Hydrogel application as a soil amendment to mitigate water deficiency effects on flaxseed cultivars grown in sandy soils

Abstract Water scarcity is a major constraint for flax production in Egypt’s sandy soils. This research aims to investigate the use of hydrogels, as water-absorbing polymers can enhance soil moisture retention and improve crop performance under water deficit conditions, thereby increasing flax yield and seed quality. Two field experiments were conducted during the 2022/2023 and 2023/2024 winter seasons at the National Research Centre, Al Nubaria, Egypt, to evaluate the effects of hydrogel (0 and 80 kg/ha) on three flax cultivars (Giza-11, Giza-12, Sakha-3) under full water irrigation quantity (100%WIQ) and deficit water irrigation quantity (75%WIQ). Showed that Giza-12 variety outperformed the other varieties in growth, yield, and seed quality under all conditions. On the other hand, water deficit significantly reduced growth, photosynthetic pigments, indole acetic acid, yield, and seed nutritional components (oil, protein, carbohydrates). While hydrogel application mitigated these effects, enhancing growth, yield, compatible solutes (proline, soluble sugars, soluble nitrogen), and leaf phenolics. Specifically, full irrigation using hydrogel application, increased seed yield and oil yield by 45.0% and 59.5% for Giza-11, and 8.8% and 12.8% for Sakha-3. Under water stress using hydrogel application, the respective increases were 44.0% and 42.9%, 28.2% and 36.7%, and 37.0% and 42.9%. These findings indicate that hydrogel application is a practical strategy to enhance flax productivity and seed quality under water deficit conditions.