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Articles 13021 - 13050 of 13590

Full-Text Articles in Life Sciences

Establishment Of Lupin Seedlings, Miles Dracup Jan 1993

Establishment Of Lupin Seedlings, Miles Dracup

Journal of the Department of Agriculture, Western Australia, Series 4

Good seedbed conditions lead to high and rapid seedling emergence and vigorous seedlings best equipped to avoid disease, weed competition and sand-blasting. Good establishment is needed for a high yielding crop.

In Western Australia, seedbed moisture and temperature are most likely to limit successful emergence of lupins, especially with the trend toward early sowing.

Research by the Department of Agriculture is helping to define seedbed temperature and moisture requirements for successful lupin establishment that will help future research for improving seedbed conditions.


Production Of High-Value Wheats : One Sustainable Answer To The Cost:Price Squeeze, Wal Anderson, Alan Peggs, Doug Sawkins Jan 1993

Production Of High-Value Wheats : One Sustainable Answer To The Cost:Price Squeeze, Wal Anderson, Alan Peggs, Doug Sawkins

Journal of the Department of Agriculture, Western Australia, Series 4

Farmers and scientists alike over the past decade have sought to address the declining terms of farm trade (the cost.price squeeze) by increasing wheat yields in ways that will ensure both their economic and ecological survival. Nevertheless, costs have continued to increase as a proportion of the value of the product.

Many farmers have increased their wheat yields substantially and the industry as a whole is more conscious of the quality of its product.

Over the past 10 years or more there has been intense interest in, and considerable adoption of. conservation farming techniques such as minimum tillage, residue retention, …


Vascular Flora Of Three Watersheds In The Fernow Experimental Forest And Factors Influencing Species Composition Of The Herbaceous Layer, Staci Dudash Smith Aulick Jan 1993

Vascular Flora Of Three Watersheds In The Fernow Experimental Forest And Factors Influencing Species Composition Of The Herbaceous Layer, Staci Dudash Smith Aulick

Theses, Dissertations and Capstones

Herbaceous layer communities respond to a number of environmental variables in forests: thus, study of the herb layer is essential for a more complete understanding of the forest ecosystem. The objectives of this study were to (1) describe the flora of the watersheds. (2) describe the species richness and diversity of watersheds 3, 4 , and 7 of the Fernow Experimental Forest, Parsons, West Virginia, and (3) examine stand and soil variables and their influence on the herbaceous communities or the forest. Watersheds were selected on the basis of stand age/history (WS3 "20yr, clearcut; WS7 "20 yr. clearcut and herbicide: …


Effect Of Light, Nitrogen, And Water Management On Rice (Oryza Sativa) Tolerance To Fenoxaprop, Roy J. Smith Jr., Aurora M. Baltazar, Paolo Nastasi Jan 1993

Effect Of Light, Nitrogen, And Water Management On Rice (Oryza Sativa) Tolerance To Fenoxaprop, Roy J. Smith Jr., Aurora M. Baltazar, Paolo Nastasi

Journal of the Arkansas Academy of Science

The effect of light intensity, nitrogen (N), and water management on rice (Oryza sativa cv. 'Newbonnet' and 'Lemont') tolerance to fenoxaprop {(+)-2-[4[(6-chloro-2-benzoxazolyl)oxy]phenoxy]propanoic acid} was determined in two field studies at the Rice Research and Extension Center, Stuttgart, AR, in 1988 and 1989. In one study, 'Newbonnet' rice was treated with 0.22 kgai ha-1fenoxaprop at 0, 1, 3, 5, 7, 10, 14, and 28 days after N application and flooding. Moderate to severe foliar chlorosis, stunting, and stand and yield reductions occurred when fenoxaprop was applied within 7 days after N application and flooding. None to slight injury or yield reduction …


Occurrence Of The Hybrid Honey Locust (Gleditsia X Texana Sarg.) In Southwest Arkansas, Brian A. Smith, Daniel L. Marsh Jan 1993

Occurrence Of The Hybrid Honey Locust (Gleditsia X Texana Sarg.) In Southwest Arkansas, Brian A. Smith, Daniel L. Marsh

Journal of the Arkansas Academy of Science

No abstract provided.


