Effects of brewer’s spent yeast concentrations and application methods on <i>Coffea arabica</i> seedling development

Brewer’s spent yeast (BSY) contains Saccharomyces cerevisiae, which is a byproduct that may be used as a biofertilizer and plant growth promoter. Improving the understanding of the ideal BSY concentration and application method for coffee seedling development will enable more targeted application strategies. We hypothesized that a given BSY concentration and application method would improve the development of coffee seedlings by adding sources of organic matter containing yeast. This hypothesis was tested by assessing the development parameters of Coffea arabica var. Typica (Cramer variety) using different concentrations (0, 2.35, 4.71, 9.40, 11.75 x 108 S. cerevisiae cells mL-1) and two application methods (foliar-FA and soil-SA). Our analysis revealed that BSY foliar application was more efficient than soil application in improving coffee seedling development. Foliar application at 2.3 x 108 S. cerevisiae cells mL-1 increased fresh shoot weight (2.35 times), fresh root weight (4.22 times), dry shoot weight (2.23 times), and dry root weight (3.62 times) in coffee plants compared to the negative control (sterile solution). Our findings provide evidence of waste reuse as an alternative method for developing coffee seedlings through the addition of materials rich in organic matter and yeast. They also align with the Sustainable Development Goals (SDGs), demonstrating strategies that support sustainable agriculture and circular economy practices.