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2001

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Articles 61 - 90 of 95

Full-Text Articles in Agricultural Science

Fallow Versus Wheat Cropping Of Unamendedand Manure-Amended Soils Related To Mycorrhizal Colonization, Yield, And Plant Nutrition Of Dry Bean And Sweet Corn, Brett L. Allen, Von D. Jolley, Charles W. Robbins, Larry L. Freeborn Jan 2001

Fallow Versus Wheat Cropping Of Unamendedand Manure-Amended Soils Related To Mycorrhizal Colonization, Yield, And Plant Nutrition Of Dry Bean And Sweet Corn, Brett L. Allen, Von D. Jolley, Charles W. Robbins, Larry L. Freeborn

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

Previous studies reported manure application to eroded Portneuf silt loam soil (Coarse-silty, mixed, superactive, Durinodic Xeric Haplocalcid) improved dry bean (Phaseolus vulgaris L., cv. Viva) yield to levels of topsoil. These yield increases only correlated with whole-plant zinc (Zn) concentration and soil organic matter. This might be related to enhanced arbuscular mycorrhizal (AM) colonization stimulated by manure application. A greenhouse study with dry bean suggested a relationship between manure application, increased AM colonization, and whole-plant Zn uptake, while field studies with wheat (Triticum aestivum L.) and sweet corn (Zea mays L.) did not. To clarify the apparent …

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Methyl-Β-Cyclodextrin: An Alternative Carrier For Intravenous Infusion Of Palmitate During Tracer Studies In Swine (Sus Scrofa Domestica), Diane Wray-Cahen, Thomas J. Caperna, Norman C. Steele Jan 2001

Methyl-Β-Cyclodextrin: An Alternative Carrier For Intravenous Infusion Of Palmitate During Tracer Studies In Swine (Sus Scrofa Domestica), Diane Wray-Cahen, Thomas J. Caperna, Norman C. Steele

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

Fatty acid-free albumin has been the standard carrier for intravenous infusion of fatty acids to study in vivo lipid metabolism. However, subjects can have adverse reactions to infusion of albumin. We sought an alternative to albumin as a carrier for intravenous infusion of fatty acids, using the pig as a model. Cyclodextrins are naturally occurring water-soluble molecules that can serve as carriers for lipid-soluble compounds. 13C-palmitate was complexed to either 20% methyl-β-cyclodextrin, 20% 2-hydroxypropyl-β-cyclodextrin, or 5% porcine albumin (isotopic purity of infusates: 99.22±0.06%). 13C-palmitate-albumin was infused under fed conditions and 13C-palmitate-methyl-β-cyclodextrin was infused under fasted and fed …

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Mechanical Barrier For Preventing Climbing By Lesser Mealworm (Coleoptera: Tenebrionidae) And Hide Beetle (Coleoptera: Dermestidae) Larvae In Poultry Houses, Christopher Geden, David Carlson Jan 2001

Mechanical Barrier For Preventing Climbing By Lesser Mealworm (Coleoptera: Tenebrionidae) And Hide Beetle (Coleoptera: Dermestidae) Larvae In Poultry Houses, Christopher Geden, David Carlson

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

Mechanical barriers consisting of bands of polyethylene terepthalate resin attached to wooden posts by latex caulk adhesive and staples were 100% effective in preventing passage of dispersing lesser mealworm, Alphitobius diaperinus (Panzer), larvae in the laboratory. Barriers continued to be 100% effective after being held in a caged layer poultry house for 3 mo. Polyethylene terepthalate barriers installed on support posts in a pullet house in Brooker, FL, were>92% effective against natural populations of lesser mealworm larvae 6 mo. after installation. The barriers also were >94% effective against natural populations of larvae of the hide beetle, Dermestes maculatus DeGeer, …

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Hymenopteran Pupal Parasitoids Recovered From House Fly And Stable Fly (Diptera: Muscidae) Pupae Collected On Livestock Facilities In Southern And Eastern Hungary, Jerome A. Hogsette, Róbert Farkas, Csaba Thuróczy Jan 2001

Hymenopteran Pupal Parasitoids Recovered From House Fly And Stable Fly (Diptera: Muscidae) Pupae Collected On Livestock Facilities In Southern And Eastern Hungary, Jerome A. Hogsette, Róbert Farkas, Csaba Thuróczy

