Effect of salt stress on growth, fatty acids and essential oils in safflower (Carthamus tinctorius L.)

This study examined the influence of salt treatment on the growth parameters (fresh and dry weights), the mineral content (K+ and Na+), total lipid contents, fatty acid composition, yields and chemical composition of the essential oil of safflower (Carthamus tinctorius L.) grown in hydroponics for 2 weeks. Results showed that the application of 50 mM NaCl reduced the fresh weight of aerial parts (shoots and leaves) while it enhanced those of the roots. The reduction of dry weight was found to be more pronounced in the aerial parts. Salt treatment increased markedly the concentrations of Na+ in both plant parts while it reduced those of K+ which resulted in a sharp reduction of K+/Na+ ratio. In response to salt treatment, total lipids contents decreased in both plant parts and great qualitative changes in the fatty acids profiles were observed. Whatever the plant parts analysed, a redirection of the lipidic metabolism towards synthesis of unsaturated fatty acids as revealed by the increase of double bond index and linoleic desaturation ratio was pointed out. The increased unsaturation index was found to be more important in roots than in aerial parts. Such treatment also reduced the essential oil yields and induced marked quantitative changes in the chemical composition of the essential oils from both plant parts. Of all the identified components, oxygenated components display a prominent salt-induced synthesis and/or accumulation in both roots and aerial parts.