A Study of factors influencing in vitro callus induction in cotton (G.hirsutum L.)

This study was undertaken to test the effect of genotype, explant type, growth regulator, explant age and gelling agents on cotton callus induction. Callus cultures were initiated from the cotyledon and hypocotyls explants of the three cotton (Gossypium hirsutum L.) cultivars Coker 310, MCU 12 and KC 3 on MS basal medium supplemented with different concentrations (0.1, 0.5, 1.0 mg L⁻¹) and combinations of growth regulators (2, 4-D and Kinetin, 2, 4-D and BAP, 2, 4-D and TDZ and 2, 4-D and Zeatin). Of the thirty six different callus induction medium (CIM) tried, CIM2 medium supplemented with 0.1mg L⁻¹ 2, 4-D and 0.5mg L⁻¹ kinetin promoted 100% callus induction irrespective of the genotypes and explants. It was also observed that callus initiation was found to be quicker in hypocotyls than cotyledon explants. Of the different explant ages (4, 7, 10, 14, 21 and 28 days), 7 day old cotyledon and hypocotyls explants exhibited highest callus induction frequency irrespective of the genotypes. Out of the two gelling agents compared, the rate of callus proliferation was found to be faster with 0.4% phytagel than with 0.8% agar. Thus, conditions for initiation of callus in cotton (Gossypium hirsutum L.) cultivars Coker 310, MCU 12 and KC 3 were optimized in this study.