Synergistic effects of light quality, carbon dioxide and nutrients on metabolite compositions of head lettuce under artificial growth conditions mimicking a plant factory

- High CO2 and nutrient supply enhanced biomass and amino acid levels in lettuce.
- Fourteen amino acids in leaves were increased by irradiation of red LED for a week.
- Irradiation of blue LED reduced biomass and organic acids.
- Combination of red light, high CO2 and nutrients improved amino acids.

Carbon dioxide (CO2), nutrient supply, and light quality are amongst the major controlling factors to improve the biomass production and nutritional outputs in plant factory. The present study employed CE-MS to investigate the effects of high CO2, nutrient formulation, and LED on the accumulation of primary metabolites in head lettuce. Results suggested that high CO2 (1000 ppm) and nutrient supply enhanced both the biomass and some amino acids. Hierarchical clustering analysis was used to evaluate effects of red LED in combination with high CO2 and Hoagland's formulation; distinctive cluster formation contained 14 amino acids (mostly branched-chain and aromatic amino acids, histidine and arginine). Thus, simultaneous treatments of monochromatic LED, high CO2 and nutrient formulation improved the amino acids accumulation, and likely reduced the inorganic nitrogen sources in planta.