The vitamin C content increased in our leaves under water limitations of 20–30 days. Drought in PBZ treated-plants showed the highest levels of ascorbic acid when compared to other treatments (Table 3). Ascorbic acid is one of the most extensively studied antioxidants. A high level of endogenous ascorbic acid ensures plant protection from oxidative damage that occurs due to abiotic stresses, such as from drought and salt exposure (Mittler, 2002). In plant cells, the most important reducing substrate for hydrogen peroxide (H2O2) scavenging is ascorbic acid, which is catalyzed by ascorbate peroxidase (Asada, 1999). Ascorbic acid has the ability to neutralize AOS, such as hydroxyl radical (OHradical dot), superoxide radical (O2−), and fatty acid peroxyl radical (LOOradical dot), against oxidative stress (Finaud et al., 2006). From our results, PBZ induces higher levels of endogenous ascorbic acid when the plants were subjected to water-deficit stress. This ability promotes plant tolerance during water stress conditions. This result is in agreement with Sankar et al. (2007) who reported that PBZ increased ascorbic acid content in Arachis hypogaea L. during conditions of water-deficit stress.