Time of planting effects on development, yield and oil quality of irrigated sunflower

Abstract

The effects of time of planting on irrigated sunflower were tested at Emerald during the 1969-70 and 1970-71 summer seasons. Plantings ranged from September to March. A growing degree day summation from a base of 0¦C (GDDo) was the most reliable index of commencement of flowering (cv. 5.7 per cent). Sunfola commenced flowering at 1331 ¦ 76 GDDo. In both seasons significantly higher seed and oil yields were obtained from a December planting (Seed yields 2628 kg ha-1 1969-70, 1808 kg ha-1 1970-71, oil yields 1025 kg ha-1 1969-70, 61 5 kg ha-1 1970-71). Lower yields at all times of planting in the second season were attributed to rust infection (Puccinia helianthi Schw) . A good correlation was obtained between oil quality (proportions of oleic and linoleic acids) and temperatures during the post flowering period. Oleic acid levels ranged from 12 to 48 per cent. Linoleic acid levels ranged from 39 to 73 per cent. Oil quality (per cent linoleic acid) improved with late sowing in association with lowered temperatures