On the Radial Variation of Spiral Angle in the Cotton Fiber

Abstract
Two current models of fibrillar orientation in the cotton fiber were examined in light of x-ray orientation measurements on six cultivars at four different stages of maturity. Neither the constant-spiral-angle nor the constant-gyre-length models for S2 secondary-wall fibrillar orientation satisfactorily explains the observations. A rapid decrease in spiral angle in the outermost diurnal layers, after which constancy in spiral angle is approached, explains the observations best.