Influence of different spectral qualities on the morphology and physiology of Cattleya crispa lindl. (Orchidaceae) during in vitro cultivation and plant acclimatization

This study evaluated the influence of different spectral light qualities during in vitro cultivation on the morphological and physiological development of Cattleya crispa L. and the persistence of these effects in ex vitro acclimatization. To this end, seeds were germinated asymbiotically in ½MS medium and, after 180 days, the seedlings were cultivated under white (400–700 nm), red (660 nm), blue (450 nm) and blue/red combination LEDs (40%/60%; 450 and 665 nm). At 270 days, the plants were transferred to commercial substrate and maintained for 120 days under the same treatments. During in vitro cultivation, white, red and blue/red lights favored greater fresh mass and root development, while isolated blue light showed a restrictive effect. During acclimatization, the blue/red combination promoted greater fresh mass, root length, and shoot size, while red light especially favored the number of roots. Leaves of plants grown under red light showed a lower SPAD index, and white and blue with red lights stimulated greater chlorophyll accumulation and photosynthetic efficiency (Fv/Fm and ETRmax). Carotenoid contents did not differ among treatments, whereas anthocyanins were not detected in the evaluated plants.. It is concluded that the blue/red combination is the most suitable for optimizing growth, vegetative development, and ex vitro acclimatization of Cattleya crispa , and is recommended for micropropagation and conservation protocols of the species.