5-day flooding followed by 3-day drainage wet-dry alternation cycle is highly effective in reducing Cd and As content in rice

Abstract

To comparatively and simultaneously investigate the reducing efficiency of the different wet-dry alternation cycles on the Cd and As absorption and transportation in rice organs, and synthesis of amino acids (AAs) in rice in two soils with different levels of Cd and As contamination, controlled pot experiments were conducted in this study. Results showed that wet-dry alternation treatments reduced Cd and As concentrations in grains by 18.8%-80% and by 77.4%-86.7% in W soil, respectively; and 76.1%-90.8% and 73.1%-80.6% in H soil, respectively. Cd and As concentrations in the soil solution were negatively and positively correlated with soil pH, respectively; but positively and negatively correlated with soil redox potential (Eh), respectively. The minimum “trade-off” values were observed in the 5 d Flooded followed by 3 d Drained treatment in both soils. The Drained treatment greatly improved AAs contents in rice organs in both soils. The changes of AAs were negatively explained more than 70% by the rachises As. Totally, the F5D3 treatment was identified as the optimal measure for simultaneously minimizing Cd and As accumulations in rice in studied soils, and water management regimes regulated the synthesis of AAs in rice organs by affecting the accumulation of As in rachises.