Carnation ( Dianthus caryophyllus L.) is one of the floriculture industry's most popular, essential cut flowers, and potted plants. Light quantity and quality significantly affect metabolism and plant growth, and they interact with various factors, including environmental characteristics and significant plant behaviors. Correspondingly, red and blue light are essential signals to regulate growth and development, particularly photosynthesis and the activities of various antioxidant enzymes. The study's main objective was to examine the effect of red, blue, and mixed red-blue (RB) LEDs at different 0.5, 3, and 6 min irradiation intervals on plant growth and flowering morphological parameters, flowering quality, and chemical composition as well as to detect the genetic diversity of all treatments' irradiation compared to the control. The results revealed that the carnation irradiated with mixed (RB) irradiation for 3 min indicated the highest plant growth and flowering parameters compared to the control. However, red irradiation for 3 min gave the shortest number of days to early flowering (50 days). The burgundy color in flowers was improved in plants exposed to mixed RB for 0.5 and 3 min. Additionally, the mixed RB irradiation at 3 min treatment gave the maximum NPK uptake and protein, pigments, total phenolic, and flavonoid contents, and enhanced both enzymatic and non-enzymatic antioxidant activity among all treatment groups. Various LED wavelength treatments significantly induce genetic variability at the carnations' phenotypic and genotypic levels, with an average polymorphism level of SRAP molecular markers of 59%. Depending on SRAP and cluster analysis, the mixed RB irradiation for 3 min treatment had the lowest genetic similarity of 0.73 among the control and other treatments' plants. Our findings highlight the promising effect of mixed RB LED in ornamental plant cultivation due to its ability to enhance plant growth, flowering, and other characteristics. • Influences of red, blue, and mixed RB treatments on growth of Carnation were assessed • Mixed (RB) was more effective in morphological and flower quality than red and blue. • Mixed (RB) markedly enhanced bioactive metabolites content than red and blue. • Blue irradiation increased vase life time but decreased growth rate than red. • Mixed RB has the lowest genetic similarity (73%) compared to control.
El-Sayed et al. (Sun,) studied this question.