Plant Sciences Commons^™

Evidence Of Ancient Maya Agriculture In The Bajos Surrounding Tikal, Guatemala, Adam Calvin Parker

Theses and Dissertations

Current Central American agricultural practices are environmentally and economically unsustainable, yet the ancient Maya who lived in the same region thrived for thousands of years. Archaeologists have attempted to understand the factors enabling the prolonged success and ultimate collapse of the Maya societies. Some have proposed that the karst seasonal wetlands, called bajos, that border many Maya sites in the region were an influential factor in the Maya's ability to flourish. For the past decade, researchers have used carbon isotope analyses to identify areas of ancient maize agriculture at Maya archaeological sites. In this study, we collected soil samples from …

Weed Dynamics During Transition To Conservation Agriculture In Western Kenya Maize Production, Judith A. Odhiambo, Urszula Norton, Dennis Ashilenje, Emmanuel C. Omondi, Jay B. Norton

Agricultural and Environmental Sciences Faculty Research

Weed competition is a significant problem in maize (Zea mays, L.) production in Sub-Saharan Africa. Better understanding of weed management and costs in maize intercropped with beans (Phaseolus vulgaris, L.) during transition to conservation agricultural systems is needed. Changes in weed population and maize growth were assessed for a period of three years at Bungoma where crops are grown twice per year and at Trans-Nzoia where crops are grown once per year. Treatments included three tillage practices: minimum (MT), no-till (NT) and conventional (CT) applied to three cropping systems: continuous maize/bean intercropping (TYPICAL), maize/bean intercropping with relayed mucuna after bean …

Biochemical And Proteomic Profiling Of Maize Endosperm Texture And Protein Quality, Kyla J. Morton

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

The research described herein, focuses on the biochemical and proteomic analysis of the maize endosperm and what influences kernel texture. Quality Protein Maize (QPM) is a hard endosperm version of the high-lysine opaque2 (o2) mutant but the genes involved in modifying the soft o2 endosperm are unknown. Pyrophosphate (PPi)-dependent fructose 6-phosphate 1-phosphotransferase (PFP) catalyzes the ATP-independent conversion of fructose 6-phosphate to fructose 1, 6-bisphosphate in glycolysis. We found a large increase in transcript and protein levels of the alpha regulatory subunit of PFP (PFPα) in QPM endosperm. In vitro enzyme assays show a significant increase in forward PFP …

A Regional Comparison Of Water Use Efficiency For Miscanthus, Switchgrass And Maize, Andy Vanloocke, Tracy E. Twine, Marcelo Zeri, Carl J. Bernacchi

Andy VanLoocke

The production of cellulosic feedstocks for renewable fuels will increase over the coming decades. However, it is uncertain which feedstocks will be best suited for bioenergy production. A key factor dictating feedstock selection for a given region is water use efficiency (WUE), the trade-off between evapotranspiration (ET) and carbon uptake or productivity. Using an ecosystem model, two of the top candidate cellulosic feedstocks, Miscanthus × giganteus (miscanthus) and Panicum virgatum(switchgrass) were compared to Zea mays L. (maize), the existing dominant bioenergy feedstock, with 0 and 25% residue removal for the Midwest US. We determined productivity in three ways: harvested yield …

Future Carbon Dioxide Concentration Decreases Canopy Evapotranspiration And Soil Water Depletion By Field-Grown Maize, Mir Zaman Hussain, Andy Vanloocke, Matthew H. Siebers, Ursula M. Ruiz-Vera, R. J. Cody Markelz, Donald R. Ort, Carl J. Bernacchi

Andy VanLoocke

Maize, in rotation with soybean, forms the largest continuous ecosystem in temperate North America, therefore changes to the biosphere-atmosphere exchange of water vapor and energy of these crops are likely to have an impact on the Midwestern US climate and hydrological cycle. As a C4 crop, maize photosynthesis is already CO2-saturated at current CO2 concentrations ([CO2]) and the primary response of maize to elevated [CO2] is decreased stomatal conductance (gs). If maize photosynthesis is not stimulated in elevated [CO2], then reduced gs is not offset by greater canopy leaf area, which could potentially result in a greater ET reduction relative …

Corn Yield And Soil Nitrous Oxide Emission Under Different Fertilizer And Soil Management: A Three-Year Field Experiment In Middle Tennessee, Qi Deng, Dafeng Hui, Junming Wang, Stephen Iwuozo, Chih-Li Yu, Tigist Jima, David Smart, Chandra Reddy, Sam Dennis

Agricultural and Environmental Sciences Faculty Research

Background

A three-year field experiment was conducted to examine the responses of corn yield and soil nitrous oxide (N2O) emission to various management practices in middle Tennessee.

