Trade-offs between yield, physiological performance, and quality in basil (Ocimum basilicum) cultivated in hydroponic versus conventional soil-based greenhouse system

Controlled Environment Agriculture, specifically high-density vertical farming, offers unprecedented spatial yields but often suffers from a “yield-quality trade-off,” in which accelerated biomass accumulation dilutes secondary metabolites. The primary objective of this study was to evaluate whether optimizing the vertical farm (VF) environment can uncouple rapid growth from quality degradation in sweet basil ( Ocimum basilicum L.). To achieve this, we compared the agronomic, ecophysiological, and nutritional performance of eight commercial cultivars. The experiment was conducted in Switzerland characterized by a continental climate with Mediterranean influences, to compare successive harvests across two setups: an indoor, high-density hydroponic VF system (fully controlled microclimate) and a conventional soil-based greenhouse. VF cultivation accelerated the crop cycle by bypassing prolonged nursery phases, doubling temporal productivity (+106%) without compromising structural dry matter. Ecophysiologically, hydroponic plants adopted a conservative water-use strategy, halving stomatal conductance and apparent transpiration while maintaining photochemical efficiency. This adaptation triggered significant ionomic shifts: rapid carbon assimilation caused a systemic dilution of nitrogen and potassium, while unhindered root bioavailability led to luxury phosphorus uptake and increased foliar calcium despite reduced transpirational pull. Crucially, the VF system successfully broke the traditional yield-quality paradigm, producing basil with enhanced visual greenness and elevated essential oil content. However, these benefits were dictated by Genotype × Environment interactions. Elite cultivars (Adi and Prospera) exhibited high phenotypic plasticity, maximizing biomass and volatile organic compounds, whereas traditional open-field varieties struggled. Ultimately, unlocking vertical farming’s full potential relies on pairing advanced hydroponic engineering with targeted genetic selection.