Dynamics of Gracilaria edulis liquid extract on agromorphology, yield, and essential oil profile of chamomile (Matricaria recutita L.)

Chamomile, widely used in foods and herbal infusions, contains bioactive compounds with antioxidant and calming effects, supporting digestion, reducing inflammation, and promoting overall health. Seaweed extracts, rich in bioactive compounds, offer a promising biostimulant strategy to improve their growth, phytochemical content, and overall quality. This study evaluates the qualitative attributes, agronomic performance, and economic feasibility of Gracilaria edulis extract (GEE) as a foliar biostimulant in German chamomile (Matricaria recutita L.) cultivation. Two field experiments were conducted during consecutive Rabi (Winter) seasons (2021–2023) using a randomized block design with seven treatments comprising the recommended dose of fertilizers (RDF) and foliar applications of GEE at concentrations ranging from 2.5% to 15%. The results revealed that GEE significantly influenced the growth, floral characteristics, essential oil yield, and quality of chamomile. The maximum dry flower yield (1.30 t ha−¹) and essential oil yield (10.60 kg ha−¹) were recorded with 10% GEE, closely followed by 15% GEE, with strong linear dose-response relationships (R² = 0.9660 for flower yield and R² = 0.9716 for oil yield). Despite no significant change in essential oil content, treatment induced variations affected the essential oil composition, displaying a complex and nonlinear response, with α-bisabolol, α-bisabolol oxide A, α-bisabolol oxide B, chamazulene, and (Z)-spiro ether identified as the major constituents. The 10% GEE treatment also recorded the highest economic returns (net income US$ 5194.28 ha−¹ Benefit : Cost ratio 2.40), confirming its economic superiority. Overall, the findings indicate that a 10% GEE foliar spray combined with fertilizers constitutes a sustainable approach for improving productivity, oil yield, and profitability in chamomile cultivation. Further studies are warranted to appraise its Sustained impact on soil health and broader applicability to other medicinal and aromatic crops.