Responses of cumin (Cuminum cyminum L.) to different seed priming methods under osmotic stress

A common problem with vegetable production in drought areas is low crop stand, but germination data are limited and inconsistent for cumin. Different priming methods positively affect the enhancement of seed germination and seedlings growth, especially under stress conditions. The objective of this study was to assess the effects of different priming treatment (unprimed seeds as control, hydro-priming, salicylic acid, jasmonic acid, paclobutrazol, and chitosan) on cumin seed germination indices and physiological traits under osmotic stress (0, -5, and -10 bar; induced by polyethylene glycol-6000). Seed germination of cumin was reduced by 9.77% and 23.95% under osmotic potential -5 and -10 bar, respectively, compared with non-stressed conditions. Nevertheless, priming enhanced germination indices and improved photosynthetic pigments and activity of peroxidase, catalase, and superoxide dismutase enzymes at all potential osmotic levels compared with non-primed seeds. Seed treated by jasmonic acid showed the highest seedling vigor index and chlorophyll and carotenoids content under stress and non-stress conditions. Under the high level of osmotic potential (-10 bar), jasmonic acid treatment was caused increasing by 59.3%, 55.19%, 54.26%, 57.52%, and 47.72% of seedling vigor index, total chlorophyll, chlorophyll a, b, and carotenoids content, respectively. In conclusion, the jasmonic acid priming can modify the negative effects of the osmotic stress by improved physiological traits resulting in enhanced germination parameters.