Enhancing Indian Rice Plant resilience to toxic heavy metals with Glycine betaine as a modulator.

Contamination of arable land with potentially toxic heavy metals (PTHMs) is a critical global issue resulting from industrialization. To tackle this problem, a two-year pot experiment was carried out on Indian rice plants (Oriza sativa L.) using four different treatments of PTHMs at varying concentrations (T1: 5; T2: 10; T3: 20; T4: 40 mg/kg). The intent was to explore the impact of glycine betaine (GB) application on the plants' resilience and stress response. Findings indicated that exposure to PTHMs led to a significant increase in the accumulation of these metals and oxidative stress indices during the 2.5th and 4th month growth stages. However, when GB was applied to the soil, there was a decrease in the accumulation of PTHMs and oxidative stress indices. This was attributed to the enhancement of antioxidant enzyme activity and metabolic functions in the rice plants. Interestingly, the study revealed that Indian rice plants had the highest accumulation of Fe, followed by Mn, Zn, Cr, Ni, Pb, Cd, and Cu in their roots. When exposed to PTHMs, the roots exhibited higher metal uptake compared to the shoots and seeds, with uptake levels rising with increasing concentrations of PTHMs. Notably, under the highest PTHMs stress (T4), the content of Cr and Pb in the roots, shoots, and seeds decreased significantly. This reduction was even more pronounced when treated with 400 mM GB, showcasing decreases of up to 33.3%, 36%, and 89.3% in Cr content, and 36.4%, 55%, and 80.5% in Pb content, respectively. Keywords: Amelioration; Oryza sativa; Heavy metals; Glycine betaine; Antioxidant