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

<title>Abstract</title> <p> This study evaluated the influence of different spectral light qualities during <italic>in vitro</italic> cultivation on the morphological and physiological development of <italic>Cattleya crispa</italic> L. and the persistence of these effects in <italic>ex vitro</italic> 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 <italic>in vitro</italic> 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 <italic>ex vitro</italic> acclimatization of <italic>Cattleya crispa</italic> , and is recommended for micropropagation and conservation protocols of the species. </p>