Iranian Journal of Seed Research

The present study sought to evaluate the effect of different temperatures on germination and to determine cardinal temperatures (i.e., base, optimum and maximum) of Secale mountanum at temperatures of 3, 5, 10, 15, 20, 25, 30 and 35^oC. Three nonlinear regression models (i.e., segmented, dent-like and beta) were used for quantifying the response of germination rate to temperature. The results showed that in addition to germination percentage, the temperature has a significant impact on germination rate. Given the root mean square of errors (RMSE) of germination time, the coefficient of determination (R²), the simple linear regression coefficients a and b, and the relationship between the observed and the predicted germination rates, the best models for determination of cardinal temperatures of Secale mountanum were dent-like and beta models. Base, optimum and maximum temperatures were estimated to be about 2.70 to 3.17, 21.27 to 30.00 and 35.00 to 35.05^°C, respectively for the dent-like model. However, given the high value of SE for temperature base and a negative estimate of the base temperature of the beta model, one can report the dent-like model as the right model. Therefore, by using the dent-like model and the estimated parameters, it is possible to use this model for predicting germination.
 

This study was conducted to evaluate the effects of accelerated aging and natural storage on seed germination and seedling heterotrophic growth of chickpea in Gorgan University of Agricultural Sciences and Natural Resources in 2014. The experiment was carried out, adopting a completely randomized design with four replications. Treatments were 8 aging levels (i.e., 2 years, and 4 years natural storage; 1, 2, 3, 4, 5 days of accelerated aging and a control). The results showed that the effect of aging treatment on all the traits was significant. Reduction of germination percentage, germination rate, root and shoot length seed vigor index and seedling dry weight of 4 and 5 accelerated aging days was higher than 2 and 4 natural storage years. The electrical conductivity of seed lots increased by an increase in accelerated aging to 4 and 5 days, which was higher than 2 and 4 natural storage years. This is due to incapability of a membrane to keep its permeability, which is the result of the higher sensitivity of seeds to accelerated aging. Reduction of the rate and efficiency of reserves used and also dynamic reserves in natural storage was lower than 4 and 5 accelerated aging days. However, maximum rate and efficiency of reserves used and also dynamic reserves were obtained at 2 accelerated aging days. This could be due to increase in repair reaction rates under these conditions and activation of hydrolytic enzymes in seeds. Finally, the results of the present study revealed that damages to chickpea seed at 4 and 5 accelerated aging days are more than 2 and 4 natural storage years, which leads to the reduction of germination percentage and rate.