Salinity effects on germination of Portulaca oleracea L.: A multipurpose halophyte from arid rangelands

Salt resistance studies have, unfortunately, mainly been focused on conventional crops, with very few studies being conducted on the potential of available halophytes as new crops in the future. Portulaca oleracea L. has been listed as one of the most used medicinal plants by the World Health Organization as an edible halophyte. It is a fast-growing herbaceous annual with high nutritional relevance. The present work was designed to determine the effect of six soluble salts (NaCl, Na₂SO₄, KCl, CaCl₂, CaCO₃, and MgCl₂) on germination of P. oleracea seeds. The effect of salinity was tested on final germination percentage (FGP%), and germination tolerance index (GTI%) using five concentrations (0, 200, 300, 400, and 600 mM) of each salt. In addition, laboratory experiments were conducted to assess the effects of salinity on germination recovery from high saline conditions (600 mM). Salinity level and salt composition significantly influenced germination attributes. P. oleracea seeds were non-dormant, exhibited approximately 100% germination in distilled water. Both FGP and GTI gradually decreased with increasing salinity. This study showed that seeds of P. oleracea can germinate under 300 mM in all tested salts. The salts causing germination inhibition exhibited specificity, with an increasing trend observed in the following sequence: MgCl₂ > Na₂SO₄ > NaCl > KCl > CaCl₂ > CaCO₃. Transferring ungerminated seeds from 600 mM to distilled water recovered their germination ability. Based on these results, we can conclude that P. oleracea is a high salt-tolerant species that can tolerate a variety of salts found in soil. Therefore, P. oleracea may be considered a promising species for improving ecological balance in saline soils.