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A Brief History Of Corn: Looking Back To Move Forward, Jon Derek Pruitt May 2016

A Brief History Of Corn: Looking Back To Move Forward, Jon Derek Pruitt

Doctoral Documents from Doctor of Plant Health Program

Maize was domesticated from teosinte in Mexico some 7,000 to 10,000 years ago and quickly spread through the Americas. It has become one of the most important crops at a local and global level. Two types, Northern Flint corn and Southern Dent corns provided the basis of the genetic background of modern maize hybrids. The development of hybrids, first double-cross and later single-cross hybrids, along with a transition to high input farming provided huge yield increases, which have continued to improve with improving technology.

Increase in maize production also caused a rise in Western corn Rootworm (Diabrotica virgifera ...


What Drives Corn Yield Stability In The Context Of Climate Variability?, Michael J. Castellano, Kirsten S. Hofmockel, Jim R. Rouse Jan 2014

What Drives Corn Yield Stability In The Context Of Climate Variability?, Michael J. Castellano, Kirsten S. Hofmockel, Jim R. Rouse

Leopold Center Completed Grant Reports

The links between nitrogen fertilizer rates and varying crop rotation schemes are examined in this project. The role that organic matter inputs play in supporting corn-soybean rotations also was investigated.


Corn Development And September Yield Forecast, 2010, Roger Elmore Sep 2010

Corn Development And September Yield Forecast, 2010, Roger Elmore

Integrated Crop Management News

The September 2010 USDA–NASS corn yield forecast remains at 179 bushels per acre (bu/acre) for Iowa – the same as the August report. If realized, 2010 will boast the third highest yield in Iowa’s history behind 2004 (181 bu/acre) and 2009 (182 bu/acre).


Crop Updates 2010 - Crop Specific, Hugh J. Beckie, Wallace Cowling, T. N. Khan, K. Adhikari, K. Siddique, J. Garlinge, L. Smith, S. Morgan, C. Boyd, Ian Pritchard, Chris Veitch, Alan Harris, Tony Leonforts, Murray Blyth, Shari Dougal, Kristy Hobson, Ben Curtis, Doug Sawkins, D. Stephens, Ciara Beard, Kith Jayasena, Kazue Tanaka, Anne Smith, Brenda Coutts, Roger Jones, Jean Galloway, Pip Payne, Tess Humphreys, William Macleod, Ravjit Khangura, M. Abberra, H. Mian, Geoff Thomas, Dusty Severtson, Peter Mangano, Monica Kehoe, Madeline A. Tucker, Neil Barker, Robert Loughman, Larisa Cato, Ken Quail, Mohammad Amjad, Mark Seymour, Justin Kudnig, Mark Thompson, Anton Mannes, Michael Uttley, Chris Fletcher, Andrew Etherton, Nick Joyce, Kate Light, Peter Hamblin, Michael Lamond, Alan Meldrum, Wayne Parker, Steve Penny Jr, Sarah Ellis, Brenda Shackley, Christine Zaicou, Shajahan Miyan, Darshan Sharma, Ben Curtis, Greg Shea, Bevan Buirchell, David Harris, Bob French Feb 2010

Crop Updates 2010 - Crop Specific, Hugh J. Beckie, Wallace Cowling, T. N. Khan, K. Adhikari, K. Siddique, J. Garlinge, L. Smith, S. Morgan, C. Boyd, Ian Pritchard, Chris Veitch, Alan Harris, Tony Leonforts, Murray Blyth, Shari Dougal, Kristy Hobson, Ben Curtis, Doug Sawkins, D. Stephens, Ciara Beard, Kith Jayasena, Kazue Tanaka, Anne Smith, Brenda Coutts, Roger Jones, Jean Galloway, Pip Payne, Tess Humphreys, William Macleod, Ravjit Khangura, M. Abberra, H. Mian, Geoff Thomas, Dusty Severtson, Peter Mangano, Monica Kehoe, Madeline A. Tucker, Neil Barker, Robert Loughman, Larisa Cato, Ken Quail, Mohammad Amjad, Mark Seymour, Justin Kudnig, Mark Thompson, Anton Mannes, Michael Uttley, Chris Fletcher, Andrew Etherton, Nick Joyce, Kate Light, Peter Hamblin, Michael Lamond, Alan Meldrum, Wayne Parker, Steve Penny Jr, Sarah Ellis, Brenda Shackley, Christine Zaicou, Shajahan Miyan, Darshan Sharma, Ben Curtis, Greg Shea, Bevan Buirchell, David Harris, Bob French

