Drought Stress Responses of Four Contrasting Provenances of Argania spinosa

The Argane tree (Argania spinosa (L.) Skeels) is an endemic species of Morocco, widely adapted to the arid and semi-arid climate of the southwest. The Argane may serve as an oilseed crop in desert areas threatened by drought and salinity. Its domestication will open up important economic opportunities for Morocco in the face of the growing demand for Argane oil and will help reduce the pressure on the wild Argane forest. In this research, we aimed to study and characterize some physiological and biochemical traits of Argane tolerance to drought stress. We measured physiological parameters related to the water content (foliar water potential and relative water content of the leaves), biochemical parameters involved in osmoregulation (proline and total sugars), and photosynthesis (chlorophylls) in Argane seedlings from four contrasting provenances (Bouizakarne, Agadir, Essaouira and Berkane) cultivated under drought stress induced by cessation of irrigation. The results showed that the basic and minimal foliar water potential, relative water content as well as chlorophyll content significantly decreased in seedlings under severe drought stress compared to control ones, whereas a significant accumulation of proline and total soluble sugars was noted in stressed seedlings. Nonetheless, inter-provenance differences were recorded for some parameters studied. Provenance effect was determinant for variation in drought stress responses of A. spinosa. The study of drought stress-adaptive traits in Argane tree can help to understand the tolerance mechanisms and discriminate between the most drought tolerant provenances in order to rehabilitate degraded Argane forests. It is also relevant for domestication and conservation programs in others abiotic stress conditions resulting from climate change