S15 - Session O4 - The agronomic potential of a new vertical growing farming system using biofertilizers and peat-based wood fibre growing medium: lettuce as a case study

Authors: Guillaume Paquet *, Thi Thuy An Nguyen, Annie Bregard, Adam Barrada, Gino Poirier, Martine Dorais

In order to offer a sustainable alternative to current food production models and contribute to urban food security, we studied the agronomic performance of a new and automated rotative growing system using LED lighting. We hypothesized that this vertical rotative growing system provides higher yield per cultivated greenhouse area than a conventional horizontal growing system. We also studied the impact of different organic growing media and biofertilizers for plants cultivated in this system. Using lettuce as a model plant, two growing systems (vertical vs horizontal) were compared, while three growing media (1-peat-based medium, 2- peat mix with wood fibre and 3- peat mix with coco fibre), two organic fertilizations (1- animal-based and 2- vegetal-based) and four biostimulant treatments (spruce vinegar [soil or leaves], bamboo vinegar [soil] and water as control) were tested in three trials of 3 to 13 replicates. Lettuce cultivated in the vertical rotative growing system had a 48% higher dry shoot biomass and 27% more fresh shoot biomass than table-grown plants, explained by a higher leaf number (+35%) and specific leaf area (+26%), while no significant difference was observed for leaf photosynthetic parameters (SPAD index and Fv/Fm ratio). Plant height was 29% higher for table-grown plants. Considering that the cultivated area per unit of greenhouse floor area in the vertical rotative growing system is 2.25 times higher than a horizontal growing system, productivity could be increased by 2.9 to 3.3 times, which confirm our hypothesis. For both systems, animal-based biofertilizers yielded up to 41% more productivity compared with plant-based fertilizers, partly due to a slower and lower mineralization rate. For the studied biostimulants, no significant difference was observed between the treatments . Further trials will be conducted to validate the agronomic performances of this new vertical rotative growing system for other plant species.