Combined effect of rice genotypes and soil characteristics on iron plaque formation related to Pb uptake by rice in paddy soils

Abstract

Purpose The formation of iron plaques and their ability to sequester heavy metals are influenced by soil properties and rice genotype. Lead accumulation in paddy soil is increasing, but in order to assess soil suitability for rice cultivation, a better understanding of the effects of iron plaques on Pb uptake by paddy rice is needed. Materials and methods Two rice cultivars, Taikang 16 (TK16) and Taichung Sen 10 (TCS10), were grown in pots to assess lead (Pb) uptake. Three paddy soils (C, D, and N) sampled from potentially contaminated sites in central Taiwan were used for the experiment, with additional Pb spiking (0, 150, and 300 mg kg −1 ). Results and discussion Pb uptake by rice plants was positively correlated with soil Pb availability. However, Pb uptake by rice plants in soils D and N, even with higher Pb availability, was much less than in soil C. We attribute this to the large amount of iron plaques coating the root surfaces of plants in soils D and N. Moreover, TCS10, which is an indica rice sensitive to metal stress, took up more Pb than TK16, which is a japonica rice. Iron plaque formation on the roots of TK16 was superior to that on the roots of TCS10.Conclusions Iron plaque formation that inhibits Pb uptake appears to be driven primarily by the soil properties and secondarily by the rice genotype. Nevertheless, the capacity of iron plaques to sequester Pb is limited by a high level of Pb contamination in the soil.

Iron Plaque: A Shield against Soil Contamination and Key to Sustainable Agriculture

“…It should be noted that when As is oxidized to arsenate by oxygen, IP will reduce absorption [96,113], which may be due to their different structure, resulting in different binding capabilities or ways to IP [174]. Li et al (2016) [66] selected three distinct types of paddy soils, denoted as C, D and N, and artificially manipulated the effective concentrations of Pb by adding 0 mg/kg, 150 mg/kg and 300 mg/kg Pb(II) to soils C, D and N, respectively. Despite higher effective concentrations of Pb in soils D and N compared to soil C, rice plants exhibited significantly lower levels of Pb absorption in these soils.…”

“…Representatives of these plants are Oryza sativa , Camellia sinensis , Iris pseudacorus , Canna indica , Rhizophoraceae , Acorus gramineus L., Jumex bulbosus , Pistia stratiotes L. and Elodea canadensis [ 17 , 18 , 43 , 64 ]. The occurrence of IP is a naturally spontaneous phenomenon in the environment, influenced by a number of abiotic and biotic factors, such as soil properties, moisture levels, root oxygenation capacity, and so on ( Figure 2 ) [ 65 , 66 ].…”