Changes in seed yield and oil fatty acid composition of high oleic sunflower (Helianthus annuus L.) hybrids in relation to the sowing date and the water regime

Sunflower is one of the most cultivated oil crops in the world. Recently, high oleic acid cultivars have been developed whose oil has higher oxidative stability and better dietary properties than standard genotypes. In Mediterranean environments where water deficit frequently occurs, early sowing and irrigation are used to overcome environmental constraints due to water scarcity. Since, in the literature, the data on the effect of these agronomic techniques on sunflower oil quality are scarce and contrasting, the aim of this paper was to evaluate the effect of the sowing time and the water regime on seed yield and oil quality of high oleic hybrids in a Mediterranean environment. For this purpose, two high oleic hybrids (Platon and Vyp70) sown in spring at two different dates were cultivated in southern Italy under two water regimes (irrigated and non-irrigated) in 1996 and 1997. Yield and its main components were positively affected by irrigation and by the earlier sowing date. With regard to fatty acid composition, a decrease in oleic and stearic acid and an increase in linoleic and palmitic acid were observed under irrigation. At early sowing, oleic and palmitic acid decreased whereas linoleic and stearic acid increased. The decrease in the oleic/linoleic acid ratio observed at early sowing and under irrigation, suggests a possible role of temperature on the activity of oleate desaturase in the developing seeds. (C) 2002 Elsevier Science B.V. All rights reserved.