Evaluating the potential drought tolerance of pansy through its physiological and biochemical responses to drought and recovery periods

Drought is one of the major factors limiting ornamental plant production. Exposure to long-term drought conditions inhibits plants growth and leads to their yield loss. In this study, various responses of pansy plants to drought stress and recovery period were comparatively studied at physiological and biochemical levels, after one, two and three week period of exposure to drought stress and one week of recovery period. This study results showed that prolonged drought stress dramatically decreased relative water content (RWC), chlorophyll a, b and total chlorophyll and antioxidants including ascorbate peroxidase (APX), superoxide dismutase (SOD) and dehydroascorbate reductase (DHAR) activities of plants while increased the accumulation of proline, sucrose, glucose, and fructose content, hydrogen peroxide (H2O2), malondialdehyde (MDA), and glutathione peroxidase (GPX) activity. Under well-watered condition, plants exhibited an increase in electrolyte leakage after three weeks period of exposure to drought stress, followed by rapid recovery. Under moderate and severe drought stress, plants displayed relatively less adaptability to drought, with a slower recovery after re-watering and a greater increase in electrolyte leakage. This study findings highlighted that enhanced antioxidative protection and osmotic adjustment plays an important role in pansy tolerance against drought. It was concluded that even though plants recovered after re-watering, the final dry matter was affected by drought stress, and its extent was depend on the drought intensity and its duration.