Night temperature affects fatty acid composition in sunflower oil depending on the hybrid and the phenological stage

Fatty acid composition is affected by plant genotype and environmental conditions with temperature a major effect. The effect of night temperature during different periods of fruit filling on the fatty acid composition of sunflower oil from hybrids with different potential oleic acid content has never been studied. This information is needed if we are further to improve oil quality. A traditional, a mid oleic and two high oleic hybrids were sown in the field on 3 November 1998. The traditional hybrid was also sown again on 22 November 1998. In each experiment, four treatments were applied; a control and three treatments in which night temperature was increased 6.9degreesC at three different consecutive periods of 200 T day after flowering. A third experiment was carried out in growth chambers using the same genotypes as in the previous experiments plus another high oleic hybrid. Three day-night temperatures (16-26, 22-20 and 26-16degreesC) were applied to plants from flowering to physiological maturity. In general, oleic acid percentage was higher with higher night temperature and was not related to daily minimum temperature. The largest variation in oleic acid percentage was observed in the traditional hybrid and the lowest in the high oleic hybrids. Higher oleic acid percentage was associated with an increase in night temperature early during fruit filling. Variation in oleic acid percentage was related to variation in linoleic acid percentage in all experiments. (C) 2002 Elsevier Science B.V. All rights reserved.