MICROPROPAGATION OF GLOBE ARTICHOKE PLANT (Cynara scolymus L.). 1- EFFECT OF SODIUM HYPOCHLORITE CONCENTRATIONS, CYTOKININS AND SUBCULTURES NUMBER ON SHOOTS MULTIPLICATION RATE.

An efficient protocol for both development of aseptic tissue cultures and shoots regeneration for Cynara scolymus L. cv. Herious was established by using in vitro micropropagation technique. Meristem tips of good young offshoots from selected globe artichoke plants were used as explants. Dipping shoot tips (1-2 cm length) in 70% ethanol for 5-10 seconds followed by 0.1% HgCl2 (W/v) for 2 minutes and then in 3% sodium hypochlorite for 20 minutes was the most effective sterilizing and disinfectant treatment for surviving the majority of meristem tip cultures after 5 weeks of culturing. In the establishment stage, adding 0.5 mg thidiazuron (TDZ) /l to MS basal medium gave the best values for both shoots and leaves number but registered middle values for average shoots length compared to the other treatments. Concerning the multiplication stage, among the different cytokinin types and concentrations used such as 2iP, BA and Kin (at 0.5, 2.5 and 5.0 mg /l for each) and TDZ (at 0.05, 0.5 and 1.0 mg /l) in addition to control treatment (hormone-free MS medium), 2iP with all concentrations recorded the highest values in this respect in terms of shoots and leaves number and average shoots length. The multiplication rate of proliferated globe artichoke shoots and average shoots length were markedly increased with increasing subcultures number on MS basal medium augmented with  5.0 mg 2iP /l + 1.0 mg IAA /l till the fourth subculture then declined thereafter during the fifth one.