Salicylic acid altered the fatty acids compositions and nutrient status of shallot (Allium hirtifolium) grown under drought stress

In arid and semi-arid regions, water shortage is a persistent challenge, significantly affecting plant growth and productivity. To mitigate the detrimental effects of drought, the use of plant growth regulators, such as salicylic acid (SA), has proven to be an effective strategy for enhancing plant resilience, as well as improving yield and quality. This study aimed to investigate the impact of SA on the nutrient composition, yield, and overall quality of shallot plants over three cropping seasons (2020, 2021, and 2022) under drought stress conditions. A split-plot design with four replicates was employed, where irrigation levels (0 %, 50 %, 75 %, and 100 % of the plant's water requirements) were the main factor, and varying concentrations of SA (0, 0.5, 0.75, and 1 mM) were the secondary factor. The results revealed that drought stress increased the concentrations of key micronutrients—iron, copper, sodium, potassium, manganese, and zinc—while reducing magnesium content, ash content, and overall yield. However, the application of SA counteracted these effects by significantly enhancing magnesium content, ash content, and yield in shallot plants. In addition, drought stress increased the levels of palmitic, palmitoleic, and oleic acids while reducing the levels of stearic, linoleic, and linolenic acids. The highest concentrations of linoleic acid (ω6, 110.1 mg) and linolenic acid (ω3, 24.242 mg) were recorded under full irrigation and 75 % water requirement treatments, respectively. SA application further enhanced the levels of stearic, oleic, and linoleic acids, improving the overall nutritional quality of shallot plants. In conclusion, the application of optimal concentrations of SA significantly improves the yield, quality, and nutritional value of shallot plants under drought stress, making it a valuable approach for managing water stress in agriculture. • Salicylic acid enhances shallot yield and quality under drought stress conditions. • SA increases stearic, oleic, and linoleic acids in drought-stressed shallot plants. • Drought stress raises iron, copper, sodium, potassium, manganese, and zinc in shallots. • Optimal SA levels boost magnesium, ash content, and yield in drought-affected shallots. • Full irrigation with SA achieves highest linoleic and linolenic acid levels in shallots.