Plant Biology Commons^™

Going Back To The Soil: An Integrated Approach To Farming., Renée V. Christie

Theses and Dissertations (Comprehensive)

Agricultural productivity is often constrained by nutrient availability; as such, copious amounts of synthetic fertilizers are applied to maintain productivity. However, the intensive use of synthetic fertilizers has reduced the capacity of the soil to carry out crucial roles such as nutrient cycling because of shifts in the microbial community composition and structure. In addition, much of the applied synthetic fertilizers become lost to the environment through run-off, which contributes to soil degradation. With the increasing demand on agricultural systems to provide food and fibre and the adverse impacts of agricultural production on the soil resource, amendments that support soil …

United States Midwest Soil And Weather Conditions Influence Anaerobic Potentially Mineralizable Nitrogen, Jason D. Clark, Kristen S. Veum, Fabian G. Fernandez, James J. Camberato, Paul R. Carter, Richard B. Ferguson, David W. Franzen, Daniel E. Kaiser, Newell R. Kitchen, Carrie A. M. Laboski, Emerson D. Nafziger, Carl J. Rosen, John E. Sawyer, John F. Shanahan

Department of Agronomy and Horticulture: Faculty Publications

Nitrogen provided to crops through mineralization is an important factor in N management guidelines. Understanding of the interactive effects of soil and weather conditions on N mineralization needs to be improved. Relationships between anaerobic potentially mineralizable N (PMN_an) and soil and weather conditions were evaluated under the contrasting climates of eight US Midwestern states. Soil was sampled (0–30 cm) for PMN_an analysis before pre-plant N application (PP_0N) and at the V5 development stage from the pre-plant 0 (V5_0N) and 180 kg N ha−1 (V5_180N) rates and incubated for 7, 14, and …

Evaluation Of Spray Pattern Uniformity Using Three Unique Analyses As Impacted By Nozzle, Pressure, And Pulse-Widthmodulation Duty Cycle, Thomas R. Butts, Joe D. Luck, Bradley K. Fritz, W. Clint Hoffmann, Greg R. Kruger

Department of Agronomy and Horticulture: Faculty Publications

BACKGROUND: The increasing popularity of pulse-width modulation (PWM) sprayers requires that application interaction effects on spray pattern uniformity be completely understood to maintain a uniform overlap of spray, thereby reducing crop injury potential andmaximizing coverage on target pests. The objective of this researchwas to determine the impacts of nozzle type (venturi vs. non-venturi), boom pressure, and PWMduty cycle on spray pattern uniformity. Research was conducted using an indoor spray patternator located at the University of Nebraska-Lincoln in Lincoln, NE, USA. Coefficient of variation (CV), root mean square error (RMSE), and average percent error (APE) were used to characterize spray pattern …

Planting Density Effects On The Growth Of Dune Grasses., Audrey Kirschner

Theses and Dissertations

Coastal dune vegetation plays a key role in dune formation and stabilization through sediment trapping and erosion control. To restore degraded dunes, revegetation of dune building species is critical. Planting density has been found to effect growth of marsh species, with closer plantings alleviating stress through facilitation. As coastal dunes are high stress environments, it is expected that dune species may also exhibit facilitative interactions based on the Stress Gradient Hypothesis. Therefore, planting grasses in clumped configurations may lead to more successful dune revegetation. The objective of this research was to determine how planting density affects the growth of two …

Enhancing Water Stress Tolerance In Floriculture Crops, Suejin Park

Graduate Theses, Dissertations, and Problem Reports (ETD)

Water deficit is one of the major constraints on plant growth and development, causing reduction of crop productivity. To minimize water loss, among many adaptation strategies, plants close their stomata to reduce transpiration. The stomatal closure is regulated by light, internal CO2 concentration, and plant hormones, mainly abscisic acid. Plants’ response mechanisms to water deficit are complex processes involving numerous genes and various signaling pathways. Floriculture crops are often exposed to water deficit during shipping and retailing, and these periods often result in damaged crops and profit loss. Understanding of plant responses to water deficit stress will provide us an …

