Parthenium Biochar Reduces chromium-induced Oxidative Stress in Rice Plant (Oryza Sativa L.) Grown in Industrial Effluent Irrigated Soil

Abstract

Purpose: Substantial chromium (Cr) accumulation in rice plants hinders its growth, cultivated in high Cr-containing submerged soils irrigated with industrial tannery effluents. The redox-active nature of Cr creates oxidative stress in plants through hydrogen peroxide (H<inf>2</inf>O<inf>2</inf>), malonaldehyde (MDA) production, which leads to increased anti-oxidative enzymes activity to combat the oxidative damage through scavenging the excess H<inf>2</inf>O<inf>2</inf> produced. Biochar, especially acid-modified biochar application to soil helps in reducing metal accumulation in plant body, thereby decrease oxidative stress. Methods: To accomplish this hypothesis, pot experiment in Cr contaminated soil was conducted taking rice as test crop with three different types of Parthenium biochar (unmodified, iron-modified and phosphoric acid-modified) at three different dosages (5, 7.5 and 10 t ha− 1) and a control in completely randomized design during July to November, 2022. Plant height, tiller number, greenness index, the N, P, K, S, Cr concentration and antioxidant enzyme activities in plant leaves were quantified to study the effect of biochar and acid-modified biochar on crop. Results: The results showed a decrease in Cr accumulation and a subsequent decrease of H<inf>2</inf>O<inf>2</inf>, malonaldehyde (~ 52% over control) content and antioxidative enzymatic activity (especially superoxide dismutase by ~ 59%) with increasing dose of biochar and modified biochar application. Among the three types of biochar, phosphoric acid-modified biochar performed better than other types especially at higher dose of 10 t ha− 1, which reduced Cr accumulation in leaves by 26.4% followed by iron-modified biochar (dose 10 t ha− 1) by 23.8% over control. This reduction in Cr toxicity enhanced plant height, tiller number, greenness index (by ~ 12%, 40% and 18%, respectively over control) and higher concentration of essential nutrients (N, P, K, S) in plant leaves of the biochar treated pots. Conclusion: The application of biochar can be an effective strategy to reduce the toxic accumulation of Cr thereby reduce the antioxidant enzyme activities while improving plant growth parameters and N, P, K and S accumulation in the leaves of a 75 days old rice seedlings. © The Author(s) under exclusive licence to Sociedad Chilena de la Ciencia del Suelo 2025.