In general, it is observed that the physic nut seeds from the three lots expressed their maximum germination potential at 25 and 30 oC in sand, where values were greater than those for paper roll (Figure 1). It was also observed that both GRI (Figure 2) and DM (Figure 3) were higher at 25 and 30 ºC also in sand substrate. Similar results were found by Martins et al. (2008). Importantly, there was higher contamination by microorganisms on paper roll than in sand, which explains the higher values of germination in the latter substrate. There is no direct contact between substrate and seedling throughout the test in sand, as opposed to paper roll. Thus, seedlings may be able to avoid microorganisms that can affect their development, resulting in higher germination.