The effect of reduced rates of fluroxypyr on the seed size and germination of common field speedwell Veronica persica.
In a field experiment fluroxypyr was applied in split plot treatments at 0, 50, 100 and 200 g a.i. ha-1 in a winter wheat crop. Samples of Veronica persica seeds were collected and separated into four size classes. Increasing herbicide rate decreased the percentage of large seeds (> 1 mm diameter) and increased the percentage of small seeds (<0.5-0.71 mm diameter). The percentage in the range 0.71-1mm were unchanged. The increase in small seeds may be due to earlier senescence through moisture loss caused by the herbicide. Rapid desiccation may have prevented the herbicide entering the seeds. In germination tests herbicide dose per se did not affect the percentage of germinating seeds. Differences in germination percentage were seen to be related to seed size.