Seed priming stimulate germination and early seedling growth of Chinese cabbage under drought stress

Abstract

Drought stress influence seed germination and seedling growth of many plants. Seed priming could be used to alleviate the depressive effects of drought stress. The improving effects are influenced by many factors including priming methods, plant species and drought intensity. The mechanisms of drought tolerance induced by seed priming have not been clearly elucidated. The study was carried out to assess whether drought tolerance could be enhanced by seed priming at the germination stage and characterize the potential physiological and biochemical alternation of drought tolerance in Chinese cabbage. The seeds were soaked at 20°C for 8h in distilled water, 200mmol/l potassium nitrate (KNO3), 200mmol/l urea, respectively. Both primed and unprimed seeds germinated under six levels of drought stress (0, −1.0, −2.0, −3.0, −4.0 and −5.0MPa osmotic potential) induced by PEG 6000. Results indicated that germination traits (germination percentage, potential and seedling vigor index) of Chinese cabbage all decreased gradually with increasing drought intensity. Three seed priming types including water, KNO3 and urea all increased germination traits at all levels of drought stress as compared to the unprimed seed. The enhanced drought tolerance conferred by seed priming treatments is associated with the modulating peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) activities and levels of soluble sugar and proline. The results suggested that priming could serve as an appropriate treatment to increase the germination and early seedling growth of Chinese cabbage under drought stress conditions.