Root system response in Argania spinosa plants under drought stress and recovery.

The argane tree is a remarkable essence by its botanical interest and its socioeconomic value. It is endemic species in the southwest of Morocco, where prolonged drought stress may occur. Although its tolerance has been commonly attributed to various mechanisms at the whole plant, the root system has a main role in the whole process of adaptation. We studied in argane tree plants the change in hydraulic conductivity, electrolyte leakage in root as well as root growth under drought stress and recovery. Our findings showed that the root hydraulic conductivity (Lpr) value significantly decreased under drought stress treatment. This was associated with an increase of root electrolyte leakage, signaling the occurrence of an injury to root cell membranes. At root growth level, stressed plants managed to maintain their root elongation despite decreased root mass. After short period of rehydration, the argane tree plants exhibited a tendency of increased hydraulic conductivity during recovery after drought stress, suggesting that this root physiological response may be intimately linked to drought stress tolerance strategies. These results also could be important to contribute to selection of tolerant genotypes and develop argane tree regeneration programs in regions that suffer from lack of water.