Abstract

Declining wheat productivity in semi-arid regions poses a serious threat to food security due to water scarcity and nutrient limitations. A two-year field experiment was conducted at the Agronomic Research Area, Institute of Agronomy, Bahauddin Zakariya University, Multan, to evaluate the effects of hydrogel application (5 kg ha⁻¹) and NPK fertilizer levels under deficit irrigation on growth, yield, biochemical traits, and nutrient use efficiency of wheat (Triticum aestivum L.). The experiment was arranged in a randomized complete block design with three replications, comprising four nutrient–hydrogel treatments: NH₀ (75% NPK), NH₁ (75% NPK + hydrogel), NH₂ (100% NPK), and NH₃ (100% NPK + hydrogel), combined with four irrigation regimes: I₀ (full irrigation), I₁ (skipped tillering), I₂ (skipped flowering), and I₃ (skipped tillering plus flowering). Results showed that hydrogel application significantly improved soil moisture retention, nutrient uptake, and crop performance. The treatment I₀ × NH₃ produced the highest plant height (103.87 cm; 21.31%), fertile tillers (483.33 m⁻²; 108.03%), thousand-grain weight (43.26 g; 55.84%), grain yield (5.40 t ha⁻¹; 32.03%), and biological yield (10.07 t ha⁻¹; 32.15%). Growth indices including crop growth rate (23.89 g m⁻² day⁻¹; 71.16%), net assimilation rate (5.61 g m⁻² day⁻¹; 81.55%), and leaf area index (4.35; 104.23%) were markedly enhanced. Biochemical traits such as SOD (68.65 units g⁻¹ FW; 32.64%), POD (48.50 units g⁻¹ FW; 53.72%), CAT (39.76 units g⁻¹ FW; 74.79%), total soluble proteins (14.28 mg g⁻¹ FW; 36.26%), total phenolics (2.65 mg g⁻¹ FW; 67.72%), chlorophyll content (2.52 mg g⁻¹ FW; 66.89%), and ascorbic acid (31.03 mg 100 g⁻¹ FW; 32.86%) were significantly improved. Water use efficiency and partial factor productivity of N, P, and K were maximized under I₃ × NH₃. Overall, integrating 5 kg ha⁻¹ hydrogel with 100% NPK is a sustainable strategy to enhance wheat productivity and resource use efficiency under optimal and water-limited conditions.