Planting Date by Variety Interactions
With the exception of oil yield, there were no significant interactions between sunflower planting date and
variety. This suggests that the varieties performed similarly across planting dates. There was an
interaction between planting date and variety for oil yield (see Figure 3). The early season variety ‘306’
had a higher oil yield than ‘7120’ when at the medium and latest (1-June and 7-June) planting dates. The
longer season variety ‘7120’ had higher oil yields when planted on the earliest planting date. We would
expect that the shorter season variety may outperform a later season variety as the planting date becomes
delayed. Likewise we would expect a later season variety to outperform a shorter season variety at earlier
planting dates. Further research needs to be conducted across a broader span of planting dates to confirm
these predictions.