A master's thesis at the faculty of Science at the University of Basraha Impact of Light Stress on Growth and Production of Secondary Product  in Some Species of Medicinal Plants, and showed the researcher's thesis (zainab khalaf kareem) to investigate the effects of different stress levels on morphological traits and to evaluate the associated changes in chemical characteristics Thesis aims to understand the mechanisms, protective strategies, and defense responses adopted by plants to alleviate the harmful effects of UV-B radiation. It also aimed to investigate the impact of UV-B stress on growth indicators and selected chemical constituents in three medicinal plant species Trigonella foenum-graecum, Catharanthus roseus , Azadirachta indica  and concluded UV-B induced significant morphological and chemical changes in plants Plant responses varied with species and exposure duration UV-B enhanced the production of valuable secondary metabolites.GC–MS revealed increased levels and diversity of bioactive compoundsCatharanthus roseus showed the highest diversity of bioactive metabolites and recommended Study long-term UV-B effects on plant metabolism, Test bioactivity of new compounds (antioxidant, antimicrobial), Explore pharmaceutical and agricultural uses of compounds, Use UV-B as controlled stimulator for chemical content, Include other medicinal plants for comparison