Woody Vegetation Of A Disjunct Bur Oak (Quercus Macrocarpa) Forest In East-Central Nebraska, Debra Ann Beightol, Thomas B. Bragg Jan 1993

Woody Vegetation Of A Disjunct Bur Oak (Quercus Macrocarpa) Forest In East-Central Nebraska, Debra Ann Beightol, Thomas B. Bragg

Biology Faculty Publications

Woody plant composition was assessed for three tree-size classes in two ravines of Oak Glen Wildlife Management Area, a disjunct oak forest in Seward County, Nebraska, using Importance Values (IV) obtained by the Point-Quarter method. Bur oak (Quercus macrocarpa Michx.) dominated the large-size class (>30 cm dbh) (IV = 258) but elms (Ulmus americana L. and U. rubra Muhl.) (IV = 130) dominated the forest in one ravine in the medium-size class (10-30cm dbh) and elm and hackberry (Celtis occidentalis L.) (IV = 114 and 27 respectively) dominated the small-size class (


Review Of American Wildflower Florilegium By Jean Andrews, David M. Sutherland Jan 1993

Review Of American Wildflower Florilegium By Jean Andrews, David M. Sutherland

Biology Faculty Publications

This book is a collection of 50 watercolor paintings of American wildflowers ("florilegium" means, literally, "a gathering of flowers"). Accompanying each full-page painting is a summary of general information about the plant, including notes about its botanical classification, the etymology of its name, life history, distribution, description, flowering period, pollination, and propagation.


Floristic Diversity In Ten Tallgrass Prairie Remnants Of Eastern Nebraska, Judith F. Boettcher, Thomas B. Bragg, David M. Sutherland Jan 1993

Floristic Diversity In Ten Tallgrass Prairie Remnants Of Eastern Nebraska, Judith F. Boettcher, Thomas B. Bragg, David M. Sutherland

Biology Faculty Publications

Ten eastern Nebraska tallgrass prairie remnants, varying in size from one to 18 ha, were studied or visited during the growing seasons from 1979 to 1993. A total of217 prairie plant species were recorded. Big bluestem (Andropogon gerardii), little bluestem (Andropogon scoparius), smooth brome (Bromus inermis subsp. inermis), New Jersey tea (Ceanothus herbaceus var. pubescens), false sunflower (Heliopsis helianthoides var. scabra), Kentucky bluegrass (Poa pratensis), and porcupine-grass (Stipa spartea) were prevalent in all the prairies although the specific floristic composition has been reported to vary depending on past management, topography, season of evaluation, and prairie size. Of the total species …


Stress Induced Protein Changes In Tall Fescue, R. L.G. Long, Lance T. Adams, J. D. Corely, Alvan A. Karlin, B. L. Parsons, Maurice G. Kleve, J. Henle Jan 1993

Stress Induced Protein Changes In Tall Fescue, R. L.G. Long, Lance T. Adams, J. D. Corely, Alvan A. Karlin, B. L. Parsons, Maurice G. Kleve, J. Henle

Journal of the Arkansas Academy of Science

Tall fescue (Festuca arundinacea Schreb.), the most important pasture grass in Arkansas, exhibits different agricultural properties when it is infected by its mutualistic endophyte Acremonium coenophialum Morgan-Jones and Gams. We postulate that the presence of endophyte exerts a stress on the host that enhances or detracts from the host's ability to express specific genes. We tested this hypothesis by heat stressing infected and non-infected, juvenile and mature tall fescue, and examining their protein profiles by SDS-PAGE analysis. The results indicate that mature, infected, stressed grass produced greater amounts of Rubisco (ribulose bisphosphate carboxylase-oxygenase) than all other treatments. Additionally, the mature, …


Additional Occurrences Of The Bog Clubmosses In Southern Arkansas, James R. Bray, Daniel L. Marsh Jan 1993

Additional Occurrences Of The Bog Clubmosses In Southern Arkansas, James R. Bray, Daniel L. Marsh

Journal of the Arkansas Academy of Science

No abstract provided.


Molecular Approaches For Control Of Tomato Bushy Stunt Virus, H. B. Scholthof, M. Borja, Thomas Jack Morris, A. O. Jackson Jan 1993

Molecular Approaches For Control Of Tomato Bushy Stunt Virus, H. B. Scholthof, M. Borja, Thomas Jack Morris, A. O. Jackson

School of Biological Sciences: Faculty Publications

I N this overview strategies are discussed that are currently being tested in our laboratory in an effort to engineer resistance against tomato bushy stunt virus (TBSV) in plants. TBSV is chosen as a model-system since this is an economically important RNA virus that is well characterized at the molecular level and the virus has some interesting and potentially useful features that can be exploited to produce resistant plants. Moreover, we anticipate that the information derived from our studies with TBSV will be applicable in developing resistance to other plant viruses. Some approaches that we are attempting to apply to …


Seasonal Relationships Between Phytoplankton Composition, Abundance, And Primary Productivity In Three Tidal Rivers Of The Lower Chesapeake Bay, Harold G. Marshall, Kneeland K. Nesius Jan 1993

Seasonal Relationships Between Phytoplankton Composition, Abundance, And Primary Productivity In Three Tidal Rivers Of The Lower Chesapeake Bay, Harold G. Marshall, Kneeland K. Nesius

