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Iowa State University

Plant Sciences

Graduate Theses and Dissertations

Yield

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Limestone Application On A Ferralsol Soil And Genotype By Environment Effects On Yield And Grain Nutrient Composition In Common Bean, Rosemary Bulyaba Jan 2019

Limestone Application On A Ferralsol Soil And Genotype By Environment Effects On Yield And Grain Nutrient Composition In Common Bean, Rosemary Bulyaba

Graduate Theses and Dissertations

Food and nutritional insecurity are prevalent in sub-Saharan Africa, where years of poor soil management have left most agricultural lands mineral deficient and low in organic matter. In Uganda, soil acidity is a major contributor to low agricultural productivity, hunger, malnutrition and the vicious cycle of poverty. To meet yield demands and nutritional needs in Uganda, publicly funded breeding programs released biofortified common bean varieties such as NAROBEAN 1 and 3, that are high yielding, drought resilient and high in commonly deficient nutrients such as iron and zinc. The main objective of this study was to determine the effect of ...


Physiology Of Genotype X Soil Fertility Effects On Yield And Accumulation Of Iron And Zinc In The Common Bean (Phaseolus Vulgaris L.) Seed, Gerald Sebuwufu Jan 2013

Physiology Of Genotype X Soil Fertility Effects On Yield And Accumulation Of Iron And Zinc In The Common Bean (Phaseolus Vulgaris L.) Seed, Gerald Sebuwufu

Graduate Theses and Dissertations

This thesis research focused on evaluating improved common bean (Phaseolus vulgaris L.) germplasm under intensified fertility regimes, and assessing how assimilate partitioning to the seed impacts seed mineral concentration. In Chapter 2, the agronomic performance of four improved varieties was evaluated on small-landholder farms using locally available manure and typical farming practices. Only one of the improved varieties, K131, yielded significantly more than the local check, Kanyebwa. Use of locally available manure significantly increased yields, but they remained less than 50% of the potential yield of improved varieties as demonstrated by the experiment station. Among resource limited farmers, options for ...


Performance Evaluation Of Nine Varieties Of Miscanthus In Iowa, Muhammad Aurangzaib Jan 2012

Performance Evaluation Of Nine Varieties Of Miscanthus In Iowa, Muhammad Aurangzaib

Graduate Theses and Dissertations

Miscanthus is a tall perennial grass species native to parts of Asia. It has the potential to produce relatively high dry matter yields across a wide range of environmental and soil conditions. The Miscanthus cultivar most commonly recommended for biofuel production is a sterile hybrid (M. × giganteus) of M. sacchariflorus × M. sinensis , but there are some challenges for its production. One of them is the occurrence of cold damage during the first winter after planting when plant losses can be high. These losses could be exacerbated by incomplete or late senescence. A field trial was established in spring 2010 with ...


Did Recurrent Selection For Yield Affect Iowa Stiff Stalk Synthetic Maize Population Grain Fill Characteristics?, Steve James Eichenberger Jan 2011

Did Recurrent Selection For Yield Affect Iowa Stiff Stalk Synthetic Maize Population Grain Fill Characteristics?, Steve James Eichenberger

Graduate Theses and Dissertations

Hybrid maize yield increases, new product development, and increased stress tolerance can be more easily achieved with a better understanding of the physiological and genetic basis for phenotypic changes in response to recurrent selection for yield. The purpose of this study was to identify changes in grain fill characteristics and their interaction with plant density in a closed population and identify a model that accurately predicts grain fill in this population. We hypothesize that recurrent selection for increased yield indirectly impacted the grain fill characteristics of maize including final kernel weight, kernel fill duration, and kernel fill rate in the ...


Agronomic And Phenotypic Responses To 75 Years Of Recurrent Selection For Yield In The Iowa Stiff Stalk Synthetic Maize Population, Brent Howard Brekke Jan 2010

Agronomic And Phenotypic Responses To 75 Years Of Recurrent Selection For Yield In The Iowa Stiff Stalk Synthetic Maize Population, Brent Howard Brekke

Graduate Theses and Dissertations

The plant density at which Zea mays L. hybrids achieve maximum grain yield has increased throughout the hybrid era while grain yield on a per plant basis has increased little. Changes in plant traits including grain yield, moisture, test weight, stalk and root lodging, flag leaf angle, anthesis-silking interval(ASI), plant height, tassel branch number, and total number of leaves have been well characterized in comparisons of commercial hybrids representing different eras of hybrid maize production but have yet to be examined in a recurrent selection program.

The objective of this experiment was to determine if direct selection for grain ...


Tillage Effects On Soybean Growth, Development, And Yield, Alecia Marie Kiszonas Jan 2010

Tillage Effects On Soybean Growth, Development, And Yield, Alecia Marie Kiszonas

Graduate Theses and Dissertations

Profit margins of soybean [Glycine max (L.) Merr.] in the United States have recently declined as a result of an increase in production and land costs. Decreased profits coupled with increasing environmental concerns such as erosion and runoff prompts more cost-efficient production practices. No-tillage production practices offer a lower cost of production in addition to decreased soil erosion and runoff. Additionally, soil quality can be improved over time in a no-tillage system, greatly increasing the yield benefits over time. Today, only 41% of Iowa's soybean production is under no-tillage production (Conservation Technology Information Center, 2010), although even more of ...


Cyst Nematode Resistance And Seed Yield Of Soybean Lines Derived From Ss97-6946, Gregory Lynn Doonan Jan 2009

Cyst Nematode Resistance And Seed Yield Of Soybean Lines Derived From Ss97-6946, Gregory Lynn Doonan

Graduate Theses and Dissertations

New sources of resistance to the soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) would be useful for soybean [Glycine max (L.) Merr.] cultivar development. The objective of this study was to determine the relationship between SCN resistance and seed yield for a new source of SCN resistance, SS97-6946, developed by the Univ. of Missouri-Columbia. F5-derived lines were developed from the cross of SS97-6946 x S27-T7, a SCN-susceptible cultivar developed by Syngenta. Nine sets of 32 F5:8 lines each were evaluated for yield in replicated tests at five Midwest locations during 2007. The lines were evaluated for resistance to four ...


Soil And Fertilizer Potassium Impacts On Corn And Soybean Grain Yield, Potassium Uptake, And Within-Field Grain Yield Variation, Matthew William Clover Jan 2008

Soil And Fertilizer Potassium Impacts On Corn And Soybean Grain Yield, Potassium Uptake, And Within-Field Grain Yield Variation, Matthew William Clover

Graduate Theses and Dissertations

Two studies were conducted in Iowa to better understand how potassium (K) fertilization affects grain yield, vegetative growth, and K concentration of different parts of modern corn (Zea mays L.) hybrids and soybean (Glycine max L. Merr.) varieties. One study was based on one- to three-year strip-trials (63 site-years) conducted from 2001 to 2007 to evaluate the effects of K fertilization on corn and soybean grain yield and post-harvest soil-test K (STK) measured with the ammonium acetate extractant. Replicated treatments were 0 and 168 kg K ha-1. Potassium increased yield as evaluated by strip averages in 21 of 63 ...