Evaluating the potential of natural and chemical water retainers on barley (Hordeum vulgare) morphological and biochemical aspect

Climate change has increased water demand while increasing water resources. To enhance water absorption and nutrient retention in soil, hydro-retainers are widely used in agriculture; however, most are synthetic, non-biodegradable acrylate-based products. This research was conducted to evaluate the impact of a hydro-retentive synthetic potassium polyacrylate and natural cladode powder from Opuntia ficus-indica, on germination of three barley (Hordeum vulgare) varieties Kounouz, Artorio and Rihane. Using natural cladode powder, potassium polyacrylate, and their combination at different concentrations (0.2%, 0.5%, and 1%), to test the germination of Kounouz and Artorio in vitro over a 15-day treatment period and Rihane in vivo over a one-month treatment period. This work focuses on the physiological and biochemical behaviour of the barley varieties in response to the application of synthetic hydrogel and natural cladode powder and their combination. The measurements included germination rate, plant height, root length, total protein, chlorophyll content, oxidative stress markers, and hydrogen peroxide levels. The findings reveal varietal-specific responses to hydro-retentive treatments, with potassium polyacrylate significantly enhancing germination rates, especially at higher concentrations. Conversely, Opuntia ficus-indica cladode powder showed positive effects at lower concentrations but inhibited germination at higher doses. Improvements in chlorophyll content and antioxidant enzyme activities at specific concentrations suggest an optimization pathway for stress resilience in barley seedlings. Mixed hydrogel treatments, particularly at a 0.5% concentration, affected positively the evaluated parameters.