-Seed storage at room temperature is an important and low-cost tool for ex situ conservation. However, the high rates of seed deterioration could reduce the potential for storage in this condition. Therefore, the knowledge of the suitable water content for this type of storage plays a critical role. This study aimed to assess the time required to stabilize the relative humidity (RH) in sealed flasks with saturated salt solutions, with or without the introduction of seeds of Caesalpinia echinata, as well as to assess the viability of these seeds stored in environments with different hygroscopic equilibrium. The results showed that 2 and about 12 days are needed to stabilize the RH, respectively, without or with the seeds. The amount of saturated salt solutions in this airtight environment influences both the speed to equilibrate the RH and the final values of the RH. Seeds of Caesalpinia echinata tolerate drying up to 5% water content (wet basis); however, the viability of these seeds at room temperature is maintained for short periods even at low water content.Index terms: storage, hygroscopic equilibrium, desiccation tolerance.Viabilidade de sementes de pau-brasil (Caesalpinia echinata Lam.) mantidas em temperatura ambiente com atmosferas controladas RESUMO -O armazenamento de sementes em temperatura ambiente é uma importante ferramenta como estratégia de conservação ex situ. No entanto, as altas taxas de deterioração diminuem o potencial de armazenamento. Diante disso, a busca do teor de água ótimo para este tipo de armazenamento assume papel fundamental. Este trabalho teve por objetivo avaliar o período necessário para equilíbrio da umidade relativa do ar (UR) em frascos herméticos a partir da introdução de soluções salinas saturadas e de sementes de Caesalpinia echinata, bem como avaliar a capacidade de manutenção da viabilidade dessas sementes em ambientes com diferentes equilíbrios higroscópicos. Os resultados permitiram verificar que são necessários dois dias para equilíbrio da UR a partir da inclusão de soluções salinas saturadas em ambiente hermético sem a presença de sementes, e cerca de 12 dias com a presença das sementes; que a quantidade de soluções salinas presente no ambiente hermético influencia a velocidade de equilíbrio da UR e o equilíbrio ao final do período e as sementes de Caesalpinia echinata suportam secagem até teores de água de 5% (base úmida), mas mesmo com baixo teor de água estas sementes conservam-se por curtos períodos quando em temperatura ambiente.Termos para indexação: armazenamento, equilíbrio higroscópico, tolerância à dessecação.

The electrical conductivity of leachates from imbibing seeds has been used as a vigor test for several species. The adaptation of this methodology to different species requires knowledge on the leaching kinetics of electrolytes. For Brazilwood seeds, the classic method was not satisfactory and rapid tests are essential because they have low storage capacity at room temperature. Leaching kinetics during seed imbibition is a function of physiological quality, presence or absence of seed coat, imbibing temperature and the initial moisture content of seed. In this study, the electrolyte leaching rate of six different categories of seeds, from two regions, was evaluated in seeds with and without seed coat and incubated with different moisture contents and at different temperatures. The results showed that the electrolyte leaching rate in Brazilwood seeds is independent of the physiological quality, the presence or absence of seed coat and imbibition temperature, but these factors changed the total amount of electrolytes leached. The leaching rate increased in the first few minutes of imbibition, suggesting that the adjustment of the methodology must consider the reduction in imbibition time, reduction in temperature, use of a controlled and slower pre-imbibition, and replacement of the imbibition solution after the first few minutes.