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Stable Carbon Isotope Evidence Of Ancient Maya Agriculture At Tikal, Guatemala, Richard Lee Burnett

Theses and Dissertations

Stable carbon isotope analyses of the humin fraction of the soil organic matter were conducted on more than 160 soil profiles from Tikal, Guatemala. The profiles were collected from near areas associated with the earthworks of Tikal; an ancient ditch and parapet construction hypothesized to have formed ancient boundaries of the polity. In addition to the isotope analyses, the physical and chemical characteristics of the horizons were determined. Maize, a C4 plant, formed an integral part of the ancient Maya diet and is the only known C4 plant cultivated by the Maya. Prior to and subsequent to the ancient Maya …

Effects Of Nitrogen Supply On The Root Morphology Of Corn And Velvetleaf, Kimberly D. Bonifas, John L. Lindquist

Department of Agronomy and Horticulture: Faculty Publications

Root morphology will affect interplant competition for soil nutrients. Research was conducted to assess fine root fraction, mean root radius, specific root length, root length density, and nitrogen (N) uptake per unit fine root biomass of corn and velvetleaf over time and in response to nitrogen supply. Pots containing either corn or velvetleaf were embedded in the ground and received one of three N treatments. Plants were destructively sampled on 10 dates during each of two years and root subsamples analyzed using root scanning software. While corn root morphology was more responsive to N supply than velvetleaf, velvetleaf N uptake …

Western Corn Rootworm ( Diabrotica Virgifera Virgifera Leconte) Population Dynamics, Lance Meinke, Thomas W. Sappington, David W. Onstad, Thomas Guillemaud, Nicholas Miller, Judit Komáromi, Nora Levay, Lorenzo Furlan, József Kiss, Ferenc Toth

Department of Entomology: Faculty Publications

1 The western corn rootworm Diabrotica virgifera virgifera LeConte is a major insect pest of field maize, Zea mays L. Larvae can cause substantial injury by feeding on maize roots. Larval feeding may destroy individual roots or root nodes, and reduce plant growth, stability, and yield. Costs associated with managing corn rootworms in continuous maize are annually one of the largest expenditures for insect management in the United States Corn Belt.

2 Even though D. virgifera virgifera has been studied intensively for over 50 years, there is renewed interest in the biology, ecology, and genetics of this species because of …

Weed Control In Maize (Zea Mays L.) With Effective Minimum Rates Of Foramsulfuron, Kami̇l Kir, M. Nedi̇m Doğan

Turkish Journal of Agriculture and Forestry

Dose-response experiments were conducted under controlled conditions to determine the effective minimum rates (ED_{90}) of foramsulfuron for 11 weed species that occur in maize growing areas in Turkey. Annual weeds were collected from maize fields in the cotyledon stage and transferred to pots containing a mixture of soil-turf (1:1 ratio). Perennial weeds were grown from rhizome pieces collected from infested fields. Weeds were then treated with different rates of foramsulfuron to determine the effective minimum rate (ED_{90}) for each weed species via dose-response experiments. Results showed that ED_{90} rates were lower than the recommended herbicide rate for most weed species. …

Limits To Maize Productivity In The Western Corn-Belt: A Simulation Analysis For Fully Irrigated And Rainfed Conditions, Patricio Grassini, Haishun Yang, Kenneth G. Cassman

Department of Agronomy and Horticulture: Faculty Publications

Unlike the Central and Eastern U.S. Corn-Belt where maize is grown almost entirely under rainfed conditions, maize in the Western Corn-Belt is produced under both irrigated (3.2 million ha) and rainfed (4.1 million ha) conditions. Simulation modeling, regression, and boundary-function analysis were used to assess constraints to maize productivity in the Western Corn-Belt. Aboveground biomass, grain yield, and water balance were simulated for fully irrigated and rainfed crops, using 20-year weather records from 18 locations in combination with actual soil, planting date, plant population, and hybrid-maturity data. Mean values of meteorological variables were estimated for three growth periods (pre- and …

Parasitoids Of Several Lepidopterous Pests In Maize Plantations In The Southeast Anatolian Region Of Turkey, Celaletti̇n Gözüaçik, Cafer Mart, Kenan Kara

Turkish Journal of Zoology

The parasitoid complex of several lepidopteran pests were studied in maize plantations in the Southeast Anatolian Region of Turkey during 2003-2004. Apenteles sp., Bracon hebetor (Say.), Chelonus oculator Panzer, Meteorus rubens Nees (Hym.: Braconidae), Conomorium patulum Walk. (Hym.: Pteromalidae), Diadegma crassicornis (Gray.) subsp. africator Aubert (Hym.: Ichneumonidae), Euplectrus sp. (Hym.: Eulophidae), Exorista larvarum (Linnaeus), E. xanthaspis (Wiedemann) Gonia bimaculata Wiedemann, Drino imberbis (Wiedemann), Pseudogonia rufifrons (Wiedemann), and Linnaemya neavei Curran (Dip.: Tachinidae) were reared from field-collected larvae. Mythimna loreyi (Duponchel) (Lep.: Noctuidae) was for the first time found to serve as a host for Diadegma crassicornis (Gray.) subsp. africator (Hym.: …

Effect Of High Amylose Maize Starches On Colonic Fermentation And Apoptotic Response To Dna-Damage In The Colon Of Rats, Ian L. Brown, Richard K. Le Leu, Graeme P. Young, Ying Hu

Faculty of Health and Behavioural Sciences - Papers (Archive)

Background

We investigated in rats the effects of feeding different forms of high amylose maize starches (HAMS) rich in resistant starch (RS) to understand what the implications of RS heterogeneity might be for colonic biology, including innate cellular responses to DNA-damage.

Methods

A range of maize starches were compared: digestible cornstarch (Control), HYLON^® VII, Hi-maize^® 1043, Hi-maize^® 240, Hi-maize^® 260 and NOVELOSE^® 330. Included in the comparison was Cellulose. End-points after 4 weeks included: pH, short chain fatty acids (SCFA) levels, colonic epithelial cell kinetics and apoptotic response to carcinogen 'azoxymethane' in the colonic epithelium. …