Salinity and drought induced antioxidant responses in different cultivars of safflower (Carthamus tinctorius L.)

Six cultivars of safflower which were (PI-387820, PI-251978, PI-170274, PI-387821, PI-386174 and Thori-78) grown in net house of NIAB under salinity (10 ds m⁻¹) and drought (60% field capacity) conditions and compared to their oxidative damage and antioxidative responses. Plant samples (leaves) were collected for the determination of malonidialdehyde (MDA), antioxidative enzymes (catalase, ascorbate peroxidase, glutathione reductase, and peroxidase), proline, and photosynthetic pigments. Salinity and drought decreased the chlorophyll a and b contents but a decrease in chlorophyll a and b was less in safflower variety (THORI-78) which could be a useful marker for selecting a stress tolerant variety. Both stresses considerable increases the accumulation of proline in PI-251978, PI-170274, PI-387821, PI-386174 and THORI-78 varieties of safflower whereas the proline accumulation did not appear to be an essential part of the protection mechanism against salinity and drought in variety PI-387820. Enzyme activity measurements revealed that THORI-78 can tolerate salinity and drought stress well by increasing the activity of catalase and APX enzymes whereas variety PI- 386174 showed increased activity of glutathione reductase enzyme under salinity and drought and appear to be very crucial antioxidative defenses during intense stress conditions. The results indicate that the photosynthetic pigments, proline and activities of the enzymes are important mechanism for the stress tolerance in safflower plant and can be considered as genetic improvement for the plant in salinity and drought soil conditions.