Behaviors of Arsenic in Paddy Soils and Effects of Absorbed Arsenic on Physiological and Ecological Characteristic of Rice Plant

A pot experiment was conducted to find out As uptake and critical levels affecting yield loss of rice plant. The arsenic was added to two soils of sand loam and loam in the from of at different As concenterations of 0, 10, 25, 50, 100, 150 ppm, respectively. Rice yields significantly decreased with increasing soil As levels and the critical As levels in soils were estimated to be 6.79 ppm for loam and 2.75 ppm for sandy loam. Yield components also decreased with higher soil As levels and the weight of 1000 grains showed the highest significant correlation with As level in soil. Most of arsenic was retained by the roots and a small amount of arsenic was translocated to the shoots. Arsenic content in plant organs was high in the order of root>stem>leaf blade>leaf sheath>brown rice. The number of sterillized grains also increased with higher As level in soil and it was much higher in sandy loam than in loam.