Morphophysiological and biochemical changes induced by sucrose during in vitro germination and post-germinative development of Paubrasilia echinata: an endangered tree species from the Atlantic Forest

Paubrasilia echinata (brazilwood) is an endangered Atlantic Forest species for which information on in vitro germination seedling establishment remains limited. Culture medium composition and sucrose concentration determine nutrient availability and the osmotic potential of the medium, directly influencing seedling establishment and explant quality. This study evaluated the effects of MS (Murashige and Skoog) and WPM (Woody Plant Medium) culture media and different sucrose concentrations on the in vitro germination, morphophysiological and biochemical development of P. echinata seedlings. Both culture media supported high germination rates (≥ 85.83%), indicating predominance of endogenous seed reserves during germination. However, post-germination development at 60 days was markedly influenced by the sucrose concentrations. MS medium supplemented with 0, 10–20 g L⁻¹ sucrose promoted superior seedling development, with greater shoot length (69.34 mm), fresh mass (0.44 g), frequency of seedlings with expanded leaves (85.5%), and higher contents of chlorophyll a (5.83 g kg − 1 ), chlorophyll b (2.65 g kg − 1 ), carotenoids (0.97 g kg − 1 ), and phenolic compounds (88.48 mg g − 1 ), indicating adequate water availability and nutrients and carbon uptake. In contrast, sucrose concentrations above 40 g L⁻¹ increased malondialdehyde content (311.66 nmol g − 1 ), accompanied by stomatal closure and exudation in the epidermal region of the epicotyl, indicating greater oxidative damage and reduce explant quality. Therefore, to obtain suitable explants, the in vitro germination of P. echinata should occur is MS medium supplemented with 0, 10, or 20 g L⁻¹ sucrose.