Effects of SNP, MgSO4, and MgO-NPs foliar application on Spinacia oleracea L. growth and physio-biochemical responses under cadmium stress

The effects of foliar application of sodium nitroprusside (SNP), magnesium sulfate (MgSO₄) and magnesium oxide nanoparticles (MgO-NPs) on the growth, physiology, and gas exchange parameters of two varieties of spinach (Spinacia oleracea L.) under cadmium (Cd) stress were examined. The experiment was arranged in a completely randomized design with 72 pots. Two varieties of S. oleracea (Desi Palak & Lahori Palak) were used. Two concentrations of Cd (0 µM and 150 µM) in the form of cadmium chloride (CdCl₂) were used. Two levels of SNP (0 ppm and 100 ppm) and two levels for each form of Mg i.e. MgSO₄ and MgO-NPs (0 and 200 ppm) were foliar sprayed on plants in control and Cd stress. Both varieties behaved similarly under Cd stress and caused reductions in growth, physiology, gas exchange, water content parameters and inorganic ion uptake. However, the biochemical parameters like relative membrane permeability (RMP), malondialdehyde (MDA), and hydrogen peroxide (H₂O₂) contents were increased. However, all foliar spray treatments increased growth, physiological and gas exchange parameters, water content and inorganic ion uptake. However, this reduced the MDA, RMP, and H₂O₂ contents. Desi Palak showed the more positive results under foliar application of MgO-NPs. However, Lahori palak showed more positive results under the SNP + MgO-NP treatment. It is concluded that foliar application of SNP, MgSO₄ and MgO-NPs could be an innovative approach to alleviated the heavy metals (Cd) toxicity in crop plants.