Osmotic stress induced by PEG is related to growth form in Piperaceae species, but not to habitat

Water deficit is one of the types of stress to which plants are exposed and which can be assessed using the electrolyte leakage (EL) method to select drought-tolerant genotypes. We aimed to characterize EL in six Piper species under different conditions of water availability, considering the variations concerning habitat and growth form. EL was measured from leaf discs that were put in polyethylene glycol (PEG) solutions with different Psi(w) (-0.6,-1.2,-1.8, and-2.4 MPa). The membrane injury index (MII) and specific leaf area (SLA) were calculated. EL varied among species according to the growth form, but this variation was independent from the habitat. Sub-shrubs showed lower MII in response to PEG-induced water deficit than shrubs and treelets. Also, there was a negative correlation between SLA and MII, indicating that Piper species with lower SLA tend to have a higher EL and, consequently, a higher MII. Here it is shown that the EL method can help to recognize drought-tolerant species in natural environments, helping to understand their sensitivity to climate changes and possible changes in their populations.