Unravelling the role silica nanoparticles to ameliorate chromium heavy metal stress in Mexican marigold (Tagetes erecta L.)

Abstract

The influence of environmental contamination on different ecosystems has become a major problem worldwide. Pollution of heavy metals in soil has become a serious global concern. The purpose of the present experimental work was to assess the effect of silica nanoparticles (SiNPs) on the growth, biochemical parameters, and physiological responses of Tagetes erecta L. plants under chromium (Cr) stress. In the current investigation, we implemented the CRD experiment, and three sets of replicates were employed, each comprising nine unique treatments; control, Cr-I (50 mg kg^− 1), Cr-II (100 mg kg^− 1), SiNPs-I (100 mg L^− 1), SiNPs-II (200 mg L^− 1), Cr-I + SiNPs-I, Cr-I + SiNPs-II, Cr-II + SiNPs-I, Cr-II + SiNPs-II). When plants were exposed to Cr, the oxidative damage was noticeable. Cr contamination markedly decreased the growth characters of the plants including shoot and root length, fresh and dry weights as well as photosynthetic pigment but increased the level of proline, hydrogen-peroxide (H₂O₂), malondialdehyde (MDA) and relative membrane permeability in plants. Significantly, the impacts of Cr on plants were avoided by SiNPs application. SiNPs applied externally lessened the concentrations of H₂O₂, MDA, and relative membrane permeability. Conversely, SiNPs enhanced the content of chlorophyll a, b, carotenoid and improved the growth of plant. They also elevated the antioxidant enzyme activity. Furthermore, SiNPs promote the defensive mechanisms of plants against the stress of toxic metals by boosting the absorption of particular elements such as Ca²⁺ and K⁺. Based on our research, treating plants with SiNPs can potentially help them to overcome abiotic stresses. Our findings suggest that SiNPs have the potential to effectively regulate stress indicators and antioxidants, which can significantly lower the adverse impact of abiotic stresses in plants.