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Determining The Extent Of Frost Damage In Maize Seed Using The Tetrazolium Test, Mindy Devries, A. Susana Goggi Dec 2006

Determining The Extent Of Frost Damage In Maize Seed Using The Tetrazolium Test, Mindy Devries, A. Susana Goggi

Agronomy Publications

Frost damage in seed corn causes a significant decrease in seed quality. The tetrazolium (TZ) test has been used to identify types of physiological damage in several plant species, including frost damage in corn. Quantifying the amount of seed damaged by frost and the consequent loss of seed vigor are important for making management decisions. The current tetrazolium test procedures provide seed viability information but do not estimate seed vigor. In our project, the tetrazolium staining procedure was modified to allow separation of viable seeds into vigor categories. Vigor categories were defined based on Association of Official Seed Analysts (AOSA ...


A Dripper-Tdr Method For In Situ Determination Of Hydraulic Conductivity And Chemical Transport Properties Of Surface Soils, Salem A. Al-Jabri, Jaehoon Lee, Anju Gaur, Robert Horton, Dan B. Jaynes Feb 2006

A Dripper-Tdr Method For In Situ Determination Of Hydraulic Conductivity And Chemical Transport Properties Of Surface Soils, Salem A. Al-Jabri, Jaehoon Lee, Anju Gaur, Robert Horton, Dan B. Jaynes

Agronomy Publications

Field determined hydraulic and chemical transport properties can be useful for the protection of groundwater resources from land-applied chemicals. Most field methods to determine flow and transport parameters are either time or energy consuming and/or they provide a single measurement for a given time period. In this study, we present a dripper-TDR field method that allows measurement of hydraulic conductivity and chemical transport parameters at multiple field locations within a short time period. Specifically, the dripper-TDR determines saturated hydraulic conductivity (Ks), macroscopic capillary length (λc), immobile water fraction (θim/θ), mass exchange coefficient (α) and dispersion ...


Field Tests Of The Soil Heat Flux Plate Method And Some Alternatives, Tyson E. Ochsner, Thomas J. Sauer, Robert Horton Jan 2006

Field Tests Of The Soil Heat Flux Plate Method And Some Alternatives, Tyson E. Ochsner, Thomas J. Sauer, Robert Horton

Agronomy Publications

Heat flux plates are commonly used to measure soil heat flux, a component of the surface energy balance. The plate method is simple and precise, but several previous studies have demonstrated the potential for relatively large errors. Here we present the results of in situ tests of the plate method, and we describe some promising alternative methods. Summertime soil heat flux was measured with heat flux plates and with two alternative methods at each of three sites. In total, three alternative methods were used: a single probe gradient method, a three needle gradient method, and a self-calibrating plate method. The ...


Method For Maintaining One-Dimensional Temperature Gradients In Unsaturated, Closed Soil Cells, J. Zhou, J. L. Heitman, R. Horton, T. Ren, T. E. Ochsner, L. Prunty, R. P. Ewing, T. J. Sauer Jan 2006

Method For Maintaining One-Dimensional Temperature Gradients In Unsaturated, Closed Soil Cells, J. Zhou, J. L. Heitman, R. Horton, T. Ren, T. E. Ochsner, L. Prunty, R. P. Ewing, T. J. Sauer

Agronomy Publications

One-dimensional temperature gradients are difficult to achieve in nonisothermal laboratory studies because, in addition to desired axial temperature gradients, ambient temperature interference (ATI) creates a radial temperature distribution. Our objective was to develop a closed soil cell with limited ATI. The cell consists of a smaller soil column, the control volume, surrounded by a larger soil column, which provides radial insulation. End boundary temperatures are controlled by a new spiral-circulation heat exchanger. Four cell size configurations were tested for ATI under varying ambient temperatures. Results indicate that cells with a 9-cm inner column diameter, 5-cm concentric soil buffer, and either ...


