Effect of Magnesium Sulfate and Rhizosphere Microorganisms on the Growth and Biosynthesis of Cymbopogon nardus L. Essential Oil

Background: Citronella oil from Cymbopogon nardus L. is used in various fields, including health, industry and pharmaceuticals. Efforts to increase the content and quality of essential oils in this research were made with the application of magnesium sulfate. Rhizosphere microorganisms, which act as biological fertilizers, are applied to assist in the absorption of nutrients. This research aims to determine the interaction between the type of rhizosphere microorganisms and the dose of MgSO4 on growth, essential oil yield and essential oil content in C. nardus. Methods: The research was carried out from February to August 2023. The research used a randomized block design arranged factorially with three replications. The first factor is the type of rhizosphere microorganisms (without RM, PGPR and AMF) and the second factor is the MgSO4 fertilizer dose (0, 190, 285 and 280 kg ha-1). Result: Providing MgSO4 fertilizer can increase the growth and yield of essential oils of C. nardus. The application of PGPR and AMF can increase efficiency of MgSO4 fertilization. Treatment without administering rhizosphere microorganisms required a higher dose of MgSO4 compared to PGPR and AMF treatments. To increase growth variables and essential oil quality, treatment without rhizosphere microorganisms requires MgSO4 of 380 kg ha-1, while PGPR and AMF only require MgSO4 at a dose of 190-285 kg ha-1.