Abstract

In vitro regeneration of cotton (Gossypium spp.) has been a subject of intense research for the last two decades because of the commercial value of the crop. A study was conducted to assess the callusing potential of two local cotton genotype varieties viz., MCU-5 and SVPR-2 and two exotic genotypes, Coker 310 and 312. High significant difference was observed between media composition, genotype and explant types used for callus induction. Among the 24 media composition screened for callusing, the medium CIM3 (MS + 0.1 mg/l 2,4-D + 0.5 mg/l kinetin) exhibited successful and faster induction of calli. Callus initiation was found to be quicker from hypocotyls than cotyledons. Calli developed from hypocotyl explants were large, rough and friable, while cotyledon-derived calli were friable and medium sized. Significantly higher callus induction frequencies were observed in hypocotyl (97.3%) than cotyledon (95.8%) explants which were collected from 7 day-old seedlings irrespective of genotype. Explants collected from younger (4 day-old) and older (14 day-old) plants showed poor and low callus induction frequencies.

Key words: Callus, cotyledon, Gossypium hirsutum, hypocotyl, media composition.