Natural plant extracts are a cost-effective and environmental friendly alternative to synthetic plant growth
regulators and phytohormones. The present in vitro study investigated the promotory activity of various concentrations (0, 10,
20 and 40 mL/L) of Aloe vera leaf extract (ALE) on the growth of hybrid aspen (Populus tremula L. × Populus tremuloides
"Michx") clone T89 and aspen (Populus tremula L.) clone W52. The extract isolated from Aloe vera leaves increased the plant
height and weight, number of shoots, leaves and roots, and the root length, as well as mineral concentrations of both Populus
clones. The rooted plants were acclimatized in the greenhouse with 90% survival. The results showed that ALE is an efficient
alternative source to improve the growth of both Populus clones under study.