The effect of salt stress on growth, chlorophyll content, lipid peroxidation and antioxidative enzymes of pumpkin seedling

Salinity is a major abiotic stress reducing the yield of a wide variety of crops all over the world. In order to investigate the antioxidant enzymes activity of four pumpkin genotypes (Iskenderun-4, AB-44, CU-7 and A-24) in response to salinity grown in hydroponic culture, 4 to 5 true leaf stages of pumpkin seedlings were subjected to 100 mM NaCl for 7 days. Salt stress induced changes in antioxidant enzymes, SOD, CAT, GR and APX, total chlorophyll content, lipid peroxidation and root and shoot fresh weight were measured. Salt treatment decreased root and shoots weight, chlorophyll content in salt sensitive genotypes more than salt tolerant genotypes. The four genotypes showed an increase in malondialdehyde (MDA) content under salt condition, but the increase in sensitive genotypes (CU-7 and A-24) were higher than that in salt tolerant genotypes (Iskenderun-4, AB-44). SOD, CAT, GR and APX activities increased salt stress. However these increases were higher in salt tolerant Iskenderun-4, AB-44 than salt sensitive CU-7 and A-24. These results indicate that pumpkin genotypes respond to salt induced oxidative stress by enzymatic defense systems.