Germination analysis in different substrates of Tabebuia cassinoides (Lam.) DC. of high restinga forest, Ubatuba, São Paulo, Brazil

Tabebuia cassinoides (Lam.) DC., popularly known as caixeta, is a well-known species for its timber harvesting. The species is dominant in flooded high restinga forest where we collected fruits and seeds from Núcleo Picinguaba, Serra do Mar State Park, Ubatuba, Brazil. The restinga, or sandy coastal forest, is a type of vegetation formed by sandy sediments from marine deposition. Thus, we asked whether the sand substrate would produce better germination indices than germitest paper or vermiculite due to its similarity to specie natural condition. We placed a total of 60 seeds in Gerboxes with duplicates of the three substrates. We placed each Gerbox with ten seeds randomly in the germination chamber at 30 °C, photoperiod of 12 h, and water at proper field capacity. We periodically evaluated the seeds and analyzed the germination percentage (%), germination speed index (GSI), and mean germination time (MGT). Our results showed that sand was the most favorable substrate for germination of caixeta seeds for at least 35 days, corroborating the initial hypothesis. We hope that our results can improve the sustainable management and conservation of the species.