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

This field survey, the second noting the occurrence and diversity of filth fly pupal parasitoid fauna in Hungary, was performed on beef and dairy feedlots and swine facilities in the southern and eastern parts of the country. The filth flies Musca domestica L. And Stomoxys calcitrans (L.) Were the two most commonly parasitized hosts. The three species of Spalangia recovered, in decreasing order of abundance, were S. Cameroni Perkins, S. Nigroaenea Curtis, and S. Endius Walker. Pachycrepoideus vindemiae Rondani, Trichomalopsis sp., two apparently undetermined Diapriidae spp. And one apparently undetermined Brachycera sp. Are believed to be new country records.

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Grain Color Stability And Classification Of Hard White Wheat In The U.S., C. J. Peterson, D. R. Shelton, T. J. Martin, R. G. Sears, E. Williams, R. A. Graybosch Jan 2001

Grain Color Stability And Classification Of Hard White Wheat In The U.S., C. J. Peterson, D. R. Shelton, T. J. Martin, R. G. Sears, E. Williams, R. A. Graybosch

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

Variability in grain color of hard white wheat was investigated in cultivars grown over two years in Nebraska and Kansas and related to variation observed in grain hardness, kernel weight, kernel size, and protein content and to color of ground meal and flour. Grain color was scored subjectively, through visual evaluation, and objectively through use of a colorimeter. Of the 543 hard white wheat samples examined by USDA-GIPSA grain inspectors, 15.5% were scored as visually darker than the 1990 grain color standard established as a minimum for hard white wheat classification. The remaining samples were scored as having grain color …

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Assessing Site Vulnerability To Phosphorus Loss In An Agricultural Watershed, Andrew N. Sharpley, Richard W. Mcdowell, Jennifer L. Weld, Peter J. A. Kleinman Jan 2001

Assessing Site Vulnerability To Phosphorus Loss In An Agricultural Watershed, Andrew N. Sharpley, Richard W. Mcdowell, Jennifer L. Weld, Peter J. A. Kleinman

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

A P index was developed as a tool to rank agricultural fields on the basis of P loss vulnerability, helping to target remedial P management options within watersheds. We evaluated two approaches, a soil P threshold and components of a P index, by comparing site vulnerability estimates derived from these two approaches with measured runoff P losses in an agricultural watershed in Pennsylvania. Rainfall–surface runoff simulations (70 mm h-1 for 30 min) were conducted on 57 sites representing the full range of soil P concentrations and management conditions found in the watershed. Each site was comprised of two, abutting …

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History, Current Status, And Collaborative Researchprojects For Bemisia Tabaci, M. R. V. Oliveira, T. J. Henneberry, P. Anderson Jan 2001

History, Current Status, And Collaborative Researchprojects For Bemisia Tabaci, M. R. V. Oliveira, T. J. Henneberry, P. Anderson

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

Bemisia tabaci was described over 100 years ago and has since become one of the most important pests worldwide in subtropical and tropical agriculture as well as in greenhouse production systems. It adapts easily to new host plants and geographical regions and has now been reported from all global continents except Antarctica. In the last decade, international transport of plant material and people have contributed to geographical spread. B. tabaci has been recorded from more than 600 plant species and there may be many additional hosts not yet formally documented. Biotypes have been identified in different areas of the world …

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Quantitative Trait Loci Associated With Milling And Baking Quality In A Soft X Hard Wheat Cross, Kimberley Garland Campbell, Patrick L. Finney, Christine J. Bergman, Daisy G. Gualberto, James A. Anderson, Michael J. Giroux, Dimuth Siritunga, Jiaqian Zhu, Francois Gendre, Catherine Roué, Aliette Vérel, Mark E. Sorrells Jan 2001

Quantitative Trait Loci Associated With Milling And Baking Quality In A Soft X Hard Wheat Cross, Kimberley Garland Campbell, Patrick L. Finney, Christine J. Bergman, Daisy G. Gualberto, James A. Anderson, Michael J. Giroux, Dimuth Siritunga, Jiaqian Zhu, Francois Gendre, Catherine Roué, Aliette Vérel, Mark E. Sorrells

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

Interclass hybridization between soft and hard wheat (Triticum aestivum L.) results in new genetic combinations of potential value.

