Seaweed Polysaccharides as Potential Biostimulants in Turnip Greens Production

Abstract

Seaweed polysaccharides can act as substitutes for synthetic compounds present in commercial stimulants and fertilizers used in agriculture to improve crop yields and vigor. In this study, three different polysaccharides (alginate, agar, and carrageenan) were extracted from one brown seaweed, Saccorhiza polyschides, and two red seaweeds, Gracilaria gracilis and Chondrus crispus, respectively, and applied to potted turnip greens (Brassica napus L.), with the intention to analyze their impact on plant growth, development, and metabolism. Turnip greens treated with polysaccharides, especially carrageenan of C. crispus, showed the best results in improving the crop productivity in terms of plant length and weight, number of leaves, nutrient and pigment content, and soil fertility compared with turnip greens from the negative control or those treated with a commercial leaf fertilizer. λ-carrageenan extracted from the tetrasporophyte generation of C. crispus had the highest bioactivity and positive effect on turnip greens among all treatments. λ-carrageenan has been shown to improve plant growth; increase the plant’s biomass (plant leaves: CC(T) (40.80 ± 5.11 g) compared to the positive control (15.91 ± 15.15 g)) and root system; enhance photosynthetic activity; increase the uptake of soil nutrients; and protect plants against abiotic and biotic stresses, stimulating the production of secondary metabolites and managing its defense pathways. Seaweed-extracted polysaccharides have the potential to be used in sustainable agriculture.