Seed Science Society of Iran Iranian Journal of Seed Science and Technology 2322-2646 8 1 2019 06 22 Determination of the Cardinal Temperatures and Studying the Effect of Temperature on the Efficiency of Priming on Onion Seed (Allium Cepa cv, Zargan) Determination of the Cardinal Temperatures and Studying the Effect of Temperature on the Efficiency of Priming on Onion Seed (Allium Cepa cv, Zargan) 265 277 119621 10.22034/ijsst.2018.120240.1159 FA M.A. Askari Sarcheshmeh Faculty of Agricultural Sciences and Engineering Z. Moradi Shakoorian Faculty of Agricultural Sciences and Engineering M. Delshad Faculty of Agricultural Sciences and Engineering R. Tavakkol Afshari Professor/ Department of Agronomy, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. Journal Article 2018 01 13 In order to study the effect of priming on onion seed germination of Zangan Cultivar in different temperature conditions, this study was carried out with 6 levels of temperature of 5 to 30 ° C and three seed pretreatment, include control, hydro-priming and halo-priming with 0.5% potassium nitrate with three replicate. The results showed that priming treatment with potassium nitrate (0.5%) could be effective on germination components. Primed seeds with potassium nitrate (0.5%) showed more germination at all temperatures. Potassium nitrate (0.5%) treatment also affected the germination reaction to temperature. These seeds showed 33.6% more germination than the other two treatments at 5°c. The results showed that germination percentage at 20°c in all treatments reaches its maximum and then remained relatively constant. In evaluating the segmented model for predicting cardinal temperatures, seed germination at base, optimum and ceiling temperatures was 1.7, 27.38, 46.09°c(in potassium nitrate (0.5%) treatment), 1, 25, 43°c (in hydro-priming treatment) and 1.9, 27.6, 46.12°c (in control treatment). For predicting time of germination at different constant temperatures used Thermal-time that constant coefficient of Thermal-time was 1872.79(°Ch). In order to study the effect of priming on onion seed germination of Zangan Cultivar in different temperature conditions, this study was carried out with 6 levels of temperature of 5 to 30 ° C and three seed pretreatment, include control, hydro-priming and halo-priming with 0.5% potassium nitrate with three replicate. The results showed that priming treatment with potassium nitrate (0.5%) could be effective on germination components. Primed seeds with potassium nitrate (0.5%) showed more germination at all temperatures. Potassium nitrate (0.5%) treatment also affected the germination reaction to temperature. These seeds showed 33.6% more germination than the other two treatments at 5°c. The results showed that germination percentage at 20°c in all treatments reaches its maximum and then remained relatively constant. In evaluating the segmented model for predicting cardinal temperatures, seed germination at base, optimum and ceiling temperatures was 1.7, 27.38, 46.09°c(in potassium nitrate (0.5%) treatment), 1, 25, 43°c (in hydro-priming treatment) and 1.9, 27.6, 46.12°c (in control treatment). For predicting time of germination at different constant temperatures used Thermal-time that constant coefficient of Thermal-time was 1872.79(°Ch). https://ijsst.areeo.ac.ir/article_119621_91304c851ca7b481327369db5e2ce23c.pdf