Green nanosilica enhanced the salt-tolerance defenses and yield of Williams banana: A field trial for using saline water in low fertile arid soil

Nanotechnology offers great opportunities for sustainable management of degraded soils and using of saline water. The use of green nanoagrochemicals (e.g., nanofertilizers) derived from plant biowastes is highly concerning from an agro-environmental point of view. The impacts of nanoagrochemicals on salt tolerance mechanisms of Williams banana (Musa spp.) plants under field conditions, particularly in soils with low fertility under salinity stress and low organic matter content, have not yet been verified. Therefore, in this study, a two-year field trial was conducted to investigate the impacts of green nanosilica (GNS) application on the enhancing the salt tolerance of Williams banana plants in arid sandy soil. Banana plants were irrigated with fresh Nile River water (EC = 0.53 dS m⁻¹) or saline groundwater (EC = 4.12 dS m⁻¹) and sprayed with GNS at doses of 0 mg L⁻¹ (control), 150 mg L⁻¹ (GNS₁), and 300 mg L⁻¹ (GNS₂) in spring, summer, and autumn. Spraying the saline water-irrigated plants with GNS₁ and GNS₂ significantly increased the total fruit yield by 30% and 45% in the first year and by 21% and 38% in the second year and reduced the concentrations of Na⁺ in leaves by 32% and 36%, respectively, compared with the control. Moreover, the foliar application of GNS₁ and GNS₂ improved the total sugar content in the banana fruits under salinity stress by 42% and 50%, respectively. We assume that GNS application induced an increase in nutrient uptake and that antioxidant and osmoregulation compounds (e.g., proline and soluble carbohydrates) enhanced banana plant tolerance to salinity stress. Although the use of GNS reduced the negative effects of saline irrigation water, banana plants that were irrigated with Nile River water remained significantly better than the saline ground water. In conclusion, the foliar application of GNS improved the productivity and quality of Williams banana fruit in sandy poor soils and enhanced their tolerance to salinity stress, which provides opportunities to expand banana cultivation using saline water in low fertile sandy arid soils. These findings might be an aid for sustainable management of degraded sandy arid soils and reusing of saline water.