Belmekki AmiraAllaoui RimaSupervisor:Fercha Azzedine2024-07-182024-07-182024633/177-Thttp://dspace.univ-khenchela.dz:4000/handle/123456789/6086This research aimed to investigate the impact of extracts from three medicinal plants (Syzygium aromaticum, Rhaponticum acaule, Rhamnus lycioides) and seaweed extract (Dalgin) on the germination and callus formation in tomato plants (Super strain B). The findings demonstrated that pre-treating seeds with these plant extracts positively influenced seed germination and the growth of tomato seedlings in vitro. Additionally, callus culture studies revealed that growing callus with a combination of auxins and cytokinins (0.2 ppm NAA & 2 ppm BAP) yielded better results compared to using leaves. The extracts, including commercial seaweed extract, had varying but generally positive effects, especially in the absence of hormones. However, the Tafgha plant extract exhibited the most significant effect on the speed and mass of callus formation when hormones were present. These beneficial effects are likely due to the chemical composition of the extracts, such as those found in the seaweed extract. Further studies and detailed chemical analyses are needed to confirm these effects and to explore the mechanisms by which plant extracts enhance growth and callus induction in tomatoes and other crops.frThesis