian Donovan

Cal Poly Humboldt theses and projects

Since the early 2010s, the seaweed aquaculture industry has steadily expanded in the United States, with states like Alaska, Maine, Hawaii, and Connecticut leading the way in the development of this emerging sector. However, information gaps remain concerning certain aspects of the domestic seaweed aquaculture industry. The purpose of this study was to examine the status of the seaweed aquaculture industry along the West Coast of the United States; specifically in the states of California, Oregon, and Washington. Seaweed farmers in these states were invited to voluntarily complete surveys asking important production, economic, and commercial questions regarding their operations. Data …

Effects Of Round-Up On The Environment, Sandra J. Marcu

Journal of Earth and Life Science

Many people around the world have used and still currently use Roundup but are unaware of the effects it has on the environment. Roundup is a spray on application weedkiller that is widely used around the world today both residentially and commercially. It enables its user to grow a garden or a field of crops with a no-tilling approach to eliminate weeds. It is a well-known and popular choice for killing weeds that has been around since the mid 1970’s (Oca, 2017). John Franz, a Monsanto scientist discovered that glyphosate (main ingredient in Roundup) was an herbicide or weedkiller, and …

In-Season Nitrogen Mmanagement: Leveraging Data Visualization For Precision Agriculture, Chathurika Harshani Narayana

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Effective nitrogen management is vital for sustainable agriculture, impacting both crop yield and environmental health. Traditional methods often use fixed application rates set before planting, which do not adapt to changing crop needs during the season. This can lead to over- or under-application, reducing efficiency and sustainability. While modern tools like sensors, satellites, and UAVs provide valuable real-time data on crop and field conditions, integrating and using this data to guide timely nitrogen decisions remains a major challenge. In-season nitrogen management offers a solution by allowing for dynamic adjustments to nitrogen applications, addressing crop needs as they arise. This approach …

Multi-Locas Gwas Mapping And Candidate Gene Analysis Of Anticancer Peptide Lunasin In Soybean (Glycine Max L. Merr), Rikki Locklear, Jennifer Kusumah, Layla Rashad, Felicia Lugaro, Sonia Viera, Nathan Kipyego, Faith Kipkosgei, Daisy Jerop, Shirley Jacquet, Mythy Addelmajid Kassem, Jiazheng Yuan, Elvira De Mejia, Rouf Mian

Biological Sciences Faculty Publications

Soybean (Glycine max) peptide lunasin exhibits significant cancer-preventive, antioxidant, and hypocholesterolemic effects. This study aimed to identify quantitative trait nucleotides (QTNs) associated with lunasin content and to annotate the candidate genes in the soybean genome. The mapping panel of 144 accessions was gathered from the USDA Soybean Germplasm Collection, encompassing diverse geographical origins and genetic backgrounds, and was genotyped using SoySNP50K iSelect Beadchips. The lunasin content in soybean seeds was measured using the enzyme-linked immunosorbent assay (ELISA) method, with lipid-adjusted soybean flour prepared from seeds obtained from the Germplasm Resource Information Network (GRIN) of USDA-ARS in 2003 and …

Greenhouse Management For The Smaller Structure--Educational And Hobby, Stacy A. Adams

Department of Agronomy and Horticulture: Faculty Publications

Greenhouses used for teaching or by hobbyist are smaller than those used for commercial production or found in the retail environment. Structural materials, covering, mechanical equipment, and control systems often are packaged as a kit made available through greenhouse suppliers. Supplier construction services may not be available, in which buyers must use local contractors to complete the installation. Greenhouses are unique structures that differ greatly from sheds or other outbuildings. They have coverings that allow maximum light transmittance, protected from UV degradation, and can handle wide inside to outside temperature extremes. This extension circular provides valuable information on the character, …

Terrarium- An Ecosystem In A Jar, Stacy A. Adams

Department of Agronomy and Horticulture: Faculty Publications

STEM education is supported through hand's-on activities in the classroom. Content understanding and reaffirmation of knowledge is supported through this informative STEM-Quick card that teachers or extension educators can distribute to participants for reference. Terrariums provide an example of a closed ecosystem where water and carbon cycling is demonstrated and plant growth can be observed. This card presents the steps to building and caring for an easy to create terrarium.

Revolutionizing Grapevine Breeding Programs: A Mobile Genome Editing System For Perennial Crops, Bridget Bolt

Theses and Dissertations--Plant and Soil Sciences

Grapevine (Vitis vinifera) faces unprecedented challenges from climate change, with up to 90% of current growing regions potentially becoming unsuitable for production within decades. Traditional breeding approaches require 25-30 years for variety development, creating a time constraint incompatible with the pace of environmental change. This research establishes the approach for a novel mobile RNA-based gene editing platform that addresses longstanding bottlenecks in grapevine improvement while preserving cultivar identity and reducing breeding timelines.

