Assessment of a Microalgae-Based Biostimulant as a Sustainable Strategy to Overcome Cumin ( Cuminum cyminum L.) Seed Dormancy and Enhance Germination

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.