Germination and organic reserves of seeds from common Amazonian floodplain tree species

ABSTRACT Amazonian várzea floodplains (approximately 450,000 km²) are dynamic ecosystems where tree species must adapt to seasonal flooding. In this context, germination patterns and the type and composition of seed reserves (lipids, soluble sugars, proteins) are critical for seedling establishment. This exploratory study examined seed biometry, reserve composition, and germination performance in eight common tree species from high- and low-várzea environments: Guazuma ulmifolia, Hura crepitans, Pseudobombax munguba, Nectandra amazonum, Zygia latifolia, Handroanthus barbatus, Macrolobium acaciifolium, and Crateva tapia, aiming to contribute to the understanding of functional strategies in tropical flooded areas. Considerable interspecific variation in seed size (length: 0.31-38.03 mm; width: 0.40-36.59 mm) and reserve content was found. Hura crepitans and P. munguba had the highest lipid levels, while H. barbatus showed elevated concentrations of soluble sugars and proteins. The highest germination rates were observed in H. barbatus, C. tapia, and P. munguba, whereas Z. latifolia and N. amazonum germinated more slowly. Despite the limited number of species and sites, patterns suggest that low-várzea species invest more in reserves and germinate more slowly, consistent with a resource-conserving strategy for early-establishment. High-várzea species showed less consistent patterns, indicating the need for broader studies. Reserve composition helps explain adaptive germination responses to flooding, evidencing the complexity of these strategies. Our results provide a basis for understanding functional diversity and guide research and restoration actions in these ecosystems.