عنوان مقاله [English]
نویسندگان [English]چکیده [English]
It is very important to find the best model to quantify seed germination rate on the response of temperature which it can be used in determination of cardinal temperatures. This study was conducted to evaluation nonlinear regressions models for description wheat (cv. Morvarid) germination rate response to temperatures and water potentials. Therefore, seeds germination rate were evaluated in temperatures of 5, 10, 15, 20, 25, 30 and 37 oC and water potentials of 0, -0.2, -0.4, -0.6 and -0.8 MPa. Four functions (Dent-like, Segmented, Beta (original) and Beta (Modified)) were evaluated to describe germination rate on the response to temperature and water potentials. The results indicated that the best model was Dent-like. The base, the lower and the upper and the ceiling temperatures were 1.5, 23.8, 33.0 and 41.0 oC in the optimum conditions of water potential. Cardinal temperatures had no significantly change under different water potentials, except for base temperature. Biological time for germination ranged from 34 to 51 h in different water potentials. Biological time increased about 20 h by decreasing 1 MPa. Estimated parameters and the relations can be used to prediction time to germination or emergence in wheat under wide environmental conditions from normal to drought stress.