*Article* **Morpho-Physiological Responses of** *Arabidopsis thaliana* **L. to the LED-Sourced CoeLux® System**

**Peter Beatrice 1,\* , Mattia Terzaghi <sup>2</sup> , Donato Chiatante <sup>1</sup> , Gabriella Stefania Scippa <sup>3</sup> and Antonio Montagnoli <sup>1</sup>**


**Abstract:** The CoeLux® lighting system reproduces the true effect of natural sunlight entering through an opening in the ceiling, with a realistic sun perceived at an infinite distance surrounded by a clear blue sky. It has already been demonstrated that this new lighting system generates long-term positive effects on human beings; however, there are no investigations so far concerning the plant responses to CoeLux® lighting. To fill this gap, the model plant *Arabidopsis thaliana* L. was grown at four different distances from the light source, corresponding to four different light intensities (120, 70, 30, 20 µmol m−<sup>2</sup> s −1 ). High-pressure sodium lamps were used as control light. Plant phenology and morpho-physiological traits were monitored to assess for the first time the ability of plants to grow and develop under the light spectrum and intensity of the CoeLux® system. Plants grown at the lower light intensities showed a delayed life cycle and were significantly smaller than plants grown with more light. Furthermore, plants grown under the CoeLux® light type showed an additional deficit when compared to control plants. Overall, our results show that both the light spectrum and intensity of the CoeLux® system had a strong impact on *A. thaliana* growth performance.

**Keywords:** CoeLux®; LEDs; light intensity; light spectrum; *Arabidopsis thaliana*; photomorphogenesis; growth and development; confined environment; low light
