Investigation of seed germination changes of wild mustard (Sinapis arvensis) during dormancy elimination

In order to investigate the changes in cardinal temperatures of wild mustard seed germination during the dormancy elimination, a split plot experiment was conducted as completely randomized design in three replications in the Seed Research Laboratory of Agricultural and Resource University Natural Gorgan in 2017. The main factor was different temperatures (5, 10, 15, 20, 25 and 30°C) and sub-factor was different concentrations of gibberellic acid (GA: 0, 100, 300, 500, 1000, 1500, 2000 ppm). A dent-like function was used to describe the response of the germination rate to temperature. For different germination stages, the base temperature decreased from 2.9 to 3.4 °C in GA0 towards -1.2 to -2/0 °C in GA2000; the ceiling temperature was 25 °C at GA0 and increased to 33.3 °C in GA2000; the temperature tolerance range from 21.6 to 22.1 °C in GA0 reached 32.4 to 35.1 °C in GA2000. Due to cardinal temperature changes, the dormancy of wild mustard is a non-deep physiological dormancy type 1. Seeds with dormancy initially have the highest germination at low temperatures, and when they come out of dormancy, they germinate at high temperatures and the temperature range of germination increase. The estimated parameters in the present study can be useful in simulation models of seed bank and for further studies on the biology and ecology of wild mustard