Evaluation of non linear regression models to description germination rate of Arugula (Eruca sativa Mill.) to temperature and water potential

This study aimed to evaluate the non-linear regression model (Beta-original, Beta-modified, Segmented and Dent-like Models) to describe the germination rate of Arugula (Eruca sativa Mill.), temperature and water potential factorial a completely randomized design with four replications in Gorgan University of Agricultural Sciences and Natural Resources was performed in 1392. Treatments were temperature to 9 levels (2.5, 5, 10, 15, 20, 25, 30, 35 and 38 ° C) and water potential to 8 levels (0, -0.2, -0.4, -0.6, -0.8, -1.0, -1.2- and -1.4 Mpa). To quantify the response of germination rate to temperature and to determine cardinal temperatures for germination, Beta-original, and Beta-modified, Segmented and Dent-like models were used. The Beta-original model descript germination rate to temperature better than the others. According to this model the base temperature, optimum temperature and ceiling temperatures were 0.0, 30.13 and 38.50 0C respectively in non-stress conditions (zero potential). Changes of water potential had significantly effect on optimum and ceiling temperature but had no significantly effect on base temperature and biological hours.