Genetic Mean Analyses of Earliness Among Brazilian and US Upland Cotton

The development of new cotton lines with improved earliness has always been an important breeding goal around the world. In Brazil, the boll weevil (Anthonomous grandis) has become a major pest of cotton, causing severe economic damage. The use of early-maturing cotton cultivars has been the major agricultural practice to reduce losses and such practice also allows planting of a second crop such as soybean after cotton in Brazil. The objective of the present work was to study the genetics and heritability for earliness using generation mean analysis (GMA) in cultivars with different maturity from Brazil and United States. These cultivars consisted of BRS 269 (cultivar), CNPA GO 2005-809 (inbred) and CNPA GO 2005-158 (inbred) from Brazil as well as three U.S. cultivars: Tamcot CAMD-E, PSC 355, and Acala 1517-99. Six basic generations (P₁, P₂, F₁, F₂, BC₁ and BC₂) for each cross were generated and sown in a randomized block design with three replications during the summer of 2011 in College Station, Texas. Experimental plots consisted of thirty five plants with measurements taken on five normally developing plants in each plot. Data were collected on: node first fruiting branch, first white flower, first open boll, vertical flowering interval, horizontal flowering interval, vertical maturation interval, and horizontal maturation interval. Fiber properties were obtained via high volume instrument (HVI).