The Influence of Microbial Biostimulators on the Yield and Economic Profitability of Sustainable Production of Pepper (Capsicum Annuum L.)

Pepper (Capsicum annuum L.) is one of the most important vegetable crops worldwide, with continuously increasing production due to its broad use in fresh consumption and processing. In the Republic of Serbia, pepper production has a significant role, particularly within intensive and sustainable cultivation systems, where producers face rising production costs and growing demands for environmentally friendly technologies. In this context, microbial biostimulants represent a promising approach for improving both yields and economic efficiency. The aim of this study was to evaluate the effects of two microbiological preparations—effective microorganisms (EM) and fungi of the genus Trichoderma— in interaction with agroecological conditions (year), on pepper fruit yield in an organic production system under protected cultivation. A two-factor experiment revealed statistically significant effects (p < 0.01) of the applied treatments. The application of Trichoderma sp. resulted in the highest average yield, exceeding the control by 19.35% and the EM treatment by 13.15%. From an economic perspective, the use of microbial biostimulants demonstrated considerable potential for improving production performance. Increased yields, combined with relatively low additional input costs, led to higher gross margins and improved overall profitability per unit area. Furthermore, lower variable costs per kilogram of produced pepper contributed to reduced production costs compared to conventional technological solutions. The results indicate that microbial biostimulants enhance the economic stability of pepper production, reduce production risk, and increase the competitiveness of sustainable and organic cultivation systems.