The effect of arsenate on the levels of phosphate contents and activities of different phosphorolytic enzymes were studied in ten days of rice seedlings var. MTU-1010. Total arsenic contents were increased both in root and shoot of rice seedlings treated with various concentrations of arsenate and increment was linear with increasing concentrations of arsenate. The effect of arsenate was manifested via a decline in phosphate contents and inhibition in the activities of phosphatase enzymes in the rice seedlings. The activities of both acid and alkaline phosphatases were inhibited with increasing concentrations of arsenate. Similarly, inorganic pyrophosphatase and ATPase activities also declined, along with an increasing concentration of arsenate. The results suggest that exposure of rice seedlings to arsenate leads to lowering of the phosphate pool and alteration in the activities of major phosphohydrolytic enzymes, which contribute to metabolic disturbance and a decrease in the growth of rice seedlings. During combined application of arsenate with phosphate exhibited better growth of the seedlings and significant alteration of different phosphatase enzymes activities. Whereas the combined application of arsenate and phosphate altered the level of arsenic accumulation in the test seedlings, which was very little in the root but high in the shoot with respect to arsenate treatment alone thus phosphate inhibits transport of external arsenate within seedlings. However, when arsenate was applied in conjunction with phosphate, the seedlings exhibited improved growth and significant changes in the activities of different phosphatase enzymes. Notably, this combined application altered arsenic accumulation levels, resulting in lower arsenic concentrations in the roots but higher levels in the shoots compared to treatments with arsenate alone. This suggests that phosphate may inhibit the transport of external arsenate within the seedlings, thereby mitigating some of the negative impacts associated with arsenate exposure. Overall, the study highlights the complex interplay between phosphate availability and arsenate toxicity in rice cultivation, emphasizing the potential benefits of managing nutrient levels in arsenic-affected soils.
