The cost and yield are two the most important criteria in agriculture by which optimization of environmental factors are needed to carry out. In the present study, we investigated the efficient lighting spectrum and elevated CO₂ concentration for cultivating healthier plants more rapidly. One of the aims of our study is to optimize LEDs light spectrum for healthier vegetable production in greenhouses and maximum economical benefits for growers. The impact of elevated carbon dioxide (CO₂) concentration on antioxidant and nutritional properties of green leaf ‘Multigreen 3’ and red leaf ‘Multired 4’ baby leaf lettuce (Lactuca sativa L.), grown under optimized light spectrum was investigated. CO₂ concentrations of 0.963 g · dm^-3and 1.938 g · dm^-3 were maintained in the growth chambers. Lettuce was grown under four wavelength (640, 455, 660 and 735 nm) light-emitting diode based (LED) illumination. Under 0.963 g · dm^-3 CO₂ conditions, ‘Multired 4’ lettuce represented higher antioxidant value due to higher ascorbic acid, anthocyanin, tocopherol contents and higher sucrose concentration, as compared to ‘Multigreen 3’ lettuce. Higher CO₂ concentration (1.938 g · dm^-3) had uneven effect on the quality of both baby leaf lettuce cultivars. Red leaf lettuce reacted to the higher CO₂ level by lowered tocopherol, ascorbic acid concentrations and significantly higher glucose contents in their leaves, when green leaf lettuce – contrarily – contained higher ascorbic acid and tocopherol concentrations under 1.938 g · dm^-3 of CO₂.

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