Effect of drought on growth, photosynthesis and total antioxidant capacity of the saharan plant Oudeneya africana

Abstract Plants in arid and semi-arid regions are often exposed to adverse environmental conditions such as drought which can affect plant growth. In this study, we investigate the physiological responses of Oudneya africana to drought, using two different irrigation regimes (treatment 1: 50 % field capacity; treatment 2: 25 % FC), a 10- and 20-d time course analysis and a 5-d re-watering period following drought. Our results show that water deficiency reduced growth mainly in T2 plants after 20 d of treatment, with a reduction of 26 % in plant height, 64 % in leaf numbers and of 39 % in leaf area, as well as a significant decrease (50 %) in the photosynthesis rate and chlorophyll content. While both instantaneous (A/E) and intrinsic (A/gs) water use efficiency were observed to increase by 96.3 % and 173.20 %, respectively, stomatal closure increased with time and the severity of drought, mainly in the abaxial side (50 %), as evidenced by gs and Ci/Ca data. Polyphenols, flavonoids and total antioxidant capacity increased close to 2−3-fold, with increasing drought stress severity. Re-watering led to a recovery in most of the parameters analyzed, mainly the photosynthetic parameters, while antioxidant capacity remained high. Given these results, the plasticity of photosynthesis and the high antioxidant capacity of O. africana appear to contribute to its tolerance to drought.