Measured And Predicted Solute Transport In A Tile Drained Field, Anju Gaur, Robert Horton, Dan B. Jaynes, James L. Baker Jan 2006

Measured And Predicted Solute Transport In A Tile Drained Field, Anju Gaur, Robert Horton, Dan B. Jaynes, James L. Baker

Agronomy Publications

Most solute transport measurement techniques are tedious and require extensive soil excavation. A field experiment was conducted to evaluate whether surface transport properties determined by a nondestructive time domain reflectometry (TDR) technique could be used to accurately predict tile flux concentrations. A 14 by 14 m field plot selected above a 1.1-m deep tile drain was studied. Low electrical conductivity (EC) water was sprinkled on the plot surface, and after reaching a steady-state condition, a pulse of calcium chloride solution (16.3 cm) with an EC of 23 dS m−1 was applied through the same sprinklers. Time domain ...


Grain Composition And Amino Acid Content In Maize Cultivars Representing 80 Years Of Commercial Maize Varieties, Marvin Paul Scott, Jode W. Edwards, C. P. Bell, J. R. Schussler, J. S. Smith Jan 2006

Grain Composition And Amino Acid Content In Maize Cultivars Representing 80 Years Of Commercial Maize Varieties, Marvin Paul Scott, Jode W. Edwards, C. P. Bell, J. R. Schussler, J. S. Smith

Agronomy Publications

In order to determine how modern hybrids have impacted grain composition and amino acid content of the corn crop, we characterized a set of cultivars that were widely grown in different eras from the 1920s through 2001. Grain composition exhibited clear trends with time, with protein decreasing and starch increasing. The effects of different plant densities were examined. The grain protein content of modern hybrids responds to plant density and environment differently than the protein content of older varieties. These differences are consistent with a model in which protein content is modulated by different growth conditions. These differences may explain ...


Light Is Essential For Degradation Of Ribulose-1,5-Bisphosphate Carboxylase-Oxygenase Large Subunit During Sudden Death Syndrome Development In Soybean, J. Ji, M. P. Scott, M. K. Bhattacharyya Jan 2006

Light Is Essential For Degradation Of Ribulose-1,5-Bisphosphate Carboxylase-Oxygenase Large Subunit During Sudden Death Syndrome Development In Soybean, J. Ji, M. P. Scott, M. K. Bhattacharyya

Agronomy Publications

Fusarium solani f. sp. glycines (Fsg) has been reported to produce at least two phytotoxins. Cell-free Fsg culture filtrates containing phytotoxins have been shown to develop foliar sudden death syndrome (SDS) in soybean. We have investigated the changes in protein profiles of diseased leaves caused by cell-free Fsg culture filtrates prepared from Fsg isolates. Two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (PAGE) was conducted to investigate the protein profiles of diseased and healthy leaves. An approximately 55 kDa protein was found to be absent in diseased leaves. Matrix-assisted laser desorption-ionization time-of-flight mass spectrometric analyses and a database search revealed that the ...


Breeding For Grain Amino Acid Composition In Maize, Audrey Darrigues, Kendall R. Lamkey, M. Paul Scott Jan 2006

Breeding For Grain Amino Acid Composition In Maize, Audrey Darrigues, Kendall R. Lamkey, M. Paul Scott

Agronomy Publications

Improving the amino acid balance of grain has been a long-standing objective of plant-breeding research. In this chapter, we review the history of maize breeding for improved amino acid balance. Following this, we present results of our experiments involving divergent selection for the levels of the amino acids tryptophan and methionine in random-mated populations.


Dehydrin-Like Proteins In Soybean Seeds In Response To Drought Stress During Seed Filling, N. H. Samarah, R. E. Mullen, S. R. Cianzio, P. Scott Jan 2006

Dehydrin-Like Proteins In Soybean Seeds In Response To Drought Stress During Seed Filling, N. H. Samarah, R. E. Mullen, S. R. Cianzio, P. Scott

Agronomy Publications

There is no information on accumulation of dehydrin proteins during seed development and maturation of soybean [Glycine max (L.) Merr.] in response to drought stress. Our objective was to study accumulation of dehydrin-like proteins in developing soybean seeds in response to drought stress. A greenhouse experiment and a field experiment were conducted. In the greenhouse experiment, three treatments were imposed on soybean plants after beginning of linear seed filling (R5): well-watered (WW), gradual stress (GS) imposed before severe stress, and sudden severe stress (SS). In the field treatments were irrigation (I) and nonirrigation (NI) (rainfed) conditions imposed from R ...