Innovative technologies for climate-resilient food production systems: strategies to increase resource use efficiency in a vertical farm with artificial light

Vertical farms (VFs) with artificial light are a typology of indoor urban agriculture systems where all the environmental parameters can be fully controlled. Thanks to the high level of technology adopted in these systems and to the possibility to integrate them within the urban metabolism, VFs have the potential to enhance climate change resilience of crop production. However, in order to maximize resource use efficiency, it is necessary to improve growing conditions according to crops’ need. In this context, the goal of this thesis is the optimization of growing system management and artificial lighting conditions aimed at increasing production and resource use efficiency for lettuce (Lactuca sativa) cultivation in VF. In this work, several cultivation trials were conducted in indoor cultivation systems with LED lights, investigating the variation in morphological, physiological, and biochemical parameters of crops when different growth systems were used or different light conditions were applied (use of pulsed light, variation of spectral conditions, light intensity and photoperiod). The results showed how the use of a high-pressure aeroponic system could increase water use efficiency compared to an ebb and flow system (+114%), and how the water recovery from the growth chamber dehumidifier could reduce water use by 67%, increasing water use efficiency by 206%. The results concerning light management showed the potential of pulsed light in modulating the content of secondary metabolites in leaves and the role of far-red radiation in increasing lighting energy use efficiency compared to a spectrum with only red and blue radiation (increase ranging 29 to 67% depending on the amount of far-red radiation and light intensity provided). Within this work, the effect on lettuce growth, morphology and physiology are discussed within the various chapters to explain the mechanisms leading to a more efficient use of resources in a VF with artificial light.