Methodology/Principal Findings

The management practices include no-tillage + regular applications of urea ammonium nitrate (NT-URAN); no-tillage + regular applications of URAN + denitrification inhibitor (NT-inhibitor); no-tillage + regular applications of URAN + biochar (NT-biochar); no-tillage + 20% applications of URAN + chicken litter (NT-litter), no-tillage + split applications of URAN (NT-split); and conventional tillage + regular applications of URAN as a control (CT-URAN). Fertilizer equivalent to 217 kg N ha-1 was applied to …

Proteomic Profiling Of Maize Opaque Endosperm Mutants Reveals Selective Accumulation Of Lysine-Enriched Proteins, Kyla J. Morton, Shangang Jia, Chi Zhang, David R. Holding

Department of Agronomy and Horticulture: Faculty Publications

Reduced prolamin (zein) accumulation and defective endoplasmic reticulum (ER) body formation occurs in maize opaque endosperm mutants opaque2 (o2), floury2 (fl2), defective endosperm*B30 (DeB30), and Mucronate (Mc), whereas other opaque mutants such as opaque1 (o1) and floury1 (fl1) are normal in these regards. This suggests that other factors contribute to kernel texture. A liquid chromatography approach coupled with tandem mass spectrometry (LC-MS/MS) proteomics was used to compare non-zein proteins of nearly isogenic opaque endosperm mutants. In total, 2762 proteins were identified that were enriched for biological processes such as protein transport and folding, amino acid biosynthesis, …

Potential For Crop Production Increase In Argentina Through Closure Of Existing Yield Gaps, Fernando Aramburu Merlos, Juan Pablo Monzon, Jorge L. Mercau, Miguel Taboada, Fernando H. Andrade, Antonio J. Hall, Esteban Jobbagy, Kenneth Cassman, Patricio Grassini

Department of Agronomy and Horticulture: Faculty Publications

Favorable climate and soils for rainfed crop production, together with a relatively low population density,results in 70–90% of Argentina grain production being exported. No assessment to date has tried to estimate the potential for extra grain production for soybean, wheat and maize, which account for 78%of total harvested area, by yield gap closure on existing cropland area and its impact at a global scale.The objectives of this paper are (i) to estimate how much additional grain could be produced without expanding crop area by closing yield gaps in Argentina, (ii) to investigate how this production and yield gaps varies across …

Response Of Stomatal Density And Bound Gas Exchange In Leaves Of Maize To Soil Water Deficit, Wensai Zhao, Yonglin Sun, Roger Kjelgren, Xiping Liu

Plants, Soils, and Climate Faculty Publications

Stomatal behavior in response to drought has been the focus of intensive research, but less attention has been paid to stomatal density. In this study, 5-week-old maize seedlings were exposed to different soil water contents. Stomatal density and size as well as leaf gas exchange were investigated after 2-, 4- and 6-weeks of treatment, which corresponded to the jointing, trumpeting, and filling stages of maize development. Results showed that new stomata were generated continually during leaf growth. Reduced soil water content significantly stimulated stomatal generation, resulting in a significant increase in stomatal density but a decrease in stomatal size and …

Promotive Effect Of Exogenously Applied Thiourea On Key Physiological Parametersand Oxidative Defense Mechanism In Salt-Stressed Zea Mays L. Plants, Cengi̇z Kaya, Muhammad Ashraf, Osman Sönmez

Turkish Journal of Botany

A greenhouse experiment was conducted to examine the alleviating role of thiourea (TU) on antioxidants and some vital physiological attributes in salt-stressed plants of two maize cultivars. The maize cv. DK 5783 performed better than cv. Apex 836 in an initial experiment. Of the six TU levels used in the initial experiment, 400 and 500 mg L-1 were chosen for subsequent studies. The two cultivars were subjected to saline stress (100 mM NaCl) and two levels of TU were applied presowing or as foliage spray. Salt stress suppressed total biomass, maximum fluorescence yield (Fv/Fm), chlorophyll, and leaf water potential ($\Psi$w), …