Advancing Arsenic Toxicity Mitigation in Rice (Oryza sativa L.) with Rice Straw Biochar and Silicon: A Study on Morpho-Physio-Biochemical Responses

Utilizing rice straw biochar (RSB) presents a novel approach to overcome toxicity of arsenic (As) in agricultural settings. Similarly, silicon (Si) has emerged as an effective agent for overcoming metal stress within agricultural crops. The present study investigates into the syringic application of RSB and Si in ameliorating As-induced stressed in Oryza sativa L. (rice) seedlings.

In the present study, we have used different levels of RSB (0, 2.5, and 5% w/w) and Si (0, 1.5, and 3 mM) to O. sativa seedlings when exposed to different levels of As stress i.e., 0, 50 and 100 µM to examine plant growth and biomass, photosynthetic pigments and gas exchange characteristics, oxidative stress indicators, and the response of various antioxidants (enzymatic and non-enzymatic) and their specific gene expression, proline metabolism, the AsA–GSH cycle, cellular fractionation in the plants.

Our results showed that the increasing concentration of As in the soil significantly (P < 0.05) decreased total plant length, root length, shoot fresh weight, root fresh weight, shoot dry weight and root dry weight by 26, 12, 18, 34, 39 and 20% respectively, compared to the plants which were grown in the 0 µM of As in the soil. Additionally, As stress in the soil increased the concentration of reactive oxygen species (ROS) causes oxidative damaged to membranous bounded organelles, increases organic acids, As concentration, affects antioxidants, proline metabolism, AsA–GSH cycle and cellular fractionation. Although, Although, the application of Si and RSB showed a significant (P < 0.05) increase in plant growth and biomass, gas exchange characteristics, enzymatic and non-enzymatic compounds, and their gene expression and also decreased oxidative stress. In addition, the application of Si and RSB enhanced cellular fractionation and decreased the proline metabolism and AsA–GSH cycle in O. sativa seedlings.

These results open new insights for sustainable agriculture practices and hold immense promise in addressing the pressing challenges of heavy metal contamination in agricultural soils.