Diversity And Evolution Of Seeds In Cuscuta (Dodders, Convolvulaceae): Morphology And Structure, Magdalena Olszewski

Theses and Dissertations (Comprehensive)

Cuscuta is a genus of nearly 200 obligate stem parasites with a nearly cosmopolitan distribution and considerable agricultural and ecological significance. Dodder seeds are considered “unspecialized”, with no morphological adaptations towards particular dispersal vectors; however, the seed coat anatomy has recently suggested an adaptation to endozoochory. This is the first attempt to provide a genus-wide overview of the diversity in morphology and anatomy of Cuscuta seeds, together with an assessment of the water gap and exploration of various form-function relationships. I surveyed 104 species belonging to all four Cuscuta subgenera. Seeds of the species of the first infrageneric dodder …

Context Is Everything: An Investigation Of Spanish River Carbonatite And Its Effects On Soil-Plant-Microorganism Systems, James Mc Jones

Theses and Dissertations (Comprehensive)

With growing concerns about agricultural sustainability and food security, the use of rock fertilizers and agrominerals is receiving renewed interest. A wide variety of geological resources have been proposed as crop nutrient sources, with silicate rocks the predominant focus. Carbonatite rocks are known to weather more readily than silicate rocks; yet, they have received relatively little attention as it is thought their high Ca and Mg contents hinder effective nutrient release. However, there is strong evidence that the nutrients within carbonatite rocks are easily accessible to plants, and that these rocks have noticable effects on crop plant growth. Here I …

Competition Or Facilitation: Examination Of Interactions Between Endangered Sida Hermaphrodita And Invasive Phragmites Australis, Samantha N. Mulholland

Theses and Dissertations (Comprehensive)

Virginia Mallow (Sida hermaphrodita) is a perennial herb of the Malvaceae family that is native to riparian habitats in northeastern North America. Throughout most of its geographical distribution however, it is considered threatened and only two populations are known from Canada. The biology and ecology of S. hermaphrodita are still poorly understood and although few studies have been performed to determine the factors that contribute to the species rarity, it is considered threatened potentially due to the loss of habitat caused by exotic European Common reed (Phragmites australis subsp. australis) invasion. Allelopathic and phytotoxic conditioning of …

The Effect Of Cold Stratification And Perigynia Removal On The Germination Of Three Prairie Carex Species, Christina M. Boeck Crew

Dissertations and Theses @ UNI

Sedges (Carex spp. Linneaus. [Cyperaceae]) are a major component of Midwestern U.S. tallgrass prairie and prairie wetland plant communities, yet they are often lacking in restoration projects because they can be difficult to germinate. Cold-wet stratification and perigynia removal have been shown to increase germination in some Carex species. The germination response of 3 native species, plains oval or shortbeak sedge (C. brevior (Dewey) Mack.), field oval or troublesome sedge (C. molesta Mack.), and prairie or Bicknell’s sedge (C. bicknellii Britton.), was tested to cold-wet stratification (28d) and perigynia removal in stored seed (10 months). Seed treatments …

Elucidating The Surface Geometric Design Of Hydrophobic Australian Eucalyptus Leaves: Experimental And Modeling Studies, Hua Guo, Zonghan Xie, Jeremy Shaw, Kingsley Dixon, Zhong-Tao Jiang, Chun-Yang Yin, Xuemei Liu

Research outputs 2014 to 2021

Three Australian native Eucalyptus species, i.e., Eucalyptus woodwardii, Eucalyptus pachyphylla and Eucalyptus dolorosa, were investigated, for the first time, with respect to the hydrophobicity of their leaves. It is well established that these leaves exhibit exceptionally high water repellency, in addition to an extraordinary ability to retain water, albeit their specific wetting mechanisms are still poorly understood. To identify the critical factors underlying this phenomenon, the surface topography of these leaves was subjected to micro-examination (SEM). Micro- and nanometer scale surface roughness was revealed, resembling that of the quintessential “lotus effect”. Surface free energy analysis was performed on two models …

Use Of Co-Immunoprecipitations And 2d Gel Electrophoresis To Identify Protein-Protein Interactions Of Maturase K, Lauren Angello

