Genetic variability was obtained by the authors for fiber strenght in cotton, through hybridization between the cultivated alotetraploid species Gossypium hirsutum L. var. latifolium Hutch. and the wild diploid species G. herbaceum L. africanum Hutch. The underlying methods and the hybrid's characteristics are reported and described. As a first step, the number of chromosomes in the diploid species was duplicated. Nine treatments with aqueous colchicina or colchicina in lanolina paste were carried out, comprising several concentrations and times of application to seeds, radicles and apical buds of the main stem. Success was obtained by treating apical buds with lanolina paste containing 1% colchicina, during 32 hours. Two hundred fourty five crosses between the duplicated africanum and cultivated varieties of cotton led to the obtention of thirteen sterile F1 plants. However, bud fertility was restaured after a first backcross. These back-crossed plants having promising agronomic characteristics and large variability for fiber strength, will be selected to develop a high fiber quality commercial variety.
cotton breeding; G. hirsutum x G herbaceum; chromosome duplication