Effects of environment and genotype on mercury and methylmercury accumulation in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Background and aims

Rice grains contaminated by mercury (Hg) and methylmercury (MeHg) pose risks to human health. This study evaluated the relative importance of genotype, environment and genotype-environment interactions on the accumulation of total Hg (THg) and MeHg in brown rice.

Methods

A pot trial with four rice genotypes and 10 Hg-contaminated paddy soils was conducted under greenhouse conditions. The effects of genotype, environment and genotype-environment interactions on brown rice THg and MeHg accumulation were assessed by an Additive Main Effects and Multiplicative Interaction (AMMI) model.

Results

THg and MeHg concentrations in brown rice ranged from 20.5 to 75.5 μg kg^?1 and 2.24 to 54.7 μg kg^?1, respectively. The AMMI model indicated that genotype explained 41.1 and 19.6%, environment described 40.6 and 55.8%, and the genotype-environment interaction explained 11.9 and 20.0% of the variation in brown rice THg and MeHg levels, respectively. Brown rice THg positively correlated with water-soluble Hg and total potassium, but negatively correlated with total sulphur, iron, total organic carbon and nickel in soils. Brown rice MeHg negatively correlated with soil pH and selenium.

Conclusion

THg accumulation in brown rice was mainly affected by both genotype and environment, whereas MeHg accumulation was largely determined by environment.