Sanghun Lee

Document Type

Thesis - University Access Only

Award Date

2005

Degree Name

Master of Science (MS)

Department / School

Poultry Science

Abstract

Global interest in selenium (Se) has increased over the past few years due to its anti-oxidant and potential anti-cancer attributes in animal and human health. Information on the benefits of Se for a healthy (wellbeing) life continues to grow. Selenium has a very narrow sufficiency range. Too much Se consumption results in toxicity while too little results in deficiency. For humans and animals, their main dietary source of Se is from soil through plants in the food chain. The demand for food products naturally rich in Se is increasing because of increasing cancer risks around the world. In high Se areas of the world (e.g., South Dakota) the management of Se uptake by plants is necessary to obtain a steady supply of certifiable Se-rich food and feed products. Therefore, understanding crop management influence on Se uptake by wheat ( Triticum aestivum) is a critical need if the producers with seleniferous soil are to capitalize on this natural resource. The objectives of this study were to: 1) determine the effect of high phosphorus (P) fertilization on wheat; 2) determine the effect of P fertilizer on Se uptake by selected wheat varieties (Triticum aestivum L. var. Oxen, Granger, Arapahoe, and Wendy) when grown on seleniferous soil materials from South Dakota; and 3) investigate the changes in Se fractionation in alkali soil materials when P fertilizer is applied. In study 1, five different concentrations (13, 100, 250, 500, and 1,000 mg P kg"1) of P fertilizer were applied to determine the effect of high P fertilization to four selected spring wheat varieties. Phosphorus fertilization of more than 100 mg P kg·1 significantly increased total biomass and grain yield when compared to P fertilization of 13 mg P kg·1. There was no negative effect of P fertilization at the high rates on biomass, yield, and P concentration in wheat tissues. And there was also no significant difference between wheat varieties. In study 2, soil (A horizon from the Promise series: very-fine, smectitic, mesic Typic Haplusterts) from Presho, South Dakota, was used in a greenhouse experiment. The high clay content soil was diluted 10% (volume/weight) with Pertite to facilitate pot drainage and aeration. The soil Se was fractionated into five fractions: 1) soluble Se (available to plants); 2) ligand exchangeable Se (available to plants); 3) acid extractable Se (conditionally available to plants); 4) oxidative acid decomposable Se (unavailable); and 5) residual Se (unavailable). The Se concentration by fraction of the Promise soil (A horizon) was measured to be 0.07, 0.08, 1.56, 1.17, and 1.36 mg Se kg·1, respectively. The main treatment was P fertilizer (KH2PO4) application at three different rates (0, 100, and 250 mg P kg"1). Four wheat seeds were planted into the pots and grown to a full maturity. Total biomass of spring and winter wheat was affected by a wheat variety X P application interaction. Phosphorus fertilization increased the available P in the soil and total P in stem and grain tissues of all wheat varieties. There was no statistical difference in total P concentration in wheat tissues between 100 and 250 mg P kg·1 fertilizer application rate. Extractable sulfur in the soil significantly increased with P fertilizer application. After wheat harvest, there were no significant changes in soil Se fractions (Fraction 1 through 5) except for Fraction 2 (ligand exchangeable Se). ligand exchangeable Se significantly decreased with increasing P fertilizer application in both spring and winter wheat But, total Se in soils was unaffected by wheat varieties or P fertilizer application. Phosphorus fertilization increased the total absorbed Se in stems and grain in all wheat varieties. However, Se concentrations in plant tissues were not significantly affected by P fertilization at 95% level.

Library of Congress Subject Headings

Phosphatic fertilizers
Wheat -- Growth
Selenium -- Bioavailability

Format

application/pdf

Number of Pages

85

Publisher

South Dakota State University

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