Biological Sciences Faculty Publications

The seasonal abundance and successional patterns of phytoplankton, including autotrophic picoplankton, are compared to spring, summer, and fall primary production maxima that occurred in three tidal rivers. The tidal freshwaters were dominated by diatoms, chlorophytes, and cyanobacteria during a late spring through early fall period of maximum growth. In contrast, downstream assemblages were dominated by estuarine diatoms, dinoflagellates, and cryptomonads which developed spring pulses and a protracted summer-fall maximum. Autotrophic picoplankton produced a major summer pulse at all river stations with reduced abundance during other seasons. The mean annual productivity rates for the tidal James, Rappahannock, and York rivers were …


Wood Anatomy Of Amanoa (Euphorbiaceae), W. John Hayden, Mark P. Simmons, Linda J. Swanson Jan 1993

Wood Anatomy Of Amanoa (Euphorbiaceae), W. John Hayden, Mark P. Simmons, Linda J. Swanson

Biology Faculty Publications

Wood anatomy of 29 specimens of seven species of Amanoa from tropical Africa, South America, and the Caribbean is described. The wood is diffuse-porous with most vessels in short radical multiples. Vessel elements are notably long, have simple perforation plates and small, alternative intervessel pits; tyloses are present in heartwood. Libriform wood fibres bear thick walls. Axial parenchyma distribution is diffuse and diffuse-in-aggregates. Chambered crystalliferous axial parenchyma is common. Rays are heterocellular, narrow, and very tall. The species examined, all from moist lowland forests, have similar wood structure. Wood of Amanoa resembles that of other primitive Euphorbiaceae.


Genetic Manipulation Of Tall Fescue, Jeffrey F. Pedersen, D. A. Sleper Jan 1993

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 Jan 1993

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 Jan 1993

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 Jan 1993

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


Remnant Vegetation Protection Scheme 1991 Blocks, J E D Fox, P Read, J - Pg Orsini Jul 1992

Remnant Vegetation Protection Scheme 1991 Blocks, J E D Fox, P Read, J - Pg Orsini

All other publications

No abstract provided.


Description And Key To The Identification Of Grasses In South-Western Australia, J G. Paterson Apr 1992

Description And Key To The Identification Of Grasses In South-Western Australia, J G. Paterson

Bulletins 4000 -

The grasses comprise one of the world's largest families of flowering plants, with about 670 groups or genera containing over 9000 individual types or species distributed throughout the world. Over 130 groups have been recorded in Western Australia but probable that the list is far from complete. About one third of these have been introduced from overseas.


A Survey Of Mucilaginous Testa In Chamaesyce, Martha S. Jordan, W. John Hayden Apr 1992

A Survey Of Mucilaginous Testa In Chamaesyce, Martha S. Jordan, W. John Hayden

Biology Faculty Publications

Seeds of Chamaesyce were studied for presence of mucilaginous testa. Samples were selected to represent all major systematic sections within the genus. Observations were made with a dissecting microscope following brief hydration of seeds; additional SEM observations of both intact and fractured dry seeds were made for selected species. With few exceptions, most of Boissier's subsections test positively for seed mucilage; however, mucilage is generally absent in subsections Gymnadeniae and "Sclerophyllae", for which absence of mucilage is regarded as secondary loss from mucilagionus ancestors. Although mucilage production is associated with a well-defined subepidermal layer of macroesclereids, it is …


Fire In A Riparian Shrub Community: Postburn Water Relations In The Tamarix-Salix Association Along The Lower Colorado River, S. D. Smith, D. E. Busch Jan 1992

Fire In A Riparian Shrub Community: Postburn Water Relations In The Tamarix-Salix Association Along The Lower Colorado River, S. D. Smith, D. E. Busch

Life Sciences Faculty Research

Higher water potentials in recovering burned salt-cedar (Tamarix ramosissima) relative to unburned plants and the opposite situation in willow (Salix gooddingii) provide evidence that postfire water stress is reduced in the former but not the latter. Similarly, diurnal patterns of stomatal conductance in these taxa are consistent with the existence of more vigor in burned salt-cedar than willow. Plots of water potential and transpiration demonstrate that hydraulic efficiencies may contribute to differences in fire recovery.


New Yellow Serradella Varieties For Low Rainfall Pastures, Clinton Revell Jan 1992

New Yellow Serradella Varieties For Low Rainfall Pastures, Clinton Revell

Journal of the Department of Agriculture, Western Australia, Series 4

Large areas of acidic, sandy soils in Western Australia's low and medium rainfall, wheatsheep areas are suited to the pasture legume, yellow serradella.

