Ammonium sulphate induces dose-dependent ammonium stress in rice seedlings

¹ Crop Nano Biology and Molecular Stress Physiology Lab, Amity Institute of Organic Agriculture, Amity University Uttar Pradesh, Sector-125, Noida - 201313
² Amity Institute of Biotechnology, Amity University Uttar Pradesh, Sector-125, Noida - 201313

^* Corresponding author: nidhikandhol29@gmail.com dktripathiau@gmail.com

Abstract

Plants require nitrogen (N) in various forms to facilitate essential physiological functions. Nitrate (NO_3^-) is one of the most readily absorbed N forms by plants and is preferred in well-aerated soils because it can be easily transported within the plant. Ammonium (NH_4⁺), on the other hand, is utilized especially in waterlogged or acidic soils, where it is directly absorbed by the roots and incorporated into amino acids. Urea (CH₄N₂O) is another significant N source found in many fertilizers; it is transformed into NH_4⁺ and nitrate in the soil through microbial processes. These diverse forms of N are crucial for supporting photosynthesis, protein synthesis, and energy production in plants. The escalating use of ammonium sulphate (NH₄)₂SO₄) as a N source in agriculture prompts a thorough examination of its impact on crop health and productivity. This study aimed to investigate the NH_4⁺ toxicity on rice (Oryza sativa) plants by administering various dosages (0 mM, 5 mM, 7 mM, 10 mM, 12 mM, and 15 mM) and assessing their effects on plant growth parameters, particularly root-shoot lengths, root-shoot fresh biomass along with dry weight. Our research utilized a controlled experimental setup to monitor the growth responses of rice plants to these NH_4⁺ concentrations. Results indicated a clear threshold of tolerance, with adverse effects becoming significant at concentrations starting from 7 mM. At this concentration and higher, there was a noticeable decline in root-shoot lengths, root-shoot biomass and dry biomass, marking the onset of toxicity symptoms in rice plants. These findings suggest a critical need for regulated application of (NH₄)₂SO₄ in rice cultivation to avoid detrimental effects on plant health and yield. The study underscores the importance of establishing safe usage guidelines for (NH₄)₂SO₄ in agriculture, ensuring sustainable farming practices while maintaining crop productivity.