Role of Iron Oxide Nanoparticles in alleviation of arsenic mediated phytotoxicity in rice (Oryza sativa L.)
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Date
2023
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RPCAU, Pusa
Abstract
The present study was done to study the effects of different concentrations of arsenic and iron oxide nanoparticles combinations on rice (Oryza sativa L.) seedlings. The objective for the study were: 1. To study the effects of different concentrations of arsenic and iron oxide nanoparticles on seed germination and seedling growth of rice. 2. To investigate the effectiveness of iron oxide nanoparticles in reducing the toxicity of arsenic based on physiological and biochemical changes in rice (Oryza sativa L.). Two rice genotypes (Rajendra Neelam & Gautam) were used for this experiment work. The experiment was carried out in two different ways: 1. In pots 2. In paper cups. In both the experiments the seeds and seedlings were subjected to different treatments and treatment combinations of arsenic and iron oxide (nanoparticles or bulk form). For paper cups experiment, the seeds were soaked in different concentrations of arsenic and iron oxide and the germination parameters were taken in 10-day old seedlings. For pot experiment, the seeds were first sown in soil filled pots and after it reached seedling stage, the plants were transplanted to plastic cups and were subjected to different combinations of arsenic and iron oxide. The treatments were as follows: T1: Control, T2: 25 µM As, T3: 50 µM As, T4: 25 mg/L FeNP, T5: 50 mg/L FeNP, T6: 25 mg/L Fe Bulk, T7: 50 mg/L Fe Bulk, T8: 25 µM As + 25 mg/L FeNP, T9: 25 µM As + 50 mg/L FeNP, T10: 50 µM As + 25 mg/L FeNP, T11: 50 µM As + 50 mg/L FeNP T12: 25 µM As + 25 mg/L Fe Bulk T13: 25 µM As + 50 mg/L Fe Bulk, T14: 50 µM As + 25 mg/L Fe Bulk and T15: 50 µM As + 50 mg/L Fe Bulk. The results showed that iron oxide reduced the germination %, shoot length, root length and also the seedling dry weight thereby, reducing the seedling vigor index I and II of seedlings exposed to Arsenic stress. The relative heavy metal injury rate increases on As treatment. The total biomass of the seedlings also reduces on As exposure. However, it gradually increases on iron oxide exposure. The relative water content (RWC) in leaves is reduced on exposure to As and it is increases on exposing it to different concentrations of iron oxide. Arsenic reduced the photosynthetic pigments, stomatal conductance and photosynthesis in leaves. On exposure of seedling to stress there is accumulation of reactive oxygen species (ROS) like hydrogen peroxide (H2O2) inducing oxidative stress, damaging the membrane lipids raising the electrolyte leakage (EL). Also there is peroxidation of lipid membrane causing rise in malondialdehyde (MDA). Iron oxide strengthen the antioxidant enzymes (Superoxide dismutase and Ascorbate peroxidase), thereby alleviating oxidative stress and reducing EL and MDA content. The results reveal that iron oxide (nanoparticles and bulk) had a positive influence on morphological, seed germination parameters, physiological and biochemical parameters. However, better results were seen in case of iron oxide nanoparticles. This shows that supplementation of iron oxide nanoparticles to arsenic stressed condition can help alleviate arsenic mediated phytotoxicity.