Length of Fiber Elongation Period in Extra Long Staple Upland Cotton Genotypes Compared with Tamcot 73

Upland cotton (Gossypium hirsutum), an oilseed and fiber crop, native to Mexico, Central America, and United States, is grown in 17 states in the U.S. and in more than 70 countries worldwide. The natural fiber of upland cotton is a high-value crop that is grown by producers as raw material for the textile industry. The objective of this work was to evaluate fiber elongation in four cotton genotypes in five different periods of harvest. Field work was conducted at the Texas A&M University Research Farm, located near College Station, TX in 2013.  The four cotton genotypes used were: Tamcot 73, TAM 11K-13 ELS, TAM B182-33ELS and NMSI 1331.  For each genotype, bolls were harvested at 22, 25, 28 and 31 post-anthesis, and at open boll. Boll age was estimated by tagging first position bolls located four nodes below the top most first position white bloom. These bolls were tagged and dated 10 days prior to date of tagging. Bolls subsequently were harvested when 22, 25, 28, and 31 days post their estimated date of anthesis.  Unopened bolls were opened by hand, the seed cotton removed, and allowed to dry. For each genotype, 50 open bolls were harvested. All samples were ginned using a roller gin. Fiber elongation of the ELS upland genotypes will be compared with Tamcot 73, a medium staple cultivar, and NMSI 1331, a Gossypium barbadense.