Structure and Utilization of Cell Walls of Normal and Brown Midrib Mutant Sorghum X Sudangrass Hybrids
Fritz, John Otto
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https://hdl.handle.net/2142/71651
Description
Title
Structure and Utilization of Cell Walls of Normal and Brown Midrib Mutant Sorghum X Sudangrass Hybrids
Author(s)
Fritz, John Otto
Issue Date
1988
Department of Study
Agronomy
Discipline
Agronomy
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Agronomy
Abstract
In the initial phase of this research, the feasibility of utilizing high resolution gas chromatographic technology to separate and quantify underivatized phenolic monomers was studied. Underivatized phenolic monomers commonly isolated from plant cell walls were separated and quantified on a phenylmentyl capillary column. Analysis of alkali-labile phenolics, which included vanillin and the cis and trans isomers of p-coumaric and ferulic acids, required less than 15 minutes. High resolution gas chromatography, utilizing a phenylmethyl-fused silica column, was found to provide a relatively low cost, rapid and sensitive system for the separation and quantitative analysis of lignin derived phenolic monomers.
In the second phase of this research, two experiments were conducted, utilizing low lignin brown midrib mutants of two sorghum x sudangrass (Sorghum bicolor (L.) Moench) hybrids, to determine the effects of lignin concentration and composition on the digestion and utilization of plant cell walls. In the first experiment, composition and in vitro digestion kinetics were determined for cell walls of morphological components of normal and brown midrib sorghum x sudangrass hybrids harvested at three levels of maturity. Differences in the concentration and chemical composition of lignin accounted for most of the differences between genotypes in cell wall composition. Differences in lignin concentration and composition had no effect on the rate of cell wall digestion; however, the greater extent of digestion observed for brown midrib genotypes was attributed to these differences. Differences between morphological components in cell wall composition were attributed to differences in the concentration and composition of their lignin and structural carbohydrate fractions. The relationship between cell wall composition and digestion for morphological components indicates that p-coumaric acid concentration and linear xylan content are important factors limiting cell wall digestibility. In the second experiment, normal and brown midrib sorghum x sudangrass hay diets were fed to non-lactating Holstein cows to assess the effects of lignin concentration on the in situ rate and extent of cell wall digestion and on ruminal liquid and particulate turnover rates. Lignin concentration had no effect on the rate of cell wall digestion or on the rate of ruminal digesta flow.
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