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Gis And Distributed Watershed Models Ii, Fred L. Ogden, Jurgen Garbrecht, Paul A. Debarry, Lynn E. Johnson Jan 2001

Gis And Distributed Watershed Models Ii, Fred L. Ogden, Jurgen Garbrecht, Paul A. Debarry, Lynn E. Johnson

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

This paper presents representative applications and models that can take advantage of spatially distributed data in a geographic information system (GIS) format for watershed analysis and hydrologic modeling purposes. The intention is to inform hydrologic engineers about the current capabilities of GIS, hydrologic analysis modules, and distributed hydrologic models, and to provide an initial guide on implementing GIS for hydrologic modeling. This paper also discusses key implementation issues for individuals and organizations that are considering making the transition to the use of GIS in hydrology. Widespread use of GIS modules and distributed watershed models is inevitable. The controlling factors are …

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Food Webs, Risks Of Alien Enemies And Reform Of Biological Control, D. R. Strong, R.W. Pemberton Jan 2001

Food Webs, Risks Of Alien Enemies And Reform Of Biological Control, D. R. Strong, R.W. Pemberton

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

As ilwasions of alien species mount, biological control will become an increasingly important tool of conservation and agriculture. In an effort to understand indirect interactions in biological control, we review food web ecology in terms of resource competition, trophic cascades, intraguild predation, apparent competition, omnivory and a diverse set of tritrophic interactions. The most inclusive study suggests that food webs in biological control are simpler than in natural communities. Risks to non-target species created by biological control have been studied seriously for only about 20 years, and knowledge of these risks is incomplete. The greatest risks are known to be …

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Innovative 15N Microplot Research Techniques To Study Nitrogen Use Efficiency Under Different Ecosystems, Ronald F. Follett Jan 2001

Innovative 15N Microplot Research Techniques To Study Nitrogen Use Efficiency Under Different Ecosystems, Ronald F. Follett

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

Use of labeled 15N techniques can help improve and refine knowledge required to understand the dynamics of the N cycle under agricultural systems. The examples reported in this paper illustrate that, with creativity and careful planning, use of 15N-enriched or depleted fertilizers can be used in many types of N experiments with various crops, cropping systems, and in many types of agroecosystems. The objective is to report examples of a wide range of field studies that researchers can hopefully draw upon to design and utilize N isotope techniques that accomplish the objectives for their own research. Examples of …

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Interlaboratory Comparison Of Soil Phosphorus Extracted By Various Soil Test Methods, Peter J.A. Kleinman, A. N. Sharpley, K. Gartley, W. M. Jarrell, S. Kuo, R. G. Menon, R. Myers, K. R. Reddy, E. O. Skogley Jan 2001

Interlaboratory Comparison Of Soil Phosphorus Extracted By Various Soil Test Methods, Peter J.A. Kleinman, A. N. Sharpley, K. Gartley, W. M. Jarrell, S. Kuo, R. G. Menon, R. Myers, K. R. Reddy, E. O. Skogley

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

The widespread use of soil phosphorus (P) data, either in the context of agronomic or environmental management, requires an explicit understanding of potential errors related to soil P testing. This study compares a variety of soil P extraction methods, each performed by 9 separate laboratories on 24 soils from across the United States. Soil clay content ranged from 0 to 47%, pH from 4.2 to 8.6, and Mehlich-3 P concentration from 2 to 205 mg kg-1. Average interlaboratory coefficients of variation (CVs) ranged from 0.11 to 0.22 for solution extracts (Bray-1 P, Fe-strip P, Mehlich-3 P, and Olsen …

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Polyacrylamide For Surface Irrigation To Increase Nutrient-Use Efficiency And Protectwater Quality, Rodrick D. Lentz, Robert E. Sojka, Charles W. Robbins, Dennis C. Kincaid, Dale T. Westermann Jan 2001

Polyacrylamide For Surface Irrigation To Increase Nutrient-Use Efficiency And Protectwater Quality, Rodrick D. Lentz, Robert E. Sojka, Charles W. Robbins, Dennis C. Kincaid, Dale T. Westermann

