Evaluation of biostimulant capacity by phytohormonal extracts from native microalgae of the Barú and Alanje Regions, Chiriquí Province, Panamá

Resumen

This study evaluated the effects of different concentrations of extracts from microalgal strains identified as Chlorella vulgaris, Chlorella sorokiniana, Scenedesmus quadricauda and Scenedesmus almeriensis, in germination bioassays using rice (Oryza sativa), tomato (Solanum lycopersicum) and watercress (Nasturtium officinale) seeds to assess the germination index (GI). The biostimulant effects were tested at different concentrations of the algal extracts coded as Al₂, Bar₁, Bar₄ and SA at 0.1 g/L and 0.5 g/L each. The extract of strain Bar₄ at 0.1 g/L exhibited the strongest biostimulant effect in most of the assays, with 19 out of 25 germinated seeds and a GI of 137±0.24% in rice seeds. The remaining extracts showed a germination-promoting effect ranging from 119% to 133%. In contrast, strain SA displayed a mild inhibitory effect, with GI of 84% and 85% at 0.1 and 0.5 g/L, respectively, both below the negative control. In the tomato seed assay, Bar₄ resulted in 18±1.89 germinated seeds and a GI of 220±0.41%. The other extracts also showed germination-promoting activity, with values ranging from 187% to 216%. Finally, in the watercress seed assay, Bar₄ at 0.1 g/L again demonstrated the highest biostimulant effect, reaching 10±3.21 germinated seeds and a GI of 319±38%. Considering the phytohormones present in microalgae as a key factor in the valorization of these microscopic organisms opens promising perspectives; it represents not only a growing opportunity but also an innovative approach that could significantly contribute to improving efficiency and sustainability in agriculture.