Early, normal and late planted cotton may have different boll distribution patterns due to environmental changes during the season. Mepiquat chloride (MC) offers the potential to alter boll distribution patterns and fiber properties. This study was conducted to compare fiber properties on a boll location basis in early, normal and late planted untreated and MC-treated cotton. Planting dates were early March, mid March and early April. Mepiquat chloride was applied to produce a plant concentration of 38 ppm in 1997 and 12 ppm in 1999. Fiber quality was assessed using the Advanced Fiber Information System (AFIS) on an individual boll basis. Boll distribution patterns were not altered by MC-treatment. Mepiquat chloride treatment increased fiber length of first position bolls at nodes 11-13 for all planting dates in 1997. Theta, the degree of cell wall thickening is related to maturity. A maturity ratio of 1 is equivalent to a theta value of
0.577. In both years MC-treatment increased fiber maturity (theta) values in first position bolls at nodes 14 and greater in the early planting date. In 1997, MC-treatment increased fiber maturity (theta) values at several boll locations in late planted cotton. In management decisions MC application rates and planting date should be considered since MC had the potential to increase or decrease fiber maturity.