Phosphorus-arsenic interaction mitigates toxicity and accumulation of arsenic in rice grown in contaminated fields

Arsenic (As) contamination in rice is a serious threat to food security worldwide. Phosphorus (P) plays a crucial role in modulating As uptake in rice plants. Elevated P content in the soil may hinder the uptake of As by competing with the transporter system and altering rhizosphere chemistry. This study aimed to investigate the effect of varied P fertilizer levels on rice ( Oryza sativa L.) plants grown in As-contaminated soil in terms of growth and As accumulation. The experiment included recommended (60 kg h ^-1 ), half (30 kg h ^-1 ), and double (120 kg h ^-1 ) doses of diammonium phosphate (DAP). Two contrasting varieties of rice were used that differed in phosphorus use efficiency (PUE): P-efficient DNA Sribala (DS) and P-inefficient Sai Kasturi (SK). SK suffered significant reductions in shoot and panicle lengths under low P doses (up to 35% and 18%, respectively), whereas DS showed non-significant effects. Arsenic accumulation in grains increased by 20% under low P doses for SK but decreased by 9-11% with higher P doses. In contrast, DS demonstrated tolerance to low phosphorus concentrations and no significant change in As accumulation was observed. In addition, the yield of rice was also increased in high P doses, which was 14-23% at two sites for SK, while 17-20% for DS. These findings underscore the critical role of P management in mitigating As toxicity and optimizing rice productivity in contaminated environments.