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.