Spectral quality modulates the morphophysiology of Sinningia rupicola (Mart.) Wiehler micropropagated seedlings: an endangered species of the Ferruginous Rupestrian Grassland

Abstract The Ferruginous Rupestrian Grassland is a highly biodiverse ecosystem that harbors endemic species vulnerable to anthropogenic activities and climate change, such as Sinningia rupicola , classified as endangered. In vitro cultivation enables large-scale seedling production with high physiological quality. Among the factors influencing the success of the technique, spectral quality stands out, acting on photosynthesis and morphophysiology with species-specific responses. This study evaluated the effects of different spectral qualities on the morphophysiology of Sinningia rupicola seedlings in the multiplication and elongation/rooting stages of in vitro culture. Tissue oxidation, vigor, number and length of shoots, leaf number and area, root formation, photosynthetic pigments, leaf anatomy, and survival in the acclimatization were assessed. LED-R promoted lower vigor in multiplication. LED-B increased leaf area but reduced the number of roots. LED-W increased the number of leaves but reduced photosynthetic pigment levels. In contrast, LED-P resulted in higher pigment contents and secondary roots in 90.9% of the explants, indicating balanced growth. In elongation/rooting, LED-W increased mesophyll thickness but reduced photosynthetic pigment levels. LED-B showed greater leaf area, high stomatal density, and reduced rooting. LED-R promoted shoot length but reduced survival. In contrast, LED-P produced vigorous plants with an efficient photosynthetic apparatus, lower stomatal density, and greater rooting, with 90% survival. Spectral quality modulates the morphophysiological traits of Sinningia rupicola grown in vitro, with LED-P being the most suitable for both multiplication and elongation/rooting, representing a strategy for species conservation through the production of high-quality seedlings.