Evaluation of growth and phenolic compounds profile of purple lettuce under indoor cultivation

Resumo

The objective of this study was to observe indoor cultivation system with LED lights (white and infrared) to purple lettuce cv. Mimosa in a micro-growing environment for home cultivation. A conventional cultivation with white lamps was used as a Control. The quality of lettuce was evaluated by measuring several parameters, including the number of commercial leaves (intact)/plant, stem diameter, height of the aereal portion, leaf area, absolute growth rate and productivity. Also individual phenolics contents and photosynthesis parameters were evaluated. The results obtained showed that indoor cultivation growing results around 60% higher number of leaves per plant and 4.75 x more leaf area in comparison to Control treatment (28 days after transplant). In addition, productivity and absolute growth rate of purple lettuce were positively affected by indoor cultivation system (a leaf area difference of 300 g.cm^-2 more than the Control). The light intensity provided by the LED’s resulted in increased biomass and yield, mainly due to the elevated photosynthetic activity of plants. At the same time, individual phenolic compounds like chlorogenic acid, caffeic acid, chicoric acid, luteoline-7-o-glucoronide, quercetin-3-malonylglucoside, quercetin acetyl hexoside and cyanidine 3-o-malonylglucoside were identified in purple lettuce cv. Mimosa. Therefore, indoor cultivation system is a viable option to provide the consumer a more natural, practical and healthy food.