Crop Updates

This session covers twenty four papers from different authors:

PLENARY

1. Challenges facing western Canadian cropping over the next 10 years, Hugh J Beckie, Research Centre, Agriculture and Agri-Food Canada, Saskatoon,

Saskatchewan

CROP SPECIFIC

Breeding

2. The challenge of breeding canola hybrids – new opportunities for WA growers, Wallace Cowling, Research Director, Canola Breeders Western Australia Pty Ltd

3. Chickpea 2009 crop variety testing of germplasm developed by DAFWA/CLIMA/ICRISAT/COGGO alliance. Khan, TN1,3, Adhikari, K1,3, Siddique, K2, Garlinge, J1, Smith, L1, Morgan, S1 and Boyd, C1 1Department of Agriculture and ...


Twisted Whorls - 2009, Roger W. Elmore, Lori Abendroth Jul 2009

Twisted Whorls - 2009, Roger W. Elmore, Lori Abendroth

Integrated Crop Management News

Pale yellow upper corn leaves abound across Iowa as corn enters the teens of growth stages with some tasseling. These once sun-starved leaves entrapped in the whorl by more mature leaves will wave for a day or more above rapidly growing crop canopies before turning green. Although incidences seem more numerous than in other years, the symptom is not unusual. We reported on it last year occurring at about the same growth stages – tenth to twelfth leaf - and have an article posted on our website that discusses earlier-season situations.


Crop Updates 2009 - Cereals, Jeff Baldock, Doug Edmeades, Mark Seymour, Paul Carmody, Ian Pritchard, Alan Meldrum, Michael Robertson, Roger Lawes, Rob Sands, Peter White, Felicity Byrne, Andrew Bathgate, Kedar Adhikari, Tanveer Khan, Stuart Morgan, Alan Harris, P. Gaur, K. M. H. Siddique, H. Clarke, N. C. Turner, W. Macleod, S. Morgan, Chris Veitch, Tony Leonforte, Kith Jayasena, Geoff Thomas, Rob Loughman, Kazue Tanaka, Ravjit Khangura, M. Amjad, Richard Oliver, Dusty Severtson, Peter Mangano, John Botha, Brenda Coutts, Manisha Shankar, Kasia Rybak, Michael Baker, Andrea Hills, Shahajahan Miyan, Peter Portmann, Nicole Rice, Robert Henry, Jeff J. Russell, B. H. Paynter, Linda Price, Brenda Shackley, Vicki Scanlan, Darshan Sharma, Christine Zaicou-Kunesch Feb 2009

Crop Updates 2009 - Cereals, Jeff Baldock, Doug Edmeades, Mark Seymour, Paul Carmody, Ian Pritchard, Alan Meldrum, Michael Robertson, Roger Lawes, Rob Sands, Peter White, Felicity Byrne, Andrew Bathgate, Kedar Adhikari, Tanveer Khan, Stuart Morgan, Alan Harris, P. Gaur, K. M. H. Siddique, H. Clarke, N. C. Turner, W. Macleod, S. Morgan, Chris Veitch, Tony Leonforte, Kith Jayasena, Geoff Thomas, Rob Loughman, Kazue Tanaka, Ravjit Khangura, M. Amjad, Richard Oliver, Dusty Severtson, Peter Mangano, John Botha, Brenda Coutts, Manisha Shankar, Kasia Rybak, Michael Baker, Andrea Hills, Shahajahan Miyan, Peter Portmann, Nicole Rice, Robert Henry, Jeff J. Russell, B. H. Paynter, Linda Price, Brenda Shackley, Vicki Scanlan, Darshan Sharma, Christine Zaicou-Kunesch

Crop Updates

This session covers twenty seven papers from different authors:

PLENARY

1. Building soil carbon for productivity and implications for carbon accounting, Jeff Baldock, CSIRO Land and Water, Adelaide, SA

2. Fact or Fiction: Who is telling the truth and how to tell the difference, Doug Edmeades, agKnowledge Ltd, Hamilton

3. Four decades of crop sequence trials in Western Australia, Mark Seymour,Department of Agriculture and Food

BREAK CROPS

4. 2008 Break Crops survey Report, Paul Carmody,Development Officer, Department of Agriculture and Food

5. Attitudes of Western Australian wheatbelt growers to ‘Break Crops’, Paul Carmody and Ian Pritchard, Development Officers ...


