The quality of LED light alters the biometrics, bioactive compounds, mineral composition, and anatomy of in vitro micropropagated pitaya

Light quality is a crucial environmental factor regulating plant physiology, serving as both an energy source for photosynthesis and a signal for growth and development through photoreceptor activation. This study evaluated biometric, physiological, biochemical, elemental, and anatomical responses of in vitro micropropagated Selenicereus undatus and Hylocereus polyrhizus cladodes grown under different LED light qualities (white, blue, purple, and red) for 65 days on MS medium. Measurements included growth parameters, photosynthetic pigments, bioactive compounds, mineral composition, and anatomical traits. S. undatus showed superior biometric performance compared with H. polyrhizus, particularly in cladode diameter, shoot length, and fresh and dry masses, with notable responses under purple and red light. H. polyrhizus exhibited higher pigment accumulation, especially under white light. Raman spectral profiling revealed that blue light enhanced carotenoid biosynthesis in S. undatus, whereas H. polyrhizus responded more strongly to purple and white light. Elemental analyses indicated potassium as the predominant element in both species; S. undatus accumulated more Mg, P, Cl, and Zn, while H. polyrhizus had higher K, Ca, S, Fe, and Na. Principal component analysis indicated that red light promotes potassium accumulation but may induce osmotic stress, while blue light stimulates redox-related elements. The results demonstrate that species-specific lighting strategies can significantly optimize pitaya micropropagation, with purple or red light recommended for S. undatus and white or blue light for H. polyrhizus.