Effect of Copper Contamination on Plant Growth and Metal Contents in Rice Plant (Oryza Sativa L.)

A pot soil experiment was conducted to investigate the effects of varying soil copper (Cu) concentration on growth, and on its accumulation pattern in different parts of rice plant (Oryza sativa L.) in 2018, Thailand. The treatments imposed were 0, 50, 100, 200, 400 Cu mg/kg (T-1 to T-5, respectively). Exposure to 100 mg Cu/kg and above at tillering stage; or to 200 Cu mg/kg and above at panicle initiation stage, significantly decreased the plant height. Exposure to 200 Cu mg/kg (T-4) produced significantly lower number tillers per pot than T-1 or T-2. Negative significant correlation between grain yield of rice and soil Cu concentrations was observed. Increasing accumulation of Cu in grain in a dose-dependent manner occurred, with the peak concentration for T-3 (11.39 mg/kg). Copper accumulation by tissue had the rank order grain < shoot < root. About 54 to 91% of total absorbed Cu was retained in the root and 2 to 12% of total Cu uptake was translocated to grain. This is beneficial from the point of view of food safety. In other words, the accumulation of Cu in brown rice in current experiment was below the permissible contaminant limit in food, in Thailand.