Seed germination of wild mustard (Sinapis arvensis L.): Factors required to break primary dormancy

The regulatory actions of light, temperature, and various nitrogenous compounds on germination of dormant Sinapis arvensis L. seeds were examined to evaluate possible strategies for manipulating germination of soil-bome weed seeds. These treatments, when given singly, had little or no promotive effect on germination. However, KNO3 plus NH4Cl combined with irradiation and a change in temperature to 20 °C after 2 days of incubation at 5 °C induced over 90% germination. The effects of NH2OH∙HCl, KNO2, CS(NH2)2, KCN, and NaN3 were also significantly enhanced when given in combination with a brief exposure to red light and a temperature shift. However, these sources of nitrogen were less effective than KNO3 or NH4Cl in stimulating germination. The promotive effect of light, a temperature shift, and KNO3 and NH4Cl declined when the period of incubation at 5 °C was less than 2 days. This combined treatment was also less effective when the treatment with nitrogen or light was delayed beyond the first 48 h of incubation. Our results indicate that applications of nitrogen fertilizers in combination with surface tillage to expose the seed to light could promote germination of dormant S. arvensis seeds in the field