Abstract
The effect of sowing time on development, yield and oil characteristics of irrigated sunflowers was studied in an experiment at the Irrigation Research Station, Ord Irrigation Area (15.degree. 30''S, 128.degree. 43''E), Western Australia in 1978. Sunflower of cv. Hysun 10, Hysun 30, Sunfola 68-2 and Polestar were sown at monthly intervals between mid-Feb. and mid-Aug. Delay in sowing from Feb. to June increased the period from sowing to physiological maturity by 10 (''Hysun 10'') - 24 days (''Hysun 30''), due mainly to an increase in the period from emergence to visible bud. May sowing of the late maturing hybrid ''Hysun 30'' was the best combination, with a seed yield of 2.3 t[tons]/ha. Oil content and quality (percent linoleic acid) were highest with April sowing, 47.0 and 57.0%, respectively. Sowings from April-July gave acceptable yields (1.8-2.0 t/ha) and oil contents (45-47%). However, oil quality, although responding to sowing date, was always lower than the accepted level of 60% linoleic acid. Seed yields, which were considerably lower than those recorded for irrigated sunflower in southern Australia, are discussed in terms of the environmental limitations of the region.

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