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

ABSTRACT

Populus euphratica Olivier is native to the Irano—Turanian areas (Middle 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 cytokinins. Ethylene inhibitors AgNO₃ and CoCl₂ were used in combination with kinetin. Hormone-free media supplemented with sucrose (20–60 mg 1⁻¹) was also tested. Ethylene was measured by gas chromatography, and both the percentage of sprouting shoots and lenticel hypertrophy in cultures were recorded. Ethylene production was higher in cultures supplemented with cytokinins (especially with meta-topolin), with high sprouting percentages, and lenticel hypertrophy. In cultures supplemented with 6-benzylaminopurine or 6-(γ,γ,-dimethylallylamino)-purine, ethylene production was lower and explants looked unhealthy. Ethylene formation was inhibited in cultures supplemented with AgNO₃ (1 mg 1⁻¹), which also decreased percentage of sprouting buds and lenticel hypertrophy.