Seasonal changes in the germination responses of buried seeds of Barbarea vulgaris

In light, fresh seeds of Barbarea vulgaris (Cruciferae) germinated to 33-62% at 30:15 and 35:20°C; and 0-5% at 15:5, 20:10, and 25:15°C; in darkness, they germinated to 0-5% at all thermoperiods. Seeds after-ripened rapidly during the first 2 wk of burial, and in August they germinated to 65-100% at all thermoperiods in light, but to only 0-3% in darkness. Seeds tested in light at the respective monthly thermoperiod germinated to 83-100% from April to October and to 45-100% in November and March. Thus, seeds brought to the soil surface at any time during the growing season can germinate when soil moisture is nonlimiting. Exhumed seeds germinated to 1-77% in darkness at July and August temperatures (35:20°C) during July and August, but they did not germinate while buried. -from Authors