Crop Updates 2008 - Cereals, Christine Zaicou, Shahajahan Miyan, Brenda Shackley, Steve Penny, Sarah Ellis, Darshan Sharma, Blakely Paynter, Jeff Russell, Andrea Hills, Glen Riethmuller, Bill Bowden, Paul Blackwell, Harmohinder Dhammu, Vince Lambert, Chris Roberts, David Cox, Sally Cox, Jeremy Lemon, Paul Damon, Zed Rengel, Geoff Thomas, Ciara Beard, Anne Smith, Kith Jayasena, Sean Kelly, Rob Loughman, Bill Macleod, Raj Malik, Ravjit Khangura, Vivien Vanstone, Colin Hanbury, Mehreteab Aberra, Gordon Masnish, Brenda Coutts, Geoff Strickland, Monica Kehoe, Dustin Severtson, Roger Jones, Dominie Wright, Megan Jordan, Xinhua He, Eli Manyol, Song-Ai Nio, Imran Malik, Tina Botwright-Acuña, Len Wade, Nigel Metz, Linda Price, Dean Diepeveen, Leisa Armstrong, Peter Clarke, Doug Abrecht, Rudi Appels, Matthew Bellgard Feb 2008

Crop Updates 2008 - Cereals, Christine Zaicou, Shahajahan Miyan, Brenda Shackley, Steve Penny, Sarah Ellis, Darshan Sharma, Blakely Paynter, Jeff Russell, Andrea Hills, Glen Riethmuller, Bill Bowden, Paul Blackwell, Harmohinder Dhammu, Vince Lambert, Chris Roberts, David Cox, Sally Cox, Jeremy Lemon, Paul Damon, Zed Rengel, Geoff Thomas, Ciara Beard, Anne Smith, Kith Jayasena, Sean Kelly, Rob Loughman, Bill Macleod, Raj Malik, Ravjit Khangura, Vivien Vanstone, Colin Hanbury, Mehreteab Aberra, Gordon Masnish, Brenda Coutts, Geoff Strickland, Monica Kehoe, Dustin Severtson, Roger Jones, Dominie Wright, Megan Jordan, Xinhua He, Eli Manyol, Song-Ai Nio, Imran Malik, Tina Botwright-Acuña, Len Wade, Nigel Metz, Linda Price, Dean Diepeveen, Leisa Armstrong, Peter Clarke, Doug Abrecht, Rudi Appels, Matthew Bellgard

Crop Updates

This session covers twenty four papers from different authors:

WHEAT AGRONOMY

1. Wheat variety performance in the Northern Agricultural Region in 2007, Christine Zaicou, Department of Agriculture and Food

2. Wheat variety performance on the Central Agricultural Region in 2007, Shahajahan Miyan, Department of Agriculture and Food

3. Response of wheat varieties to sowing time in the Great Southern and Lakes Region in 2007, Brenda Shackley and Steve Penny, Department of Agriculture and Food

4. Wheat variety performance in the South Coastal Region in 2007, Sarah Ellis, Department of Agriculture and Food

5. Flowering dates of wheat varieties in Western ...


Crop Updates 2007 - Cereals, R. Loughman, R. Lance, I. Barclay, G. Crosbie, S. Harasymow, W. Lambe, C. Li, R. Mclean, C. Moore, K. Stefanova, A. Tarr, R. Wilson, Matu Peipi, Matt Whiting, Christine Zaicou, Shahajahan Miyan, Brenda Shackley, Len J. Wade, Lindsay W. Bell, Felicity Byrne (Nee Flugge), Mike A. Ewing, Blakely Paynter, Andrea Hills, Raj Malik, Kelly Winfield, Harmohinder Dhammu, Vince Lambert, Chris Roberts, Jeromy Lemon, Geoff Thomas, Ian Hartley, Andrew Taylor, Manisha Shankar, John Majewski, Vivien Vanstone, Brenda Coutts, Monica Kehoe, Roger Jones, Geoffrey Dwyer, Belinda Welsh, Cuiping Wang, Linda Price Feb 2007

