干旱区生态环境知识资源中心

Discontinuity during the rehydration process of seeds that germinate in arid and semi-arid ecosystems leads to the occurrence of hydration and dehydration cycles (HD cycles). HD cycles play an important role in the persistence and dynamics of plants in these ecosystems. Pilosocereus catingicola subsp. salvadorensis is a cactus that occurs in different ecosystems of northeast Brazil. This species is submitted to different environmental conditions, such as irregularity of soil water availability. This factor directly influences seed production, germination and establishment of new individuals in these ecosystems. The aim of this study was to evaluate the effects of HD cycles on the initial growth of P. catingicola subsp. salvadorensis seedlings from different ecosystems under water-deficit conditions. Seeds collected in two different ecosystems were submitted to 0, 1, 2 and 3 HD cycles and seedlings from these seeds were submitted to water-deficit treatments. HD cycles had effects not only during germination, but also in the initial growth and establishment of seedlings. Seeds from different populations had distinct responses to HD cycles and water-deficit treatments. These effects, as acquisition of a greater tolerance of water deficit, were differentiated between populations of the same species that are established in different ecosystems. The effects of HD cycles interfere directly with seedling recruitment dynamics and the maintenance of these populations.