EFFECT OF GROWTH REGULATORS ON CALLUS INDUCTION AND SHOOT REGENARATION OF LETTUCE (BARI Lettuce-1)

An experiment was carried out at the Plant Biotechnology Lab, Department of Horticulture, Patuakhali Science and Technology University, Dumki, Patuakhali during the period from Nov. 2013 to Mar. 2014. The experiment was laid out in a Completely Randomized Design with four replications. The experiment was conducted in vitro for the development of an efficient regeneration protocol in BARI Lettuce-1 from leaf explant. The leaf explants were used in in vitro culture for callus induction, shoot regeneration and root formation. Different concentrations and combinations of growth regulators were added to Murashige and Skoog medium to observe their efficacy on callus induction, shoot initiation and root formation. The combination of 2.5 mg/L BAP+0.1 mg/L NAA (Fresh wt. of callus 1.624g at 45 DAC) and 1.5 mg/L BAP+0.25 mg/L NAA ( Dry wt. 0.159g at 45 DAC)   was found the best for callus initiation. Shoots were regenerated from the initiated calli upon transfer to Murashige and Skoog medium supplemented with different concentrations and combinations of PGRs. Murashige and Skoog medium supplemented with 2.5 mg/L BAP+0.1 mg/L NAA was the best for shoot induction. Regenerated shoots were transferred to medium containing various levels of Indole-6-Butyric Acid for rooting. Indole-6-Butyric Acid at 1.25 mg/L produced maximum number of roots (14.57), maximum number of leaves (13.82) and the longest (6.382 cm) of plantlets at 45 days after culture.