Potency of silicon in reducing cadmium toxicity in Cempo Merah rice

Abstract

Cadmium (Cd) is a toxic and harmful heavy metal that contaminates agricultural soil when released into the environment. The beneficial element silicon (Si) can be used to reduce Cd stress. However, the mechanism for reducing Cd toxicity in Cempo Merah rice remains unclear. In this study, we conducted an experiment to determine the required potency of Si for reducing Cd toxicity in the plant. We used a randomized design with two factorials, i.e., calcium silicate and cadmium sulfate at various concentrations (0 mg kg−1, 50 mg kg−1, and 100 mg kg−1) with three replicates. The plants were maintained for 8 weeks. The measured parameters included the Cd, Si, and malondialdehyde (MDA) contents, superoxide dismutase (SOD) activity, and plant biomass. Using microscopy, we observed the anatomical root structure, including the thicknesses of the exodermis, sclerenchyma, and endodermis cell walls. The experimental results showed that an excess of Cd inhibited plant growth and increased the MDA content. Increased plant tolerance against the effect of Cd is required for their growth and survival in overcoming the negative impact of Cd exposure. As silicon is involved in the formation by roots of an apoplast barrier to limit Cd uptake, a combination of Cd and Si treatment in plants was found to produce lower Cd contents in the plant shoots and a minimum Cd translocation factor. The addition of Si was also observed to increase the SOD activity in plants under Cd stress. Therefore, Si is suggested to have potency in reducing Cd toxicity in Cempo Merah rice and increasing rice growth.