Plant Biology Commons^™

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.

Dataset Supporting "Functional Trait Responses Of Alternanthera Philoxeroides To Increasing Salinity: Stress Tolerance, Avoidance And Escape Strategies Support Invasiveness With Sea Level Rise, Brenda J. Grewell*, Blanca Gallego-Tévar, Jesús M. Castillo, Caryn J. Futrell, Rebecca E. Drenovsky, Nathan E. Harms, Paul D. Pratt

Alligator Weed Salinity Exp for NeoBiota

No abstract provided.

Bigger Meristem, Higher Yield? The Roles Of Rel2 And Relk In Maize Meristem Function And Yield Enhancement, Janlo M. Robil, Thu M. Tran

Biology Faculty Publications

No abstract provided.

Spatial Analysis Of American Chestnut (Castanea Dentata) Distribution And Ecology In Kentucky’S Federal Lands, Jacob Raymond Pease

Murray State Theses and Dissertations

Anthropogenic factors have been the cause of the decline of tree species across the globe. From unsustainable logging and development to disease and improper management, threats to forests have taken their toll. The American chestnut (Castanea dentata) was once an integral basal tree species in Appalachian forests, but chestnut blight drove the species to functional extinction by the mid-1900s. The recent creation of genetically modified chestnuts gives hope for future restoration of the species throughout its historical range. Despite blight resistance, effective restoration will require optimal site selection for finding and planting chestnuts, which will maximize limited resources. …

Isolation, Characterization & Identification Of Cultivable Field Pea Seed Bacteria In South Dakota, Diana Wairimu Njuguna

Electronic Theses and Dissertations

Pea (Pisum sativum L.) is a legume, cultivated on over 25 million acres, particularly in Canada, France, China, Russia, and the United States. Its seeds harbor microbiota including bacteria and fungi, either on the surface (epiphytes) or within seed tissues (endophytes). These microbes can be pathogenic or beneficial, enhancing seedling metabolism and protection from environmental stresses. Characterizing beneficial seed microbiota enables development of microbial inoculants for seed treatment. Seeds from 12 varieties (green or yellow seed coats) were harvested from Sturgis and Dakota Lakes in 2021. Epiphytes were extracted using sonication followed by grinding the seeds to obtain endophytes. Isolates …

Bioremediation In The Chesapeake Bay: Anthropogenic Ocean Acidification Mitigation In An Interactive Multi-Trophic Ecosystem, Cree Taylor

AUCTUS: The Journal of Undergraduate Research and Creative Scholarship

Zostera marina is a species of marine macrophyte that has been largely prioritized in past submerged aquatic vegetation (SAV) restoration initiatives within the Chesapeake Bay because of its 1) previous abundance, 2) demonstrated carbon burial abilities, and 3) observed ability for meadows of Z. marina to ameliorate low pH conditions. Due to the temperature variability and poor water quality in the Chesapeake Bay, Z. Marina beds have experienced several die-off events with limited capacity for regrowth. Ruppia maritima, an opportunistic species with tolerance to temperature shifts within the bay, may have the potential to maintain SAV coverage in areas …

Physiological Responses And Plant Trait Interactions With Coastal Dune And Swale Development, Emily C. Riffe

Theses and Dissertations

Vegetation is crucial to coastal ecosystems experiencing climate change and storm-induced disturbance. Plant species interact with the physical environment and are considered “ecosystem engineers.” Sand dunes and barrier islands are at the forefront of climate change impacts as they are barriers that protect landward habitat and communities. Nature based solutions are utilized to protect infrastructure on developed coastlines. Understanding how dominant plant species interact with and alter the physical environment enhances our understanding of the mechanisms of change and consequences to the system. The goal of this research was to quantify physiological and functional trait differences in dominant species found …

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 …

Characterizing The Targeting Of Toc159 Receptors To The Chloroplast Outer Envelope Membrane And Their Role In The Assembly Of Distinct Toc Complexes, Michael Fish

Theses and Dissertations (Comprehensive)

Global agriculture and food security face challenges from climate change, population growth, and other human-driven pressures. Enhancing our understanding of plant biology, particularly chloroplast function, is critical for improving crop yield and stress resilience. As the sites of photosynthesis and key regulators of plant responses to environmental cues, chloroplasts depend on the precise import of thousands of nuclear-encoded proteins to maintain their biogenesis and function. While much is known about the core translocon components in the chloroplast outer envelope membrane that form the TOC complex, the mechanisms underlying their targeting, assembly, and regulation remain incompletely understood.

