Memória de hidratação no escuro de sementes: quando o fotoblastismo altera as respostas das sementes à hidratação descontínua para aumentar sua longevidade

Abstract

This study aimed to investigate the influence of light during the discontinuous hydration of Cereus jamacaru DC. subsp. jamacaru seeds and its relationship with the longevity of seeds present in the soil seed bank. We tested two hypotheses: (1) discontinuous hydration promotes the maintenance of seed viability, being represented by an increase in longevity and (2) seeds that go through discontinuous hydration in the presence of light will keep their viability in the bank for a longer time. Seeds were submitted to 0, 1, 2 and 3 hydration/dehydration cycles (HD cycles) in the presence and absence of light. After discontinuous hydration, we created a soil seed bank in an area of Caatinga and the germinative behavior (seedling emergence and T50) and biochemical analyzes (reducing sugars and total soluble proteins concentration) were evaluated at intervals of 0, 3, 6, 9, 12 and 15 months. HD cycles prolonged seed longevity, corroborating the first hypothesis of this study. However, only the treatments of HD cycles in the dark provided the maintenance of the viability of the seeds for a period equal to or greater than nine months, prolonging their longevity. This study proposes the existence of the seed dark hydration memory, which is related to the increase of its longevity in the soil. Thus, the response to light incidence during discontinuous hydration represents an important strategy for the reproductive success of positive photoblastic species in the natural environment, as the studied species.