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

Furrow irrigation systems have a greater application capacity, are less costly, and use less energy than sprinkler systems but furrow irrigation produces greater runoff, erosion, and deep percolation losses. Phosphorus (P) and nitrogen (N) losses are associated with runoff sediment, and can be minimized by eliminating irrigationinduced erosion. Excessive leaching of inorganic and organic solutes commonly occurs at the inflow region of furrow irrigated fields where infiltration opportunity times are longer. In one conservation practice, a high molecular weight, anionic polyacrylamide (PAM) is applied to advancing furrow stream flows at a concentration of 10 mg L-1. Because PAM …

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Genomic Regions That Underlie Soybean Seed Isoflavone Content, K. Meksem, V. N. Njiti, W. J. Banz, M. J. Iqbal, My. M. Kassem, David L. Hyten, J. Yuang, T. A. Winters, D. A. Lightfoot Jan 2001

Genomic Regions That Underlie Soybean Seed Isoflavone Content, K. Meksem, V. N. Njiti, W. J. Banz, M. J. Iqbal, My. M. Kassem, David L. Hyten, J. Yuang, T. A. Winters, D. A. Lightfoot

Department of Agronomy and Horticulture: Faculty Publications

Soy products contain isoflavones (genistein, daidzein, and glycitein)that display biological effects when ingested by humans and animals, these effects are species, dose and age dependent. Therefore, the content and quality of isoflavones in soybeans is a key to their biological effect. Our objective was to identify loci that underlie isoflavone content in soybean seeds. The study involved 100 recombinant inbred lines (RIL)fr om the cross of ‘Essex’ by ‘Forrest,’ two cultivars that contrast for isoflavone content. Isoflavone content of seeds fromeach RIL was determined by high performance liquid chromatography (HPLC). The distribution of isoflavone content was continuous and unimodal. The …

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Uneasy Unions: Quality Effects Of Rye Chromatin Transfers To Wheat, Robert A. Graybosch Jan 2001

Uneasy Unions: Quality Effects Of Rye Chromatin Transfers To Wheat, Robert A. Graybosch

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

A number of genes of agronomic importance have been transferred from rye (Seale cereale L.) to its close relative, common bread wheat (Triticum aestivum L). Largely through the production of interspecific chromosomal translocation and substitution lines, rye chromatin now rides within the genome of a large number of wheat breeding lines and cultivars. Rye chromosomal materials have been used to transfer resistance genes to fungal pathogens, especially rusts and powdery mildew, resistance to insect pests, and in some cases, may enhance grain yield, grain yield stability, and grain protein content. Unfortunately, the transfer of some rye chromosomal materials …

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Discovery And Deployment Of Molecular Markers Linked To Fusarium Head Blight Resistance: An Integrated System For Wheat And Barley, David Van Sanford, James Anderson, Kimberly A. Garland-Campbell, Josè Costa, Perry Cregan, Carl Griffey, Patrick Hayes, Richard Ward Jan 2001

Discovery And Deployment Of Molecular Markers Linked To Fusarium Head Blight Resistance: An Integrated System For Wheat And Barley, David Van Sanford, James Anderson, Kimberly A. Garland-Campbell, Josè Costa, Perry Cregan, Carl Griffey, Patrick Hayes, Richard Ward

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

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe [teleomorph Gibberella zeae (Schwein.)], is a devastating disease that reduces yield, quality and economic value of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.).

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Net Grassland Carbon Flux Over A Subambient To Superambient Co2 Gradient, P. C. Mielnick, W. A. Dugas, H. B. Johnson, H. W. Polley, J. Sanabria Jan 2001

Net Grassland Carbon Flux Over A Subambient To Superambient Co2 Gradient, P. C. Mielnick, W. A. Dugas, H. B. Johnson, H. W. Polley, J. Sanabria

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

Increasing atmospheric CO2 concentrations may have a profound effect on the structure and function of plant communities. A previously grazed, central Texas grassland was exposed to a 200-µmol mol-1 to 550 µmol mol-1 CO2 gradient from March to mid-December in 1998 and 1999 using two, 60-m long, polyethylene-covered chambers built directly onto the site. One chamber was operated at subambient CO2 concentrations (200-360 µmol mol-1 daytime) and the other was regulated at superambient concentrations (360-550 µmol mol-1). Continuous CO2 gradients were maintained in each chamber by photosynthesis during the day and …

