Life Sciences Commons^™

Evaluation Of Switchgrass Rhizosphere Microflora For Enhancing Seedling Yield And Nutrient Uptake, John J. Brejda, Lowell E. Moser, Kenneth P. Vogel

Department of Agronomy and Horticulture: Faculty Publications

Many rhizosphere microorganisms enhance nutrient uptake and plant growth, but their effectiveness can vary with host species and with genotype within species. This study evaluated the effectiveness of rhizosphere microflora indigenous to the rhizosphere of switchgrass (Panicum virgatum L.) for enhancing seedling yield and nutrient uptake. Switchgrass roots and rhizosphere soil were collected from native prairies and seeded stands in Nebraska, Kansas, Iowa, Missouri, Virginia, and North Carolina. Seedlings of four switchgrass cultivars were inoculated with root fragments and rhizosphere soil from each collection, fertilized with a nutrient solution, and gown in steamed sand for 12 wk in a …

Growth Responses Of Warm-Season Tall Grasses To Dormant Season Management, Walter H. Schacht, Alexander J. Smart, Bruce Anderson, Lowell E. Moser, Richard J. Rasby

Department of Agronomy and Horticulture: Faculty Publications

A study on Conservation Reserve Program (CRP) land was established in southeastern Nebraska to determine the effect of dormant-season management on subsequent-year growth rates and yields of tallgrasses. The purpose of the management practices was removal of standing dead material and litter that negatively impact plant growth and grazing efficiency. Treatments consisted of a control with no residue manipulation and 5 residue manipulation practices including (1) October shredding and leaving residue; (2) October haying; (3) October intensive grazing; (4) March intensive grazing; and (5) spring prescribed burning. The study was conducted in 1994195 and 1995/96 on a switchgrass (Panicum …

Prediction Of Leaf:Stem Ratio In Grasses Using Near Infrared Reflectance Spectroscopy, Alexander J. Smart, Walter H. Schacht, Jeffrey F. Pedersen, Daniel J. Undersander, Lowell E. Moser

Department of Agronomy and Horticulture: Faculty Publications

Leaf:stem ratio of grass stands is an important factor affecting diet selection, quality, and forage intake. Estimates of leaf:stem ratios commonly are based on a labor intensive process of hand separating leaf and stem fractions. Near infrared reflectance spectroscopy (NIRS) has been used successfully to predict forage quality and botanical composition of vegetation samples. The objective of this study was to evaluate the use of NIRS to predict leaf:stem ratios in big bluestem (Andropogon gerardii Vitman), switchgrass (Punicum virgatum L.), and smooth bromegrass (Bromus inermis Leyss.). A total of 72 hand-clipped samples of each species was taken …

Morphological Development Of 2 Warm-Season Grasses In The Nebraska Sandhills, J. R. Hendrickson, Lowell E. Moser, K. J. Moore, Steven S. Waller

Department of Agronomy and Horticulture: Faculty Publications

Morphological development of grasses has numerous implications to rangeland management including the timing and amount of herbivory. The objective of this study was to quantify the developmental morphology of prairie sandreed [Calamovilfa longifolia (Hook.) Scrihn.] and sand bluestem [Andropogon gerardii var. paucipilus (Nash) Fem.] tiller populations. Tier populations of these 2 grasses were studied for 2 years in the Nebraska Sandhills. Plant development was evaluated using a growth staging system which quantifies the development of tiller populations. A morphological growth index for each species was calculated from either the weighted average of tiller numbers reported as mean stage …

Waxy Wheats: Origin, Properties, And Prospects, Robert A. Graybosch

Department of Agronomy and Horticulture: Faculty Publications

Starch amylose is synthesized through the activity of the granule-bound starch synthase (GBSS). In wheat (Triticum aestivum L. ), there are three structural genes encoding iso- forms of GBSS. Naturally occurring mutations (null alleles) resulting in the loss of one or more GBSS isoforms have recently been identified. The presence of one or two GBSS null alleles results in the production of starch with reduced amylose content. Reduced amylose wheats have been termed `partial waxy'. Wheats with three GBSS null alleles produce essentially amylose-free, or waxy, starch. Partial waxy wheats are sources of flours with optimal quality characteristics in …

