Physiological and biochemical changes in Periploca angustifolia plants under withholding irrigation and rewatering conditions

Periploca angustifolia (Labill.) is a multipurpose xerophytic shrub widely distributed in arid zones. It is used in rehabilitation programs; its exploitation and utilization require the understanding of its behavior under stress conditions such as drought. To evaluate drought response and at what level it becomes irreversible, a new analysis of physiological and biochemical performances of this threatened shrub was conducted to assess possible mechanisms of drought tolerance and how these relate to its ecological success. Eleven-month-old plants, grown under semi-controlled conditions, were subjected to a well-watered control treatment or progressive drought by withholding water for 7, 14 and 21 d with subsequent recovery for 7-d. After 7 days of drought, followed by rewatering period, no significant effect on all studied parameters was recorded for P. angustifolia. However, from 14 until 21 days of withholding irrigation, drought becomes irreversible causing plant damages, may be rewatering has no effect to reduce these damages. A water deficit of 21 days RWC (33%), chlorophyll a content (0.083 mg·g− 1 DW), transpiration 14.7%, as well as water and osmotic potential (− 3.40 and − 3.78 MPa) decreased significantly compared with control. While, proline content (0.25 μmol·g− 1 FW), soluble sugars (80.52 mmol·g− 1 DW) and vitamins C, E (1.9 mM·g− 1 FW) increased significantly that could indicate ability of osmotic adjustment in this species. Also the increases in RWC, water and osmotic potentials values after rewatering period indicate the good recovery of this plant. Based on these experiments, responses of P. angustifolia to water stress were typical of those of xerophytic plants.