Rapeseed seed viability reaction to priming treatments and drying conditions of primed seeds

To investigate the effects of drying methods (desiccation treatment), heat shock and osmotic stress treatments on the viability of primed seeds from different rapeseed cultivars, an experiment was conducted in 2017-2018 at the Seed Research Laboratory of Gorgan University of Agricultural Sciences and Natural Resources. In this study, seeds of three canola cultivars i.e. Dk-xpower, Teraper and Hayola50, which had observed priming treatments, were exposed to desiccation, heat shock and osmotic stress treatments. Thereafter, to investigate the effects of different treatments, the treated seeds were subjected to controlled deterioration test. Finally, after fitting the three-parameter logistic model to germination percentage during controlled deterioration test, time for decrease of germination to 50% was Calculated and used as the criterion for comparing seed viability. Results showed that the response of rapeseed cultivars to different treatments were different. Also, priming methods and different treatments in drying phase of primed seeds, displayed different effects on seeds' lifespan. In general, heat shock treatments were found efficient in Dk-xpower and Traper cultivars as they increased seeds' lifespan. In contrast, osmotic stress treatments often had negative effects on seed viability in all canola cultivars. Even, "osmopriming" and subsequent slow drying of primed seeds had more negative effects than "hydroperiming" associated with fast drying methods.