Trials were carried out in two years (1992 and 1993) and two different locations in the centre of Italy (Pisa and Grosseto) and the main objective was to evaluate the influence of four different environmental conditions (Pisa, 1992; Grosseto, 1992; Pisa, 1993 and Grosseto, 1993) and the effects of two different water availabilities (without and with irrigation) on six sunflower hybrids: Ares, Cisa, Granada and Oleica, with high oleic content and Gloriasol and Select, conventional hybrids (high linoleic), used as controls. The experimental scheme adopted was a split-block experimental scheme with 5 replications. The main yield characteristics, seed and oil yield, mechanical hull extraction and oil fatty acid profile were analyzed.

No significant difference in achene yield potential was observed among the hybrids analyzed in all environments, except at Pisa 1993, where, under high temperature during flowering period and limited water availability, the conventional hybrids showed higher yield potential than the high oleic hybrids. The high oleic hybrids showed a significant lower achene oil content than the Select. Of the high oleic hybrids present in the Italian national varieties register an influence of the different environments on fatty acid composition was found only in Ares, which presented an oleic acid content lower and more unstable than the other genotypes, with an elevated range of variability (about 14%) by its oleic content mean (72.3 %) calculated across environments and water managements. This confirms that the genetic control of the high oleic could be different among the genotypes analyzed. Achene mechanical dehullability was affected both by genetic characteristics and environmental conditions.