University Of Tehran Press Pollution 2383-451X 12 1 2026 01 01 The Impact of Titanium Dioxide Nanoparticles (TiO₂ NPs) on the Vegetative Characteristics of Alfalfa (Medicago sativa L.) and the Ameliorative Role of C-Phycocyanin 477 492 105166 10.22059/poll.2025.404523.3157 EN Safa Ayad Jassem Department of Biology, College of Education, University of Al-Qadisiyah, Iraq Dhafir Abed Alkhadim Jameel Department of Biology, College of Education, University of Al-Qadisiyah, Iraq Haider Abdul Wahid Alghanmi Department of Biology, College of Education, University of Al-Qadisiyah, Iraq 0000-0002-6078-3145 Journal Article 2025 10 17 This work investigated the impacts of C-Phycocyanin on Titanium Dioxide Nanoparticles (TiO₂ NPs)-induced stress in alfalfa (Medicago sativa L.) plants. The study focused on evaluating the effects of TiO₂ NPs on the vegetative growth, biochemical composition, oxidative stress markers, and DNA integrity of alfalfa plants. TiO₂ NPs stressed the alfalfa plants in a concentration-dependent manner through decrease in plant height, branch number, leaf area, and biomass production. Biochemical parameters like chlorophyll, nitrogen, and potassium contents were reduced, revealing diminished physiological and photosynthetic activities. Contrarily, the co-application of TIO2 NPs and C-Phycocyanin mitigated the detrimental effects, as they promoted the growth and biochemical parameters recovery at low and moderate nanoparticle concentrations. TIO2 NPs treatment increased the level of Catalase, Superoxide Dismutase, Malondialdehyde, Reactive Oxygen Species (CAT, SOD, MDA, and ROS) oxidative stress biomarkers, while C-Phycocyanin application decreased these indicators values, masking their scavenging potential. DNA integrity analysis through Comet Assay suggested that C-Phycocyanin effectively resist cells from TIO2 NPs -induced DNA damage and retain genomic stability. Therefore, co-application of C-Phycocyanin mitigated these adverse effects, demonstrating its potential as a natural biostimulant that enhances plant tolerance to nanoparticle-induced phytotoxicity. https://jpoll.ut.ac.ir/article_105166_cae3c4c4b975882c11975a819cd96bd3.pdf