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

Abstract

In light, fresh seeds of Barbarea vulgaris 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 were buried in pots of soil in mid-July 1983 and 1984 and kept in a greenhouse without temperature controls. Beginning on 1 August, seeds were exhumed monthly for 26.5 (1983 seeds) and 30.5 (1984 seeds) months and tested in light and darkness over the range of thermoperiods. Seeds after-ripened rapidly during the first 2 weeks of burial, and in August they germinated to 65 – 100% at all thermoperiods in light, but to only 0–3% in darkness. Throughout the study, 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; however, they did not germinate while buried.