Salicylic Acid and Iron Improve Maize Yield and Quality under Water Deficit

Water deficit stress is one of the most important limiting factors for maize grain production and quality in arid and semi-arid regions of the world. This research was conducted to investigate the effect of foliar application of salicylic acid and iron on improving water status, reducing oxidative damage, and enhancing quantitative and qualitative grain yield of Single Cross 704 maize seeds pre-treated with ethephon under water deficit stress conditions. The experiment was carried out as a split-split plot design based on a randomized complete block design with four replications over two cropping years in a farm with a semi-arid climate located in Gotvand County, Khuzestan Province. The factors included irrigation regime (full irrigation and irrigation cessation at the silking stage), salicylic acid foliar application (0, 100, 200, and 300 mg L–1), and iron foliar application (0, 2, and 4 kg ha–1). All seeds were pre-treated with ethephon (0.05 mM) as a constant priming treatment. The results showed that drought stress increased the concentration of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and decreased relative water content, chlorophyll a and b concentrations, grain iron content, and grain yield, but increased grain protein percentage. Application of salicylic acid and iron, especially at the highest levels (300 mg L–1 and 4 kg ha–1), reduced 8-OHdG concentration and improved other traits. The three-way interaction of irrigation, salicylic acid, and iron on grain yield was significant, and the treatment of 300 mg L–1 salicylic acid with 4 kg ha–1 iron produced the highest grain yield under both irrigation conditions. In general, seed priming with ethephon and foliar application of salicylic acid (300 mg L–1) and iron (4 kg ha–1) improved maize yield under water deficit stress by reducing oxidative DNA damage, improving water status and photosynthesis, and enhancing grain quality.