Crop Updates 2007 - Cereals, R. Loughman, R. Lance, I. Barclay, G. Crosbie, S. Harasymow, W. Lambe, C. Li, R. Mclean, C. Moore, K. Stefanova, A. Tarr, R. Wilson, Matu Peipi, Matt Whiting, Christine Zaicou, Shahajahan Miyan, Brenda Shackley, Len J. Wade, Lindsay W. Bell, Felicity Byrne (Nee Flugge), Mike A. Ewing, Blakely Paynter, Andrea Hills, Raj Malik, Kelly Winfield, Harmohinder Dhammu, Vince Lambert, Chris Roberts, Jeromy Lemon, Geoff Thomas, Ian Hartley, Andrew Taylor, Manisha Shankar, John Majewski, Vivien Vanstone, Brenda Coutts, Monica Kehoe, Roger Jones, Geoffrey Dwyer, Belinda Welsh, Cuiping Wang, Linda Price

Crop Updates

This session covers twenty six papers from different authors:

CEREAL BREEDING

1. Strategies for aligning producer and market imperatives in cereal breeding in Western Australia, R. Loughman, R. Lance, I. Barclay, G. Crosbie, S. Harasymow, W. Lambe, C. Li, R. McLean, C. Moore, K. Stefanova, A. Tarr and R. Wilson, Department of Agriculture and Food

2. LongReach plant breeders wheat variety trials – 2006, Matu Peipi and Matt Whiting, LongReach Plant Breeders

WHEAT AGRONOMY

3. Response of wheat varieties to sowing time in the northern agricultural region in 2006, Christine Zaicou, Department of Agriculture and Food

4. Response of wheat varieties ...


Relationship Between Concentration Of Isoflavones In Soybean Grain And Potassium Fertilization , Mario Valadez Ramirez Jan 2006

Relationship Between Concentration Of Isoflavones In Soybean Grain And Potassium Fertilization , Mario Valadez Ramirez

Retrospective Theses and Dissertations

Soybean grain contains isoflavones that may prevent various human diseases. Previous studies in Canada found that K fertilization and high grain K concentration can result in increased isoflavones concentration in grain, but effects were inconsistent across sites and soil-test K (STK) levels. The objective of this study was to assess (1) effects of K fertilization on the concentration of isoflavones and K in soybean grain and (2) relationships between soybean grains K concentration, isoflavone concentration, and yield. The study was based on analyses of grain collected from selected treatments and years of six Iowa long-term experiments that investigated effects of ...


Crop Updates 2004 - Cereals, Wal Anderson, Vivian Vanstone, Robert Loughman, Vanessa Stewart, Darshan Sharma, Christine Zaicou-Kunesch, Brenda Shackley, Mohammad Amjad, Steve Penny Jr, Glen Riethmuller, Jeromy Lemon, Mario D'Antuono, Veronika Reck, Ben Curtis, Judith Devenish, Melaine Kupsch, Anne Smith, Blakely Paynter, Roslyn Jetter, Leanne Schulz, Jocelyn Ball, Tom Sweeny, Stephen Loss, Ashleigh Brooks, Justin Fuery, Geoff Anderson, Zed Rengel, Paul Damon, Eddy Pol, Narelle Hill, Ray Tugwell, Ron Mctaggart, Nathan Moyes, John Majewski, Manisha Shanker, James Piotrowski, Ciara Beard, Kithsiri Jayasena, Kazue Tanaka, Grey Poulish, Debbie Thackray, Rohan Prince, Roger Jones, Peter Nelson, Nigel Metz, Leisa Armstrong, Yee Leong (Alex) Yung, Moin Salam, David Tennant Feb 2004

Crop Updates 2004 - Cereals, Wal Anderson, Vivian Vanstone, Robert Loughman, Vanessa Stewart, Darshan Sharma, Christine Zaicou-Kunesch, Brenda Shackley, Mohammad Amjad, Steve Penny Jr, Glen Riethmuller, Jeromy Lemon, Mario D'Antuono, Veronika Reck, Ben Curtis, Judith Devenish, Melaine Kupsch, Anne Smith, Blakely Paynter, Roslyn Jetter, Leanne Schulz, Jocelyn Ball, Tom Sweeny, Stephen Loss, Ashleigh Brooks, Justin Fuery, Geoff Anderson, Zed Rengel, Paul Damon, Eddy Pol, Narelle Hill, Ray Tugwell, Ron Mctaggart, Nathan Moyes, John Majewski, Manisha Shanker, James Piotrowski, Ciara Beard, Kithsiri Jayasena, Kazue Tanaka, Grey Poulish, Debbie Thackray, Rohan Prince, Roger Jones, Peter Nelson, Nigel Metz, Leisa Armstrong, Yee Leong (Alex) Yung, Moin Salam, David Tennant