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Clear-Sky Albedo Measured At Seven Rangland Sites In Southwest Idaho, Clayton L. Hanson Jan 2001

Clear-Sky Albedo Measured At Seven Rangland Sites In Southwest Idaho, Clayton L. Hanson

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

As a component of the energy budget, albedo is used in the calculation of evapotranspiration in many natural resource and hydrologic models. There are few measurements of albedo over sagebrush-dominated rangelands, so albedo was measured at seven sites on the Reynolds Creek Experimental Watershed in southwest Idaho during 1989–1993. For all sites, the average albedo measured during midday under clear skies was 0.14 during the growing season. Albedo varied from a low of 0.11 during June at the Mountain big sagebrush site to a high of 0.17 at the low-elevation Wyoming big sagebrush site. Albedo varied little between about 2 …

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Research Needs Concerning Non-Target Impacts Of Biological Control Introductions, K.R. Hopper Jan 2001

Research Needs Concerning Non-Target Impacts Of Biological Control Introductions, K.R. Hopper

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

Two workshops were held in 1999 on research needs concerning non-target impacts of biological control introductions. One took place on the Internet for 9 months, and the other in Montpellier, France, for 1 day. Altogether, over 200 researchers from over 30 countries participated, representing a wide variety of viewpoints on the issues involved. The deliberations of these workshops are summarized here. Both workshops highlighted the need for retrospective studies to: (i) identify cases of significant non-target impacts; (ii) explore mechanisms involved when such impacts are found; (iii) evaluate the reliability of host-range testing protocols; and (iv) determine whether and under …

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Innovative Remote Sensing Techniques To Increase Nitrogen Use Efficiency Of Corn, Walter C. Bausch, Kenan Diker Jan 2001

Innovative Remote Sensing Techniques To Increase Nitrogen Use Efficiency Of Corn, Walter C. Bausch, Kenan Diker

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

Nitrogen (N) fertilizer recommendations made without adequate knowledge of the N supply capability of a soil can lead to inefficient use of N. Proper crediting of N from manure and legumes as well as mineralization of N from organic matter is difficult. Remote sensing techniques that use the crop to indicate its N status show considerable promise for improving N management. Objectives of this paper were twofold: 1) to compare the N Reflectance Index (NRI) calculated from ground-based radiometer measurements acquired over irrigated corn (Zea mays L.) at a nadir view (0 °) and an oblique view (75 °) …

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Oxidative Metabolism In Plant/Bacteria Interactions: Characterization Of The Oxygen Uptake Response Of Bacteria, C. Jacyn Baker, Norton Mock, Kenneth L. Deahl, Bryan Bailey, Daniel P. Roberts Jan 2001

Oxidative Metabolism In Plant/Bacteria Interactions: Characterization Of The Oxygen Uptake Response Of Bacteria, C. Jacyn Baker, Norton Mock, Kenneth L. Deahl, Bryan Bailey, Daniel P. Roberts

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

An increase in oxygen uptake has been previously described in plant cell suspensions treated with bacteria or bacterial elicitors. These studies, regarding oxygen uptake, have all been undertaken from the perspective of the host plant cell reacting to the invading pathogen. In contrast, here we describe and characterize an increase in oxygen uptake by bacterial cells in response to plant suspensions or autoclaved plant cell filtrates. Autoclaved plant cell filtrates stimulated bacterial oxygen uptake by as much as sevenfold within a few minutes after addition. This oxygen uptake response was proportional to both the concentration of the plant cell filtrate …

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Oxidative Metabolism In Plant/Bacteria Interactions: Characterization Of A Unique Oxygen Uptake Response Of Potato Suspension Cells, C. Jacyn Baker, E. W. Orlandi, Kenneth L. Deahl Jan 2001

Oxidative Metabolism In Plant/Bacteria Interactions: Characterization Of A Unique Oxygen Uptake Response Of Potato Suspension Cells, C. Jacyn Baker, E. W. Orlandi, Kenneth L. Deahl

