Diallel Analysis of Earliness Among Brazilian and U.S. Upland Cotton

Improving earliness has been and continues to be an important goal in many cotton breeding programs.  While the boll weevil (Anthonomus grandis  Boh.) has been functionally eradicated in the most of the U.S., it  is a problem for the Brazilian cotton industry. Early maturing cultivars provide an avoidance mechanism and allow double cropping with soybean in Brazil. Objectives of this study were to estimate general combining ability (GSA) and specific combing ability (SCA) for earliness traits among cultivars with a range of maturity developed in Brazil and the United States. One cultivar (BRS 269) and two inbred lines (CNPA GO 2005 – 809 and CNPA GO 2005 – 158) from Brazil,  and three U.S. cultivars (Tamcot CAMD–E, PSC 355 and Acala 1517-99), were mated  in a partial diallel  during 2009  at College Station, Texas. Parents and F₁ progeny were evaluated in a randomized complete block design with three replications during the summer of 2010 in College Station.  Experimental plots consisted of ten plants with measurements taken on five normally developing plants. Data collected were: node first fruiting branch;  days from emergence to first square,  first white flower,  and first open boll; vertical flowering interval; horizontal flowering interval; vertical maturation interval; and horizontal maturation interval.  Griffing´s method 4, model 1 analysis and HVI fiber properties also will be presented.