Differential effects of salinity and drought on germination and early seedling growth of Parkinsonia praecox

Abstract

Context. Germination and seedling growth are critical stages in the establishment of a species under adverse environmental conditions. Parkinsonia praecox is a species that can establish in soils with high salt concentrations and water deficit conditions. Aims. This study focused on the germination and early growth responses of P. praecox seeds exposed to different salinity and water deficit treatments, to understand its distribution and its potential to persist in stressful environments. Methods. P. praecox seeds were exposed to solutions containing NaCl (for salinity) and polyethylene glycol (PEG; for water deficit) at a range of potentials −0.4, −0.8, −1.2, −1.5 and −1.9 MPa, and germination and early growth responses were evaluated. Controls were exposed to distilled water treatments (0 MPa). Key results. The highest germination was obtained in the distilled water treatment, whereas drought imposed by PEG and salinity caused a decrease in the percentage and speed of germination. Seed germination significantly decreased at 1.2 MPa in the saline treatments but at −0.8 MPa in PEG solutions. However, at −1.2 MPa and higher, the germination rate was higher in PEG-treated seedlings compared to those exposed to NaCl. Considerable early seedling growth was observed in low potentials and high saline conditions. Conclusions. The effects of salinity and drought on germination and early growth response of P. praecox contributes to the species’ restricted distribution in arid and saline regions. Implications. These findings advance our knowledge of P. praecox responses under stressful conditions, highlighting this woody species’ potential as acandidate in the rehabilitation of degraded environments.