Foliar Application of Silicon-based Nanoparticles Improve the Adaptability of Maize (Zea mays L.) in Cadmium Contaminated Soils

Abstract Heavy metals (HMs) are a serious threat all over the world and show a different impact on plants and human life by contaminating the plant. Among all HMs cadmium (Cd) is one of the serious metals that are absorbed by the roots of the plant and are transported from root to leaves and fruit. Cd stunted plant growth causes the death of plants, causes, and disturbance in photosynthetic machinery and nutrient homeostasis process. Based on a serious problem a controlled experiment was conducted in the Department of Botany, University of Central Punjab, Bahawalpur Campus, Bahawalpur, Pakistan on “inducing cadmium stress tolerance in maize by exogenous application of silicon nanoparticles” in an experiment with a completely randomized design (CRD) with the factorial arrangement was used with five different treatments of silicon nanoparticles Si NPs (To = control group, T1 = Si NPs @ 100 ppm, T2 = Si NPs @ 200 ppm, T3 = Si NPs @ 300 ppm and T4 = Si NPs @ 400 ppm) and three cadmium treatment (Co= control, C1 = Cd @ 15ppm and T2 = Cd @ 30 ppm( on a maize hybrid (‘SF-9515’ F1 Single cross maize hybrid) and each replicated thrice. Results of the controlled experiment indicated that the Cd at 30 ppm affects the maize plants and reduced the morphological attributes such as shoot length (39.35 cm), shoot fresh weight (9.52 g) and shoot dry weight (3.20 g), leaf pigments such as chlorophyll a (0.55 mg/g FW), chlorophyll b (0.27 mg/g FW), total contents (0.84 mg/g FW) and carotenoids contents (0.19 µg/g FW), biochemicals traits such as TSP (4.85 mg/g FW), TP (252.94 nmol/g FW), TSAA (18.92 µmol g-1 FW), TSS (0.85 mg/g FW) and antioxidant activities such as POD (99.39 min-1 g-1 FW), CAT (81.58 min-1 g-1 FW), APX (2.04 min-1 g-1 FW), and SOD (172.79 min-1 g-1 FW) but root length (87.63 cm) and root fresh weight (16.43 g) and root dry weight (6.14 g) of maize and Cd concentration in the root (2.52 µg/g-1) and shoot (0.48 µg/g-1) were increased through the application of Cd. The silicon nanoparticles (Si-NPs) treatment significantly increased all measured attributes of maize. There is highest value was noted of all the parameters such as chlorophyll a (0.91 mg/g FW), chlorophyll b (0.57 mg/g FW), total chlorophyll contents (1.48 mg/g FW), total carotenoids contents (0.40 µg/g FW), TSP (6.12 mg/g FW), TP (384.56 nmol/g FW), TSAA (24.64 µmol g-1 FW), TSS (1.87 mg/g FW), POD (166.10 min-1 g-1 FW), CAT (149.54 min-1 g-1 FW), APX (3.49 min-1 g-1 FW), and SOD (225.57 min-1 g-1 FW) in which the treatment T4 were silicon nanoparticles added at the rate of 400 ppm compared to the control group