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

Plant suspension cells have been shown to respond to bacteria or microbial elicitors by producing active oxygen as well as increasing oxygen uptake. Here we characterize a unique two stage oxygen uptake response of potato suspension cells to heat-killed bacteria. Stage 1 occurred within minutes after the addition of heat-killed bacteria; the potato suspension cells responded with a rapid increase in oxygen uptake and reached a steady state approximately 50 % greater than the initial basal rate. Stage 2 began 20-30 min after this new steady state was achieved and was characterized by a slow increase in the oxygen uptake …

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Induction Of Defense Responses In Tobacco By The Protein Nep1 From Fusarium Oxysporum, James C. Jennings, Patricia C. Apel-Birkhold, Norton M. Mock, C. Jacyn Baker, James D. Anderson, Bryan A. Bailey Jan 2001

Induction Of Defense Responses In Tobacco By The Protein Nep1 From Fusarium Oxysporum, James C. Jennings, Patricia C. Apel-Birkhold, Norton M. Mock, C. Jacyn Baker, James D. Anderson, Bryan A. Bailey

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

Fusarium oxysporum produces a 24-kDa protein, Nep1, which induces necrosis and ethylene production in leaves of many dicot plant species. Detached Nicotiana tabacum L. cv. Xanthi leaves respond with concentration-dependent necrosis after infiltration with Nep1 or when Nep1 is taken up by the vascular tissue. This response follows the induction of ethylene biosynthesis and accumulation of ACC synthase and ACC oxidase transcripts. Pretreating the leaves with 100 µl/l ethylene prior to elicitation enhanced Nep1-induced ethylene production. Nep1 (208 nM) causes extensive necrosis of mature tobacco leaf tissue when applied to Xanthi tobacco as a foliar spray (129 ml/m2). …

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Conservation And Evaluation Of Natural Enemies In Ipm Systems For Bemisia Tabaci, Steven E. Naranjo Jan 2001

Conservation And Evaluation Of Natural Enemies In Ipm Systems For Bemisia Tabaci, Steven E. Naranjo

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

Conservation biological control emphasizes the preservation and enhancement of natural enemies and is the cornerstone of all approaches to biological control. This review critically examines recent and current research efforts in conservation biological control by predators and parasitoids of Bemisia tabaci worldwide. A large number of natural enemy species have been identified from many agricultural systems. Further research has demonstrated that these natural enemies may act along with other mortality agents to inflict high levels of mortality on populations of B. tabaci. Less effort has been placed on determining the factors constraining or potentially enhancing biological control. The widespread …

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Managing Crop Residue With Green Manure, Urea, And Tillage In A Rice–Wheat Rotation, Milkha S. Aulakh, T. S. Khera, John W. Doran, Kevin F. Bronson Jan 2001

Managing Crop Residue With Green Manure, Urea, And Tillage In A Rice–Wheat Rotation, Milkha S. Aulakh, T. S. Khera, John W. Doran, Kevin F. Bronson

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

Most double-crop grain farmers in South Asia remove or burn cropresidue to facilitate seedbed preparation and to avoid possible yield reductions. This results in loss of soil organic matter (SOM) and nutrients. In this study, we determined whether incorporating wheat (Triticum aestivum L.) residue, rice (Oryza sativa L.) residue, and sesbania (Sesbania aculeta L.) green manure with urea fertilizer N in a rice–wheat cropping system can improve grain yields, N use efficiency, and SOM. We incorporated wheat residue (6 Mg ha-1, C/N = 94), rice residue (6 Mg ha-1, C/N = 63), or …

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Simplified Method For Soil Particle-Size Determination To Accompany Soil-Quality Analyses, T. A. Kettler, John W. Doran, T. L.. Gilbert Jan 2001

Simplified Method For Soil Particle-Size Determination To Accompany Soil-Quality Analyses, T. A. Kettler, John W. Doran, T. L.. Gilbert

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

Soil textural analysis is a key component of any minimum data set used for assessing soil quality and sustainability of agricultural-management practices. However, conventional methods of soil textural analysis can be costly and time-consuming. The objective of this study was to develop a rapid and simple method for evaluating soil particle-size distribution, which could be employed as a tool for initial soil-quality assessment. The method uses a combination of sieving and sedimentation steps and is designed to be used in conjunction with analysis of particulate organic matter (POM), or as a stand-alone textural analysis. Soils of varied texture and organic-matter …

