Nanotreatment improves agronomic traits of Amaranth (Amaranthus spp.) under arid field conditions

Climate change and increasing water scarcity pose major challenges to agricultural sustainability, particularly in arid and semi-arid regions such as Uzbekistan. This study evaluated the effects of nano-treatment (NT) under full (FI), moderate (MI), and deficit irrigation (DI) regimes on the growth, yield, and physiological performance of ( Amaranthus spp.). Seeds were treated with nano-silicon fertilizer at 10 mL kg⁻¹ before planting, and foliar spraying (100 mL ha⁻¹ in 300 L water) was applied twice during the growing season at the 3–5 leaf and flowering stages. Results revealed that NT significantly enhanced crop grain yield, with the highest value (5.2 Mg ha⁻¹) recorded under the FI regime, whereas the respective control plot produced of 4.6 Mg ha⁻¹. This was followed by NT under MI (4.7 Mg ha⁻¹) and DI (3.3 Mg ha⁻¹), whereas their control plots produced 3.4 Mg ha⁻¹ and 2.4 Mg ha⁻¹, respectively. The highest efficacy of NT was found under DI, exhibiting a 57.1% increase, whereas the corresponding increases under MI and FI were 38.2 and 13.0%, respectively. The crop was more responsive to NT under DI, indicating that NT was particularly effective in drought stress conditions. Moreover, NT application reduced wilt disease incidence, while physiological traits such as chlorophyll content, leaf area index, and relative water content were consistently improved, supporting enhanced photosynthetic capacity and stress resilience. Water Use Efficiency (WUE) also demonstrated substantial improvements with NT application, reaching the highest point under DI (2.75 kg m − 3 ) compared to MT (2.61 kg m − 3 ) and FI (2.17 kg m − 3 ). Biochemical changes in leaves show a strong induction of osmotic adjustment and enhanced stress tolerance mechanisms with NT, especially under DI. Overall, these findings highlight NT along with drip irrigation technologies emerges as a promising climate-smart strategy for improving crop resilience, optimizing resource efficiency, and sustaining agricultural productivity under drought stress conditions.