| Most cotton Gossypium hursutum (Malvaceae) genotypes of commercial interest present problems of in vitro regeneration. Aiming at improving regeneration rate, meristems and caulinar apices (region with about 5 mm length, immediately below the meristematic region) of IAC 22 and COKER 312 cultivars were extracted from plants with 2 or 3 primordia leaves and grown in Murashige and Skoog (MS) medium containing thidiazuron (TDZ), with concentrations ranging between 0.02 µM and 5.0 µM, in 3- to 7-day periods, with naphthaleneacetic acid (NAA) and gibberellic acid (GA3). The number of shoots from meristems was higher in 0.02 µM TDZ concentrations. In the case of caulinar apices, best results were obtained with 0.5 and 1.0 µM... |
