Effect of Straw Removal on Cd Uptake and Accumulation in Rice (Oryza Sativa L.) and Brown Rice Safety and Quality

Abstract

Abstract: Straw return could affect the soil cadmium (Cd) bioavailability and increase the risk of Cd accumulation in rice in Cd-contaminated paddies. In this study, the influence of different amounts of rice straw removal on rice growth, photosynthesis, Cd accumulation and uptake in rice, and soil Cd availability at different growth periods, as well as brown rice safety and quality, were evaluated through a field trial. The results showed that straw removal decreased photosynthetic pigment content in rice leaves, which affecting rice growth. The chlorophyll a and chlorophyll b contents in the removal of 100% rice straw and 100% roots treatment declined by 36.72% and 22.74%, respectively, relative to the control at booting stage,and the biomass of brown rice at the maturation stage was also significantly reduced by 22.77%. However, straw removal reduced the bioavailability of Cd in soil and accumulation and uptake of Cd in rice. At the tillering stage, soil acid-extractable and oxidizable Cd fractions at the removal 100% rice straw and 100% roots treatment were reduced by 11.46% and 10.69%, respectively, and residual Cd content increased by 26.03%. Furthermore, the Cd content in brown rice in all straw removal treatments decreased by 17.71%-24.79% at the maturation stage. The nutritional components (such as essential amino acids) of brown rice were slightly influenced by all the straw removal treatments, and the ecological risk of soil Cd was significantly reduced. Therefore, straw removal may be an effective measure for reducing Cd uptake by rice in Cd-contaminated paddies.

Keywords: Straw removal, Cd-contaminated soil, Uptake and accumulation, Availability, Brown rice quality, Amino acid