SUNFLOWER OIL YIELD RESPONSES TO PLANT POPULATION AND ROW SPACING: VEGETATIVE AND REPRODUCTIVE PLASTICITY

•Oil yields in the 0.7 m row-spacing treatment increased over the whole of the 2.0-14.3 plants m-2 range of populations explored.•This increase was a reflection of a continuous increase of total crop biomass with increased plant population, together with an unchanging harvest index.•Over the 2-7 plant m-2 range of plant populations shared between 0.7 m and 1.40 m the row-spacing treatments yields did not differ between row spacings.•Vegetative and reproductive plasticities did not vary for the range of plant populations greater than 2.0 plant m-2 in either row spacing