Iranian Medicinal Plants Society Journal of Medicinal plants and By-products 2322-1399 15 3 2026 05 01 Bioactivity of Medicinal-Plant Extracts of Nettle, Chamomile and Dandelion on Germination, Seedling Growth and Antioxidant Enzymes in Canola 402 408 135031 10.22034/jmpb.2026.371311.2095 EN Seyed Ahmad Khatami Department of Agronomy, Varamin-Pishva Branch, Islamic Azad University, Varamin, Iran Pourang Kasraie Department of Agronomy, Varamin-Pishva Branch, Islamic Azad University, Varamin, Iran Sara Khatami Department of Biology, Bu-Ali Sina University, Hamadan, Iran Journal Article 2025 11 05 Seed priming with extracts from medicinal plants offers a sustainable route to create value-added, bioactive treatments for crop seeds and to valorize plant by-products. This study evaluated the bioactivity of aqueous extracts of three medicinal species: nettle (<em>Urtica dioica</em>), chamomile (<em>Matricaria chamomilla</em>), and dandelion (<em>Taraxacum officinale</em>) as seed-priming agents for canola (<em>Brassica napus</em>). Seeds of four cultivars (Okapi, Zarfam, RG-5003, Ahmadi) were soaked in 0 (control), 5, and 10% aqueous preparations prior to germination assays. We quantified germination percentage, seedling length, and biomass, and measured activities of key antioxidant enzymes (catalase, CAT; peroxidase, POD; ascorbate peroxidase, APX) to assess modulation of oxidative-stress defenses during early growth. Responses were cultivar- and extract-specific. Nettle extract at 10% produced the most consistent bioactive effect across genotypes, significantly improving germination, seedling vigour and biomass while strongly up-regulating CAT, POD and APX activities. Chamomile extract conferred moderate, broadly beneficial effects, whereas dandelion extract yielded variable outcomes and was associated with partial inhibition of APX in some cultivars. The Ahmadi cultivar displayed the largest enzymatic induction in response to nettle and chamomile, indicating genotype-dependent sensitivity to plant-derived antioxidants. We interpret these results considering known antioxidant phytochemicals in the three species and propose that phenolic/flavonoid constituents likely underlie the observed modulation of seed oxidative status. Overall, aqueous preparations of medicinal plants, particularly nettle, show promise as eco-friendly, value-added seed treatments for oilseed crops. Given that 5% extracts often outperformed 10% in several assays, future work should include phytochemical profiling, extract standardization, and targeted dose optimization to refine reproducible formulations for practical application. https://jmpb.areeo.ac.ir/article_135031_7776b6e4265df0a342a173ff7fd9bda5.pdf