Plant population and row spacing for irrigated and rainfed oilseed sunflowers (Helianthus annuus) on the Darling Downs

Abstract

Effects of plant population and row spacing on the growth and yield of irrigated and rainfed oilseed sunflowers were investigated by means of factorial trials on the heavy clay soils of the Darling Downs, Queensland. General yield and oil levels and treatment responses were determined principally by water availability. Plant population x row spacing interactions were recorded but were considered of no consequence. Responses to population treatments varied in individual experiments, but in general highest oil yields were obtained with populations of 50,000 to 100,000 plants ha-1 in irrigated trials and 40,000 to 60,000 plants ha-1 in rainfed trials. Rows 36 cm wide outyielded 108 cm rows in five out of seven trials. Where paired rows were tested in three rainfed trials, no advantage over evenly-spaced rows was recorded.