Effects of Soil Cu Stress on Grain Yield and Quality of Indica Rice cultivars

In order to investigate the effect of soil Cu stress (400 mg · kg-1) on the rice yield and quality, pot experiments were conducted using indica rice cultivars. Main results showed that paddy rice, brown rice and polished rice productivities were all decreased by 14%~27%. According to the significance of the decrease, it could be divided into three groups: none significantce (P0.05), significantce (P0.05) and very significantce (P0.01). Milling quality (brown rice percentage, milled rice percentage), appearance quality (chalky grain percentage, chalkiness area, chalkiness degree), cooking quality (amylose content, gel consistency) and sanitation quality (Cu concentration) were not significantly affected under Cu stress. The content of protein concentration of brown rice increased significantly (P0.05) compared with the control, but itsthe total content of protein decreased very significantly (P0.01) because of its more seriously decreased yield productivity. Cu concentration differed greatly in different parts of grain structure. On the concentration distribution, it was about 2-fold in cortex (embryo) than in chaff and polished rice. With regard to Cu quantities accumulated in the rice grain, about 13% of the total Cu in grain was in chaff, about 12% in cortex (embryo), and about 75% in polished rice. So, about 1/4 of the Cu in grain was eliminated after grain processing (chaff, cortex and embryo were removed).