This research developed a three-component system for transgene-free gene editing in grapevine. First, a mobile CRISPR/Cas9 system was established using Agrobacterium rhizogenes transformation and the cut-and-dip …

Longitudinal And Ensemble Modeling Of Beef Cattle Feed And Water Intakes, Nathan El Blake

Graduate Theses, Dissertations, and Problem Reports (ETD)

Beef cattle production remains a cornerstone of global food systems, providing highly bioavailable protein and essential micronutrients that are difficult to secure from plant-based foods alone. Yet this production is also resource-intensive, requiring substantial land, feed, and water inputs while contributing significantly to greenhouse gas emissions. Efficiency of dry matter intake (DMI) and water intake (WI) is central to both productivity and sustainability, but accurate measurement of these traits—particularly in grazing systems—remains a major limitation. National WI standards continue to rely on pen-level data collected in the 1950s, while most existing DMI prediction equations perform poorly when applied beyond the …

Optimization Of Transformation And Regeneration In The Sunflower (Helianthus Annuus), Sara M. Kilar

Masters Theses

In addition to their value as prized ornamentals, sunflowers are important crop species due to the nutritional value and high oil content of the seeds. Sunflower oil is a significant contributor to global seed oil production, which can be used as a food additive and cooking agent as well as a raw material for biodiesel production. While traditional breeding efforts have led to the development of many unique cultivars, genetically modified variations have proven more difficult due to the recalcitrance of sunflower plants to genetic transformation. As a result, facile and efficient transformation methods for sunflowers have the potential to …

Mathematical And Computational Modeling For Organic And Insect Frass Fertilizer Production: A Systematic Review, Malontema Katchali, Edward Richard, Henri E.Z. Tonnang, Chrysantus M. Tanga, Dennis Beesigamukama, Kennedy Senagi

All Peer-Reviewed Publications

Organic fertilizers have been identified as a sustainable agricultural practice that can enhance productivity and reduce environmental impact. Recently, the European Union defined and accepted insect frass as an innovative and emerging organic fertilizer. In the wider domain of organic fertilizers, mathematical and computational models have been developed to optimize their production and application conditions. However, with the advancement in policies and regulations, modelling has shifted towards efficiencies in the deployment of these technologies. Therefore, this paper reviews and critically analyzes the recent developments in the mathematical and computation modeling that have promoted various organic fertilizer products including insect frass. …

Earth Observations Reveal Impacts Of Climate Variability On Maize Cropping Systems In Sub-Saharan Africa, Adomas Liepa, Michael Thiel, Hannes Taubenböck, Doris Klein, Ingolf Steffan-Dewenter, Marcell K. Peters, Sarah Schönbrodt-Stitt, Insa Otte, Tobias Landmann, Zeyaur R. Khan, Michael Ochieng Obondo, Frank Chidawanyika, Emily A. Martin, Tobias Ullmann

All Peer-Reviewed Publications

In Kenya, climate variability and change threaten smallholder, rainfed farms, with crop failures, yield reductions, and pest infestations. Efficient agroecological strategies, such as Push-Pull intercropping, offer documented benefits including pest control, improved soil fertility, and water conservation compared to traditional maize monocropping. To date, no studies exist comparing traditional maize monocropping and Push-Pull intercropping using earth observation tools over several growing seasons in East Africa. Our research addresses this by harmonizing Landsat 7, 8, 9 with Sentinel-2 remote sensing time series from 2016 to 2023. Phenological metrics of 15 growing seasons are extracted based on a threshold method using the …

Unpacking The Benefits Of Black Soldier Fly Frass Fertilizer Towards Nematode Suppression And Potato Production, Emmanuel O. Anedo, Dennis Beesigamukama, Benson Mochoge, Nicholas K. Korir, Solveig Haukeland, Xavier Cheseto, Moses Nyongesa, Patrick Pwaipwai, Sevgan Subramanian, Abdou Tenkouano, Betty Kibaara, Chrysantus M. Tanga

All Peer-Reviewed Publications

Potato production is hindered by soil degradation and nematode infestation. Mineral fertilizers and synthetic nematicides are costly and cause negative impacts on humans and the environment, while organic fertilizers are less effective for soil health and nematode management. This study demonstrates the contribution of black soldier fly frass fertilizer (BSFFF) in nematode suppression and potato productivity when compared to commercial mineral fertilizer, organic fertilizer (SAFI), and nematicide. The on-farm experiments consisted of eight treatments: BSFFF, SAFI, BSFFF+5%chitin, NPK+nematicide, 50%BSFFF+50%NPK, 50%SAFI+50%NPK, 50%BSFFF+5% chitin+50%NPK, and control (unfertilized soil). Results revealed that all fertilizer treatments significantly increased potato growth, number of tubers (34 …