Application of mycorrhizae as biological agent to optimize potassium fertilization for enhancing biomass and essential oil yield of citronella (Cymbopogon nardus L.) under shaded conditions

Citronella (Cymbopogon nardus L.) is an economically valuable commodity in Indonesia which is used in perfumes, insect repellents, and for its aromatic properties. The plant could be cultivated with other crops in intercropping to optimize of agricultural land. Intercrops might challenge with citronella for resources, such as water, nutrients and light, potentially affecting citronella growth and yield. The application of mycorrhizae and potassium fertilizer is a strategy to optimize intercropping with citronella. The effect of mycorrhizae application with different potassium fertilizer dosages under 25% shading conditions on the growth and yield of citronella were determined. Split-plot design was employed to arrange the treatments. Mycorrhizae inoculation was expected to not only enhance yields but also improve the efficiency of potassium fertilizer use, contributing to the stability of agroforestry-based agriculture under shaded conditions. The obtained results showed that the application of mycorrhizae together with 40 K2O kg ha^-1 fertilizer increased growth and yield parameters, including leaf number 25.15%, leaf area 3.04%, total fresh biomass 25.06%, and total dry biomass 31.79%. The treatment also elevated essential oil yield by 3.05%, essential oil content 57.16%, and citronellal content 13.12%.