This work is part of the exsitu conservation of Ruta montana (L.) L., a spontaneous Rutaceae, known for its many therapeutic properties. The aim is to study, under controlled conditions, the effects of daylight and darkness, temperature, salt, and water stress on the germination of its seeds. Salt stress was induced by different molar concentrations of NaCl (0–200 mM), and water stress was simulated using different concentrations of polyethylene glycol (PEG6000) corresponding to different water potentials (0-1.2 MPa).
The results obtained showed that R. montana seeds were viable and could germinate both in daylight and in continuous darkness. Germination was possible at temperatures between 10 and 30 °C, with the maximum final germination percentage (FGP = 81.66%) recorded at 20 °C. At this optimum temperature, FGP decreased significantly when the seeds were placed under salt and water stress (p< 0.01).This decrease became more and more significant when the osmotic pressure induced by NaCl increased and when the water potential induced by PEG6000 in the medium decreased. The depressive effect of salt and water stress on FGP was verified by a linear regression analysis, which showed high values of the coefficient of determination (R2):0.934 for water stress and 0.890 for salt stress. This effect on the velocity coefficient and latency time was more moderate or lower. The thresholds of tolerance to salinity and water deficit found were 150 mM and −1 MPa, respectively, for which the lowest FGP values were recorded with 16.25% for water stress and 11.10% for salt stress.
