Seed germination of the tropical tree <i>Tabebuia roseo-alba</i> (Bignoniaceae) under distinct substrate moisture levels: (Bignoniaceae) under distinct substrate moisture levels:

The substrate moisture level for the germination tests in the Brazilian Seed Testing rules is based on the mass of the paper substrate. For most forest species, the recommended mass of water ranges from 2‐ to 3‐times the mass of the paper substrate. However, few studies have quantified the impact of the substrate water content on seed germination of native trees. Here, we tested the effect of various substrate moisture levels on seed germination and seedling vigour of the tropical tree Tabebuia roseo-alba . The germination and seedling vigour trials were conducted at 30 and 35°C using rolled Germitest ® paper towels under five substrate moisture levels ranging from 2‐ to 3‐times the mass of the substrate. Seeds exhibited rapid and high germination (≥ 90%) in most substrate moisture levels at both tested temperatures. However, germination percentages slightly decreased (to 86%) at moisture levels of 2.8‐ and 3.0‐times the paper mass at 35°C. The seedling length was more significant at a substrate moisture level of 2.5‐times the paper weight at 30°C. Overall, the substrate moisture level had little effect on germination rates; however, the substrate water content of 2.5‐times is most recommended to increase seedling vigour.