Microalgae-based biostimulants are gaining increasing interest worldwide for promoting sustainable agriculture. The environmental risks associated with synthetic agrochemicals can be mitigated by using microalgae to enhance crop yield and quality. Cumin (Cuminum cyminum L.) is an herbaceous plant and ranks among the most popular seed spices worldwide. It is characterized by a low germination rate and poor seedling establishment, which negatively impact overall crop yield. To address these challenges, the present study investigates the potential of Chlorococcum sp. aqueous extract as a sustainable and cost-effective solution to overcome cumin seed dormancy and enhance germination. Results showed that Chlorococcum sp. exhibits a notably rapid growth rate (0.45 day⁻¹) and high biomass productivity (1.51 g/L/day). Additionally, the biochemical composition of the extract revealed a high concentration of bioactive compounds, including polyphenols (63.46%), flavonoids (29.36%), and Indole-3-acetic acid (5.38%), which make it an eco-friendly biostimulant for agricultural applications. Regarding germination, a single seed treatment with doses of 0.5 g/L and 1 g/L was efficient in achieving final germination percentages of 100% and 96.66%, respectively, and significantly increased the seedling vigor index and photosynthetic pigment content. Furthermore, these concentrations stimulated the synthesis and accumulation of key primary metabolites, including proteins and polysaccharides, while increasing phenolic and flavonoid levels compared to the control, suggesting enhanced growth and improved antioxidant defenses against environmental stressors. Overall, these findings highlight that Chlorococcum sp. aqueous extract serves as an innovative biological approach to overcoming cumin seed dormancy and enhancing germination, offering an alternative and sustainable solution to conventional synthetic fertilizers.

The transition toward sustainable agriculture requires innovative biostimulants that enhance crop performance while reducing reliance on synthetic agrochemical inputs, such as mineral fertilizers and chemical pesticides, including herbicides, insecticides, and fungicides. Microalgae have gained considerable attention as sustainable biostimulants due to their diverse biochemical composition, including primary metabolites, phenolic compounds, and phytohormones. This work examined how Chlorococcum sp. extract influences seed germination, early seedling development, pigment content, and biochemical composition of soybean (Glycine max L.). Biochemical characterization of the extract revealed it was rich in polyphenols and flavonoids. Seeds were treated with four concentrations (0.1–2 g L⁻¹) and compared to an untreated control. The extract significantly improved the final germination percentage, from 57% in the control to 70% (0.5 g L⁻¹) and 80% (1 and 2 g L⁻¹), with a similar trend observed for the seed vigor index. Radicle and hypocotyl lengths increased significantly. Results also showed that pigment levels increased, especially under the 0.5 g L⁻¹ treatment. Seedling biochemical parameters, including carbohydrates, proteins, reducing sugars, phenolic compounds, and DPPH radical-scavenging activity, increased under microalgal treatments. Overall, the findings highlight the potential of microalgae-derived biostimulants as renewable and environmentally friendly alternatives to conventional crop inputs, supporting more sustainable soybean production and contributing to the development of resilient and resource-efficient agricultural systems.