STUDY OF MICROALGAE AS BIOSTIMULANT FOR LETTUCE SEED GERMINATION

GIL ROCIO MARIEL; GROFF, M. CARLA; BIZUTTI VICTORIA; GOLDSTEIN MILAGRO; SOLAR, D. M; FERNANDEZ MARIA CECILIA; SCAGLIA, GUSTAVO JUAN EDUARDO

San Juan

Otro; XLI REUNIÓN CIENTÍFICA ANUAL DE LA SOCIEDAD DE BIOLOGÍA DE CUYO; 2023

Sociedad Biología de Cuyo

The depletion of non-renewable fossil fuels has spurred the quest for alternative renewable resources to meet the growing energy demand while reducing carbon dioxide emissions. Modern global energy strategies are anchored in economically viable and environmentally friendly alternatives. Within this context, circular processes such as anaerobic digestion of urban solid waste, augmented by the cultivation of microalgae, have gained prominence. The resulting waste from this process has emerged as an alternative for maintaining and enhancing agricultural productivity. Microalgae, with their extensive species biodiversity and versatile metabolism, produce a variety of compounds that facilitate nutrient capture and supply, enhance soil properties, and stimulate plant growth. In this study, we assessed the germination capacity of Chlorella vulgaris (Dra. Gagneten, FHUC, UNL), Desmodesmus spinosus(Cepa FAUBA-4), Golenkinia brevispicula (FAUBA-3) and Haematococcus pluvialis (FAUBA-57), through phytotoxicity tests based on the lettuce (Lactuca sativa) germination index. For microalgae biostimulant experiment, 2.5 of sterile distilled water were deposited on sterile filter paper fitted in the lid of a 90 mm Petri dish. Fifteen seeds were placed on and each seed was punctually inoculated with 15 µL of active microalgae suspension (2.5 x 106 cells/mL). This was repeated for all microalgae species, and three dishes were prepared for each microalgae, resulting in 45 seeds per lettuce treatment. The plates were then kept at 20ºC in a 12:12 light:dark regime receiving 200 μmol.m−2.s−1 photosynthetically active radiation on its surface using fluorescent lamps. Germination for lettuce was defined by the radicle emerging at least 3 mm. They were watered with sterile distilled water according to demand each day (approximately 1.5 mL). The percentage germination index (%GI) was assessed for 45 seeds per microalga treatment, with the control group receiving seeds inoculated with sterile water. The results indicate that Desmodesmus spinosus achieved a germination index of 95.55%, surpassing the control group which reached 91.11%. Chlorella vulgaris exhibited a germination index like that of the control. On the other hand, Golenkinia brevispicula and Haematococcus pluvialis obtained %GI of 86.67% and 83.08%, respectively. It can be concluded that Desmodesmus spinosus had a positive effect on lettuce seed germination, suggesting that microalgae of this genus could be beneficial for the production of sustainable lettuce crops. However, the results also underscore the significance of carefully selecting the type of microalgae for agricultural applications. This highlights the need for further research and applications in agriculture that could harness the potential of microalgae to enhance crop productivity. Microalgae may offer natural and cost-effective alternative biostimulants to synthetically produced agrochemicals. Then, in future experiments, we will study the production of plant hormones by microalgae, such as betaines, auxins, cytokines and gibberellins.