A comparison of two cotton cultivars differing in maturity for within-canopy fiber property variation
Improving uniformity in cotton (Gossypium hirsutum L.) fiber properties increases fiber processing performance. Our objective was to compare two cultivars differing in relative maturity for within-canopy variability of fiber physical properties and fiber surface chemical constituents. The cultivars (DPL 555 BG/RR [mid-full maturity] and PM 1218 BG/RR [early maturity]) were grown in plots on a Goldsboro loamy sand in 2004 and 2005. Fiber physical properties and extractable glucose and salts were determined on first (FP1) and second (FP2) reproductive branch position bolls. Whole-crop yield and fiber properties were determined after machine harvest. The two cultivars did not differ for whole-crop yield (2-yr mean of 1040 kg ha–1) in either year. Averaged over all mainstem node positions, DPL 555 had fibers that were longer and finer than fiber of PM 1218 in both years. PM 1218 had higher fiber glucose and fiber extract conductivity than DPL 555 among FP1 bolls both years. First-branch-position bolls that developed early during a prolonged rain-free period in 2005 had shorter fibers that were coarser than bolls that began developing near the end of the rain-free period. The data suggest water-deficit stress conditions during boll development affects fiber length of these two cultivars similarly, but water-deficit stress effect on fiber secondary wall characteristics is genotype dependent.