Agricultural Science Commons^™

Models To Predict Yield Loss Due To Weeds In Rice Ecosystems, John L. Lindquist

Department of Agronomy and Horticulture: Faculty Publications

Yield loss models have been developed and evaluated for irrigated rice ecosystems with respect to effects of Echinochloa crusgalli. Simple regression models that give the relation between yield loss and weed density or relative leaf area are discussed with respect to their practical value in weed management in rice. More complex eco-physiological process models have been developed and used for rice ecosystems as well. Such models can be useful as a tool in research, whereas more simple approaches are needed for practical application in weed management.

Cdna Sequence For The Ribulose 1,5 Bisphosphate Carboxylase/Oxygenase Complex Protein A Protein That Accumulates In Soybean Leaves In Response To Fruit Removal, Paul E. Staswick, Steven J. Crafts-Brandner

Department of Agronomy and Horticulture: Faculty Publications

Soybean (Glycine max L.) transiently accumulates two abundant vegetative storage proteins, VSP A and VSP B, in vacuoles of above-ground vegetative tissues (Wittenbach, 1983; Staswick, 1990). As older leaves and stems become a source of exported metabolites for developing sinks, the VSPs are preferentially degraded and the resulting metabolites are presumably mobilized in the xylem and phloem stream. A striking feature of these proteins is that VSP gene expression is dramatically increased in mature leaves following the remova1 of reproductive sinks (seed pods) and the amount of these proteins increases accordingly (for review, see Staswick, 1994). Other changes …

Fractal Description Of Soil Fragmentation For Various Tillage Methods And Crop Sequences, Bahman Eghball, Lloyd N. Mielke, Guillermo A. Calvo, Wallace Wilhelm

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Soil structure has been difficult to quantify and, at best, has been studied semiquantitatively. Fractal representation of soil fragmentation can provide an indication of soil structure. The purpose of our study was to use fractal analysis to quantify soil fragmentation under various tillage and crop sequence treatments at different times during the growing season. We collected soil samples from four tillage treatments (established 10 yr earlier) of chisel, disk, no-till, and moldboard plow in factorial arrangement with two crop sequences of corn (Zea mays L.)-soybean [Glycine max (L.) Merr.]-corn (C-SC), and soybean- cornaoybean, (S-C-S) on a Sharpsburg (fine, …

Residual Effects Of No-Till Crop Residues On Corn Yield And Nitrogen Uptake, M. S. Maskina, James F. Power, John W. Doran, Wallace Wilhelm

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The residual effects of crop residues on N availability and crop growth are largely unknown. A field experiment was conducted from 1986 through 1988 at Lincoln, NE, to determine the residual effects on no-till corn (Zea mays L.) production and N uptake of 0,50, 100, and 1509'0 of the amount of crop residues produced by the previous crop during the previous 5 yr. These effects were evaluated with and without tillage (disking), N fertilizer (60 kg N ha^-1), and hairy vetch (Vicia villosa Roth ssp. villosa, 'Madison') winter cover crop. Increasing the previous crop residue …

Above-Ground Vegetative Development And Growth Of Winter Wheat As Influenced By Nitrogen And Water Availability, Wallace Wilhelm, Gregory S. Mcmaster, R. W. Rickman, Betty Klepper

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Assessing the influence of nitrogen and water availability on development and growth of individual organs of winter wheat (Triticum aestivum L.) is critical in evaluating the response of wheat to environmental conditions. We constructed a simulation model (SHOOTGRO 2.0) of shoot vegetative development and growth from planting to early boot by adding nitrogen and water balances and response functions for seedling emergence, tiller and leaf appearance, leaf and internode growth, and leaf and tiller senescence to the existing wheat development and growth model, SHOOTGRO 1.0. Model inputs include daily maximum and minimum air temperature, rainfall, daily photosynthetically active radiation, …

Proceedings Of The Workshop On Adaptation Of Plants To Soil Stresses, J.W. Maranville, V.C. Baligar, R.R. Duncan, J. M. Yohe

INTSORMIL Impacts and Bulletins

Sustainable production of food and forage with a focus on plant adaptation to stress environments will be a continued priority for developing countries in the future. Since many areas of the world which support substantial human populations are drought prone, such as the subsaharan African zone and others, the primary focus has been on drought. However, one of the greatest restraints to sustainability of agriculture worldwide is the lack of sufficient soil nutrients for crop growth, or other soil constraints such as acidity or salinity which hinder crop production substantially.

