Effects of seed priming with different concentrations and forms of silicon on germination and growth of rice under cadmium stress

Cadmium (Cd), as a pervasive heavy metal, poses significant toxic risks to both plants and humans. Extensive research indicates that the application of exogenous silicon (Si) - encompassing inorganic silicon (IS), organic silicon (OS), and nano‑silicon (NS) - can mitigate the deleterious effects of Cd on plants. However, the precise mechanisms underlying the seed priming effects of these three forms of Si on rice seedlings remain not fully understood. To address this gap, the current study evaluated growth indices, Cd distribution, antioxidant system activity, and ionomic responses in rice seedlings. The results reveal that priming with all three types of Si confers a degree of resistance to Cd, with IS proving to be the most efficient. Specifically, IS treatment enhanced germination rates and significantly promoted seedling stage growth. Moreover, it alleviated oxidative damage in rice seedlings and reduced malondialdehyde (MDA) concentration within tissues. Additionally, Si priming decreased Cd absorption rates and hindered its translocation to the edible parts of the plant. It also augmented the levels of essential elements such as Magnesium (Mg), Potassium (K), Manganese (Mn), Phosphorus (P). In conclusion, under Cd stress conditions, IS effectively fosters rice seedlings growth, reduces oxidative damage, and limits Cd uptake, outperforming the other two Si forms.