Plastids, including chloroplasts, evolved …

Npr1 As A Temperature-Sensitive Regulator Of Pipecolic Acid-Mediated Plant Systemic Immunity, Spencer Tout

Theses and Dissertations (Comprehensive)

Healthy plant development requires balancing both abiotic (e.g. climate) and biotic (e.g. pathogen) challenges, which intercept important signaling pathways in plants. For example, climate change-associated elevated temperature can negatively modulate various aspects of plant immunity, including the production of central immune signals salicylic acid (SA) and N-hydroxypipecolic acid (NHP). Since SA and NHP signaling both require the master immune co-activator protein NON-EXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1), it is important to investigate NPR1 as a potentially temperature-regulated molecular hub. Although the NPR1 gene is not transcriptionally downregulated at elevated temperatures (28° C vs. 23° C), little is known about …

Effects Of Gas Exchange Rates Between C3 And C4 Plant Species, Samantha L. Moya, Mollie Ouk, Aisha Goni

Undergraduate Research Posters

Spinach and basil (C3 plants) were compared with corn (C4 plant) to

explore how photosynthetic pathways affect CO2 consumption. Corn

seeds were obtained and planted in Miracle-Gro® soil to be observed

over the duration of a month. Leaves (starting from 3,4, and 10) from

each plant were then taken and placed into a bottle and closed off

with a CO2 gas probe that measured levels of carbon dioxide in ppm.

Spinach and basil leaves were used as a comparison for measuring

the rate of CO2 concentration. This is done to compare the gas

exchange rates between C3 and C4 plants. …

The Aussie Oddballs: Identifying The Existence Of Censer And Trample Burr Dispersal In Australian Bush Tomatoes, Abigail Motter

Honors Theses

Australian bush tomatoes in northern Western Australia likely have seed dispersal mechanisms that depend on processes outside of frugivory, which is unusual for this genus. Solanum tudununggae seeds are wind dispersed by the censer mechanism, meaning that seeds fall from holes in the top of the fruit when the branches move. In another species, piles of abscised and burr-like fruits have been found strewn around the bases of S. ossicruentum, possibly due to the extinction of animals that may have been a means of dispersal via epizoochory. In this study, we attempt to provide support for the theorized dispersal …

Investigating The Mechanisms Of Freeze Tolerance In Lemna Minor, Tamara Bouchard

Honors Theses and Capstones

Freezing presents a significant abiotic stress to aquatic plants, yet little is known about the mechanisms by which species like Lemna minor (duckweed) survive subzero temperatures in nature. This study investigates whether L. minor employs freeze-avoidance or freeze-tolerance strategies and explores the potential role of its microbiome in enhancing cold resilience. Using both field-collected fronds from naturally frozen ponds and controlled freezing experiments in the lab, I assessed survival through viability staining and post-thaw survival. Results showed that L. minor can survive natural ice encasement and that prior cold acclimation significantly improves tissue survival under induced freezing. Trypan blue staining …

A Mystery Of Microecology: Revealing The Ecological Relationship Between Allorhizobium Vitis And Missouri Native Grape Species, Hunter White

Graduate Theses/Dissertations

Crown gall disease can be very detrimental to grape and wine producers around the world by reducing vine vigor and yield. It is caused by the bacteria Allorhizobium vitis (A. Vitis) carrying a tumor inducing (Ti) plasmid. The A. vitis bacteria have been found in soil and cane tissues in vineyards around the world, and infect all cultivated grapes. However, there have been no reports of crown gall on native wild grapevines, and very little is known about the ecology of A. vitis in native ecosystems. I have sampled cambium tissues from three native wild grape species of …

The Effects Of Calcium Availability On Growth And Calcium Content Of Hydroponic Daikon Radish Microgreens, Cory Michael Reichmuth

Graduate Theses/Dissertations

Microgreens are young, edible seedlings harvested upon emergence of the first true leaf. Their popularity is growing as a nutritionally dense food source that can be grown quickly in space-efficient systems. However, little is known about optimal cultivation practices and the effects of fertilization on growth and nutrition of microgreens. This study investigates the role of calcium (Ca) fertilization in optimizing the growth, yield, and nutrient content of daikon radish (Raphanus sativus) microgreens. A hydroponic system was designed to consistently deliver nutrient solution to microgreens grown in a closed-environment chamber. This study tested different Ca fertilization rates of 0, 5, …

Restoration Of Giant River Cane (Arundinaria Gigantea) In Southwest Missouri, Lyndsey D. Rightnowar

Graduate Theses/Dissertations

Giant river cane (Arundinaria gigantea), a native bamboo species, once dominated riparian landscapes across the southeastern United States but has declined to approximately 2% of its historic range. This study evaluated restoration techniques for giant cane in southwest Missouri by examining the influence of rhizome source (putative genotype), planting type, and restoration site on restoration success. I compared two planting types: greenhouse-to-field (G2F) transplanting, where rhizomes were first propagated in the greenhouse before planting, and field-to-field (F2F) transplanting, where rhizomes were directly transplanted from source canebrakes to restoration sites. Rhizomes were collected from four existing canebrakes in Taney …

Geometric Modeling, Reconstruction And Evaluation Of Maize Leaf Morphology In 3d, Zhaocheng Xiang

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Maize is a vital crop for global food security, yet quantitative characterization of its three-dimensional (3D) morphology remains a major challenge due to the geometric complexity of curved leaf structures and occlusions during data collection. This work presents an integrated framework for the digital reconstruction, parametric modeling, and functional analysis of maize leaf morphology and canopy architecture, advancing the precision and interpretability of phenotyping and modeling in smart agriculture.

First, we propose a descriptive and parametric model that represents maize leaves through three fundamental components: midrib, cross-section, and blade contour. Each is described by geometric curves and controlled by biologically …