High temperature enhances the oleic acid content in the oil of normal
cultivars but conflicting results are reported on temperature effects on oleic acid
content in HO cultivars: either no effect or an increase in oleic acid content with
temperature. To investigate the effects of temperature on HO genotypes under
natural field conditions, a three-year field trial was conducted using two sowing
dates and three HO genotypes (two inbred lines and one hybrid). To compare
our results with previous works, growing degree-days (GDD) were computed
(base temperature 1⁄46°C). GDD accumulated during the “flowering – 25 days
after flowering” period influenced fatty acid composition of seed. Oleic and
linoleic acid contents were affected by accumulated GDD in two HO genotypes
(one inbred line and the hybrid). There was an increase of about 3% in oleic acid
content as response to more high GDD accumulated. Their content was not
modified by GDD in the other inbred line. There was a genotype environment
interaction that we suppose depending on modifier genes. These genetic factors
affected oleic acid content. This indicated the importance of breeding targeted to
select hybrids with a stable oleic acid content and higher than 90%. Saturated
fatty acids (palmitic and stearic) were also influenced by temperature, and there
was genetic variability among genotypes.
