HPLC and TGA Investigations of the Secondary Cell Wall Development in Cotton Fibers

Two cotton cultivars (Gossypium hirsutum L. cv.) were planted in the greenhouse and fibers were harvested at different stages of development (from 10 until 56 days post-anthesis). The percentage of sugars present on the fibers was determined by High Performance Liquid Chromatography and the cellulose content was determined using the anthrone method. The percentage of sugars (sucrose, glucose, fructose, and galacturonic acid) showed statistically significant changes during fiber development. The decrease in the percentages of these sugars as the secondary cell wall develops was associated with an increase in the cellulose content.  Thermogravimetric analysis was used to investigate the structural changes that occur during cotton fiber development starting at 10 days post-anthesis.  The percent weight losses attributed to water, non-cellulosic materials, and cellulose macromolecules were calculated from the thermograms.  Valuable information was obtained related to the composition of the cell wall and the timing of the transition between the primary cell wall and the secondary cell wall.  The results indicated that the two cultivars investigated exhibited different structural evolution.