EFFECT OF THIDIAZURON AND 2,4-DICHLORO PHENOXY ACETIC ACID ON CALLUS DEVELOPMENT IN TEA CLONE UPASI 9 TDZ AND 2,4-D ON TEA CALLUS INITIATIONRISHIKESH M., N. MANIKANDA BOOPATHI, P. MEENAKSHISUNDARAM, D. KEISAR LOURDUSAMY AND M. KANNANAbstract A commonly cultivated tea clone, UPASI 9, is currently propagated through cuttings, an endeavor that has been proved to be environmentally hazardous (due to the use of large quantities of excavated soil) and unprofitable. As an alternative, this study highlights tissue culture as a viable option for the robust and easy regeneration strategy for the tea clone UPASI 9. A study was initiated to establish an in vitro culture protocol for Nilgiris tea (Camellia sinensis) by standardizing explant sources, disinfestation methods, and the constitution of culture media. Segments were dissected from greenwood stem (current year growth) internodes of field-grown tea plants. Disinfestation was achieved by successive treatments of fungicide (Bavistin), 0.1% mercuric chloride, and 7.5% CaCl2. MS medium supplemented with sucrose (30 g/l), citric acid (100 mg/l), and ascorbic acid (100 mg/l) was used with combinations of the auxins (2,4- dichlorophenoxyacetic acid; 2,4-D) and cytokinin (Thidiazuron; TDZ). It was found that 1.1 mg of 2,4-D and 1.1 mg of TDZ induced the most callus proliferation. Though equal proportions of TDZ (1.1, 2.2, 3.3 mg) and 2,4-D (1.1, 2.2, 3.3 mg) were effective in inducing callus formation, it was noticed that 1.1 mg each of TDZ and 2,4-D made a major impact by reducing the time required for the callus initiation and proliferation. |