Determination of Germination Traits and Evaluation of Cardinal Temperatures of Eryngo as an Endemic Leafy Plant (Eryngium caucasicum Tratvu.) by Application of Regression Models

Eryngo (Eryngium caucasicum Tratvu.)is an endemic plant used as a leafy herb that its seed germination behavior has not been well studied. Research on its domestication and propagation can enhance its maintenance and commercialization. Therefore, a laboratory experiment was carried out with eight constant temperatures ranging from 0-35 °C (0, 5, 10, 15, 20, 25, 30 and 35 °C with three replicates in a completely randomized design at Agriculture Faculty, Ferdowsi University of Mashhad, Iran in 2016. Two regression models, including Intersected Lines Model and Quadratic Polynomial Model were applied to germination data to evaluate cardinal temperatures and R2 value was used as criteria for comparison between the models. Results showed that seed germination occurred at temperature of 10-25 °C. Optimum germination uniformity was obtaned at temperature of 10 to 20 °C. The temperature of 15 °C with highst germination percentage (88.33 %), germination energy (92.5 %), time to 90 % germination and germination uniformity (7.17 day) was found as the optimum temperature for seed germination. Quadratic Polynomial Model was found as a better model to evaluate eryngo seed germination. The temperature of 0.85, 15.33 and 29.81 °C were respectively estimated as minimum, optimum and maximum temperatures for eryngo seed germination. It is concluded that the data can be used to predict germination of eryngo response to temperature and management of the plant in agriculture as a new leafy herb.