Crop Updates

This session covers twenty eight papers from different authors:

PLENARY

1. Declining profitability in continuous cropping systems. Is more wheat the answer on Duplex soil? Dr Wal Anderson, Department of Agriculture

2. Disease implications of extending the wheat phase in low-medium rainfall areas, Dr Vivian Vanstone and Dr Robert Loughman, Department of Agriculture

3. Prolonged wheat phase on duplex soils – where do weeds set the boundary? Vanessa Stewart, Department of Agriculture

WHEAT AGRONOMY

4. Management of small grain screenings in wheat, Dr Wal Anderson and Dr Darshan Sharma, Department of Agriculture

5. Agronomic responses of new wheat varieties, Christine Zaicou-Kunesch ...


The Structure-Function Relationships Of Maize Starch Synthase, Zhong Gao Jan 2001

The Structure-Function Relationships Of Maize Starch Synthase, Zhong Gao

Retrospective Theses and Dissertations

This research was to study the structure-function relationships and catalytic mechanisms of maize starch synthase IIa (SSIIa). Chemical modification of maize SSIIa showed that pyridoxal-5-phosphate, which specifically modifies lysine residues, inactivated maize SSIIa activity in a time and concentration dependent manner. Substrate ADP-glucose completely protected SSIIa from inactivation by pyridoxal-5-phosphate, indicating that lysine residue(s) is important for ADP-glucose binding of maize SSIIa. To identify lysine residues possibly involved in substrate ADP-glucose binding, site-directed mutagenesis was used to generate mutants at conserved lysine sites. Lysine-193 located at the conserved KTGGL domain has been widely suggested as a putative ADP-glucose binding ...


Crop Water Use Or Evapotranspiration, Mahdi Al-Kaisi May 2000

Crop Water Use Or Evapotranspiration, Mahdi Al-Kaisi

Integrated Crop Management News

Crop water use, also known as evapotranspiration (ET), represents soil evaporation and the water used by a crop for growth and cooling purposes. This water is extracted from the soil root zone by the root system, which represents transpiration and is no longer available as stored water in the soil. Consequently, ET is used interchangeably with crop water use. The evapotranspiration process is composed of soil evaporation (E) and transpiration (T). Transpiration is the water transpired or lost to the atmosphere from small openings on the leaf surfaces. Evaporation is the water evaporated or lost from the wet soil and ...


Growth And Water Relations Of Bt And Non-Bt Corn Plants Subjected To Soil Moisture Stress , Seydou Brehima Traore Jan 1999

Growth And Water Relations Of Bt And Non-Bt Corn Plants Subjected To Soil Moisture Stress , Seydou Brehima Traore

Retrospective Theses and Dissertations

A study was conducted at the Iowa State University Hinds Irrigation Farm, Ames, IA during the summers of 1997 and 1998 to compare the Bt and non-Bt versions of two maize (Zea mays, L.) hybrids. The plants were grown in buried, one meter deep, containers filled with a Nicollet loam (Aquic Hapludoll) soil. A rainout shelter protected the plots from the interruption of water deficit by rainfall. Irrigation was scheduled so that the plants experienced water deficit during the peak egg hatch of the first and second European corn borer, Ostrinia nubilalis (Hubner) generations. Water deficit during the vegetative period ...


Effects Of Stress Temperatures Of Germination On Polyamine Titers Of Soybean Seeds , Renan Pineda Mejia Jan 1999

Effects Of Stress Temperatures Of Germination On Polyamine Titers Of Soybean Seeds , Renan Pineda Mejia

Retrospective Theses and Dissertations

High and low stress temperatures during seed germination and seedling development limit total germination and the rate of germination and growth. Changes in polyamine (PA) concentrations in seeds of different species have been associated with germination, growth and environmental stresses such as temperature, drought, oxygen, chilling injury and osmotic conditions. Two studies were conducted to determine the effect of stress temperatures during germination and seedling development on polyamine titers in soybean seeds. Three germination temperatures, 25, 30, and 36 0C were used in the first study to evaluate their influence on changes in polyamine concentrations in soybean seeds germinated at ...


