We investigated the relationship between elemental (inorganic) composition and strength of cotton fiber in different genotypes. Fiber samples from the new higher strength cotton variety for the MidSouth, Mississippi Delta 51 ne (MD51) were assayed and compared with the popular Deltapine 90 (DPL90). The F1 cross (MD51 x DPL90) and two selected BC-3 (backcrosses) F2/F3 progenies were evaluated from progeny rows in three replicates at Stoneville, MS.

Levels of phosphorus, calcium and magnesium had significant variety effects, whereas zinc and arsenic had significant replication effects. A significant variety and replication interaction was determined for potassium, sulfur, chlorine, aluminum, silicon and iron. Conventional strength evaluations have indicated MD51 to be -11% higher in strength than DPL90. Single fiber strength (tenacity) for MD51 was higher than DPL90 by 30%. Separate regressions for key components versus physical properties indicated significant relationships between: (1) potassium and tenacity (bundle), tenacity (single fiber), extension-at-break (single fiber), 2.5% S.L., linear density (negative); (2) calcium or magnesium and micronaire (negative), tenacity (bundle), linear density (negative), tenacity (single fiber), and extension-at-break (single fiber); (3) phosphorus and micronaire (negative), linear density (negative), tenacity (single fiber), extension (single fiber). Only phosphorus correlated (negatively) with cellulose crystallinity.

Regression coefficients were highest between calcium or magnesium and strength. These results indicate that, despite low levels (0.1%) of calcium and magnesium, their role in fiber strength is potentially large.