Date of Award:

1980

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Animal, Dairy, and Veterinary Sciences

Advisor/Chair:

Lorin E. Harris

Abstract

This study was concerned with development of chromatographic methods suitable for determination of plant sugars. The resultant methodology was applied to the comprehensive study of plant carbohydrates as they vary during plant growth. Plant cell walls were isolated with boiling water followed by delignification with acid chlorite. The soluble portions were hydrolyzed with 2N sulfuric acid and the total sugars and individual monosaccharides were quantified using gas chromatography and colorimetry. The insoluble residues were hydrolyzed with 72% sulfuric acid followed by dilution with water to 2N and further hydrolysis. The effects of duration of delignification and acid hydrolysis were interpreted in terms of carbohydrate yield monitored colorimetrically and with gas chromatography.

The rapid derivation of sugars was perfected using N-methyl-imidazole as an acetylation catalyst. This catalyst was also employed for the derivatization of lactonized aldonic acids, enabling the gas chromatographic quantitation of uronic acids.

The growth of reed canarygrass was interpreted with empirical and non-empirical methodology. the empirical procedures provided little insightinto plant cell wall composition. The non-empirical methodology which included DMSO extraction and gas-liquid chromatography revealed the possible presence of a branched galactoarabinoxylan and a linear arabinoxylan in reed canarygrass hemicellulose. The presence of β-glucan was also confirmed using selective enzymatic hydrolysis. As the plants matured, the proportion of linear xylan increased. The occurence of galactose, mannose, fucose and rhamnose in cell wall extracts may be the result of acid catalyzed degradations and transformations of other cell wall sugars.

The results revealed the value of chromatography as it is applied to interpretation of plant growth and composition. Gas-liquid chromatography was proposed as a tool for the evaluation of forage digestibility and forage quality.

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