The ‘‘Foliage Is The Fruit’’ Hypothesis: Complex Adaptations In Buffalograss (Buchloe Dactyloides), John Ortmann, Walter H. Schacht, James L. Stubbendieck, Dennis R. Brink

Department of Agronomy and Horticulture: Faculty Publications

Buffalograss (Buchloe dactyloides) has been described as an excellent fit for Janzen’s ‘‘Foliage is the Fruit’’ (FF) hypothesis, which suggests that large grazing animals ingest and later disperse seeds of some herbs when consuming their foliage. We tested this hypothesis by feeding buffalograss burs and legume seeds to ruminally fistulated beef steers. Our objectives were to determine (1) rumen residence times of buffalograss burs, free buffalograss caryopses and legume seeds; (2) total tract residence times for the three types of propagules; (3) percentage propagule survival after passage and (4) germinability of fed and unfed burs and caryopses. Bur …

Tolerance And Velvetleaf (Abutilon Theophrasti) Suppressive Ability Of Two Old And Two Modern Corn (Zea Mays) Hybrids, John L. Lindquist, David A. Mortensen

Department of Agronomy and Horticulture: Faculty Publications

Improved crop tolerance and weed suppressive ability are tactics that may reduce the negative effect of weeds on crop yield. Irrigated field experiments were conducted to compare leaf area index (LAI), intercepted photosynthetic photon flux (PPF), and relative tolerance and velvetleaf suppressive ability among two old (circa1 940) and two modern corn hybrids. Each hybrid was grown in monoculture and in mixture with velvetleaf at 1, 4, 16, and 40 plants m^-1 row. Plants were periodically harvested in monoculture plots to obtain estimates of corn LAI, and PPF interception was measured. Variation in hybrid tolerance to velvetleaf competition for …

Economic Importance Of Managing Spatially Heterogeneous Weed Population, John L. Lindquist, J. Anita Dieleman, David A. Mortensen, Gregg A. Johnson, Dawn Y. Wyse-Pester

Department of Agronomy and Horticulture: Faculty Publications

Three methods of predicting the impact of weed interference on crop yield and expected economic return were compared to evaluate the economic importance of weed spatial heterogeneity. Density of three weed species was obtained using a grid sampling scheme in 11 corn and 11 soybean fields. Crop yield loss was predicted assuming densities were homogeneous, aggregated following a negative binomial with known population mean and k, or aggregated with weed densities spatially mapped. Predicted crop loss was lowest and expected returns highest when spatial location of weed density was utilized to decide whether control was justified. Location-specific weed management resulted …

Seedbank Characteristics Of A Nebraska Sandhills Prairie, Claudio J. Perez, Steven S. Waller, Lowell E. Moser, James L. Stubbendieck, Allan A. Steuter

Department of Agronomy and Horticulture: Faculty Publications

Evaluating seedbank ecology is critical for understanding plant community development and successional patterns and for identifying factors regulating population dynamics. The relationships among seedbank composition, seedbank depth, seed dormancy, and vegetative expression were evaluated for a range site on a Valentine fine sand soil (mixed, mesic Typic Ustipsamments) in the Sandhills Prairie. Twenty soil samples were collected at each of 2 depths (0 to 5, 15 to 20 cm) in early June 1990 and 1991 from 12 macroplots (32 X 32 m) representing 3 range condition classes. A seed extraction and germination trial was conducted to determine the diversity, size, …

Statistical Design And Analysis Of Producer/Consumer Evaluations To Assess Plant Quality, Walter W. Stroup, Stacy A. Adams, Ellen Paparozzi

Department of Agronomy and Horticulture: Faculty Publications

Researchers in ornamental horticulture often want to assess the effects of experimental treatments on plant quality. Producers often use the results of such experiments to establish the minimum level of a treatment, for instance, the amount of a growth regulator or a nutrient, such as nitrogen, needed to achieve desired plant quality. For edible plants, quality can be quantified objectively by using numeric response variable such as yield or nutritional content. However, for ornamental plants, quality depends on aesthetic appeal and consumer acceptance, traits which are subjective and qualitative.

