Effect of hydroclimatic seasonality on the phenological behavior of <scp> <i>Euterpe oleracea</i> </scp> in the Amazon estuary

Abstract The fruit of Euterpe oleracea provides an energetic and nutritional juice that moves the Brazilian economy. The major obstacle in the production chain of this species is the scarcity of fruit in the off‐season and the lack of knowledge about the environmental or genetic factors that control its production. We collected seeds from two populations of E. oleracea that produce fruits at different times of the year in the Amazon estuary (population 1, west region; population 2, east region) and performed two progeny tests (installed in the west region) to determine the hydroclimatic factors that are related to their production. For 4 years and 1 month, we monitored the reproductive and vegetative phenology of the two progeny populations. Population 1 presented subannual peaks of flowering (nonseasonal) and fruiting (high seasonality), that occurred in the rainy or dry season. Population 2 showed annual and seasonal peaks of flowering (rainy season) and fruiting (dry season). The number of flowering individuals was highly related to the increase in rainfall, river level, and relative humidity for both populations. Fruiting was highly related to the increase in maximum temperature and insolation time. The reproductive phenological patterns of E. oleracea are greatly influenced by the environmental dynamics of the Amazon estuary. This synchronization with the climate and flooding allows multiple reproductive strategies, justifying their dominance in this environment. The two populations present phenological patterns characteristic of their mother palms, showing that the genetic factor is a key aspect in the selection of individuals for off‐season production.