Characterizing organic biostimulants from Kappaphycus alvarezii (Doty) and assessing their stimulant potential on Zea mays (maize)

Marine algae are rich in minerals and phytochemicals and are utilized in agriculture as biostimulants for plant growth after industrial extraction. Therefore, in the current study, red marine algae (RMA) were extracted using cow urine and water to produce suitable biostimulants for organic agriculture. The raw RMA and its extracts were characterized for nutrients and bioactive metabolites. The extracted RMA biostimulants were tested at different concentrations using maize species to optimize the most effective concentrations for growth promotion. Results showed that cow urine extracts (CUE) contained higher essential nutrients compared to aqueous extracts (AQE), with average extractions of 34% primary nutrients, 31% secondary nutrients, 10% micronutrients, and 5% heavy metals in CUE, and 3%, 6%, 6%, and 12% in AQE, respectively. Maize germination parameters were significantly higher at 2.5% concentration for both CUE and AQE solutions, and also performed well at 5% concentration. Germination percentage, energy, and index ranged from 25-35%, 20-30%, and 0.6-0.9%, respectively, with higher values observed with CUE. Seedling parameters such as seedling vigor index, length, and biomass were significantly higher with 7.5% CUE and 5% AQE. Similar results were observed for root traits, except for root tips, which were higher at 10%. The study suggests that concentrations of 5.0-7.5% for CUE and 2.5-5.0% for AQE are optimal for enhancing maize germination and seedling growth. Furthermore, cow urine-based extract of red marine algae at 5% and 7.5% concentrations showed superior performance compared to aqueous extract in promoting plant growth. These findings warrant further validation under field conditions to assess their impact on crop production and quality.