Abstract
A sustainable biostimulant has been gaining more attention, as it provides eco-friendly agriculture practices and helps achieve sustainable results. This study investigated the effects of microalgae-based biostimulants on tomato seedling vigor, plant growth, and fruit productivity. Four microalgae biomasses from different strains and conditions were tested (Limnospira maxima in seawater and freshwater cultivation, Leptolyngbya sp. and Chlorella sp.) for the early stage of cultivation and later followed by testing in mature stages. Limnospira maxima freshwater was found to significantly improve germination up to 99.3% and reduced T50 from 38.4 to 29.6 h. It was also found to increase the mean germination time (MGT) from 12.6 to 9.96 h. Overall, the germination index (GI) increased from 1.2 to 1.6. Root length was also found to increase significantly in the microalgae biostimulant, similar to the effect of a commercial biostimulant. In terms of productivity, the algal-based biostimulant has higher fruit productivity than the control and commercial biostimulant (2.64 kg, 2.2 kg, and 1.9 kg, respectively). These findings highlight the potential of algal-based biostimulants for sustainable tomato crop cultivation for clean agriculture practices in semi-arid environments. Linking to the carbon footprint, the application also avoided emissions of more than 14,000 kg CO2 equivalent per hectare per crop cycle. These outcomes position locally produced microalgae biostimulants as a green product that couples crop productivity with carbon mitigation and supply chain resilience in semi-arid environments.