In the past, a lack of varieties with suitable maturity has limited the use of this species.

New varieties developed in Western Australia and significantly earlier in maturity than traditional types can now extend the use of yellow serradella into these regions.


Opportunity Knocks : Sowing Wheat Early In The North-Eastern Wheatbelt, Nicole Kerr, Doug Abrecht Jan 1992

Opportunity Knocks : Sowing Wheat Early In The North-Eastern Wheatbelt, Nicole Kerr, Doug Abrecht

Journal of the Department of Agriculture, Western Australia, Series 4

Farmers consider many factors in deciding whether to start sowing wheat, but the most important are the amount of rain and time of year. In this study we assessed the chances of farmers in the north-eastern wheatbelt (less than 325 mm rainfall) receiving enough rain to sow wheat early. In low rainfall areas such as this, where an early finish to the season is likely, it is especially important that farmers take advantage of all early sowing opportunities. The potential benefits of sowing wheat early generally outweigh the associated risks, particularly in lower rainfall areas. However, early sowing depends on …


The Impact Of Red Kangaroos On The Rangelands, Grant Norbury, Dale Norbury Jan 1992

The Impact Of Red Kangaroos On The Rangelands, Grant Norbury, Dale Norbury

Journal of the Department of Agriculture, Western Australia, Series 4

Kangaroos and other native animals should be maintained across their natural range, including areas set aside for pastoral use. But the added grazing pressure on native vegetation from sheep, cattle and feral animals, together with unnaturally high numbers of kangaroos, has seriously degraded much of our rangelands. Cattle and sheep numbers are relatively easy to control. The same cannot be said for kangaroos. Access to widespread man-made watering points has allowed kangaroos to continue breeding when normally a shortage of water would suppress reproduction.

Pastoralists complain that commercial kangaroo shooting is not always effective in preventing damage caused by kangaroos. …


Local Polyploid Variation In The Native Prairie Grass Andropogon Gerardii, Kathleen H. Keeler Jan 1992

Local Polyploid Variation In The Native Prairie Grass Andropogon Gerardii, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

The microscale distribution of polyploid variants of the dominant grass big bluestem (Andropogon gerardii) in virgin tallgrass prairie was mapped using flow cytometry. The correlation between DNA content and polyploidy allows the use of flow cytometry for nondestructive determination of polyploidy in intact plants. At Konza Prairie, local plots contained from 0 to 100% hexaploid cytotypes but most showed fine-scale mixing of the polyploid variants. The relationship of cytotype frequency to moisture availability or burning history was nonsignificant


Measuring Shrubland Vegetational Structure Using Avian Habitats As An Example, Douglas A. James Jan 1992

Measuring Shrubland Vegetational Structure Using Avian Habitats As An Example, Douglas A. James

Journal of the Arkansas Academy of Science

Vegetational sampling of avian habitats stresses the use of methods primarily designed for forest birds. This paper describes a technique for sampling vegetational structure in uneven patchy habitats such as shrublands. Using the method, avian habitats in old field shrublands of northwestern Arkansas were analyzed.


New Records Of Vertebrates In Southwestern Arkansas, C. Renn Tumlison, Mark R. Karnes, Mark E. Clark Jan 1992

New Records Of Vertebrates In Southwestern Arkansas, C. Renn Tumlison, Mark R. Karnes, Mark E. Clark

Journal of the Arkansas Academy of Science

No abstract provided.


Synopsis Of The Genus Tropisternus (Coleoptera Hydrophilidae) In Arkansas, George L. Harp Jan 1992

Synopsis Of The Genus Tropisternus (Coleoptera Hydrophilidae) In Arkansas, George L. Harp

Journal of the Arkansas Academy of Science

No abstract provided.


Clearwing Moths Are Key To Dock Control, Kingsley Fisher Jan 1992

Clearwing Moths Are Key To Dock Control, Kingsley Fisher

Journal of the Department of Agriculture, Western Australia, Series 4

Two clearwing moths imported from Morocco and France could be the key to controlling dock (Rumex pulcher) - one of the worst weeds of high rainfall pastures in southern Australia


Jasmonate, Genes, And Fragrant Signals, Paul E. Staswick Jan 1992

Jasmonate, Genes, And Fragrant Signals, Paul E. Staswick

Department of Agronomy and Horticulture: Faculty Publications

Although first recognized for its growth-inhibiting activity about 20 years ago, JA2 and its fragrant methyl ester MeJA (referred to here collectively as jasmonate) are receiving renewed interest as potentially important signaling molecules in plants. This is because jasmonate markedly increases the expression of specific plant genes, some of which are wound responsive. Similarities with fatty acid-derived stress signaling molecules in animals (1) make jasmonate of general biological interest.