Abstract This study aimed to determine the biometric characteristics of seeds of Tabebuia aurea and evaluate the effect of different periods of water immersion on the initial growth of seedlings. For this, the following dimensions were analyzed: length, width, and thickness of seeds with lateral wings and embryo. The moisture content, weight of a thousand seeds, and the number of seeds per kilogram were determined. The seeds were subjected to 11 treatments, as follow: control (no immersion in water; 0 hours) and periods of water immersion for 6, 12, 18, 24, 30, 36, 42, 48, 54, and 60 hours, with four replications of 25 seeds in each treatment. The aerial part and seedling root lengths were analyzed 30 days after sowing. The water content was 9.81% and the weight of a thousand seeds was 130.260 g, corresponding to about 7,677 seeds/kg. The seeds with lateral wings had mean length, width, and thickness of 5.252, 1.226, and 0.147 cm, respectively. For the embryo, these dimensions corresponded to 1.355, 0.805, and 0.103 cm. Regarding the aerial part and root length of T. aurea seedlings, immersion for 48 hours is recommended because this treatment had the best results.

Abstract This study aimed to evaluate the biometric characteristics of seeds of Jatropha mollissima (Pohl) Baill. and Cnidoscolus urens (L.) Arthur from different matrices in the semi-arid region of Brazil. For biometric evaluation, the length, width, and thickness dimensions and mass of 100 seeds of each species. The data were analysed by univariate statistics, corresponding to the position (mean, minimum and maximum values) and dispersion (standard deviation and coefficient of variation) measurements. In addition, histograms were constructed to analyse the frequency distribution pattern of biometric characteristics. J. mollissima seeds had an average length of 1.278 cm, width of 0.823 cm, thickness of 0.697 cm, and mass of 0.2220 g. The low standard error values indicated that the sampling accurately reflects the population. The frequency distribution analysis showed length between 1.240 and 1.321 cm, width between 0.787 and 0.886 cm, thickness intervals from 0.691 to 0.709 and from 0.653 to 0.671 cm, and mass of seeds concentrated between 0.1684 and 0.2477 g. For C. urens seeds, the registered biometric data were: average length of 0.789 cm, width of 0.238 cm, thickness of 0.405 cm, and mass of 0.0248 g. The sampling also accurately reflects the population as low standard error values were obtained. The frequency distribution analysis showed length between 0.768 and 0.835 cm, width between 0.234 and 0.251 cm, thickness from 0.408 and 0.423 cm, and seed mass ranging from 0.0215 to 0.0240 g. Therefore, the information provided contributes to the identification of species, and diagnosis of their genetic variability.