Optimization of Growth Regulators for Induction of Callus from Cotton (Gossypium hirsutum)

The objective of this study was to optimize the concentration of different plant growth regulators or hormones for callus induction of cotton (Gossypium hirsutum L.). Different types and concentrations of growth regulators were tested in order to obtain the best callus formation. Four growth hormones such as 1-naphthalene acetic acid NAP), 6-Benzylaminopurine (BAP), Kinetin and 2,4-dichlorophenoxyacetic acid (2,4–D) were used in this study. It was found that growth regulator type and concentration had a significant effect on the callus induction, the increment of callus index and callus physical appearance. The higher frequency of callus growth (95 - 100%) were observed on both epicotyls and cotyledon explants cultured on basal medium supplemented with 0.1 mg/l NAA + 0.5 mg/l Bap and various concentrations such as 0.2 + 0.1, 0.5 + 0.1, 1.0 + 0.2 mg/l of NAA + BAP also shows good callus response but at higher concentration of the same hormones shuts the callus growth. The concentration of BAP and 2,4- D also shows good callus response in higher concentration whereas low concentrations of this hormone combination show nil effect. The morphology of callus differs upon the hormonal concentration from green to white and green to brown with various textures. This protocol paves the way for the development of in vitro regeneration for cotton and consequently will promote the application of plant tissue culture.