Folic acid supplementation improves seed germination, seedling growth and cadmium uptake in a mining ecotype of Solanum nigrum L.

Cadmium (Cd) contamination poses a significant threat to global agricultural production and hyperaccumulating plant species, such as Solanum nigrum (L.), face challenges in phytoremediation due to limited biomass production. Application of plant growth regulators such as, folic acid (FA) is a promising strategy to increase biomass production in these plant species. Therefore, a study was conducted to assess the interaction between FA and Cd in the mining ecotype of S. nigrum. The study involved two phases: germination and growth. In the first phase, seeds were exposed to different concentrations of CdCl2 (i.e. 0, 10, 25, 50, 100, 200, and 400 mu M) in the presence (0, 25, 50 and 100 mu M) or absence of FA for ten days. Results showed that FA enhanced seed germination under Cd stress and acted as an antioxidant and stimulated germination and emergence at moderate concentrations. At higher concentrations, it reduced germination percentage. The study also found significant variations (P <0.05) in growth attributes and Cd uptake in all FA concentrations. Cd was generally higher in shoots than roots, with the highest Cd concentration found in T6 (200 mol Cd + 50 mu mol/L FA) with a 170-fold difference (mean value: 1690 mg/kg) from control (10 mg/kg). Furthermore, an increase in exposure time led to a 2-fold increase in reduced glutathione (GSH) level in leaves at T3 (100 mu mol/L Cd + 50 mu mol/L FA).Therefore, we concluded that FA is a biostimulant that activates protective mechanism, alleviates oxidative stress and improves Cd uptake and accumulation in hyper-accumulating species.