Various extracts of the brown seaweed Cystoseira barbata with different compositions exert biostimulant effects on seedling growth of wheat.

Worldwide, where the demand for novel and greener solutions for sustainable agricultural production is increasing, the use of eco‐friendly products such as seaweed‐derived biostimulants as pre‐sowing treatment represent a promising and important approach for the future. Cystoseira barbata, a brown seaweed species abundant in the Mediterranean Region, was collected from the Marmara Sea and subjected to water, alkali, and acidic extractions, and the biostimulant activity of these extracts was tested on wheat (Triticum durum cv. Saricanak‐98) using different rates through application to the seeds or germination medium (substrate) applications. The different extracts were characterized by mineral, total phenolic, free amino acid, mannitol, polysaccharide, antioxidant concentrations and hormone‐like activity. The effects of the extracts on growth parameters, root morphology, esterase activity, and mineral nutrient concentrations of wheat seedlings were investigated. Our results suggest that the substrate application was more effective in enhancing the seedling performance compared to the seed treatment. High rates of seaweed extracts applied to substrates increased the shoot length and fresh weight of wheat seedlings by up to 20 and 25%, respectively. The substrate applications enhanced the root fresh weights of wheat seedlings by up to 25% when compared to control plants. Among the biostimulant extract applications, the water extract at the highest rate yielded the most promising results in terms of the measured parameters. Cystoseira barbata extracts with different compositions can be used as effective biostimulants to boost seedling growth. The local seaweed biomass affected by mucilage problems, has great potential as a bioeconomy resource and can contribute to sustainable practices for agriculture. [ABSTRACT FROM AUTHOR]