Seaweed Extracts Improve Salinity Tolerance in Cereal Crops—A Meta‐Analysis

Seaweeds are considered an essential component of the blue economy. Because seaweed extracts are rich in bioactive compounds that enhance plant stress resilience, exploiting this resource could offer a sustainable solution for crop production. Salinity is a major abiotic challenge that significantly impacts crop yield and food security. Through meta-analysis, we explored whether the exogenous application of seaweed extracts improves the salt tolerance of cereal crops. All the studies chosen for this study utilized aqueous seaweed extracts as foliar sprays. A multi-level meta-analysis with a mixed effects model was performed to determine the effect size. This meta-analysis demonstrated that applying aqueous seaweed extracts enhanced the shoot and root biomass under normal and salinity stress conditions, suggesting that seaweed extract can help improve crop stress tolerance. The seaweeds studied belonged to three classes: Phaeophyceae, Rhodophyta, and Chlorophyta, with extracts from Chlorophyta and Phaeophyceae significantly enhancing biomass production under salinity conditions. Applying aqueous seaweed extracts effectively improved salinity tolerance at both 34.2–100 mM and 101–400 mM NaCl equivalent salinity stress. Moreover, exogenous foliar application of ≤ 25% aqueous seaweed extracts was most effective for improving salinity tolerance in cereals. The impact of seaweed extracts on cereal crop yields has not been extensively reported; therefore, further studies should focus on this aspect.