Articles
Agronomic performances of a new vertical rotative growing system: organic lettuce as a case study
Article number
1428_11
Pages
81 – 92
Language
English
Abstract
To meet the growing global demand for vegetables and fruits amid challenges such as climate change, declining arable land, freshwater scarcity, and the need for sustainable food systems, vertical farming has emerged as a promising solution, particularly in urban and peri-urban areas.
These systems offer a sustainable alternative to conventional agriculture by enhancing productivity per unit of cultivated floor area and supporting local food production.
In this study, we evaluated an innovative vertical rotative growing system (VRGS) with LED supplemental lighting in comparison to a conventional horizontal growing system (HGS) illuminated by high-pressure sodium (HPS) lamps.
Organic lettuce was selected as a model crop due to the increasing consumer interest in organic produce in North America and current regulatory provisions allowing soilless organic cultivation.
We also examined the effects of incorporating alfalfa and shrimp meals – rich in triacontanol and chitin, respectively – into a poultry-based organic fertilizer.
Two fertilizer blends were tested: one with 100% poultry-based fertilizer, and another combining 63% poultry, 19% shrimp, and 17% alfalfa meals.
These treatments were evaluated at three nitrogen (N) concentrations (330, 700, and 1000 mg N L‑1) using a split-plot design.
Measurements were taken 28 days after transplanting.
The VRGS outperformed the HGS, with fresh and dry shoot biomass per square meter 1.72 and 4.05 times higher, respectively, despite a 23% lower fresh weight per plant.
However, the number of leaves per plant increased by 21%. In addition, the VRGS improved lettuce quality, lowering water content to 90.8% and reducing total nitrogen content by 26%. No significant effects were observed from the use of shrimp and alfalfa meals on SPAD readings, chlorophyll fluorescence (Fv/Fm, PI), leaf nitrate (NO3–) content, or growth parameters.
Similarly, increasing nitrogen concentration did not significantly affect fresh and dry biomass, plant height, growth index, SPAD value, or photosynthetic performance indicators, although foliar NO3– content increased with higher nitrogen levels.
Yield gains plateaued beyond 330 mg N L‑1. Higher nitrogen concentrations led to a decrease in the pH of the growing medium and increases in electrical conductivity (EC), as well as in NO3– and NH4+ concentrations, but had no effect on microbial activity.
Overall, the VRGS demonstrated strong potential for increasing lettuce productivity per unit of greenhouse floor area, thereby contributing to a reduced carbon footprint.
Under the conditions tested, neither the incorporation of shrimp and alfalfa meals nor the application of nitrogen levels above 330 mg N L‑1 provided significant agronomic benefits.
These systems offer a sustainable alternative to conventional agriculture by enhancing productivity per unit of cultivated floor area and supporting local food production.
In this study, we evaluated an innovative vertical rotative growing system (VRGS) with LED supplemental lighting in comparison to a conventional horizontal growing system (HGS) illuminated by high-pressure sodium (HPS) lamps.
Organic lettuce was selected as a model crop due to the increasing consumer interest in organic produce in North America and current regulatory provisions allowing soilless organic cultivation.
We also examined the effects of incorporating alfalfa and shrimp meals – rich in triacontanol and chitin, respectively – into a poultry-based organic fertilizer.
Two fertilizer blends were tested: one with 100% poultry-based fertilizer, and another combining 63% poultry, 19% shrimp, and 17% alfalfa meals.
These treatments were evaluated at three nitrogen (N) concentrations (330, 700, and 1000 mg N L‑1) using a split-plot design.
Measurements were taken 28 days after transplanting.
The VRGS outperformed the HGS, with fresh and dry shoot biomass per square meter 1.72 and 4.05 times higher, respectively, despite a 23% lower fresh weight per plant.
However, the number of leaves per plant increased by 21%. In addition, the VRGS improved lettuce quality, lowering water content to 90.8% and reducing total nitrogen content by 26%. No significant effects were observed from the use of shrimp and alfalfa meals on SPAD readings, chlorophyll fluorescence (Fv/Fm, PI), leaf nitrate (NO3–) content, or growth parameters.
Similarly, increasing nitrogen concentration did not significantly affect fresh and dry biomass, plant height, growth index, SPAD value, or photosynthetic performance indicators, although foliar NO3– content increased with higher nitrogen levels.
Yield gains plateaued beyond 330 mg N L‑1. Higher nitrogen concentrations led to a decrease in the pH of the growing medium and increases in electrical conductivity (EC), as well as in NO3– and NH4+ concentrations, but had no effect on microbial activity.
Overall, the VRGS demonstrated strong potential for increasing lettuce productivity per unit of greenhouse floor area, thereby contributing to a reduced carbon footprint.
Under the conditions tested, neither the incorporation of shrimp and alfalfa meals nor the application of nitrogen levels above 330 mg N L‑1 provided significant agronomic benefits.
Authors
G. Paquet, T.T.A. Nguyen, A. Brégard, M. Dorais
Keywords
organic fertilisation, controlled environment agriculture (CEA), vertical farming, indoor agriculture, lettuce
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