Honors Theses

Maturase K (MatK) is the only group II intron encoded protein in the chloroplast of land plants. Maturases are prokaryotic enzymes that catalyze formation of the lariat structure needed for intron removal from precursor RNAs. The chloroplast maturase MatK, is a descendant of prokaryotic maturases, however, unlike its prokaryotic relatives, MatK is thought to catalyze excision of, not only its own intron, but also the introns of other group II introns in the plastome. Similar to the multiprotein and snRNA spliceosomal complex of the nucleus, it is postulated that MatK is not working alone to excise these introns but most …

Respon Pertumbuhan Dan Hasil Tanaman Hanjeli Pada Panen Awal Akibat Pemberian Dosis Pupuk Biosilika Dan Paklobutrazol Di Lahan Kering Jatinangor, Ruminta, Tati Nurmala, Yuyun Yuwariah, Nita Yuliani Pratiwi

Jurnal Kultivasi

Hanjeli (Coix lacryma-jobiL) merupakan salah satu tanaman pangan alternatif dan tanaman fungsional. Hanjeli belum sepenuhnya dimanfaatkan petani salah satunya karena tanaman yang cukup tinggi dan memiliki umur cukup lama. Penelitian ini bertujuan untuk mengetahui dosis pupuk biosilika dan konsentrasi paklobutrazol yang dapat memberikan pengaruh terbaik terhadap pertumbuhan dan hasil tanaman hanjeli pulut dipanen awal (matang kuning). Penelitian dilaksanakan bulan Agustus 2017-Januari 2018 di Ciparanje, Universitas Padjadjaran, Jatinangor, Sumedang. Rancangan percobaan yang digunakan adalah rancangan petak terbagi yang terdiri dari petak utama pupuk biosilika dengan dosis 0 kg/ha; 100 kg/ha; 200 kg/ha dan anak petak paklobutrazol dengan konsentrasi 0 ppm; 1250 …

Recoupling Fire And Grazing Reduces Wildland Fuel Loads On Rangelands, Heath D. Starns, Samuel D. Fuhlendore, R. Dwayne Elmore, Dirac L. Twidwell Jr, Eric T. Thacker, Torre J. Hovick, Barney Luttbeg

Department of Agronomy and Horticulture: Faculty Publications

Fire suppression and exclusion, the historically dominant paradigm of fire management, has resulted in major modifications of fire-dependent ecosystems worldwide. These changes are partially credited with a recent increase in wildfire number and extent, as well as more extreme fire behavior. Fire and herbivory historically interacted, and research has shown that the interaction creates a unique mosaic of vegetation heterogeneity that each disturbance alone does not create. Because fire and grazing have largely been decoupled in modern times, the degree to which the interaction affects fuels and fire regimes has not yet been quantified. We evaluated effects of fire-only and …

Effects Of Calcium Fertilization On Growth, Yield, And Nutrient Content Of Hydroponically Grown Radish Microgreens, Cady C. Goble

Graduate Theses/Dissertations

Radish microgreens were grown in a hydroponic wicking system and subjected to a range of calcium chloride (Ca) solutions to evaluate growth, yield, and mineral content. A solution range of 0 to 160 mM Ca was applied to determine upper limits of Ca fertilization. Solutions above 20 mM Ca showed toxic effects to germination and growth, while 5 and 10 mM Ca resulted in the greatest percent of shoots that grew to a desired size for harvest (%H), as well as greater average hypocotyl length per plant (HL) and cotyledon surface area per plant (CSA). For subsequent experiments, Ca solution …

Physiological Characterization Of The Soynam Parental Lines Under Field Conditions, Akshita Mishra

Graduate Theses and Dissertations

The narrow genetic pool of soybean (Glycine max L. Merr.) in North America can limit its future yield gains. Among the worldwide germplasm collection of 45,000 unique landraces, only 80 contribute 99% to the collective parentage of North American soybean cultivars. Among these 80 landraces, just 17 contribute to 86% of the collective parentage of the modern cultivars. The Soybean Nested Association Mapping population (SoyNAM) was therefore developed with the objective of diversifying the soybean gene pool. Forty diverse soybean genotypes from maturity groups (MG) 1 through 5 were crossed with a common MG 3 parent to develop 40 recombinant …

