Multiple shoot regeneration of cotton (Gossypium hirsutum L.) via shoot apex culture system

Induction of multiple shoots of cotton (Gossypium hirsutum L.) plant in two commercial varieties (Sahel and Varamin) using shoot apex was done. Explants were isolated from 3 - 4 days old seedlings, then they were cultured on a shoot induction media, modified MS nutrient agar with combinations: 1- Kinetin (0.0, 0.5, 1.0, 1.5 mg l-1) and 6-benzyaminopurine (BAP) (0.0, 0.1, 0.5, 1.0, 1.5 mg l-1), 2- α- naphthaleneacetic acid (NAA) (0.0, 0.1, 1.0 mg l-1) and BAP (0.0, 0.1, 0.5, 1.0, 1.5 mg l-1). After 1.5 - 2 months, multiple shoot induction medium with 0.1 mg l-1 NAA and 0.1 mg l-1 BAP resulted in the highest number of regenerated shoots per explant (3 - 4 shoots per explant) for the two cultivars. Elongation of multiple shoots was obtained on modified MS nutrient agar without any phytohormone. In vitro shoots were rooted on half-strength agar-solidified MS basal medium supplied with 0.1 mg l-1 Iidole-3-butyric acid (IBA) and MS vitamins.Key words: Cotton, Shoot apex, multiple shoot