Germination ecology of Veronica arvensis.

A high proportion of the freshly-matured seeds of Veronica arvensis were dormant at maturity in late May. During the summer after-ripening period, the proportion and the rate of germination increased, and the range of temperature at which seeds could germinate widened. Seeds required light for germination, and they germinated equally well at constant and alternating temperatures, but none germinated at 25oC or at the simulated August field temperature regime of 35/20oC. Seeds in an unheated glasshouse on soil kept at field capacity and on soil that was alternately wetted and dried during summer had a low germination; 3 and 1%, respectively, in the 1st summer after planting, and none during the 2nd and 3rd summers. This lack of germination during the summer was probably because the temperature was above that required for germination. By September and October the temperature in the field has fallen sufficiently to allow a high proportion of the seeds to germinate if light and soil moisture are adequate. Seeds that do not germinate during the 1st autumn after dispersal may germinate during the following spring or in some subsequent autumn or spring. -from Authors