Seaweed Extract Boosts Onion Growth and Bulb Quality: A Sustainable Alternative to Chemical Fertilizers

The Green Revolution Beneath the Waves

Recent research published in The Nucleus has shown that seaweed extract (SWE)—a natural bio-stimulant derived from marine algae—can dramatically enhance onion productivity and bulb quality. This discovery marks a pivotal step toward sustainable agriculture, reducing dependence on chemical fertilizers while promoting healthier crops.

Seaweed extracts are rich in polysaccharides, phytohormones, micronutrients, and amino acids, making them powerful natural enhancers of plant metabolism and stress tolerance.

Study Insight:
Applying 50% seaweed extract via foliar spray boosted onion yield 1.6 times compared to traditional fertilization, with notable improvements in bulb weight, size, and total soluble solids (TSS).

What the Study Found

Researchers from ITM University, Lovely Professional University, and Dr. Rajendra Prasad Central Agriculture University conducted a detailed experiment with varying concentrations and application methods of SWE.

Best Result: 50% foliar spray concentration
Yield Increase: 36.2 tons/ha
Bulb Quality: Increased carotenoid, chlorophyll, and TSS levels
Environmental Impact: Reduced damaged bulbs and enhanced stress resilience

This proves that optimized seaweed extract can improve not only growth but also the nutritional and visual appeal of onion bulbs.

Why Seaweed Extract Works

The bioactive compounds in SWE—like cytokinins, auxins, and gibberellins—stimulate cell division and nutrient uptake. These promote better root systems, more efficient photosynthesis, and ultimately bigger and healthier bulbs.

Seaweed extract also helps in:
Enhancing soil microbiota
Improving drought and salinity tolerance
Boosting nutrient absorption efficiency

Sustainable Agriculture in Action

This research is a major win for eco-conscious farmers. Instead of relying on synthetic fertilizers, biostimulant-based farming can maintain soil health while achieving higher productivity.

For example, farmers using seaweed extract can reduce greenhouse gas emissions linked to fertilizer use while ensuring consistent, high-quality yields.

Conclusion

This study provides solid evidence that seaweed extract biostimulants can revolutionize onion farming—enhancing yield, bulb quality, and environmental sustainability. The 50% foliar spray application emerges as the most effective strategy for sustainable onion cultivation.

Farmers adopting this method will not only achieve higher profitability but also contribute to climate-resilient, eco-friendly agriculture.

Reference

Thirumalesh, S., Singh, S. K., Upadhyay, P., & Bakshi, M. (2025). Seaweed extract: a potential modulator of productivity and bulb quality in onion (Allium cepa L.). The Nucleus. https://doi.org/10.1007/s13237-025-00603-9