Abstract

In recent years, environmental pollution with heavy metals and toxic metalloids, including arsenic (As), has become a global challenge for food security and ecosystem health. Arsenic, which enters the environment through natural sources and human activities such as mining and the use of pesticides and chemical fertilizers, disrupts physiological and biochemical processes in plants. This leads to reduced growth, impaired photosynthesis, oxidative stress, and ultimately decreased agricultural productivity. Thiourea, as an organic sulfur compound, can help mitigate arsenic stress in plants. Green synthesis of nanoparticles is recognized as a suitable method for nanoparticle production due to its non-toxic nature and simplicity. Accordingly, this study investigated the protective effects of thiourea nanoparticles against arsenic stress in rapeseed (Brassica napus L.). In this research, thiourea nanoparticles were first synthesized via a hydrothermal method using pomegranate peel extract. Subsequently, under hydroponic conditions, plants were treated with different concentrations of sodium arsenate (0, 200, 400, and 600 µM) and thiourea nanoparticles (0, 200, and 400 mg/L). The results indicated that arsenic stress, particularly at 600 µM, significantly reduced growth parameters, decreased chlorophyll content, and led to considerable arsenic accumulation in plant tissues, especially in the roots. Additionally, markers of oxidative stress, including hydrogen peroxide production and alterations in antioxidant enzyme activities, were observed. However, the application of thiourea nanoparticles effectively improved growth indices, increased chlorophyll content by 34%, reduced hydrogen peroxide by 45%, and decreased arsenic accumulation in roots by 50%. Furthermore, the activities of key antioxidant enzymes such as glutathione reductase, glutathione S-transferase, and peroxidase increased by 25%, 30%, and 20%, respectively. These findings demonstrate that thiourea nanoparticles possess a significant ability to mitigate the toxic effects of arsenic through multiple mechanisms, including neutralization of reactive oxygen species, reduction of arsenic uptake and translocation in plants, activation of the antioxidant defense system, and enhancement of plant metabolism. This study clearly shows that thiourea nanoparticles can be used as a novel, effective, and environmentally friendly strategy for managing arsenic-contaminated soils and improving the growth of crops under stress conditions. The application of this technology not only has the potential to increase agricultural production in polluted areas but also represents a significant step towards achieving sustainable agriculture and maintaining environmental health. Given the high potential of rapeseed for phytoremediation and its economic importance, the use of thiourea nanoparticles could be a promising strategy to address the challenge of soil contamination with heavy metals.    Keywords: Thiourea Nanoparticles, Arsenic, Brassica napus, Heavy Metals, Nanotechnology, Sustainable Agriculture.