Optimizing soil fertility or amending acid and saline soils to …

Scales: A Computer Program To Convert Among Three Developmental Stage Scales For Wheat, Dorothy M. Harrell, Wallace Wilhelm, G. S. Mcmaster

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The Haun, Feekes, and Zadoks-ChanpKonzak developmental stage scales are often used to report phenological information for wheat (Triticum aestivum L.) development. Agronomists familiar with one of these scales may have only a passing acquaintance with developmental scales other than the one they consider most appropriate for their purposes. This makes review and interpretation of the literature more difficult. Although wheat development models often report phenological results, they generally use no more than one scale. For these reasons, and because there is not a simple numeric correspondence among the three scales, a computer program to convert among them is a …

Proceedings Of The 20th Annual Meeting, Southern Soybean Disease Workers (March 28-30, 1993, Fort Walton Beach, Florida), Patrick D. Colyer, Glenn R. Bowers Jr., John C. Rupe, Brian M. Anderson, Glenn G. Hammes

Southern Soybean Disease Workers: Conference Proceedings

Contents

Sustainable agriculture symposium

Sustainable Agriculture and the Soybean Industry: Building a Winning Strategy. D Hubbard and MS Fitzner

Impact of Pest Interactions on Management Programs. J Funderburke

Introducing Procedures of Sustainable Agriculture, a Team Approach. J Bradley

Sustainable Agriculture Practices and Their Impact on Plant Diseases. C Rothrock

Graduate student competition

Effect of Increasing Initial Inoculum Levels of Rotylenchus reiformis on Soybean. JJ Cornelius and GW Lawrence

Effect of Frogeye Leaf Spot on Yield of Soybean Lines Near-Isogeneic for Resistance. PF Pace, DB Weaver, LD Flopper, and PA Backman

Heritability and Genotype X Environment Interaction of Partial Resistance to …

Modeling Of Carbon Dioxide Transport And Production In Soil 1. Model Development, Jiří Šimůnek, Donald L. Suarez

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Knowledge of the CO₂ concentration in the unsaturated zone is essential for prediction of solution chemistry in the vadose zone and groundwater recharge as well as for quantifying carbon source/sink terms as as part of the global CO₂ mass balance.  In this paper we present a predictive simulation model, SOILCO2, based on process-oriented relationships.  The model includes one-dimensional water flow and multiphase transport of CO₂ utilizing the Richards and the convection-dispersion equations, respectively, as well as heat flow and a CO₂ production model.  The transport of CO₂ in the unsaturated zone can occur in both …

Identification Of Plasmid And Chromosomal Copies Of 987p Pilus Genes In Enterotoxigenic Escherichia Coli 987, Thomas A. Casey, Robert A. Schneider, Evelyn A. Dean-Nystrom

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

A DNA probe derived from the subunit gene of a cloned 987P determinant was used to characterize the locations of the 987P genes in several Escherichia coli strains. We examined E. coli 987, a nonpiliated mutant of strain 987 (136) that does not express 987P in vitro, and a variant of I36 that expressed 987P following growth in vivo. We found that plasmid and chromosomal copies of the 987P subunit gene could be differentiated in strain 987 by restriction endonuclease analysis and Southern blot hybridization. The nonpiliated mutant 136 had lost the plasmid copy but retained the chromosomal copy of …

Influence Of Improvement Practices On Big Bluestem And Indiangrass Seed Production In Tallgrass Prairies, Robert A. Masters, Robert B. Mitchell, Kenneth P. Vogel, Steven Waller

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Taligrass prairies provide a valuable source of diverse native plant germplasm. Seed harvested from native prairies can be used to revegetate highly erodible or marginal cropland and degraded rangeland if adequate quantities of seed can be produced. The effect of spring burning, fertilization, and atrazine [6-chloro-Nethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] on big bluestem (Andropogon gerardii Vitman var. gerardii Vitman) and indiangrass [Sorghastrum nutans (L.) Nash] reproductive stem density and seed production was determined in 9 tallgrass prairie environments (each year by site was considered a unique environment). Studies were conducted at tallgrass prairies near Bloomfield, Lincoln, and Virginia, Nebr., from 1987 through …

Future Developments In Artificial Insemination Technology, Murray R. Bakst

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The development of artificial insemination (AI) technology over the past decade has resulted in some significant advances in poultry breeding.  However, because there are few poultry scientists performing fundamental research to advance AI technology, alternative approaches must be examined in an effort to expand AI technology.  This paper suggests that the technology available for cell and tissue culture propagation should be evaluated and the applicability of this technology to poultry AI technology assessed.  Instrumentation and clinical testing procedures used for the evaluation of somatic cells in culture could provide objective data before and after semen storage on large numbers of …

