Importance of maternal resources in pollen limitation studies with pollinator gradients: A case study with sunflower

Pollen limitation studies are scarce in entomophilous crops, as it can be very tedious to supplement plants with hand pollination at the relevant plant scale. To overcome this, recent studies have used pollinator gradients over several fields to assess whether crops were pollen-limited. But the plant maternal resources and thus the yield potential may vary between fields of the same crop. If these resources are not properly controlled, it may affect the conclusions of the study We investigated the relationship between yield, measured as seed number, seed mass, and seed oil content per head, and pollinator density in sunflower (Helianthus annuus L.) by using a gradient of pollinator densities set both across and within fields. We analysed the yield and the % of yield potential, the latter being assessed with pollen supplementations applied at the whole plant scale. We analysed the data both with and without random effects including year, cultivar, field, and sampling plot. We also compar..., , ,