Effect of water stress and re-watering on relative water content, protective enzyme and photosynthetic characteristics of wild jujube

Seedlings relative water content (RWC), tissue water content, water consumption rate, protective enzyme (SOD, POD and CAT) activity, relative membrane permeability, transpiration rate (Tr), photosynthetic rate (Pn) and stomatal conductance (Gs) were analyzed to study the effects of water stress and re-watering on wild jujube. Four treatments, including one circle (Ⅰ), two circles (Ⅱ) and three circles (Ⅲ) water stress/re-watering treatments, and a normal watering (CK) treatment were designed in the experiment. Based on the results, RWC initially decreased, and then stabilized after re-watering. Generally, RWC increased with increasing water stress/re-watering circle after the third day of re-watering. While water consumption rate was highest on the day of re-watering after water stress, tissue water content was lowest on the second day of re-watering. On the second day after re-watering, protective enzyme activities in wild jujube seedlings increased with increasing water stress/re-watering circle. Relative membrane permeability was higher under treatments with lower protective enzyme activity, indicating serious damage of seedling cell membranes. Wild jujube seedling Tr, Pn and Gs after one water stress/re-watering circle were lowest on the day of re-watering. The experiment further showed that wild jujube seedlings became drought resistant after several water stress/re-watering circles. After two or three water stress/re-watering circles, transpiration and photosynthesis in wild jujube seedlings were recovered and drought damage was decreased.