Evaluation of Response of Rice Varieties Differing in Phosphorus Use Efficiency Under Arsenic Stress

Arsenic (As), in the form of arsenate [As(V)], enters into the plants through phosphate transporters and hence it was postulated that the utilization of rice varieties with high phosphorus use efficiency (PUE) might assist in reducing As accumulation. To explore the interaction between arsenic (As) and phosphorus (P) in rice plants, with a focus on reducing As accumulation in rice grains. The research utilized hydroponic cultivation of 15 rice genotypes under varying P levels (optimum: 0.32 mM, deficit: 0.16 mM, 0.08 mM, 0.032 mM) for screening. Two contrasting genotypes were chosen based on PUE and growth response: variety DNA Sribala (DS) demonstrated the highest PUE, while Sai Kasturi (SK) exhibited the lowest PUE. These selected genotypes were then analyzed for physiological response, antioxidant enzyme activity, and elemental accumulation (P, As) under various treatments such as control, As, ½ P, ½ P + As, ¼ P, and ¼ P + As, spanning durations of 7 and 12 days. Results indicated that under the ¼ P + As condition, SK exhibited significant physiological damage, including increased electrolytic leakage and malondialdehyde content. Arsenic accumulation was notably higher in SK than in DS across all treatments, while P accumulation displayed the opposite trend. Maximum observed As accumulation was 2022 µg g⁻¹ at 12 days in SK roots under the ¼ P + As condition, whereas DS showed lower As accumulation 1241 µg g⁻¹ under the same treatment. A differential expression pattern of phosphate transporters, Pht1;1 and Pht1;8 was also observed in root and shoot of DS and SK. The study concludes that rice varieties with high PUE, like DS, may be recommended for cultivation in As-contaminated areas to mitigate As contamination in rice grains.