The germination responses of primed Canola seeds to varying temperatures

Optimal seed germination guarantees the plant durability, establishment and yield. Uniform and rapid germination and emergence of seeds under various environmental conditions play a significant role in achieving suitable yield. Nowadays, there are several ways to improve seed characteristics, and one of the most commonly used ones is seed priming. Priming can increase the percentage, rate and uniformity of seed germination and emergence. These in turn results in the establishment of strong plant especially under environmental stresses and lead to success in production. In addition, knowledge on the physiological responses of primed seeds to different environmental conditions, including temperature stress, can increase the effectiveness of this technique. Therefore in this study, the reaction of primed seeds from canola cultivars to temperature was investigated. The canola cultivars used in this study included DK-xpower, Traper and Hayola50. Hydroperiming and osmopriming were used as the priming treatments. Germination tests in primed and non-primed seeds were carried out at 5, 10, 15, 20, 25, 30, 35, 37 and 40 °C. Then the response of germination rate and germination percentage to temperature were investigated. The seed germination percentages of canola cultivars were different in response to temperature and priming treatments, and each cultivar had a distinct behavior. The effects of priming on germination percentage at low temperatures were significant in Hayola50 and Traper cultivars. Also, priming in all the studied cultivars could increase significantly the germination percentages at high temperatures. Germination rates were also affected by priming treatments and temperature. At each temperature, the germination rates of primed seeds were higher than non-primed ones. In all three canola cultivars, priming reduced the base temperature (from 0.4 to 1.5 °C). The optimum temperature was also strongly affected by priming treatments, especially in the Traper and Hayola50 cultivars. Also, ceiling temperatures in primed seeds increased with respect to control seeds (by about 1 to 5°C). In addition, under various temperatures, hydroperiming was more effective than osmopriming.Finally, priming could reduce the temperature sensitivity of seed germination and increase its tolerance to high temperatures. In general, priming treatments were able to improve seed germination of canola cultivars at different temperatures. Also, priming by either removing the secondary dormancy at low temperatures and /or improved germination under high temperatures was able to improve germination indices at examined temperatures. Finally, priming could reduce the temperature sensitivity of seed germination and increase its tolerance to high temperatures.