Boosting Arugula’s Nutritional Power: How Salicylic Acid and Melatonin Revolutionize Leafy Greens

Introduction

In a world increasingly conscious about food quality and nutrition, science is turning to nature’s own plant bioregulators to enhance the value of everyday crops. A recent study published in BMC Plant Biology (2025) reveals how foliar spraying of salicylic acid and melatonin can significantly elevate the nutritional profile of Arugula (Eruca vesicaria subsp. sativa Mill.) — a beloved leafy vegetable packed with vitamins, minerals, and antioxidants.

The Research at a Glance

Researchers from the University of Tabriz, Iran, explored how different concentrations of melatonin (0, 50, 100 µM) and salicylic acid (0, 50, 100 µM) influence the nutrient content of Arugula. The treatments were applied under greenhouse conditions, and the results were both intriguing and promising.

Key nutrients analyzed included:

Macronutrients: Nitrogen (N), Phosphorus (P), Potassium (K), Sulfur (S)
Micronutrients: Iron (Fe), Zinc (Zn), Copper (Cu), and Manganese (Mn)

Major Findings: Nature’s Hormones Boost Nutrition

Salicylic Acid: The Nitrogen and Iron Enhancer
- 50 µM of salicylic acid increased nitrogen by nearly 4.9% and iron concentration to 0.075 mg/g, making it a potent natural stimulator for nutrient assimilation.
Melatonin: The Potassium and Phosphorus Booster
- 50 µM of melatonin enhanced potassium content to 18.9 mg/g, while 100 µM elevated phosphorus by 22.2%.
- Melatonin also boosted sulfur concentration by 60.3%, strengthening plant metabolism and antioxidant capacity.
Combined Application: A Delicate Balance
- When salicylic acid and melatonin were applied together, some negative interactions were observed — particularly at higher doses — reducing nitrogen and sulfur uptake.
- This indicates the importance of precise concentration management for maximizing plant health and nutrition.

Why It Matters: Toward Sustainable Crop Enhancement

This study emphasizes how naturally occurring compounds like salicylic acid and melatonin can:

Improve nutrient uptake efficiency
Enhance food nutritional quality
Reduce dependency on synthetic fertilizers
Promote sustainable, eco-friendly agriculture

By optimizing foliar applications, farmers can produce more nutrient-rich, high-value crops, aligning with global efforts toward sustainable food systems and biofortification.

Practical Takeaways for Growers

Start small: Begin with 50 µM foliar applications for both compounds to test crop response.
Monitor leaf nutrient profiles: Excess concentrations can reduce efficiency or cause antagonistic effects.
Combine wisely: Sequential or separate sprays may yield better outcomes than simultaneous applications.
Think beyond yield: Nutrient density and crop quality are the future of profitable and sustainable farming.

Scientific Insight

Melatonin acts as a universal plant regulator, enhancing photosynthesis, antioxidant defense, and nutrient mobilization. Salicylic acid, meanwhile, fine-tunes enzymatic activities and boosts nitrogen metabolism. Their integration into horticultural practices can serve as a biotechnological breakthrough for both organic and conventional agriculture.

Conclusion

The synergy between salicylic acid and melatonin offers a new path for improving the nutritional quality of crops like Arugula. This eco-friendly strategy supports the next generation of functional foods, rich in essential nutrients and antioxidants, and empowers farmers to adopt sustainable plant biostimulant technologies for a healthier planet.

Reference

Amani, M., Alizadeh-Salteh, S., Bolandnazar, S., Ostadrahimi, A., & Jafari, S. (2025). Foliar spraying of salicylic acid and melatonin enhances the nutritional value of Arugula (Eruca vesicaria subsp. sativa mill.). BMC Plant Biology, 25(1), 1312. https://doi.org/10.1186/s12870-025-07375-z