Investigations on the Cardinal Temperatures for Germination of Alhaji pseudalhagi

In order to investigate the germination characteristics and cardinal temperatures of biotype Alhaji pseudalhagi، A laboratory experiment was conducted randomized completely design with four replications of 25 seeds. Various constant temperatures 5، 8، 10، 15، 20، 25، 30، 35، 40، 45 and 50ºC were considered. The characteristics such as percentage of seed germination، rate of seed germination، the time of reaching 50% seed germination were recorded. In order to select best estimate of germination criteria based on three regression models namely: Five-parameters Beta (FPB)، Intersected-lines (ISL) and Quadratic Polynomial (QPN) models. The effect of temperature on rate and percentage of germination was significant. The highest germination percentage (GP) was within the range of 20-35ºC while the highest germination rate (GR) occurred in 25ºC. Best model fit over the entire temperature range was obtained by the FPB model. Based on the regression between germination rate and temperature in biotype، the cardinal temperatures (Tbase، Topt and Tmax) were: (7. 2-8. 8)، (27. 5-30. 6) and (42-50. 5) °C، respectively.