Single Fiber Strength Variations of Developing Cotton Fibers—Strength and Structure of G. hirsutum and G. barbedense

Abstract

This paper reports on the single fiber strength and crystalline structure of two cotton fiber species, G. hirsutum (Texas Marker 1) and G. barbedense (Pima S7), at varying developmen tal stages from 20 days post-anthesis (dpa) to maturity. For both species, the force required to break single fibers increases with fiber development, with the most significant increases occurring during the fourth week of cell development. The patterns of increasing breaking force through the end of the fourth week of fiber development are similar for these two species. As fibers develop beyond 30 dpa, the single fiber breaking force and tenacity of G. barbedense fibers are higher than those of G. hirsutum fibers. Both developing fibers show characteristic cellulose I diffraction patterns. The overall crystallinity and apparent crystallite sizes increase with development for both species. The most significant increases in L101, L101, and crystal linity occur between 20 and 35 dpa, corresponding to the first two weeks of cellulose synthesis or the fourth and fifth weeks of overall fiber development. Development beyond five weeks does not contribute to any change in crystallite dimensions or crystallinity, consistent with the leveling of tenacity at this later stage of development.