# The Influence of Elevated Oxygen Input and LED Lighting on the Bioactive Compounds Profile of Lactuca sativa L. cultivars ‘Carmesi’ and ‘Lugano’

## TL;DR

This study shows that using elevated oxygen and LED lighting in hydroponic greenhouses increases antioxidant compounds in lettuce.

## Contribution

The study introduces a novel growth strategy combining elevated oxygen and LED lighting to enhance bioactive compound accumulation in lettuce.

## Key findings

- Lettuce grown with elevated oxygen and LED lighting had up to 48% higher total phenolic content.
- The same treatment increased total flavonoid content by up to 87%.
- EOC+LED showed the highest antioxidant capacity confirmed by DPPH, FRAP, and CUPRAC assays.

## Abstract

Enhancing bioactive compounds with antioxidant activities has always been a pursuit of growers in the hydroponic production of lettuce in greenhouses with artificial lighting. Light-Emitting Diode (LED) lighting represents an effective lighting strategy that promotes the accumulation of bioactive compounds in lettuce by reducing dark periods under unfavorable meteorological conditions and extending the photosynthetic duration. In this study, the accumulation of bioactive compounds and their antioxidant activities, using lettuce-adapted growth technologies such as elevated oxygen concentration and elevated oxygen combined with LED red-blue light, were investigated. These technologies were compared to the control, which consisted of the natural oxygen concentration, in a controlled hydroponic system, for the two lettuce cultivars, Carmesi and Lugano. Our results demonstrate that lettuce grown under elevated oxygen combined with LED lighting exhibited increases of up to 48% in total phenolic content and up to 87% in total flavonoid content, depending on cultivar and growing season, compared to control growth technology. The highest antioxidant capacity was recorded under the EOC+LED growth technology, as confirmed by DPPH, FRAP, and CUPRAC assays. This study proposes an effective growth strategy for hydroponic lettuce cultivation that enhances bioactive compound accumulation and provides theoretical and technical guidance for energy-efficient greenhouse production.