University of Tabriz Journal of Plant Physiology and Breeding 2008-5168 15 2 2025 12 01 Minimizing adverse effects of drought stress on maize (Zea mays L.) using foliar application of jasmonic and salicylic acids 147 170 20994 10.22034/jppb.2025.69241.1383 EN Fatemeh Nasr Department of Plant Production and Genetics, School of Agriculture, Shiraz University, Shiraz 7155713876, Iran. Yahya Emam Department of Plant Production and Genetics, School of Agriculture, Shiraz University, Shiraz 7155713876, Iran. Afshin Zamani Department of Plant Production and Genetics, School of Agriculture, Shiraz University, Shiraz 7155713876, Iran. Journal Article 2025 09 20 Drought stress is a major factor limiting the growth and yield of maize (Zea mays L.). This experiment aimed to examine the effects of foliar application of salicylic acid (SA) and methyl jasmonate (MJ) in both single and combined concentrations on morphological, physiological, and biochemical traits of maize plants under varying levels of water deficit. Methods: The experiment was carried out in the greenhouse of the School of Agriculture, Shiraz University, Iran, using a completely randomized design with three irrigation levels (100, 75, and 50% of full irrigation, FI) and nine foliar spray treatments (control, SA 0.5 and 1 mM, MJ 10 and 20 μM, and four SA and MJ combinations) in 2022. Growth traits such as shoot height, stem diameter, leaf area, as well as fresh and dry weights of shoots and roots, SPAD index, and chlorophyll content (chlorophyll a, b, and total), along with biochemical traits including anthocyanin, hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) were measured. Results: Drought stress resulted in a notable decline in vegetative growth and an elevation in oxidative indices; however, the combined treatments effectively mitigated these adverse effects. In severe drought (50% FI), root dry weight increased from 2.0 g in the control to 4.6 g in the SA1&MJ20 treatment. Leaf area, which was less than 400 cm² in the control, was found to be 487 and 456 cm² with SA0.5&MJ10 and SA0.5&MJ20, respectively. The SA1&MJ10 combination maintained total chlorophyll above 1.2 mg g-¹ FW under 100% FI conditions and preserved chlorophyll a at a higher level than the control during 70% FI. The combinations also resulted in the greatest reduction in H2O2 and MDA; under 50% FI, H2O2 and MDA levels decreased from 0.47 and 88 µmol g-¹ FW in the control to 0.28 and 28.7 µmol g-¹ FW in the SA0.5&MJ10 treatment. Furthermore, the anthocyanin content in the combined treatments, particularly SA1&MJ20, reached levels exceeding 6.0 mmol g-¹ FW, indicating an enhancement of secondary defense pathways and protection against reactive oxygen species. Similarly, the individual application of SA or MJ also exerted positive effects on several growth and biochemical traits depending on the irrigation level, indicating that single-hormone treatments also could be beneficial under specific FI conditions. Conclusion: Reducing irrigation from 100% FI to 75% FI and 50% FI impaired growth and pigments and enhanced oxidative damage. Effects of SA and MJ were trait- and FI-dependent. Overall, SA&MJ (especially SA1&MJ20 and SA0.5&MJ10) tended to better support biomass under 50% FI, whereas MJ alone often maintained SPAD/chlorophyll more effectively under 75% FI. Thus, SA and MJ should be applied using a target-trait, FI-specific strategy, with co-application as a conditional option.

https://breeding.tabrizu.ac.ir/article_20994_89a5a138cecff7cb2c348cc480970d18.pdf