Biological silicon nanoparticles improve Phaseolus vulgaris L. yield and minimize its contaminant contents on a heavy metals-contaminated saline soil.

The synthesis of biological silicon nano-particles (Bio-Si-NPs) is an eco-friendly and low-cost method. There is no study focusing on the effect of Bio-Si-NPs on the plants grown on saline soil contaminated with heavy metals. In this study, an attempt was made to synthesis Bio-Si-NPs using potassium silica florid substrate, and the identified Aspergillus tubingensis AM11 isolate that separated from distribution systems of the potable water. A two-year field trial was conducted to compare the protective effects of Bio-Si-NPs (2.5 and 5.0 mmol/L) and potassium silicate (10 mmol/L) as a foliar spray on the antioxidant defense system, physio-biochemical components, and the contaminants contents of Phaseolus vulgaris L. grown on saline soil contaminated with heavy metals. Our findings showed that all treatments of Bio-Si-NPs and potassium silicate significantly improved plant growth and production, chlorophylls, carotenoids, transpiration rate, net photosynthetic rate, stomatal conductance, membrane stability index, relative water content, free proline, total soluble sugars, N, P, K, Ca2+, K+/Na+, and the activities of peroxidase, catalase, ascorbic peroxidase and superoxide oxide dismutase. Application of Bio-Si-NPs and potassium silicate significantly decreased electrolyte leakage, malondialdehyde, H2O2, O2•-, Na+, Pb, Cd, and Ni in leaves and pods of Phaseolus vulgaris L. compared to control. Bio-Si-NPs were more effective compared to potassium silicate. Application of Bio-Si-NPs at the rate of 5 mmol/L was the recommended treatment to enhance the performance and reduce heavy metals content on plants grown on contaminated saline soils.

Integrative application of silicon and/or proline improves Sweet corn (Zea mays L. saccharata) production and antioxidant defense system under salt stress condition.

Silicon (Si) and/or proline (Pro) are natural supplements that are considered to induce plants' stress tolerance against various abiotic stresses. Sweet corn (Zea mays L. saccharata) production is severely afflicted by salinity stress. Therefore, two field tests were conducted to evaluate the potential effects of Si and/or Pro (6mM) used as seed soaking (SS) and/or foliar spray (FS) on Sweet corn plant growth and yield, physio-biochemical attributes, and antioxidant defense systems grown in a saline (EC = 7.14dS m-1) soil. The Si and/or Pro significantly increased growth and yield, photosynthetic pigments, free proline, total soluble sugars (TSS), K+/Na+ratios, relative water content (RWC), membrane stability index (MSI), α-Tocopherol (α-TOC), Ascorbate (AsA), glutathione (GSH), enzymatic antioxidants activities and other anatomical features as compared to controls. In contrast, electrolytes, such as SS and/or FS under salt stress compared to controls (SS and FS using tap water) were significantly decreased. The best results were obtained when SS was combined with FS via Si or Pro. These alterations are brought about by the exogenous application of Si and/or Pro rendering these elements potentially useful in aiding sweet corn plants to acclimate successfully to saline soil.

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 O 2 · - ) 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.