Degree Type

Dissertation

Date of Award

2016

Degree Name

Doctor of Philosophy

Department

Agronomy

Major

Crop Production and Physiology

First Advisor

Kenneth J. Moore

Abstract

Corn (Zea mays L.) grain in part has been used in Midwestern U.S. for bioethanol production; however, corn stover for lignocellulosic ethanol is gaining interest as an alternative source of energy. Over two years, three studies explored the biomass potential of tropical corn, corn adapted from tropical regions, for biomass production toward lignocellulosic ethanol. The first study investigated the phenology of adapted and non-adapted tropical corn populations grown under central Iowa conditions. Field trials were conducted where three adapted populations (Tuxpeño, Suwan, and Tuson) and their non-adapted counterparts were planted at three dates during the 2014 and 2015 growing seasons. Although the adapted populations yielded more grain and had earlier reproductive development, non-adapted populations had 22% greater total biomass and 43% greater non-grain biomass, were taller, and showed greater vegetative development. Results of the first study suggest that non-adapted populations have a high potential as bioenergy feedstock when grown under Iowa conditions. The second study evaluated the biomass production and composition of temperate and tropical corn using a defined set of management practices. Additional field trials were established using six genotypes of different relative maturities planted with two plant densities, two row spacings, and two levels of nitrogen fertilization. The measurements included: (a) total biomass, height at the final leaf collar, and stem diameter at one meter above ground; (b) protein, oil, and starch concentrations in grain; and (c) lignocellulose, ash, and nitrogen concentrations of non-grain tissues. Temperate corn had greater grain yield, grain starch and matured earlier, as well as greater cellulose, lignin, and ash concentrations in non-grain tissues. However, tropical corn were taller and had greater non-grain biomass and up to 20% greater total biomass than temperate corn. Row spacing affected biomass yield: the narrower the rows, the greater the biomass. Nitrogen fertilizer rate affected grain and feedstock composition: the lower the rate, the higher the grain starch and lignocellulose composition. Lastly, the third study evaluated the growth, light interception, and nitrogen concentration of temperate and tropical corn during the middle of the growing season using a set of management practices oriented towards biomass production. The same field trials as the second study were used but at one level of nitrogen. Leaf area index (LAI), height at the final leaf collar, biomass, and nitrogen concentrations were measured. Using narrower rows, both temperate and tropical corn were taller, had greater stem and leaf nitrogen concentrations, and showed greater biomass accumulation, especially beyond 100 days after planting. However, LAI was greater for corn grown in wider rows at all the harvest dates. Tropical corn had greater LAI, plant height, and biomass than temperate at mid growing season, which continues through the season until final harvest. Overall, tropical corn proved to have good potential for use as a bioenergy feedstock for ethanol production.

Copyright Owner

Pedro Alexander Infante-Posada

Language

en

File Format

application/pdf

File Size

155 pages

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