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Background. One of the promising directions in agriculture is the rational use of biologically active substances or plant growth stimulators obtained from local raw materials. In Mexico, seaweed can be considered a cheap, abundant, and accessible local resource along the Mexican coast. It represents great potential for eventual commercial exploitation as a source of plant growth promoters. Previous reports have emphasized the importance of seaweed extracts and their utilization with significant results to improve seed germination, seedling development, growth, and yield of plants, increasing crop productivity. The main effects should be in the first stages of plant ontogenesis, beginning with seed germination and seedling growth. The effects of seaweed liquid extracts in the early stages of plant growth are on root-system growth, providing a signal of the value and quality of the future crop. Therefore, the search for the most effective extracts that stimulate plant development is considered a priority. Goals. Show an overview of the application of seaweed extracts in Mexican agriculture. Results. Information is provided on the administration and regulation for the harvest of marine algae, and the research carried out in Mexico. The management and harvest regulations for the algae, including seaweed liquid extract composition, biological efficacy of promoting plant growth, as well as elicitors of disease defense caused by pathogens. Conclusions. Seaweeds from Mexico have enough potential for the isolation of biologically active compounds that could increase agriculture productivity. This research is essential for the future of Mexican agriculture, to develop effective strategies to use seaweed extracts.

The proximate chemical composition ofSargassum horridumwas determined monthly, including extract yields of alginate, crude fucoidan, and ethanolic extract. In addition, the biological activity (antioxidant and antibacterial) of the ethanolic extract and anticoagulant activity of the fucoidan were examined. Significant monthly variation was found in the chemical composition (moisture, protein, ash, crude lipids, crude fiber, carbohydrates, and gross energy), as well as in the alginate, fucoidan, and ethanolic extract yields. The maximum yield of crude fucoidan (13.5% dry weight) and alginate (21.4% dry weight) occurred in May. Crude fucoidan increased the clotting time at all concentrations tested during all months, based on activated partial thromboplastin and prothrombin time assays. The maximum yield of ethanolic extract occurred in April and August (6% dry weight). The ethanolic extract was evaluated for free radical scavenging activity using the 2,2-diphenyl-1-picrylhydrazyl method, with the highest reduction percentage in April (53%). Only the extracts from March, July and August showed slight antibacterial activity againstVibrio parahaemolyticus,V. alginolyticus, andStaphylococcus aureus.Sargassum horridumthus represents a potential source of carbohydrates, anticoagulant, antioxidants and antibacterial compounds. The best time of year for harvesting the alga is from May to July.

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Background. The interest in studying seaweed polysaccharides as plant growth biostimulants is recent and has generally focused on seaweed liquid extracts for compounds content that have positive effect on plant development. Within these compounds are the carbohydrates such as alginate and fucoidan, among others. Goals. To evaluate the effect of crude fucoidan and alginate on seed germination and their growth-stimulating activity on seedling of mung bean (Vigna radiata). Methods. Fucoidan and alginate from Eisenia arborea and Sargassum horridum at six different doses (0.6, 1.2, 2.5, 5, 10, and 20 mg m -1 ) were evaluated on seed germination and seedling growth of mung bean. Results. Alginate from both algae species in this study did not show a significant effect on mung bean growth. Fucoidan from S. horridum produced the significant effect on mung bean growth by increasing root length (16.2%) and seedling total length (11.9%) at a concentration of 0.6 mg mL -1 and an increase in the dry weight of the seedling (31%) at a concentration of 20 mg mL -1 .While fucoidan from E. arborea had the higher effect on shoot growth (10.5%) and total length (10.7%), compared to the control when applied at a concentration of 10 mg mL -1 . Conclusions. Overall, this study showed that fucoidan from both S. horridum and E. arborea can stimulate seedling growth and increase the germination percentage of mung bean seeds compared to the control.