Cotton Fiber Structure and Physical Properties Altered by Environment

Abstract

By varying light and temperature, differences in diurnal ring structure were produced in cotton fibers from inbred lines of Deltapine 14 and Rex 25C belonging to the species Gossypium hirsutum. The relationships of the secondary wall structure to physical and chemical properties were then investigated. When fibers were swollen with a mixture of cuprammonium and cupriethylene diamine hydroxides solutions, optical microscopic methods indicated that variations in the temperature had caused a diurnal ring structure. If the temperature was held constant, even though the light varied by alternating with dark periods, no diurnal rings were observed. When fibers were swollen with a methanol-water mixture and embedded in methyl methacrylate, the electron microscope method of layer expansion technique indicated no differences in the cell-wall structure related to the light and temperature fluctuations. Although segments of the secondary wall, with and' without rings ruptured tangential to the primary wall and followed the pattern of a ring structure, no evidence was found that the rupture planes were correlated with the ring structure when such existed. The period between flowering and boll opening varied with environmental conditions; the shortest period occurred when the temperature was constant at 85°F and the light was continuous. The gross properties of fibers, such as linear density. length, and maturity, differed with growth conditions. For cottons grown under controlled environments, the varia tions were small in cellulose density, percentage of crystalline cellulose, cellulose orienta tion, and moisture regain. At a constant angle of cellulose orientation, cottons with the diurnal rings were stronger and by bundle test methods, had slightly lower elongations at break. When the cottons of different ring structures were treated with a cross-linking agent, the cottons with no rings decreased in strength and elongation slightly more than the cottons with rings. The tensile properties showed the most consistent relations to the diurnal ring structure, but differences between cottons with and without rings were small.