Quality modulation of essential oils in lemongrass and citronella through Melia dubia Cav.-Cymbopogon agroforestry

Although quantitative data regarding Melia dubia Cav.-Cymbopogon interactions remains limited, silvi-aromatic agroforestry systems are progressively recognized for their ability to enhance land-use efficiency, agricultural income and sustainability by modifying microclimates and regulating secondary metabolism in aromatic crops. This research employed a replicated split-plot design with five replications over three harvests from 2024 to 2025 to evaluate the performance of two M. dubia clones (MTP-1 and MTP-2) intercropped with lemongrass (Cymbopogon citratus) and citronella (Cymbopogon nardus) at the University of Agricultural Sciences, GKVK, Bengaluru, India (13°04′ N; 77°35′ E). We assessed growth parameters, forage output, oil yield and oil content. We employed GC-MS to analyse the composition of the essential oil, utilizing spectral libraries and authentic standards for chemical identification. MTP-1 consistently surpassed MTP-2 in vegetative growth and biomass production during all harvests. At the third harvest, plants cultivated with MTP-1 measured 138.65 cm in height and produced 135.65 tillers. Plants cultivated with MTP-2 attained a height of only 88.15 cm and produced 67.75 tillers. The MTP-1 system produced greater quantities of fresh and dried herbage and oil (44.37 vs. 29.96 kg ha-1), with the MTP-1 and lemongrass combination yielding the maximum oil output (46.36 kg ha-1). The MTP-2 × citronella combination had a higher oil content (2.12 % compared to 1.76 %), indicating a trade-off between biomass accumulation and oil concentration. In citronella oil, shady conditions decreased citronellal while increasing geranyl acetate. The citral (geranial + neral) concentration in lemongrass oil was increased. Agroforestry systems with M. dubia enhance growth and oil yield while altering the composition of essential oils. This renders them beneficial for both the environment and the economy and they can be utilized to achieve market and quality objectives.