Germination enhancement, antioxidant enzyme activity, and metabolite changes in late Argania spinosa kernels under salinity

Abstract

In arid and semi-arid environments, soil salinization has a negative impact on agricultural systems and natural vegetation. For the reforestation of low-to medium-salinity soils in Morocco, which borders one of the world's largest deserts, the argan tree (Argania spinosa (L.) Skeels) is essential. Therefore, early and late kernels were used in this study to investigate the effect of various salt levels on germination, antioxidant enzyme activities, and metabolite alterations. In terms of results, the kernels of late fruits had better germination performances under 102.6 mmol/L NaCl salinity. The final germination percentage (FGP) at the last count was at its maximum (54.4%), and the germination speed index (GSI) was significantly high, reaching 12.8 ± 0.8. Proline and sugar metabolites, as well as catalase (CAT) and peroxidase (POX) activities, have increased as salinity increased up to 102.6 mmol/L, followed by a dramatic decrease beyond 136.8 mmol/L, mainly for the early kernels. However, the late kernels have performed better in triggering adjustment pathways before entering their irreversible state. These findings represent another contribution toward comprehending the processes underlying the argan tree's resilience, which is critical to reversing desertification and soil degradation inside and potentially beyond its current biosphere.