Nano-sulfides of Fe and Mn Efficiently Augmented the Growth, Antioxidant Defense System, and Metal Assimilation in Rice Seedlings

[Image: see text] Physiological and biochemical mechanisms behind nanoparticle (NP)-induced seed germination by nanopriming with metal sulfide NPs are lacunae in the field of agriculture. Sonochemically synthesized aqua-dispersed ferrous sulfide NPs (FeS-NPs) and manganese sulfide NPs (MnS-NPs) were examined as nanopriming agents for physiological, pathological, and antioxidative defense parameters of rice in the present study. Under pot house conditions, in vivo nanopriming of rice seeds with FeS NPs and MnS-NPs at a concentration of 35 μg/mL for 8 h significantly improved the physiological parameters, viz., germination percentage, seed germination index, mean germination time, dry weight, and vigor index, and decreased the phytopathological parameters of nanoprimed rice seeds, viz., mortality, seed rot, and seedling blight. Stimulation of superoxide dismutase (SOD ≥ 28.16%), ascorbate peroxidase (APX ≥ 52.38%), and catalase (CAT ≥ 28.57%) enzymes in FeS-NP- and MnS-NP-nanoprimed seeds as compared to control (hydroprimed seeds) enhanced the fitness of rice seedlings. The augmented levels of Fe and Mn content in the shoots and roots of NP-treated seedlings as compared to hydroprimed seedlings confirmed the incorporation nanometals in rice seedlings as nanonutrients for effective plant growth. Inclusively, FeS-NPs and MnS-NPs were shown to be effective nanopriming agents for promoting the germination of naturally fungal infested rice seeds.