Iron and Zinc Physiology in Sweetpotato
Sweetpotato [Ipomoea batatas (L.) Lam.] is an important provider of nutrition in developing countries. High productivity in the form of starch and beta carotene richness underlies its potential. A sweetpotato with adequate levels of iron and zinc would greatly aid efforts to reduce dietary deficiencies of iron and zinc. The objective of this work is to document the physiological accumulation of iron and zinc in sweetpotato during development and the mechanisms responsible for iron uptake.
Six varieties (IPS 163, Beauregard,Koto-puki, Pung-mi, Duanyanghon, and Xushu 18) were compared to understand iron and zinc accumulation during development. Results showed that micronutrient content in developing roots varied minimally during storage root development (13-16 weeks after planting). Varieties tend to accumulate these micronutrients similarly throughout development. These results suggest that varieties can be assayed for iron and zinc concentration anytime roots are of sufficient size for analysis.
Hydroponic studies were conducted to determine how high and low iron concentration genotypes respond to the absence of iron in nutrient solution. Variables included iron reductase, pH, and root mass development. Results from the nutrient solution study showed that the pH of nutrient solution increased. A low pH environment facilitates the transition from an unavailable form of Fe (III) to an available form Fe (II). Sweetpotato may respond differentially than other species.
Iron reductase activity differed among varieties. High iron accumulating Pata de Oso showed reduced iron reductase activity in plants grown in an iron deficient environment. In contrast, Pung-mi, a low iron accumulating variety, significantly increased iron reductase activity when grown in an iron deficient environment. These results suggest that high iron accumulating varieties did not increase iron reductase activity. Varieties poor in iron accumulation either did not vary or seemed to increase iron reductase activity in an iron deficient environment. A greater root mass is also a means by which plants can uptake greater amounts of iron. High iron concentration varieties had the lowest root mass in comparison to low concentration varieties. When Fe-sufficient and Fe-deficient treatments were compared, only Pung-mi showed a significantly smaller root mass when grown in an Fe-deficient environment.
Advisor:Jeffrey Beasley; Edward Bush; Don La Bonte
School:Louisiana State University in Shreveport
School Location:USA - Louisiana
Source Type:Master's Thesis
Date of Publication:11/13/2008