The Sticky Card: Device For Studying The Distribution Of Adult House Fly (Diptera: Muscidae) Populations In Closed Poultry Houses, Jerome Hogsette, Roger Jacobs, Richard Miller

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

A commercially available sticky card was evaluated for use in adult fly distribution studies in large, closed poultry houses in Florida and Maryland. Results showed that house flies, Musca domestica L., preferred the interior parts of the houses, away from the walls. No vertical stratification was observed in Maryland, but flies in Florida stayed closer to the floor. In-house dispersal studies using fluorescent dust showed that flies would move =50 m, or one-third the length of the house, in Hydrotaea aenescens (Wiedemann) (formerly Ophyra aenescens) were recovered in both states.

Biology And Control Of Cattle Grubs, Philip J. Scholl

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

PERSPECTIVES AND OVERVIEW

Two species of cattle grubs (Diptera: Oestridae) affect cattle in the Northern Hemisphere: Hypoderma iineatum, the common cattle grub or lesser cattle warble fly, and Hypoderma bovis, the northern cattle grub or larger cattle warble fly. The word warble is Anglo-Saxon for boil.

Adults of the cattle grub are commonly known as heel flies, warble flies, bomb flies, or gad flies. This parasite has been observed and recorded for centuries (159), and Bracy Clark (50) cited and discussed references from Biblical times to Shakespeare. Scientific observations on the biology were first recorded in the 1700s …

Modeling Of Carbon Dioxide Transport And Production In Soil 2. Parameter Selection, Sensitivity Analysis, And Comparison Of Model Predictions To Field Data, Donald L. Suarez, Jiří Šimůnek

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

In paper 1 of this two-paper series (Šimůnek and Suarez, this issue) we presented a description of the numerical model, SOILCO2, for CO₂ transport and production in the unsaturated zone.  In paper 2 the model sensitivity to various parameters is evaluated by both steady state and trasient simulations, with a range in the parameter values typically found under field conditions.  We also select parameter values for optimal plant and microbial CO₂ production and production dependence on temperature, water content, osmotic potential and gas composition for plant and microbial respiration, all based on literature review.  The predictive capabilities of …

Genetic Manipulation Of Tall Fescue, Jeffrey F. Pedersen, D. A. Sleper

Department of Agronomy and Horticulture: Faculty Publications

Genetic manipulation of tall fescue (Festuca arnndinacea Schreb.) has not been altered by the discovery of the Acremonium coenophialum (Morgan-Jones and Gams) / grass interaction. However, tall fescue breeding programs have been affected greatly. The basic methods for genetically manipulating the grass have remained static. Tall fescue is an obligate out-crossing species, and most improvements are, therefore, captured in the form of an improved population developed through some form of mass or recurrent selection. What has changed is the breeder's ability to recognize genetic differences in the grass because of the confounding effect of A. coenophialum on plant phenotype. It …

Comparison Of Sorghum And Indiangrass Chloroplast Genomes Using Rflps, Jeffrey F. Pedersen, R. D. Lee, D. J. Lee, K. P. Vogel

Department of Agronomy and Horticulture: Faculty Publications

Sorghum (Sorghum bicolor (L.) Moench) and indiangrass (Sorghastrum nutans (L.) Nash) appear closely related based on morphological and chemotaxonomic characters. Each species could potentially provide desirable traits to the other. However, traditional breeding techniques have been unsuccessful in hybridizing these two species. The objective of this study was to determine the relatedness of sorghum and indiangrass chloroplast DNA using RFLPs. Eleven sorghum lines in several cytoplasms, two indiangrass popu1ations, and a corn line were studied using 60 proberestriction enzyme combinations. Principal component analysis of the results showed sorghum to be as closely related to corn as to indiangrass, with no …

Developmental Morphology Of Tropical Sorghum And Sorghum X Sudangrass, R. B. Mitchell, K. J. Moore, Jeffrey F. Pedersen, T. A. Peterson, L. E. Moser, D. D. Redfearn

Department of Agronomy and Horticulture: Faculty Publications

Tropical sorghum and sorghum x sudangrass are known to be efficient scavengers of soil nitrogen and are important forage crops in the U.S. Nitrate contamination of groundwater due to disposal of organic wastes and excessive fertilization is a major concern in the Central Great Plains. A common disposal method of municipal wastes is application to fallow cropland. Quantification of the developmental morphology of tropical sorghum and sorghum x sudangrass is important to developing management strategies that allow multiple applications of organic wastes to optimize nitrogen removal and dry matter production. The objective of this study was to quantify the developmental …