Variation In Alfalfa (Medicago Sativa L.) For Germination And Seedling Vigor At Suboptimal Temperatures: And Laboratory And Field Response To Selection Within Six Alfalfa Populations , Kathy Lynn Esvelt Klos Jan 1999

Variation In Alfalfa (Medicago Sativa L.) For Germination And Seedling Vigor At Suboptimal Temperatures: And Laboratory And Field Response To Selection Within Six Alfalfa Populations , Kathy Lynn Esvelt Klos

Retrospective Theses and Dissertations

Establishment of alfalfa stands planted in the early spring requires rapid germination and vigorous seedling growth at cool temperatures. The extent of variation among ten alfalfa cultivars, 'Marathon' red clover, and 'Norcen' birdsfoot trefoil for germination time and radicle growth rate at 5, 10, and 15 C was evaluated, variation for germination time at 5 and 10 C among seven alfalfa cultivars was compared with variation among seed lots within these cultivars, and same of these cultivars were evaluated for field emergence. The initial radicle growth rate of cultivars increased with temperature, and the germination time of cultivars and of ...


Changes In Physiology, Molecular Biology, And Biochemistry Associated With Maize Seedlings Germinated From Freeze-Damaged Seed , Jack Alan Hartwigsen Jan 1999

Changes In Physiology, Molecular Biology, And Biochemistry Associated With Maize Seedlings Germinated From Freeze-Damaged Seed , Jack Alan Hartwigsen

Retrospective Theses and Dissertations

Injury to immature maize seed caused by early season frost is of great economic concern to seed producers. Surprisingly, there has been very little research investigating the adverse effects of freezing on immature seed and the resulting biochemical changes in seedlings germinated from freeze damaged seed. In this three part study, we investigated the effects of freezing injury, first as they pertained to the overall viability of the seed, then to how exposure of immature seed to freezing induces biochemical changes in seedlings germinated from these seed. We found that the extent of freezing injury as determined by reduced viability ...


Dynamics Of Maize Endosperm Development , Anthony Onwuli Iheanyi Anaele Jan 1998

Dynamics Of Maize Endosperm Development , Anthony Onwuli Iheanyi Anaele

Retrospective Theses and Dissertations

An understanding of cellular events contributing to normal endosperm formation in the maize kernel may provide better models of the construction of grain yield. A commercial hybrid maize, Dekalb 580, was grown in a controlled environment to study dynamics of cellular events in three regions during endosperm development, and to ascertain if this genotype has an indeterminate pattern of endosperm cell division. Longitudinal sections in two planes of endosperm show uniform sizes for both nuclei and cells during the early stages of endosperm development. As endosperm develops, nuclei and cells become increasingly variable in size. In addition, cells acquire irregular ...


Sink-Pulled Simulation Of The Maize Crop , Samiha Abou El-Fetouh Hamed Ouda Jan 1998

Sink-Pulled Simulation Of The Maize Crop , Samiha Abou El-Fetouh Hamed Ouda

Retrospective Theses and Dissertations

Current maize simulation models (CORNF and CERES-Maize) are "source-oriented", in which kernel weight is predicted without simulating sink demand of the kernels. The major goal of this research is to develop a physiologically sound model to simulate vegetative and reproductive growth of maize;The objectives of this study are: (1) to develop a subroutine to predict maize vegetative development; (2) to develop mechanisms to calculate silk growth, fertilization of the silk, and kernel set; (3) to address some of the problems that CENTLI has and use it to simulate grain filling period; (4) to develop a mechanism to predict the ...


Seed Development Of Shrunken-2 Sweet Corn (Zea Mays L.) And The Use Of Film Coating And Field Chemical Applications To Improve Seed Quality , Xianming Duan Jan 1997

Seed Development Of Shrunken-2 Sweet Corn (Zea Mays L.) And The Use Of Film Coating And Field Chemical Applications To Improve Seed Quality , Xianming Duan

Retrospective Theses and Dissertations

This study investigated the impacts of shrunken-2 (sh2) endosperm mutation on sweet corn embryogenesis and germination acquisition during seed development and maturation. Comparison between three pairs of sh2 and sugary (su) isogenic inbred lines and two dent corn inbreds showed that sh2 not only reduced the endosperm reserve accumulation, but also significantly retarded embryo development, especially during early seed development, resulting in a smaller embryo after maturation. Developing seed of sh2 lines acquired the same germinability at least 10 days later than su and dent corn seeds. During the late maturation stage, the germinability of sh2 seeds tended to decline ...


