Responses of wild Piper species to drought and rehydration cycles considering stomatal closure as a marker of the alarm phase

Studies that simulate recurrent drought events with subsequent episodes of rehydration better reflect natural conditions and allow visualization of differential acclimatization responses resulting from memory and tolerance mechanisms. Piper aduncum and Piper tuberculatum were grown in a greenhouse and were subjected to three successive cycles of drought and subsequent rehydration. After suspending irrigation, gas exchanges were measured daily with IRGA. When stomatal conductances close to zero were obtained, the plants were rehydrated and kept irrigated. In P. tuberculatum, stomatal conductance was always higher after periods of rehydration compared to the period before the drought, while the transpiration rate was lower only during the drought. The damage to the photosynthetic apparatus was caused by the influence of the interception of the flow of electrons in the transport chain. We came to the conclusion that the dehydrated plants showed an alert signal, which triggered response mechanisms to prevent or deal with the water stress situation.