Where Are All Of Arkansas' Chinquapins? An Ecological Assessment Of Castanea Throughout The State, Logan Pierce Estes

Graduate Theses and Dissertations

Around the turn of the twentieth-century, the chestnut blight fungus (Cryphonectria parasitica) was accidentally introduced into North America. This strong pathogen, which specializes on trees of the genus Castanea, spread rapidly and within half a century had nearly extirpated North America’s Castanea natives from their ranges. During this catastrophe, the American chestnut (Castanea dentata) garnered much of the scientific attention, pushing the other Castanea natives – the chinquapins – to the wayside. More than a century following the spread of the blight, little research into the ecology of North America’s chinquapins had been performed, leaving these trees significantly underrepresented. The …

Grazing Strategy Effects On Utilization, Animal Performance, Aboveground Production, Species Composition, And Soil Properties On Nebraska Sandhills Meadow, Aaron Shropshire

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

Ultrahigh stocking density (a.k.a., mob grazing) is proposed as a management tool that results in greater harvest efficiency, animal performance, aboveground plant production, species richness, and soil carbon content. The study objective was to determine grazing treatment, haying, or non-defoliated control effects on forage utilization, aboveground production, animal performance, and soil properties. In 2010, 25 ha of Sandhills meadow were divided into 2 replications of 3 grazing, a hay, and control treatment. Grazing treatments were a 120-pasture rotation with one grazing cycle (mob), a 4-pasture rotation with one cycle (4PR1), and a 4-pasture rotation with two cycles (4PR2) at stocking …

Understanding Spatial Dynamics Of Tallgrass Prairie Dominated By Tall Fescue, Callie Griffith

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

This study was conducted on restored tallgrass prairie and invaded tallgrass prairie located in the Grand River Grasslands of southern Iowa to determine differences in heterogeneity of plant structure and functional group composition at different scales. Restored tallgrass prairies were seeded with a species-rich seeding mixture and managed by burning the entire prairie, every three years. Data were collected in August 2014 and 2015 to compare heterogeneity of restoration of native plant structure and functional group composition to the heterogeneity of invaded tallgrass prairies that were managed with patch burning and conventionally grazed. Invaded tallgrass prairies were managed with patch-burning …

Evaluation Of Rice Stink Bug, Oebalus Pugnax (F.), Damage And Monitoring Techniques In Rice, Oryza Sativa L., And Grain Sorghum, Sorghum Bicolor (L.), Aaron Joseph Cato

Graduate Theses and Dissertations

Rice stink bug, Oebalus pugnax (F.), is a serious pest of headed rice, Oryza sativa L. and an occasional pest of heading grain sorghum in the Mid-south. Work from this dissertation focuses on resolving gaps in and knowledge of rice stink bug sampling and management, and attempts to create a basis for rice stink bug damage assessment in future studies.

Field experiments were conducted from 2016-2018 to asses variation in sweep net sampling by observing producers, researchers, extension personnel, consultants and their workers. Large levels of variation were found in sweep lengths between observed sweepers and reliability of smaller sweep …

Influence Of Loss Of Function Of The Fatty Acid Desaturase 7 Gene On Photosynthetic Activity And Foliar Redox Status, Janithri Savindya Wickramanayake

Graduate Theses and Dissertations

Fatty Acid Desaturase7 (FAD7) is a chloroplast-localized enzyme that converts 16 and 18 carbon dienoic fatty acids to trienoic fatty acids. The suppressor of prosystemin-mediated response2 (spr2) mutant in tomato (Solanum lycopersicum) and the fad7-1 mutant in Arabidopsis (Arabidopsis thaliana) result in the loss of function of FAD7, which alter the fatty acid profiles of chloroplast membranes and enhance resistance against aphids. This research contributes toward the long-term goal of identifying factors that determine aphid resistance in FAD7 mutants. Previous data suggested constitutive differences between spr2 and WT including increased expression of genes associated with photosynthesis and differences in redox …