Production, Evaluation, And Utilization Of Hybrid Soybean [Glycine Max (L.) Merr.] , Kimberly Suzanne Lewers Jan 1996

Production, Evaluation, And Utilization Of Hybrid Soybean [Glycine Max (L.) Merr.] , Kimberly Suzanne Lewers

Retrospective Theses and Dissertations

Soybean is an autogamous crop species, and the production of large numbers of hybrid seeds has been tedious. Nevertheless, hybrid seed is important to certain types of research. Insect pollination of male-sterile plants facilitates the production of hybrid soybean seed. A new method of hybrid soybean seed production, the Cosegregation Method, which was developed in this dissertation research, utilizes close genetic linkage between a male-sterility locus, Ms6, and a seedling marker locus, W1. This closely-linked marker system allows identification of male-sterile plants at the seedling stage and improves hybrid seed production through greater efficiency and higher yield of hybrid seed ...


Iowa Survey For Leafy Spurge (Euphorbia Esula) And Study Of Leafy Spurge And Aphthona Nigriscutis Interaction In The Northern Great Plains, Sheri Colleen Huerd Jan 1994

Iowa Survey For Leafy Spurge (Euphorbia Esula) And Study Of Leafy Spurge And Aphthona Nigriscutis Interaction In The Northern Great Plains, Sheri Colleen Huerd

Retrospective Theses and Dissertations

No abstract provided.


Barley Growth, Physiology, And Forage Quality As Influenced By Defoliation And Water Stress , El-Houssine El-Mzouri Jan 1994

Barley Growth, Physiology, And Forage Quality As Influenced By Defoliation And Water Stress , El-Houssine El-Mzouri

Retrospective Theses and Dissertations

Information on how limited water supply might affect the physiological changes that take place after defoliation of barley (Hordeum vulgare L.) after defoliation and their effects on forage-quality characteristics is needed. The objectives of this study were to investigate defoliation and water deficit stress effects on regrowth, physiology and forage quality characteristics of four barley cultivars known to differ in response to grazing. Two studies were conducted in the greenhouse, and in the field; one on defoliation intensity at two maturity stages and the other on defoliation during water stress;In the first study, defoliation generally decreased grain yield and ...


Identification Of Quantitative Trait Loci (Qtl) In Maize On The Basis Of F3 And Testcross Progeny Performance , Thomas Lane Gocken Jan 1993

Identification Of Quantitative Trait Loci (Qtl) In Maize On The Basis Of F3 And Testcross Progeny Performance , Thomas Lane Gocken

Retrospective Theses and Dissertations

Associations between genotypes of molecular marker loci and phenotypic performance can be used to identify QTL. Phenotypic performance is subject to the choice of progeny for evaluation and environmental conditions where evaluation occurs. The objectives of this study were to compare the effectiveness of F[subscript]3 and testcross (TC) progeny evaluation in detecting QTL on the basis of empirical results and theoretical considerations and to determine the stability of QTL detection across environments;One hundred eighty-two F[subscript]2 individuals derived from a B52 x B73 cross were genotyped at 87 segregating RFLP loci. Field performance of F[subscript ...


Mycorrhizal Fungi-Bradyrhizobium-Soybean Tripartite Symbiosis In Iowa Soils , Samina Khalil Jan 1991

Mycorrhizal Fungi-Bradyrhizobium-Soybean Tripartite Symbiosis In Iowa Soils , Samina Khalil

Retrospective Theses and Dissertations

Soybean [Glycine max (L.) Merr.] makes use of two important symbiotic microbial systems: the rhizobial system, in which Bradyrhizobium japonicum fix atmospheric N2 in root nodules, and the vesicular-arbuscular mycorrhizal system, in which VAM fungi increase uptake of phosphate and/or other nutrients from the soil or improve plant drought tolerance. Research has confirmed the advantage of bradyrhizobial and mycorrhizal associations in N and P deficient soils; however, these associations may be inhibitory, or have little effect on plant growth in well-fertilized soils. In Iowa over the past 30-40 years, farmers have been adding large quantities of fertilizers to get ...