Statistical models for the design and analysis of experiments involving numeric …

Growth Traits Among Sorghum Genotypes In Response To Aluminum, J. H. Bernal, R. B. Clark

Department of Agronomy and Horticulture: Faculty Publications

Aluminum (Al) has many detrimental effects on plant growth, and shoots and roots are normally affected differently. A study was conducted to determine differences among sorghum [Sorghum bicolor (L.) Moench] genotypes with broad genetic backgrounds for growth traits of plants grown at 0,200,400,600, and 800 uM Al in nutrient solutions (pH 4.0). Genotypes were categorized into "Al-sensitive", "intermediate Al-tolerant", "Al-tolerant", and SC 283 (an Al-tolerant standard). As Al increased, shoot and root dry matter (DM), net main axis root length (NMARL), and total root length (TRL) became lower than controls (0 Al). Aluminum toxicity and/or nutrient deficiency symptoms become …

Tiller Demographics And Leaf Area Index Of Four Perennial Pasture Grasses, Robert B. Mitchell, Lowell E. Moser, Kenneth J. Moore, Daren D. Redfearn

Department of Agronomy and Horticulture: Faculty Publications

Developing grazing systems requires basic information on the growth and development of adapted species. The objective of this field study was to determine seasonal tiller demographics and leaf area index (LAI) of intermediate wbeatgrass [Thinopyrum intermedium (Host) Barkw. & D.R. Dewey], smooth bromegrass (Bromus inermis Leyss.), switchgrass (Panicum virgatum L.), and big bluestem (Andropogon gerardii Vitman) tiller populations. This study was conducted in 1992 and 1993 near Mead, NE, on a silty clay loam soil (Typic Argiudoll) as a randomized complete block. Monocultures were harvested six times each year for tiller demographics. Additionally, mean stage count …

Baking Quality Of Hard Winter Wheat: Response Of Cultivars To Environment In The Great Plains, C. J. Peterson, R. A. Graybosch, D. R. Shelton, P. Stephen Baenziger

Department of Agronomy and Horticulture: Faculty Publications

Inconsistency of wheat end-use quality has long been a problem for the milling and baking industries, which require high levels of uniformity for modern, high speed, processing. Extensive research was conducted to characterise genetic, environmental, and biochemical factors that contribute to variation in wheat quality. Samples from 17 locations of trials with 30 cultivars grown over two years were evaluated for grain quality, milling yield, mixograph parameters and baking properties. Protein quality and composition of flour samples were determined by SDS sedimentation and size-exclusion chromatography. Test sites were monitored for soil fertility, and meteorological data was collected hourly during grain …

Mycorrhizal Colonization And Nutrition Of Wheat And Sweet Corn Grown In Manure-Treated And Untreated Topsoil And Subsoil, David D. Tarkalson, Von D. Jolley, Charles W. Robbins, Richard E. Terry

Department of Agronomy and Horticulture: Faculty Publications

Dry bean yields (Phaseolus vulgaris L.) were raised to similar levels as the topsoil by manure application to eroded or leveled Portneuf silt loam soil (coarse-silty mixed mesic Durixerollic Calciorthid). Only soil organic matter and zinc (Zn) content of leaf tissue were correlated with improved yields. Manure application increased mycorrhizal colonization and Zn uptake in pot experiments with dry bean which would explain the increased yields in the field. A field study was conducted to see if similar effects of manure and mycorrhizal colonization could be observed in field grown spring wheat (Triticum aestivum L.) and sweet corn …

Weather And Management Impact On Crop Yield Variability In Rotations, Charles Yamoah, Gary E. Varvel, Charles Francis, William Waltman

Department of Agronomy and Horticulture: Faculty Publications

Crop rotations are designed to increase productivity and reduce costs. These advantages are contingent upon favorable weather and require appropriate management. Unpredictable weather poses risks to dryland crop production. Information on how weather affects yields in different cropping systems and how farmers could respond with management would help minimize risk and stabilize yield and income. We evaluated the effects of preseason and growing season weather variability on continuous and sequential cropping of corn, sorghum, and soybean in a 12-yr span, and suggest how management decisions could influence cropping system performance.
Models of different levels of sophistication have been developed to …