Influence of time of sowing and plant density on the yield and oil content of dryland sunflowers

Abstract

Three experiments were conducted in the Wimmera district of Victoria to determine the agronomic and water use requirements of dryland sunflowers. Using a series of monthly sowings from June to March, any delay in sowing from June until February progressively shortened both the total growing period and the time between sowing and flower initiation. In two further experiments using three times of sowing (mid-September, mid-October and mid-November) with plant densities of 25,000, 50,000, 75,000 and 150,000 plants ha-1, the highest grain and oil yields were obtained from a November sowing and a plant density of 25,000 or 50,000 plants ha-I. The experiments were sown on a friable grey clay which stored up to 500 mm of water in the surface metre at sowing; water use efficiency was low compared with wheat and was in the range 24.2 to 49.2 kg ha-1 cm-1.