THE ROLE OF CYTOKININS AND ETHYLENE INHIBITORS ON LENTICEL HYPERTROPHY GENERATION AND ETHYLENE PRODUCTION IN IN-VITRO CULTURES OF POPULUS-EUPHRATICA OLIVIER

Populus euphratica Olivier is native to the Irano-Turanian areas (Midd le East). Elche (Alicante province, SE Spain) is known to be its only European location. Nodal segments from root shoots were established in vitro in a Murashige and Skoog medium supplemented with several cytok inins. Ethylene inhibitors AgNO3 and CoCl2 were used in combination wi th kinetin. Hormone-free media supplemented with sucrose (20-60 mg l(- 1)) was also tested. Ethylene was measured by gas chromatography, and both the percentage of sprouting shoots and lenticel hypertrophy in cu ltures were recorded. Ethylene production was higher in cultures suppl emented with cytokinins (especially with meta-topolin), with high spro uting percentages, and lenticel hypertrophy. In cultures supplemented with 6-benzylaminopurine or 6-(gamma,gamma-dimethylallylamino)-purine, ethylene production was lower acid explants looked unhealthy. Ethylen e formation was inhibited in cultures supplemented with AgNO3 (1 mg l( -1)), which also decreased percentage of sprouting buds and lenticel h ypertrophy.