Lead accumulation and distribution in different rice cultivars

Abstract

This experiment was conducted to investigate the characteristics of lead (Pb) accumulation and distribution among rice organs in 35 rice cultivars of different genotypes. The 35 rice cultivars of four cultivar groups (temperate japonica, tropical japonica, tongil-type, and Indica) were grown with irrigation water containing 10 ppm throughout all growing seasons at the experimental farm of Seoul National University, Korea. Rice plants were sampled and analyzed for Pb accumulation and distribution in each rice organ at harvest. The results showed that Pb concentration, accumulation, and distribution in rice organs except roots were significantly different among 35 rice cultivars. Pb levels in different rice organs followed the order: root > shoot > grain. Grain Pb concentration and accumulation ranged from 0.05 to 0.22 mg kg-1 and from 0.016 to 0.127 mg m-2, respectively. The lowest and highest grain Pb concentration and accumulation were observed in a temperate japonica cultivar ‘Hwajin’ and a tropical japonica cultivar ‘IR71204’, respectively. Grain Pb concentration showed highly significant correlations with the shoot-grain redistribution ratio among 35 cultivars. However, it was not correlated with shoot Pb concentration and accumulation, root Pb concentration, and the root-shoot translocation factor. Significant differences in Pb concentration, accumulation, and distribution in rice organs among four cultivar groups were only found in shoot Pb accumulation. Indica showed the highest Pb accumulation in shoots, while temperate japonica was the lowest. Grain Pb concentration for four cultivar groups was found to be significantly correlated with the shoot-grain redistribution ratio in common.