Effect of NaCl Stress on Chlorophyll Biosynthesis, Proline, Lipid Peroxidation and Antioxidative Enzymes in Leaves of Salt-Tolerant and Salt-Sensitive Barley Cultivars

In this research, the salt tolerance of salt-tolerant (Avci-2002) and salt-sensitive (Tokak 157/37) barley cultivars were analyzed. The seedlings were grown in a hydroponic culture containing 0, 100, 200 and 300 mM NaCl. The decrease in dry weight was more significant in Tokak 157/37 than in Avci-2002. On the other hand, no significant correlations were found between the altered delta-aminolevulinic acid dehydratase (ALAD) activity and the chlorophyll content. The chlorophyll and carotenoid contents in leaves of Avci- 2002 decreased significantly at only 300 mM NaCl, whereas the pigment contents of Tokak 157/37 decreased at all NaCl concentrations. The increase in proline content was significantly higher in Avci-2002 than in Tokak 157/37 at 300 mM NaCl. The lipid peroxidation level measured in terms of malondialdehyde (MDA) content was higher in Tokak 157/37 than in Avci-2002. Salt stress caused significant increases in superoxide dismutase (SOD), guaiacol peroxidase (POD), ascorbate peroxidase (APX) and catalase (CAT) activity. However, Avci-2002 had relatively lower SOD and CAT activities and higher POD and APX activities than Tokak 157/37. As a result, dry weight, pigments content, proline content, lipid peroxidation and activities of POD and APX results are in good correlation with supporting Avci-2002 being relatively salt-tolerant.