Breeding Systems For Cross-Pollinated Perennial Grasses, K. P. Vogel, Jeffrey F. Pedersen

Department of Agronomy and Horticulture: Faculty Publications

I. Introduction

II. Reproductive and Breeding Characteristics

III. Breeding Systems

A. Ecotype Selection

B. Recurrent, RestricteclPhenotypic Selection

C. Half-sib Progeny Test

D. Between and Within Family Selection

E. Recurrent Multistep Family Selection

IV. Gains From Selection

A. Time Interval per Cycle

B. Potential Gain per Cycle .

C. Potential Inbreeding per Cycle

V. Polycrossing

VI. Hybrid Cultivars

VII. Conclusions

Literature Cited

Low Pressure Center Pivot And Soil Management Effects On Runoff, L. N. Mielke, J. R. Gilley, Wallace Wilhelm

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The objective of this research was to determine the influence center-pivot sprinkler irrigation methods in combination with tillage practices for corn (Zea mays L.) have on surface runoff of irrigation and rainfall. A center pivot irrigation machine was redesigned to apply water by high-pressure-impact (HPI), low-pressure-impact (LPI), and low-pressure-spray (LPS) nozzles. The center-pivot was a standard 10-tower machine, 395 meters in length and 38.4 meters tower spacing. Three tillage systems were used -- till-plant (T), disk (D), and subtill (S) which was till-plant with subsoiling between rows with straight single shanks, 360 mm deep, after last cultivation. The soil …

Simulating Winter Wheat Spike Development And Growth, Gregory S. Mcmaster, Jack A. Morgan, Wallace Wilhelm

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Mechanistic crop simulation models can aid in integrating and directing research, and in improving farm management strategies. Information derived from recent research on spike development and growth of winter wheat (Triticum aestivum L.) was incorporated into a submodel, SPIKEGRO, and added to an existing model called SHOOTGRO. This manuscript discusses the SPIKEGRO submodel.

SPIKEGRO emphasizes the reproductive functioning of the shoot apex. The complete developmental sequence of the shoot apex is outlined and quantified. All developmental events and growth stages are predicted, most using the phyllochron approach. Spikelet and floret primordium initiation, growth, and abortion; ovule fertilization and growth; …

Simulating Winter Wheat Shoot Apex Phenology , G. S. Mcmaster, Wallace Wilhelm, J. A. Morgan

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Simulation models are heuristic tools for integrating diverse processes and help to increase our understanding of complex processes and systems. Models that predict crop development can serve as decision-support tools in crop management. This paper describes a phenology simulation model for the winter wheat shoot apex and reports validation and sensitivity analysis results.

The complete developmental sequence of the winter wheat shoot apex is quantitatively outlined and correlated with commonly recognized phenological growth stages. The phyllochron is used to measure the thermal time between most phenological growth stages, thereby increasing the flexibility over the growing degree-day (GDD) and photothermal approaches. …

American Ginseng Production In Woodlots, Robert L. Beyfuss

Agroforestry Notes (USDA-NAC)

For the past 3,000 years or more the roots of a perennial plant called ginseng have been an important component of traditional Chinese medicine. The roots of wild American ginseng have been harvested, dried, and exported from the United States and Canada to China, since the mid 1700’s. Today, American ginseng is also a very important part of traditional Chinese medicine. It is used as an “adaptogen” that allows the body to adjust to various types of stress. It is not used as a specific cure or remedy for any particular ailment but as a component of many medicinal herbal …

Proceedings Of The Workshop Social Science Research And The Crsps, C. Milton Coughenour, John M. Yohe, Anne E. Ferguson, Jere L. Gilles, Jo Purcell

INTSORMIL Impacts and Bulletins

Contents

Executive Summary: A New Agenda for CRSP Social Science Research - C. Milton Coughenour . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

Session 1

Developing a Strategic Research Agenda David G. Cummins, Chair

Framing a Strategic Research Agenda.-John Yohe ................ 3

Social Sciences and Collaborative Research: Toward an Agenda for the Social Sciences in Agriculture -Jere Lee Gilles ............... 7

Session 2

Technology Development and Sustaining Household Food Security Kathleen DeWalt, Chair

