Seed treatment with seaweed extract biofertilizers and foliar application of blended microalgae extracts enhanced barley (Hordeum vulgare) crop yield

Barley (Hordeum vulgare) is a versatile cereal crop known for its high productivity and nutritional value. It plays a crucial role in ensuring food security worldwide. Sustainable solutions are needed to enhance barley yields. This underscores the need for sustainable solutions to enhance barley yields. The aim of this field study was to assess the impact of two commercial mineral fertilizers (referred to as FR and FG) containing seaweed extract (Kappaphycus alvarezii and Ascophyllum nodosum) in combination with aqueous extracts of blended microalgae (Arthrospira platensis, Tetradesmus obliquus, and Chaetoceros muelleri) on barley growth and yield. A randomized block design with four replications was employed in a 3 × 3 factorial arrangement, with three seed treatments (control, commercial FR, and aqueous extracts of blended microalgae) as the primary factor and three foliar treatments (control, commercial FG, and blended microalgae aqueous extracts) as the secondary factor, resulting in 36 experimental units. Seed treatment with commercial FR increased the number of tillers per plant by 19.37% and plant height by 8.47%; but led to a 10.80% decrease in ear length and a 5.43% decrease in 100-grain weight. Applying commercial FR via seeds increased barley yield by 32.22% when combined with foliar application of the microalgae blend, and by 32.85% when combined with commercial FG via foliar application compared to the control. The combination of commercial FR seed treatment with commercial FG or aqueous extracts of blended microalgae increased barley yield by 49.73% (784.24 kg ha–1) and 50.53% (788.84 kg ha–1), respectively. This study suggests that using macroalgae-based products with blended microalgae extract is a promising sustainable approach to enhance barley development and productivity.