Distribution of single fiber tensile properties of four cotton genotypes

The distributions of breaking force and elongation of single fibers from five cultivated cotton varieties, African-51 (G. herbaceum), Asian-163 (G. arboreum), Maxxa and Texas Marker-1 (G. hirsutum), and Pima-S7 (G. barbadense), are studied. The range and distribution patterns of single fiber breaking force and elongation are significantly different for these cultivars and appear to be highly dependent on genotypes. Single fiber breaking force ranges from 16, 17, 20, 24, and 28 g for Pima-S7, TM-1, Maxxa, African-51, and Asian- 163, respectively, and single fiber breaking elongation ranges from 16, 17, 18, 18, and 24% for these varieties. The single fiber breaking forces of Pima-S7 and TM-1 are symmetrically distributed, whereas those of the other three are asymmetrically distributed. African-51 and Maxxa have longer right tails, whereas Asian-163 has a longer left tail. Distributions of single fiber breaking elongation for all five varieties are asymmetrical and positively skewed, with the African and Asian cultivars having longer right tails. Within each cultivar, fibers of varying lengths have similar distributions in their breaking forces and elongation. This lack of relationship with fiber length suggests that these fibers' tensile properties may be independent of length development, i.e., during elongation of the primary cell wall through the early stage of secondary cell wall synthesis. Single fiber breaking force and elongation are positively correlated (r = 0.259 to 0.443) for all five varieties, with Pima having the highest correlation coefficient.