Integrated organic and biostimulant strategies to improve wheat productivity under salt-affected soil conditions

Soil salinity is a major abiotic constraint limiting wheat (Triticum aestivum L.) production in arid and semi-arid regions, where excessive Na⁺ accumulation restricts nutrient uptake, disrupts photosynthesis, and suppresses biomass and grain formation. This greenhouse study evaluated the individual and interactive effects of a plant-derived liquid organic fertilizer (SOLF; 40% organic matter) applied at four doses and six foliar biostimulant treatments—plant-derived amino acids (P-AA), animal-derived amino acids (A-AA), seaweed extract (SW), and their combinations—on wheat grown in salt-affected soil. A 4 × 6 factorial experiment arranged in a randomized complete block design (96 pots) revealed that both SOLF and foliar treatments significantly improved plant height, tiller production, leaf chlorophyll (SPAD), leaf area, key yield components, and grain yield (p < 0.05). The highest yield was obtained with the integrated D₃F₅ treatment (high SOLF × A-AA + SW), which produced 26.8 g pot⁻¹ (≈ 5.42 t ha⁻¹), representing a 58.7% increase compared with the untreated control. SOLF application substantially improved post-harvest soil properties by increasing soil organic matter (0.82% → 1.32%) and reducing electrical conductivity (5.2 → 3.8 dS m⁻¹), while foliar applications enhanced physiological performance and nutrient assimilation. Combined treatments produced clear synergistic effects, reflected in greater N, P, and K uptake and improved canopy vigor under salinity stress. Overall, the results demonstrate that integrating soil-applied organic carbon with amino acid– and seaweed-based foliar biostimulants offers a highly effective and sustainable approach to improving wheat growth, nutrient use, and productivity in saline soils. These findings highlight the potential of integrated organic-input strategies to reduce the negative impacts of salinity and contribute to more resilient wheat production systems.