Seasonal changes in the germination responses of seeds of Veronica peregrina during burial, and ecological implications.

Freshly matured seeds were dormant, but they came out of dormancy in June and July and germinated to 98-100% in light in August at thermoperiods of 20:10, 25:15, 30:15, and 35:20oC. Seeds retained the ability to germinate to high percentages at these temperatures until late winter and spring, but they never germinated to high percentages in darkness. Thus, in the natural habitat in July and August germination is prevented only by darkness and/or insufficient soil moisture. At simulated habitat temperatures, seeds germinated to 88-100% in March and April but to only 21-69% in May and June. Seeds incubated at 15:6oC showed a decline in germination percentages in late summer and autumn and an increase during late autumn and winter. The same general pattern of seasonal changes in germination response to temperature occurred during the 2nd year of burial. -from Authors