Articles
Effects of different light spectra on the performance of lettuce in a closed vertical system
Article number
1391_25
Pages
185 – 190
Language
English
Abstract
Production of leafy vegetable crops in indoor vertical farms allows plant growth regardless of weather conditions with efficient use of resources.
With the introduction of light-emitting diode (LED) technology for plant cultivation, huge attention has been paid to the optimization of the lighting environment indoor.
Light quality influences many vital processes, such as plant growth, morphology, physiology, quality and yield.
In the present study growth and performance of lettuce were investigated in a plant factory system with the nutrient film technique.
To do so, a system was designed with recirculation nutrient flow in a vertical multi-layer.
Since spectral range in the domain of red and blue (RB) light spectra are the primary absorbing spectra of the chlorophyll pigment, different light recopies based on R and B light spectra with different ratios (including RB, 90:10%; RB, 80:20%; RB, 70:30%), together with a light recipe supplemented with far red (Fr) light (RBFR, 3:1:1) and combination of red and white (W) lights (RW, 1:1) were used at fixed intensity of 250±20 μmol m‑2 s‑1 for a duration of 18 h.
Results showed that having more R light in the overall spectrum induces the growth of lettuce plants.
FR light caused the emergence of stem and elongation of lettuce plants.
While more B light, resulted in the production of compact plants.
In conclusion, utilizing both R and B light is recommended for optimal growth, yield, and quality of lettuce.
The RB, 80:20% lighting combination has been determined as the appropriate lighting environment for lettuce cultivation in a plant factory system.
With the introduction of light-emitting diode (LED) technology for plant cultivation, huge attention has been paid to the optimization of the lighting environment indoor.
Light quality influences many vital processes, such as plant growth, morphology, physiology, quality and yield.
In the present study growth and performance of lettuce were investigated in a plant factory system with the nutrient film technique.
To do so, a system was designed with recirculation nutrient flow in a vertical multi-layer.
Since spectral range in the domain of red and blue (RB) light spectra are the primary absorbing spectra of the chlorophyll pigment, different light recopies based on R and B light spectra with different ratios (including RB, 90:10%; RB, 80:20%; RB, 70:30%), together with a light recipe supplemented with far red (Fr) light (RBFR, 3:1:1) and combination of red and white (W) lights (RW, 1:1) were used at fixed intensity of 250±20 μmol m‑2 s‑1 for a duration of 18 h.
Results showed that having more R light in the overall spectrum induces the growth of lettuce plants.
FR light caused the emergence of stem and elongation of lettuce plants.
While more B light, resulted in the production of compact plants.
In conclusion, utilizing both R and B light is recommended for optimal growth, yield, and quality of lettuce.
The RB, 80:20% lighting combination has been determined as the appropriate lighting environment for lettuce cultivation in a plant factory system.
Authors
M. Karimi, M. Roozban, M. Seifikalhor, M. Mohammadian, Z. Mokhtarpour, S. Hasan Mousavi, S. Aliniaeifard
Keywords
controlled environment agriculture, vertical farming, lettuce, light quality
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