Effect Of Weed Water Stress On Postemergence Herbicide Activity , Emilio Sabas Oyarzabal Jan 1991

Effect Of Weed Water Stress On Postemergence Herbicide Activity , Emilio Sabas Oyarzabal

Retrospective Theses and Dissertations

Shattercane (Sorghum bicolor (L.) Moench) and woolly cupgrass (Eriochloa villosa (Thunb.) Kunth) growing under water stress conditions suffer morphological and physiological changes that may affect the activity of postemergence herbicides. Morphological and physiological changes in shattercane and woolly cupgrass growing under different levels of water stress were determined. Leaf area expansion was the growth variable most affected in both species. Both plants exhibit decreased dry matter accumulation due to water stress treatments. Woolly cupgrass stomatal conductance was more affected by water stress than shattercane. Photosynthesis was greatly reduced in both weeds, but only partially related to decreased stomatal conductance, indicating ...


Characterization Of The Alternative Respiratory Pathway In Soybean , David Michael Obenland Jan 1989

Characterization Of The Alternative Respiratory Pathway In Soybean , David Michael Obenland

Retrospective Theses and Dissertations

The alternative respiratory pathway may be important in the energy economy of higher plants. The objective of this study was to characterize the alternative pathway in soybean and to gain a better understanding of the importance of this respiratory pathway to soybean productivity;Capacity for the alternative pathway was assessed in leaf and root tissue of male-sterile and fertile soybean plants and in leaf, embryonic axis and epicotyl tissue, as well as isolated mitochondria, of pea (Pisum sativum L.) by measurement of oxygen uptake in the presence and absence of KCN and salicylhydroxamic acid (SHAM). Male-sterile and fertile soybean tissues ...


Characterization Of The Joint Effects Of Tridiphane And Paraquat In Soybean , Christopher Paul Dionigi Jan 1989

Characterization Of The Joint Effects Of Tridiphane And Paraquat In Soybean , Christopher Paul Dionigi

Retrospective Theses and Dissertations

Visual ratings of percent injury indicated that exposure to tridiphane may increase herbicide-induced oxidative stress in field-grown plants. The objectives of these studies were to characterize the combined effects of tridiphane and paraquat-induced oxidative stress and to determine the physiological factors that underlie these combined effects. Field studies indicate that, under certain conditions, exposure to tridiphane can increase paraquat-induced leaf injury and inhibition of soybean plant height accumulation compared to the injury produced by paraquat applied alone. However, chlorophyll bleaching studies conducted in the field, and electrolyte leakage studies conducted under controlled environmental conditions indicate that exposure to tridiphane does ...


Seed Dormancy Characteristics In Six Weed Species As Affected By After-Ripening Temperatures And Field Conditions , Primo L. Chavarria Jan 1986

Seed Dormancy Characteristics In Six Weed Species As Affected By After-Ripening Temperatures And Field Conditions , Primo L. Chavarria

Retrospective Theses and Dissertations

Dormant seeds of Amaranthus retroflexus L. (AMARE), Chenopodium album L. (CHEAL), Digitaria sanguinalis (L.)Scop. (DIGSA), Echinochloa crus-galli (L.)Beauv. (ECHCG), Polygonum pensylvanicum L. (POLPY), and Setaria glauca (L.)Beauv. (SETLU) were collected in both 1983 and 1984 at the Curtiss Experimental Farm, Ames, Iowa. They were planted both on the soil surface, and at 2 cm in pots, and then exposed to field conditions from January to June, 1984, and from October, 1984 to July, 1985. Five replications of each treatment were removed from the field every month and carried to the greenhouse to test germination capacity, along with ...


Physiological Basis For Transgressive Yielding In Bean-Maize Intercrops , Ethel Ann Clark Jan 1980

Physiological Basis For Transgressive Yielding In Bean-Maize Intercrops , Ethel Ann Clark

Retrospective Theses and Dissertations

No abstract provided.


Soil-Moisture Stress Effects On Reproductive And Vegetative Components Of Soybeans, Mohammad-Mehdi Karimi-Abdachi Jan 1979

Soil-Moisture Stress Effects On Reproductive And Vegetative Components Of Soybeans, Mohammad-Mehdi Karimi-Abdachi

Retrospective Theses and Dissertations

No abstract provided.