<![CDATA[Basil (Ocimum basilicum L.) was classified as a vegetable and aromatic plant used in health, culinary, and essential oil production. The main challenges in basil cultivation include limited land availability, soil degradation, water scarcity, and land conversion caused by urban development. A promising alternative to overcome these constraints was soilless culture, commonly known as hydroponics, which enables efficient plant production without soil. Various types of substrates can be applied in hydroponic systems, including organic media derived from agricultural residues. In addition, the use of PGPR plays an important role in enhancing plant growth through nutrient mobilization and phytohormone production. This study aimed to evaluate the optimal type of growing media and PGPR concentration to support basil growth in a substrate hydroponic system. The research was conducted using a factorial randomized block design (RBD), with two factors, the type of planting media (three levels) and the PGPR concentration (four levels). The results showed that cocopeat supported superior basil growth compared to rice husk and husk charcoal. Furthermore, the application of PGPR significantly enhanced plant growth relative to treatments without PGPR. Regression analysis indicated that each type of planting media required a different optimum PGPR concentration to achieve maximum biomass production. Specifically, cocopeat required 8.87 mL/L, husk charcoal required 9.3 mL/L, and fresh husk required 14.4 mL/L. Considering both yield performance and production cost efficiency, the use of cocopeat combined with PGPR at a concentration of 8–10 mL/L was recommended as the most effective treatment.]]>
