Seed size improves vigor and emergence of Cenostigma tocantinum seedlings

Cenostigma tocantinum is a tree native to Brazil, with high timber and urban landscape potential. This species is propagated by seeds; however, few studies have reported the production of seedlings with higher quality standards. This study aimed to evaluate the emergence and initial growth of C. tocantinum seedlings of contrasting seed sizes (small and large). The design was completely randomized with two treatments [small seed (dimensions of length 1.20 cm; width 1.00 cm; thickness 0.32 cm; and fresh weight 0.18 g) and large seed (dimensions of length 1.52 cm; width 1.35 cm; thickness 0.39 cm; and fresh weight 0.37 g)] and four replicates of 25 seeds each. One hundred seeds from each group were randomly selected for measurements of the length, thickness, width and fresh weight. During the experiment, the following emergence and emergence speed index (ESI) were assessed. After 10 days of sowing, the shoot and root lengths, stem diameter, and shoot and root dry weights were assessed. The results showed that the length, width, thickness, and fresh weight of large seeds were 27, 35, 22, and 106% greater, respectively, than those of the small seeds. Regarding emergence (ranging from 21.8 to 23.8%) and ESI (ranging from 4.4 to 4.8), no significant differences were observed (P > 0.05) between large and small seed sets. More importantly, large seeds favored the development of seedlings with shoot length, root length, collar diameter, shoot dry weight, and root dry weight that were 29, 38, 17, 93, and 109% higher, respectively, than those of small seeds. Thus, C. tocantinum seeds can be stratified into two different sizes (small and large), with large seeds providing the initial growth of more vigorous seedlings (e.g., growth, development, and dry weight). The findings of this study can aid seedling producers in improving their product to meet higher quality standards.