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Impact Of Solar Radiation Rainfall And Cannibalism On Disappearance Of Maize Stemborers In Kenya, M. J. Bonhof, W. A. Overholt Jan 2001

Impact Of Solar Radiation Rainfall And Cannibalism On Disappearance Of Maize Stemborers In Kenya, M. J. Bonhof, W. A. Overholt

All Peer-Reviewed Publications

The effect of solar radiation, rainfall and cannibalism on the disappearance of eggs and larvae of the cereal stemborer Chilo partellus (Swinhoe) were studied. Disappearance and nonviability of egg batches was higher on plants exposed to solar radiation than on shaded plants. Significantly fewer small larvae were recovered from plants exposed to rainfall than from shielded plants. Cannibalism among larvae of the same size was not common except at high larval densities. Contrary to the common belief that disappearance is the result of prédation, these studies show that solar radiation and rainfall might also play an important role in the …

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Greenhouse Trials Of New Bacillus Thuringiensis Isolates For Control Of Chilo Partellus Larvae In Sorghum, Michael Brownbridge Jan 2001

Greenhouse Trials Of New Bacillus Thuringiensis Isolates For Control Of Chilo Partellus Larvae In Sorghum, Michael Brownbridge

All Peer-Reviewed Publications

Eight new Bacillus thuringiensis Berliner (Bt) isolates originally recovered from different source materials and geographic locations in Kenya were tested against Chilo partellus (Swinhoe) on sorghum grown in a greenhouse. All isolates had been demonstrated previously to be toxic to this pest. Bt strains were cultured in a liquid growth medium and preserved as powders for experimental application. Three-week-old sorghum plants (4-6 leaves) were artificially infested with 20 neonate C. partellus and sprayed 24 h later with Bt suspensions. Non-infested sorghum and infested non-treated sorghum served as the comparative checks within each experimental trial. Plant development and dead-heart formation were …

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Distribution And Species Composition Of Stemborers And Their Natural Enemies In Maize And Sorghum In Ethiopia, Emana Getu, W. A. Overholt, E. Kairu Jan 2001

Distribution And Species Composition Of Stemborers And Their Natural Enemies In Maize And Sorghum In Ethiopia, Emana Getu, W. A. Overholt, E. Kairu

All Peer-Reviewed Publications

Surveys were conducted to determine the species composition of stemborers and their natural enemies in maize and sorghum in 1999 and 2000 in eastern, northern, southern and western Ethiopia. The six species of stemborers found attacking maize and sorghum were Cltilp partellus (Swinhoe) (Lepidoptera: Crambidae), Busseolafiisca Fuller, Sesamia calamistis Hampson (Lepidoptera: Noctuidae), S. nonagrioides botanephaga Tarns and Bowden (Lepidoptera: Noctuidae), Rhynchaenus niger (Horn) (Coleoptera: Rhynchophoridae) and Pissodes dubious (Stroöm) (Coleoptera: Rhynchophoridae). Twenty species of primary parasitoids of eggs, larvae and pupae of Ch. partellus, B. fusca and S. calamistis were recorded. Other natural enemies, including predators, fungi and nematodes, were …

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Relationships Of Stemborer Damage And Plant Physical Conditions To Maize Yield In A Semi-Arid Zone Of Eastern Kenya, Josephine Moraa Songa, Zhou Guofa, William Allan Overholt Jan 2001

Relationships Of Stemborer Damage And Plant Physical Conditions To Maize Yield In A Semi-Arid Zone Of Eastern Kenya, Josephine Moraa Songa, Zhou Guofa, William Allan Overholt

All Peer-Reviewed Publications

A field survey on maize stemborers, stemborer damage, maize plant physical conditions, and maize yield was conducted in eastern Kenya under natural conditions. Chilo partellus was the dominant stemborer accounting for 89.5 % of all borers. Stemborer damage greatly reduced maize yield, with tunnel lengths greater than 20 cm causing a 40 % reduction of potential yield. A 33 % yield loss was found in plants with more than one stemborer exit hole. Each stemborer (at harvest time) was correlated with a 8-10 % yield loss. Good plant physical characteristics significantly increased grain yield. Principle component analysis showed that stemborer …

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