Impact of co-application of iron and silicon on the root plaque formation in rice plants (Oryza sativa L.) grown in arsenic infested soil of gangetic Bengal, India

The present work is a biomarker-based analysis to understand reduction in arsenic toxicity in rice plants due to co-application of iron and silicon. Both iron and silicon have been co-applied in the soil of the potted rice plants with a specific dose of arsenic. The results showed, increase in root arsenic content with only Fe application (E1) as 115% and decrease in shoot arsenic content as 35.4% against control, with Fe + Si application (E2) the root arsenic increased 44% compared to E1 and shoot arsenic content decreased almost 50%, 73% and 25% increase in root Fe content in E1 and E2 is due to formation of Fe-plaque on the root surface which is further justified by the SEM image. The increased arsenic content in the plant root is due to deposition of arsenic in the root Fe-plaque. Plant health parameters revealed that 18% increase in Carbohydrate in E1 compared to control and 9% increase in E2 compared to E1, chlorophyll and protein content followed a similar trend. Malonaldehyde (MDA) content revealed a decrease of 20% in E1 and E2 plants. Super Oxide-dismutase (SOD), an antioxidant enzyme, the unique biomarker to understand the plant stress, showed a decreasing trend of 11% in E1 compared to control and more than 50% in E2 compared to E1, the expression study of the SOD-gene also showed a positive correlation with the biochemical data.