Estimating Cardinal Temperatures and Effect of Different Levels of Temperature on Germination Indices of Redstem Filaree (Erodium cicutarium L.)

In order to study the responses of redstem filaree (Erodium cicutarium L.) seed germination to temperature levels, an experiment was carried out in a completely randomized design with four replications and twelve levels of temperature (0, 3, 5, 7, 10, 12, 15, 20, 25, 30, 35, 40 0C). Results showed that the effect of treatments on germination properties of redstem was significant, so the highest percentage of germination was achieved at 150C and reduced with increasing temperature and was totally inhibited at 40ºC. Based on linear regression between germination rate and temperature, the cardinal temperatures: minimum (Tmin), optimum (To) and maximum (Tmax) were determined: 0, 15.20 and 37.18 ºC, respectively. Significant difference was not observed in plumule length at a range of 5-30°C that showed that it is less sensitive to temperature in comparison with root length. Highest wet dry weight was achieved at 20 °C that was not different by 10, 12 and 20°C. Above results suggest that redstem failure could grow in a wide range of growing conditions, but prefers temperate zones. The results of this study are important to understand thermal requirements and improvement of management strategies of redstem filaree.