Effects of CO2 concentration, light intensity and nutrient level on growth of leaf lettuce in a plant factory

We determined the environmental factors required for optimal leaf lettuce growth (Lactuca sativa L. var. crispa cv. Grand Rapids) in a plant factory. Plants were allowed to grown under different CO2 concentrations, light intensities and nutrient levels in an environmentally controlled room. Photosynthetic rate increased with CO2 enrichment and light intensity. At 1000 and 2000 mgL(-1) of CO2, growth rate was maximum. Under CO2 enrichment, optimum light intensity was determined to be around 200 mu mol(.)m(-2)s(-2), but nutrient levels did not affect growth rate.