Effect of salinity stress on antioxidant enzymes and chlorophyll content of salt-tolerant and salt-sensitive safflower (Carthamus tinctorius L.) genotypes

The effect of salinity stress on the antioxidant activity of catalase and peroxidase enzymes، relative water content، chlorophyll and carotenoid contents of eight safflower (‍Carthamus tinctorius L.) genotypes differing in salinity tolerance (4 salt tolerant and 4 salt sensitive) were evaluated. This study was conducted using a split plot design arranged as a completely randomized design replicated three times under greenhouse conditions. Salinity treatments were imposed by irrigating with Hoagland solution containing 0، 50، 100، 150 and 200 mM of NaCl in a 30 days period. The results of analysis of variance showed significant effects of genotype، salinity، and genotype × salinity interaction for all the measured traits. Salinity stress led to an increase in chlorophyll and carotenoid contents and peroxidase enzyme activity and a decrease in relative water content and catalase enzyme activity. Salt sensitive genotypes showed less catalase activity under salt treatments. Under salinity stress chlorophyll content of salt tolerant genotypes of safflower was higher than salt sensitive ones. The most salinity tolerant genotype PI-506426 recorded the highest chlorophyll and carotenoid contents under the highest salt stress.