Evaluation of Genotypic Variation in Lead and Cadmium Accumulation of Rice (Oryza sativa) in Different Water Conditions in Egypt

Lead (Pb) and cadmium (Cd) can be absorbed and transported effectively by rice plants and could easily enter into the food chain. This research aimed at identifying rice germplasm with low Pb and Cd concentrations, and to assess their potential risks to human health. A 2-year pot experiment if 30 rice genotypes were conducted in a greenhouse at Rice Research and Training Center (RRTC) Sakha Kafr El-Sheikh, Egypt during 2012 and 2013 rice growing seasons, under irrigating with fresh water from the River Nile (FW), drainage water from El-Gharbia main drain Kitchener (DK) and drain No. 8 (D8). The pots were arranged in a randomized complete block design with four replications. All genotypes tested in this study gave high grain and straw yield under irrigation by DK than irrigation by D8 and FW. The concentrations of Pb and Cd in all organs of tested rice genotypes (roots, straw and grains) decreased in the sequence of Indica > Japonica >Indica /Japonica types under all sources of irrigation water in this study. Pb and Cd concentrations in grains of some rice genotypes were above the safety limits 2.00 and 0.40 ppm, respectively. In the same time grains of 13 genotypes were below the safety limits. The risk assessment of Pb and Cd through consumption of some rice genotypes indicated that the target hazard quotient of Pb (THQPb) and Cd (THQCd) in some rice genotypes exceeded the permissible limits (1.00) for an adult but not in all tested genotypes. THQPb and THQCd values for Pb and Cd through the consumption of rice decreased in the order Indicia > Japonica >Indicia /Japonica. Rice germplasm with a strong tendency for accumulating Pb and Cd should be avoided when using poor water quality in irrigation.