Impact of UV light on poinsettia (Euphorbia pulcherrima) architecture and quality

The variations in plant architecture, which are crucial in ornamental plants, are known to be induced by UV radiation, boosting their economic value. One of the most popular decorative pot plants is the poinsettia (Euphorbia pulcherrima). The goal of this study was to see how varied UV-A exposure times affected poinsettia plant architecture, morphological and physiological parameters. We used three treatments in this study: 2-h under UV-A, 4 h under UV-A and 0 h under UV-A (HPS, control). The plants were grown in pots in a rooftop greenhouse with an 8-h photoperiod. Results showed that the treatment of 4 h UV-A had an influence on plant architecture and increased poinsettia quality. Poinsettia plants cultured under 2 h UV-A and 4 h UV-A were found to have an increased fresh mass, dry mass and chlorophyll content than those plants cultured under HPS without UV-A (control). Plants cultured under 4 h UV-A showed a significant decrease in plant height while a significant increase in relative chlorophyll content. This research will allow for an improved selection of UV-A lighting for quality poinsettia production.