Technology Development and Household Food Security - …

Response Of Central Plains Taligrass Prairies To Fire, Fertilizer, And Atrazine, Robert A. Masters, Kenneth P. Vogel, Robert B. Mitchell

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Tallgrass prairies are an important forage resource in the eastern Central Great Plains. The effect of spring burning, fertilization, and atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine- 2,4-diamine] on standing crop of selected herbaceous species and categories of vegetation was determined in 6 tallgrass prairie environments located near Lincoln and Virginia, Neb., from 1987 through 1989 and 1 site near Bloomfield, Neb., in 1987. The grasslands were in good to excellent condition at the time these studies were conducted. Portions of each site were burned in mid-to late spring, atrazine was applied at a rate of 2.2 kg a.i. ha^-1 in late April to …

Simulating Winter Wheat Production In Three Tillage Systems Using The Nitrogen Tillage Residue Management Model, B. Davidoff, Wallace Wilhelm, Joseph M. Skopp

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Crop production system analysis is necessary to identify tillage and residue management practices that affect crop production. The objective of this study was to evaluate the potential of using the Nitrogen Tillage Residue Management (NTRM) model to evaluate the influence of tillage practices on winter wheat (Triticum aestivum L.) yield. Modifications of the NTRM model were required to simulate winter wheat production. The model was calibrated using site-specific information obtained from a tillage-nitrogen rate experiment conducted at the High Plains Agricultural Laboratory near Sidney, NE, on an Alliance silt loam (fine silty, mixed, mesic Aridic Argiustoll). Model output was …

Proceedings Of The 19th Annual Meeting, Southern Soybean Disease Workers (February 19-20, 1992, St. Louis, Missouri), J. Allen Wrather, Patrick D. Colyer, Glenn R. Bowers Jr., Brian M. Anderson, Glenn G. Hammes

Southern Soybean Disease Workers: Conference Proceedings

Contents

Southern Soybean Disease Workers 1991-1992 officers

1991-1992 Program Committee

Graduate student competition

Interactions of Macrophomina phaseolina with two soybean cultivars under four irrigation regimes. SR Kendig and JC Rupe

Influence of soybean planting dates on the incidence and severity of Sudden Death Syndrome. SS Alghamdi, PT Gibson, and MA Shenaut

The interrelationship of Heterodera glycines and Fusarium solani in sudden death syndrome of soybean. KS McLean and GW Lawrence

Frogeye leaf spot of soybean: evaluation of cultivars and isolates. PF Pace, DB Weaver, and LD Ploper

Soybean cyst nematode race symposium

SCN race scheme: a historical perspective. JA Fox …

Comparison Of Restriction Fragment Length Polymorphisms In Chloroplast Dna Of Five Leafy Spurge (Euphorbia Spp.) Accessions, Scott Nissen, Robert A. Masters, Donald Lee, Martha Rowe

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Chloroplast DNA (cpDNA) restriction fragment length polymorphisms (RFLPs) were analyzed to assess genetic variation and relatedness among selections of North American and Eurasian leafy spurge. Leafy spurge accessions from Nebraska, Montana, Russia, Italy, and Austria were evaluated. Total DNA was extracted from young leaves and digested with the restriction endonuclease, EcoRI. CpDNA fragment patterns were determined by Southern blot analysis using mung bean cpDNA probes. Colinearity between the mung bean and leafy spurge chloroplast genomes was indicated by the observation that common fragments were hybridized by adjacent probes. Minimum estimates of chloroplast genome size for the five leafy spurge …

Loop Rating Curves From Goodwin Creek, Roger A. Kuhnle, Andrew J. Bowie

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Two types of hysteresis loops have been observed on Goodwin Creek: those with a greater flow depth for a given discharge on the falling limb of the hydrograph (type 1) and those with a greater flow depth for a given discharge on the rising limb of the hydrograph (type 2). Causes of these 2 loop types are investigated in this paper.

Spontaneous Tetraploid Melons, Perry E. Nugent, Dennis T. Ray

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Since 1968, three spontaneous 4x melons (Cucumis melo L.) plants were discovered in our field or greenhouse plantings. Two were found in the cultivar Planters Jumbo and one in the virescent marker C879-52. Each of these 4x plants had rounded cotyledons, shorter internodes, thicker stems and leaves, more hairs, and smaller fruits, with larger stem and blossom scars, than their 2x counterparts. Also, their flowers, pollen grains, stomates, and seeds were larger. The discovery of a 4x virescent plant in 1987 allows easier germplasm transfer between ploidy levels. Morphological characteristics of 2x and 4x melons will allow identification without …