Modulation of Physiological and Biochemical Traits of Two Genotypes of Rosa Damascena Mill. By Nano Silicon Under in Vitro Drought Stress

Drought is a major abiotic stress that prevents plant growth and efficiency. Silicon increases drought tolerance by regulating the biosynthesis and acumulation of some osmolits.This study was conducted to modulate dought stress induced by Polyethylene glycol (PEG) in two genotypes of damasks by nano silicon dioxide (nSiO2). The experiment included three levels of nSiO2 (0, 50 and 100 mg L-1) and PEG (0, 25, 50, 75 and 100 g L-1) added to culture medium. Drought stress decreased protein content while Maragheh genotype under normal conditios and treating with 100 mg L-1 nSiO2 had the highest protein content. Under severe drought stress Maragheh genotype had stronger membrane stability index (MSI) than Kashan genotype and explants treated with 100 mg L-1 nSiO2 had the highest MSI in control plants. Contrary to the negative effects of drought, plants treated with 100 mg L−1 nSiO2 maintained more of their photosynthetic parameters in comparison with other treatments and showed higher amount of protein and proline in Maragheh rather than kashan genotype. Drought stress reduced the values of Fm, Fv/Fm, and Fv. In general, under drought stress, treatment with nSiO2 increased the mentioned characteristics before. It also improved water deficit tolerance through enhancing in the activity of antioxidant enzymes such as catalase, peroxidase, guaiacol peroxidase and superoxide dismutase while the amount of lipid peroxidation and hydrogen peroxide decreased. The results showed that Maragheh genotype may be more stronger in counter with water deficit by improving in water balance, antioxidant enzyme activities, and membrane stability.

Selective Thermal Transformation of Automotive Shredder Residues into High-Value Nano Silicon Carbide

Automotive waste represents both a global waste challenge and the loss of valuable embedded resources. This study provides a sustainable solution to utilise the mixed plastics of automotive waste residue (ASR) as a resource that will curtail the landfilling of hazardous waste and its adverse consequences to the environment. In this research, the selective thermal transformation has been utilised to produce nano silicon carbide (SiC) using mixed plastics and glass from automotive waste as raw materials. The composition and formation mechanisms of SiC nanoparticles have been investigated by X-ray diffraction (XRD), X-Ray-Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The as synthesised SiC nanoparticles at 1500 °C has uniform spherical shapes with the diameters of the fixed edges of about 50–100 nm with a porous structure. This facile way of synthesising SiC nanomaterials would lay the foundations for transforming complex wastes into value-added, high-performing materials, delivering significant economic and environmental benefits.

The Role of Nano-Silicon and Other Soil Conditioners in Improving Physiology and Yield of Drought Stressed Barley Crop

A field experiment was conducted in sandy soil to assess the effect of different sources of soil conditioners on barley (Hordeum vulgare L. cv. Giza 137) growth and its yield under drought stress. Plants were exposed to two levels of drought stress until grain maturity: (A) drought at 75% available water (AW) with NPK as control (treatment, T1); (B) mild drought stress at 50% AW with foliar spray of nano-silicon at 75 ppm (treatment, T2), foliar spray of nano-zeolite at 75 ppm (treatment, T3), perlite at 4 tons/h (treatment, T4), natural zeolite at 600 kg/ha (treatment, T5), bentonite at 4 tons/h (treatment, T6), and a combined treatment of T2+T3+T4+T5+T6 at the half amount of each material (T7). All the treatments received the recommended doses of organic matter. Vegetative growth and yield characters as well as anatomical characters were recorded. The physical and chemical soil properties were significantly improved by both foliar and soil conditioners application. The nutrients content of the barley crop were augmented under combined treatment (T7) as compared to other treatments. Under that treatment, barley crop chemical components, i.e. protein, ash, chlorophylls, amino acids, vitamins, and fibre were significantly higher compared to other treatments. In addition, gibberellic acid (GA3) and abscisic acid (ABA) content besides antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD) activities were significantly affected by all treatments. The economical profits were achieved, as reflected by an investment factor value equal to or higher than 3, and this was achieved for all tested nanosilicon, zeolite, and soil conditioners indicated the effectiveness and profitability of studied treatments.

Physio-Biochemical and Agronomic Responses of Faba Beans to Exogenously Applied Nano-Silicon Under Drought Stress Conditions

Nano-silicon application is an efficient novel approach to mitigate the deleterious impacts of drought stress on field crops, which is expected to increase owing to climate change, especially in arid regions. Two-season field studies investigated the influence of foliar-applied nano-silicon (0.5, 1, and 1.5 mM) on physiological and biochemical attributes and their impacts on crop water productivity (CWP) and the agronomic traits of faba beans (Vicia faba). The plants were evaluated under two irrigation regimes: well-watered (100% ETc giving 406 mm ha−1) and drought stress (65% ETc giving 264 mm ha−1). It was found that drought stress significantly decreased gas exchange (leaf net photosynthetic rate, stomatal conductance, and rate of transpiration), water relations (relative water content and membrane stability index), nutrient uptake (N, P, K+, and Ca+2), flavonoids, and phenolic content. In contrast, drought stress significantly increased oxidative stress (H2O2 and O2·-) and enzymatic and non-enzymatic antioxidant activities compared with the well-watered treatment. These influences of drought stress were negatively reflected in seed yield-related traits and CWP. However, foliar treatment with nano-silicon, particularly with 1.5 mM, limited the devastating impact of drought stress and markedly enhanced all the aforementioned parameters. Therefore, exogenously applied nano-silicon could be used to improve the CWP and seed and biological yields of faba bean plants under conditions with low water availability in arid environments.