Optimizing salt tolerance in carob plants (<i>Ceratonia siliqua</i> L.) by cultivating in association with the halophyte <i>Spergularia salina</i>

Salinity poses a major challenge to agriculture, underscoring the urgent need to find alternative solutions.Exploiting halophytic plants represents a promising biological adaptation to this challenge.This article presents a comparative study on the effectiveness of the association between Ceratonia siliqua and the halophytic plant Spergularia salina in counteracting the effects of saline stress.The study was conducted in a greenhouse for two months.Carob seeds were scarified and planted at the age of 6 months in pots.Four levels of NaCl concentration were applied: 0 mM/L (non-saline control), 85 mM/L, 171 mM/L, and 257 mM/L.Spergularia salina was co-cultivated with the carob plants at concentrations of 171 mM/L and 257 mM/L.The findings revealed that salt adversely affected the growth of carob plants.Growth reduction was more pronounced at higher concentrations of NaCl (reductions of 19%, 25%, and 56% respectively at salt concentrations of 85 mM/L, 171 mM/L, and 257 mM/L).Growth in the presence of Spergularia salina mitigated the negative consequences of salt stress on the carob.Ceratonia siliqua co-cultivated with Spergularia salina had the highest growth rate, better water content, and improved photosynthesis.Association cultivation showed that carob plants did not exhibit signs of stress in fact, proline, total sugars, and polyphenol concentrations were low compared to plants cultivated without halophytic plants, indicating better adaptation to saline stress.These results highlight the promising potential of association in saline-prone soils, planting carob when halophytic plants are present, particularly with Spergularia salina, this helps agriculture cope with climate change.